TCM E806-2 Wheel Loader Technical Manual SEW-603-MAE - PDF DOWNLOAD

INTRODUCTION To Readers of This Manual This manual provides service staff who have completed basic training with technical information necessary for service activity. For obtaining satisfaction and trust from customers, you are expected to read through this manual and acquire correct product knowledge and service technique.

To obtain customers satisfaction and credit, please read the full contents of this manual to learn and master proper knowledge and service techniques on the products, before you perform any service activity.

Reference Material This manual does not, in principle, describe basic items and overlapped areas with other materials (below) to eliminate redundancy. ・ For basic items, refer to training materials such as "Sales and Technical Material."

・ For handling and inspection procedures, refer to "Instruction Manual." ・ For structure and component parts, refer to "Parts Catalog." ・ For handling, maintenance procedure and parts of the engine, refer to materials issued by the engine manufacturer.

Organization ・ This manual is organized into four parts: 1. General Instructions 2. Construction and Function 3.

Oveahaul 4. Troubleshooting ・General Instructions： Safety during maintenance work and general cautionary instructions are compiled. ・ Construction and Function ： An explanation of the construction and function and an explanation of operation (function) by illustrations, circuit diagrams and system diagrams are compiled.

・Troubleshooting：Probable causes and corrections for troubles are compiled. ・ Oveahaul ： Methods of removing hydraulic equipment from a vehicle, its disassembly and reassembly, its adjusting method, standard values used for service work and service limits are compiled.

INTRODUCTION Symbols and notation ・

CAUTION ： indicates potential hazards or unsafe practices that MAY result in minor or medium injury in a box.

・ IMPORTANT ： indicates important items maintenance in a box.

for

operation

・

NOTE ： indicates informative items such as technical information and know-how in a box.

and

Indication of Unit ・ n this manual, unit indication of quantity and unit is mainly based on SI (International System) unit system (right table).

Example : 24.5 MPa (250 kgf/cm2, 3560 psi)

Example of main unit conversion SI unit (Conventional unit) Pressure 1 Mpa （10.197 kgf/c㎡） Force

1 N

（0.10197 kgf）

Torque

1 N・m （0.10197 kgf・m）

Power

1 kw

（1.360 PS）

SAFETY RECOGNIZE SAFETY INFORMATION ・This is the SAFETY ALERT SYMBOL. ・When you see this symbol on your machine or in this manual, be alert to the potential for personal injury. ・Follow recommended precautions and safe operating practices.

UNDERSTAND SIGNAL WORDS ・On machine safety signs, signal words designating the degree or level of hazard DANGER, WARNING, or CAUTION - are used with the safety alert symbol.

DANGER： indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.

WARNING：indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.

CAUTION： indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury. ・DANGER or WARNING safety signs are located near specific hazards. General precautions are listed on CAUTION safety signs. ・Some safety signs don t use any of the designated signal words above after the safety alert symbol are occasionally used on this machine. ・CAUTION also calls attention to safety messages in this manual.

・To avoid confusing machine protection with personal safety messages, a signal word IMPORTANT indicates a situation which, if not avoided, could result in damage to the machine. ・

NOTE indicates an additional explanation for an element of information.

Ｓ‑4

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SAFETY FOLLOW SAFETY INSTRUCTIONS Carefully read and follow all safety signs on the machine and all safety messages in this manual. ・Safety signs should be installed, maintained and replaced when necessary. ・If a safety sign or this manual is damaged or missing, order a replacement from your authorized dealer in the same way you order other replacement parts (be sure to state machine model and serial number when ordering). ・Learn how to operate the machine and its controls correctly and safely. ・Allow only trained, qualified, authorized personnel to operate the machine ・Keep your machine in proper working condition. ・Unauthorized modifications of the machine may impair its function and/or safety and affect machine life. ・The safety messages in this SAFETY chapter are intended to illustrate basic safety procedures of machines. However it is impossible for these safety messages to cover every hazardous situation you may encounter.

If you have any questions, you should first consult your supervisor and/or your authorized dealer before operating or performing maintenance work on the machine.

PREPARE FOR EMERGENCIES ・Be prepared if a fire starts or if an accident occurs. ・Keep a first aid kit and fire extinguisher on hand. ・Thoroughly read and understand the label attached on the fire extinguisher to use it properly. ・To ensure that a fire-extinguisher can be always used when necessary, check and service the fire-extinguisher at the recommended intervals as speci-fied in the fire-extinguisher manual. ・Establish emergency procedure guidelines to cope with fires and accidents. ・Keep emergency numbers for doctors, ambulance service, hospital, and fire department posted near your telephone.

Ｓ‑5

SAFETY WEAR PROTECTIVE CLOTHING ・Wear close fitting clothing and safety equipment appro-priate to the job. ・You may need: A hard hat Safety shoes Safety glasses, goggles, or face shield Heavy gloves Hearing protection Reflective clothing Wet weather gear Respirator or filter mask. ・Be sure to wear the correct equipment and clothing for the job. Do not take any chances. ・Avoid wearing loose clothing, jewelry, or other items that can catch on control levers or other parts of the machine. ・Operating equipment safely requires the full attention of the operator. Do not wear radio or music headphones while operating the machine.

PROTECT AGAINST NOISE ・Prolonged exposure to loud noise can cause impairment or loss of hearing. ・Wear a suitable hearing protective device such as earmuffs or earplugs to protect against objectionable or uncomfortably loud noises.

Ｓ‑6

SAFETY USE HANDHOLDS AND STEPS ・Falling is one of the major causes of personal injury. ・When you get on and off the machine, always face the machine and maintain a three-point contact with the steps and handrails. ・Do not use any controls as hand-holds. ・Never jump on or off the machine. Never mount or dismount a moving machine.

・Be careful of slippery conditions on platforms, steps, and handrails when leaving the machine.

ADJUST THE OPERATOR'S SEAT ・A poorly adjusted seat for either the operator or for the work at hand may quickly fatigue the operator leading to misoperations. ・The seat should be adjusted whenever changing the operator for the machine. ・The operator should be able to fully depress the pedals and to correctly operate the control levers with his back against the seat back. ・If not, move the seat forward or backward, and check again.

Ｓ‑7

SAFETY FASTEN YOUR SEAT BELT ・If the machine should overturn, the operator may become injured and/or thrown from the cab.

Additionally the operator may be crushed by the overturning machine, re-sulting in serious injury or death. ・Prior to operating the machine, thoroughly examine webbing, buckle and attaching hardware. If any item is damaged or worn, replace the seat belt or component before operating the machine. ・Be sure to remain seated with the seat belt securely fastened at all times when the machine is in operation to minimize the chance of injury from an accident. ・We recommend that the seat belt be replaced every three years regardless of its apparent condition.

MOVE AND OPERATE MACHINE SAFELY ・Bystanders can be run over. ・Take extra care not to run over bystanders.

Confirm the location of bystanders before moving, swinging, or operating the machine. ・Always keep the travel alarm and horn in working con-dition (if equipped). It warns people when the machine starts to move. ・Use a signal person when moving, swinging, or op-erating the machine in congested areas.

Coordinate hand signals before starting the machine. ・Do not allow personnel and obstacles to enter the operation area of machine. ・Use appropriate lighting.

Ｓ‑8

SAFETY OPERATE ONLY FROM OPERATOR'S SEAT ・Inappropriate engine starting procedures may cause the machine to runaway, possibly resulting in serious injury or death. ・Start the engine only when seated in the operator's seat. ・NEVER start the engine while standing on the track or on ground.

・Do not start engine by shorting across starter terminals. ・Before starting the engine, confirm that all control levers are in neutral.

$#66'4;

JUMP STARTING ・Battery gas can explode, resulting in serious injury. ・If the engine must be jump started, be sure to follow the instructions shown in the OPERATING THE ENGINE chapter in the operator s manual. ・The operator must be in the operator s seat so that the machine will be under control when the

engine starts. Jump starting is a two-person operation. ・Never use a frozen battery. ・Failure to follow correct jump starting procedures could result in a battery explosion or a runaway machine.

KEEP RIDERS OFF MACHINE ・Riders on machine are subject to injury such as being struck by foreign objects and being thrown off the ma-chine. ・Riders also obstruct the operator s view, resulting in the machine being operated in an unsafe manner. ・Only the operator should be on the machine.

Keep rid-ers off. ・A person other than operator must sit on the second seat with the seatbelt fastened, if the machine has a second seat.

Ｓ‑9

SAFETY PROVIDE SIGNALS FOR JOBS INVOLVING MULTIPLE NUMBERS OF MACHINES ・For jobs involving multiple machines, death or serious injury may be caused by clashing the machines each other. ・For jobs involving multiple numbers of machines, provide signals commonly known by all personnel involved. Also, appoint a signal person to coordinate the job site. Make sure that all personnel obey the signal person s directions.

TRAVEL SAFELY ・Beware of the possibility of slipping and/or turning over the machine when traveling on a slope. ・When traveling on level ground, hold the bucket at mark (A) 400 to 500 mm above the ground as illus-trated. ・Avoid traveling over any obstacles. ・Drive the machine slowly when traveling on rough terrain. ・Avoid quick direction changes. Failure to do so may cause the machine to turn over. ・If the engine stops while traveling, the steering function becomes inoperative. Immediately stop the machine by applying the bake to prevent personal accident.

Ｓ‑10

SAFETY AVOID INJURY FROM ROLLAWAY ACCIDENTS ・Death or serious injury may result if you attempt to mount or stop a moving machine. ・To avoid rollaways: ・Select level ground when possible to park machine. ・Do not park the machine on a grade. ・Lower the bucket to the ground. ・Place the F-N-R lever in neutral, and put the park brake switch in the ON (parking brake) position.

・Run the engine at slow idle speed without load for 5 minutes to cool down the engine. ・Stop the engine and remove the key from the key switch. ・Pull the lock lever to LOCK position. ・Block both tires and lower the bucket to the ground. ・Position the machine to prevent rolling. ・Park a reasonable machines.

distance

from

other

Ｓ‑11

SAFETY AVOID ACCIDENTS FROM BACKING UP AND TURNING ・Make sure no one is working under or close to the machine before backing up or turning the machine to avoid personal injury and/or death by being run over or entangled in the machine. ・Keep all personnel away from the machine by sounding the horn and/or using hand signals.

Use extra care to be sure no one is in from the articulation area before turning the machine. ・Keep windows, mirrors, and lights in good condition.

・Reduce travel speed when dust, heavy rain, fog, etc., reduce the visibility. ・In case good visibility is not obtained, use a signal per-son to guide you.

Ｓ‑12

SAFETY AVOID TIPPING ・Do not attemp to jump clear of tipping machine_serious or fatal crushing injuries will result. ・Machine will tip over farter than you can jump free. ・Fasten your seatbelt.

・The danger of tipping is always present when operating on a grade, possibly resulting in serious injury or death. ・Do not turn the machine suddenly. ・Prepare machine operating area flat. ・Keep the bucket low to the ground and close to the machine. ・Reduce swing speed as necessary when swinging loads. ・Do not apply a load more than the capacity of the machine.

・Be careful when working on frozen ground. ・Temperature increases will cause the ground to be-come soft and make ground travel unstable. ・Keep sufficient distance from the road shoulder

AVOID POWER LINES ・Serious injury or death can result from contact with electric lines. ・Never move any part of the machine or load closer to any electric line than 3 m (10 ft) plus twice the line insulator length.

Ｓ‑13

SAFETY OBJECT HANDLING ・If a lifted load should fall, any person nearby may be struck by the falling load or may be crushed underneath it, resulting in serious injury or death. ・When using the machine for craning operations, be sure to comply with all local regulations. ・Hoisting mechanism (crane) and its safety system are not equipped with this product.

PROTECT AGAINST FLYING DEBRIS ・If flying debris hit eyes or any other part of the body, seri-ous injury may result. ・Guard against injury from flying pieces of metal or debris; wear goggles or safety glasses. ・Keep bystanders away from the working area before striking any object.

Ｓ‑14

SAFETY PARK MACHINE SAFE ・To avoid accidents: ・Park machine on a firm, level surface. ・Lower bucket to the ground. ・Place the F-N-R lever in neutral, and put the park brake switch in the ON (parking brake) position.

・Run engine at slow idle speed without load for 5 min-utes. ・Turn key switch to OFF to stop engine. ・Remove the key from the key switch. ・Lower the lock lever to the LOCK position. ・Close windows, roof vent, and cab door. ・Lock all access doors and compartments.

HANDLE FLUIDS SAFELY − AVOID FIRES ・Handle fuel with care; it is highly flammable. If fuel ignites, an explosion and/or a fire may occur, possibly resulting in serious injury or death. ・Do not refuel the machine while smoking or when near open flame or sparks. ・Always stop the engine before refueling the machine. ・Fill the fuel tank outdoors. ・All fuels, most lubricants, and some coolants are flam-mable. ・Store flammable fluids well away from fire hazards. ・Do not incinerate or puncture pressurized containers. ・Do not store oily rags; they can ignite and burn sponta-neously. ・Securely tighten the fuel and oil filler cap.

Ｓ‑15

SAFETY TRANSPORT SAFELY ・Take care the machine may turn over when loading or unloading the machine onto or off of a truck or trailer. ・Observe the related regulations and rules for safe transportation. ・Select an appropriate truck or trailer for the machine to be transported. ・Be sure to use a signal person.

・Always follow the following precautions for loading or unloading: 1. Select solid and level ground.

2. Always use a ramp or deck strong enough to support the machine weight.

3. Use the low speed gear.

4. Never steer the machine while on the ramp.

If the traveling direction must be changed while the ramp, unload the machine from the ramp, reposition the ma-chine on the ground, then try loading again.

5. After loading, install the lock bar to securely hold the articulation mechanism.

6. Wedge the front and rear of tires. Securely hold the machine to the truck or trailer deck with wire ropes. ・Be sure to further follow the details described in the TRANSPORTING section.

Ｓ‑16

SAFETY PRACTICE SAFE MAINTENANCE ・Understand service procedures before starting work. ・Keep the work area clean and dry. ・Do not spray water or steam inside cab. ・Never lubricate or service the machine while it is mov-ing. ・Keep hands, feet and clothing away from power-driven parts.

・Before servicing the machine: 1. Park the machine on a level surface.

2. Lower the bucket to the ground.

3. Turn the auto-idle switch off.

4. Run the engine at slow idle speed without load for 5 minutes.

5. Turn the key switch to OFF to stop engine.

6. Relieve the pressure in the hydraulic system by mov-ing the control levers several times.

7. Remove the key from the switch.

8. Attach a "Do Not Operate" tag on the control lever.

9. Lower the lock lever to the LOCK position.

10. Lock bar connects the front and rear frames.

11. Allow the engine to cool.

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・If a maintenance procedure must be performed with the engine running, do not leave machine unattended.

・Never work under a machine raised by the lift arm. ・Inspect certain parts periodically and repair or replace as necessary. Refer to the section discussing that part in the "MAINTENANCE" chapter of this manual.

Ｓ‑17

SAFETY ・Keep all parts in good condition and properly installed. ・Fix damage immediately. Replace worn or broken parts. Remove any buildup of grease, oil, or debris. ・When cleaning parts, always use nonflammable detergent oil. Never use highly flammable oil such as fuel oil and gasoline to clean parts or surfaces. ・Disconnect battery ground cable ( − ) before making adjustments to electrical systems or before performing welding on the machine. ・Sufficiently illuminate the work site. Use a maintenance work light when working under or inside the machine. ・Always use a work light protected with a guard.

In case the light bulb is broken, spilled fuel, oil, antifreeze fluid, or window washer fluid may catch fire.

WARN OTHERS OF SERVICE WORK ・Unexpected machine movement can cause serious injury. ・Before performing any work on the machine, attach a "Do Not Operate" tag on the control lever. ・This tag is available from your authorized dealer.

Ｓ‑18

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SAFETY SUPPORT MACHINE PROPERLY ・Never attempt to work on the machine without securing the machine first. ・Always lower the attachment to the ground before you work on the machine. ・If you must work on a lifted machine or attachment, securely support the machine or attachment. Do not support the machine on cinder blocks, hollow tires, or props that may crumble under continuous load. Do not work under a machine that is supported solely by a jack.

STAY CLEAR OF MOVING PARTS ・Entanglement in moving parts can cause serious injury. ・To prevent accidents, care should be taken to ensure that hands, feet, clothing, jewelry and hair do not become entangled when working around rotating parts.

SUPPORT MAINTENANCE PROPERLY ・Explosive separation of a tire and rim parts can cause serious injury or death. ・Do not attempt to mount a tire unless you have the proper equipment and experience to perform the job. Have it done by your authorized dealer or a qualified repair service. ・Always maintain the correct tire pressure. DO NOT inflate tire above the recommended pressure. ・When inflating tires, use a chip-on chuck and exten-sion hose long enough to allow you to stand to one side and not in front of or over the tire assembly. Use a safety cage it available. ・Inspect tires and wheels daily. Do not operate with low pressure, cuts bubbles, damaged rims, or missing lug bolts and nuts. ・Never cut or weld on an inflated tire or rim assembly. Heat from welding could cause an increase in pressure and may result in tire explosion.

Ｓ‑19

SAFETY STORE ATTACHMENTS SAFELY ・Stored attachments such as buckets, hydraulic hammers, and blades can fall and cause serious injury or death. ・Securely store attachments and implements to prevent falling. Keep children and bystanders away from storage areas.

Use tools appropriate for the work to be done. ・Makeshift tools and procedures can create safety hazards. ・For loosening and tightening nuts and bolts, use correct size tools. ・Otherwise, tightening tools may slip, potentially causing personal injury.

PREVENT BURNS Hot spraying fluids: ・After operation, engine coolant is hot and under pressure. Hot water or steam is contained in the engine, radiator and heater lines. ・Skin contact with escaping hot water or steam can cause severe burns.

・To avoid possible injury from hot spraying water. DO NOT remove the radiator cap until the engine is cool. When opening, turn the cap slowly to the stop. Allow all pressure to be released before removing the cap. ・The hydraulic oil tank is pressurized. Again, be sure to release all pressure before removing the cap.

Ｓ‑20

SAFETY Hot fluids and surfaces: ・Engine oil, gear oil and hydraulic oil also become hot during operation. ・The engine, hoses, lines and other parts become hot as well. ・Wait for the oil and components to cool before starting any maintenance or inspection work.

REPLACE RUBBER HOSES PERIODICALLY ・Rubber hoses that contain flammable fluids under pres-sure may break due to aging, fatigue, and abrasion. It is very difficult to gauge the extent of deterioration due to aging, fatigue, and abrasion of rubber hoses by inspec-tion alone. ・Periodically replace the rubber hoses. (See the page of "Periodic replacement of parts" in the operator's man-ual.) ・Failure to periodically replace rubber hoses may cause a fire, fluid injection into skin, or the front attachment to fall on a person nearby, which may result in severe burns, gangrene, or otherwise serious injury or death.

AVOID HIGH-PRESSURE FLUIDS ・Fluids such as diesel fuel or hydraulic oil under pressure can penetrate the skin or eyes causing serious injury, blindness or death. ・Avoid this hazard by relieving pressure before discon-necting hydraulic or other lines. ・Tighten all connections before applying pressure. ・Search for leaks with a piece of cardboard; take care to protect hands and body from highpressure fluids. Wear a face shield or goggles for eye protection. ・If an accident occurs, see a doctor familiar with this ty-pe of injury immediately. Any fluid injected into the skin must be surgically removed within a few hours or gan-grene may result.

Ｓ‑21

SAFETY PREVENT FIRES Check for Oil Leaks: ・Fuel, hydraulic oil and lubricant leaks can lead to fires. ・Check for oil leaks due to missing or loose clamps, kinked hoses, lines or hoses that rub against each other, damage to the oil-cooler, and loose oil-cooler flange bolts.

・Tighten, repair or replace any missing, loose or dam-aged clamps, lines, hoses, oil-cooler and oil-cooler flange bolts. ・Do not bend or strike high-pressure lines. ・Never install bent or damaged lines, pipes, or hoses.

Check for Shorts: ・Short circuits can cause fires. ・Clean and tighten all electrical connections. ・Check before each shift or after eight(8) to ten(10) hours operation for loose, kinked, hardened or frayed electrical cables and wires. ・Check before each shift or after eight(8) to ten(10) hours operation for loose, kinked, hardened or frayed electrical cables and wires. ・Check before each shift or after eight(8) to ten(10) hours operation for missing or damaged terminal caps. ・DO NOT OPERATE MACHINE if cable or wires are loose, kinked, etc..

Ｓ‑22

SAFETY Clean up Flammables ・Spilled fuel and oil, and trash, grease, debris, accumulated coal dust, and other flammables may cause fires. ・Prevent fires by inspecting and cleaning the machine daily and by removing spilled or accumulated flammables immediately. ・Do not place flammable fluid near an open flame. ・Do not attempt to burn or push a pressurized container. ・Do not leave rags dampen with oil. They may be burnt.

Check Heat Shields ・Damaged or missing heat shields may lead to fires. ・Damaged or missing heat shields must be repaired or replaced before operating the machine.

Check Key Switch ・If a fire breaks out, failure to stop the engine will escalate the fire, hampering fire fighting. ・Always check key switch function before operating the machine every day: 1) Start the engine and run it at slow idle.

2) Turn the key switch to the OFF position to confirm that the engine stops. ・If any abnormalities are found, be sure to repair them before operating the machine.

Ｓ‑23

SAFETY EVACUATING IN CASE OF FIRE ・If a fire breaks out, evacuate the machine in the following way: ・Stop the engine by turning the key switch to the OFF position if there is time. ・Use a fire extinguisher if there is time.

・Exit the machine.

BEWARE OF EXHAUST FUMES ・Prevent asphyxiation. Engine exhaust fumes can cause sickness or death. ・If you must operate in a building, be sure there is ade-quate ventilation. Either use an exhaust pipe exten-sion to remove the exhaust fumes or open doors and windows to bring enough outside air into the area.

Ｓ‑24

SAFETY PRECAUTIONS GRINDING

FOR

WELDING

AND

・Welding may generate gas and/or small fires. ・Be sure to perform welding in a well ventilated and prepared area. Store flammable objects in a safe place before starting welding. ・Only qualified personnel should perform welding. Nev-er allow an unqualified person to perform welding. ・Grinding on the machine may create fire hazards.

Store flammable objects in a safe place before starting grind-ing. ・After finishing welding and grinding, recheck that there are no abnormalities such as the area surrounding the welded area still smoldering.

AVOID HEATING FLUID LINES

NEAR

PRESSURIZED

・Flammable spray can be generated by heating near pressurized fluid lines, resulting in severe burns to yourself and bystanders. ・Do not heat by welding, soldering, or using a torch near pressurized fluid lines or other flammable materials. ・Pressurized lines can be accidentally cut when heat goes beyond the immediate flame area.

Install temporary fire-resistant guards to protect hoses or other materials before engaging in welding, soldering, etc..

AVOID APPLYING HEAT TO LINES CONTAINING FLAMMABLE FLUIDS ・Do not weld or flame cut pipes or tubes that contain flammable fluids. ・Clean them thoroughly with nonflammable solvent before welding or flame cutting them.

Ｓ‑25

)#51.+0'

SAFETY REMOVE HEATING

PAINT

BEFORE

WELDING

OR

・Hazardous fumes can be generated when paint is heated by welding, soldering, or using a torch. If inhaled, these fumes may cause sickness. ・Avoid potentially toxic fumes and dust. ・Do all such work outside or in a well-ventilated area. Dispose of paint and solvent properly. ・Remove paint before welding or heating: 1)If you sand or grind paint, avoid breathing the dust.

2)Wear an approved respirator.

3)If you use solvent or paint stripper, remove stripper with soap and water before welding.

Remove solvent or paint stripper containers and other flammable ma-terial from area.

Allow fumes to disperse at least 15 minutes before welding or heating.

PREVENT BATTERY EXPLOSIONS ・Battery gas can explode. ・Keep sparks, lighted matches, and flame away from the top of battery. ・Never check battery charge by placing a metal object across the posts. Use a voltmeter or hydrometer. ・Do not charge a frozen battery; it may explode.

Warm the battery to 16 °C ( 60 °F ) first. ・Do not continue to use or charge the battery when electrolyte level is lower than specified.

Explosion of the battery may result. ・Loose terminals may produce sparks. Securely tighten all terminals. ・Battery electrolyte is poisonous. If the battery should ex-plode, battery electrolyte may be splashed into eyes, possibly resulting in blindness. ・Be sure to wear eye protection when checking electro-lyte specific gravity.

Ｓ‑26

SAFETY SERVICE AIR CONDITIONING SYSTEM SAFELY ・If spilled onto skin, refrigerant may cause a cold contact burn. ・Refer to the freon container for proper use when servicing the air conditioning system. ・Use a recovery and recycling system to avoid venting freon into the atmosphere. ・Never let the freon stream make contact with the skin.

HANDLE CHEMICAL PRODUCTS SAFELY ・Direct exposure to hazardous chemicals can cause seri-ous injury. Potentially hazardous chemicals used with your machine include such items as lubricants, coolants, paints, and adhesives. ・A Material Safety Data Sheet (MSDS) provides specific details on chemical products: physical and health haz-ards, safety procedures, and emergency response techniques. ・Check the MSDS before you start any job using a haz-ardous chemical. That way you will know exactly what the risks are and how to do the job safely. Then follow procedures and use recommended equipment. ・See your authorized dealer for MSDS's (available only in English) on chemical products used with your ma-chine.

Ｓ‑27

SAFETY DISPOSE OF WASTE PROPERLY

recycling cen-ter, or from your authorized dealer.

・Improperly disposing of waste can threaten the environ-ment and ecology. Potentially harmful waste used with HITACHI equipment includes such items as oil, fuel, coolant, brake fluid, filters, and batteries. ・Use leakproof containers when draining fluids.

Do not use food or beverage containers that may mislead someone into drinking from them. ・Do not pour waste onto the ground, down a drain, or into any water source. ・Air conditioning refrigerants escaping into the air can damage the Earth's atmosphere.

Government regula-tions may require a certified air conditioning service center to recover and recycle used air conditioning refrigerants. ・Inquire on the proper way to recycle or dispose of waste from your local environmental or

CHECKS AFTER MAINTENANCE ・Checks must be carried out for proper machine operation after maintenance. ・All parts must be checked/maintained as they are in a good condition. ・Any part with safety concerns must be checked in a certain manner. ・All worn/damaged parts must be repaired/ replaced.

Ｓ‑28

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SECTION AND CONTENTS

GROUP

SECTION 1 GENERAL

Specification Component Layout SECTION 2 SYSTEM

Hydraulic SYSTEM Electrical SYSTEM TECHNICAL MANUAL T R O U B L E S H O O T I N G

SECTION 3 COMPONENT OPERATION

HST PUMP HST MOTOR CONTROL VALVE REDUCTION・AXLE POWER STEERING OTHERS SECTION

4

OPERATIONAL PERFORMANCE TEST

INTRODUCTION ENGINE TEST WHEEL LOADER TEST COMPONENT TEST STANDARD SECTION 5 TROUBLESHOOTING

DIAGNOSING PROCEDURE FAILURES ENGINE SYSTEM PERFORMANCE OTHERS

(Blank)

SECTION 1

GENERAL − CONTENTS − Specification Specifications.............................................1-31 Engin Accesso.ries.....................................1-32 HST Pump...............................................1-33

Component Layout Main Component Location........................1-34 Engin..........................................................1-35 Electrical Component Location 1................1-36 Electrical Component Location 2................1-37 Electrical Component Location 3................1-38 HST Pump................................................1-39 Reduction Gear.........................................1-40

(Blank)

GENERAL ／ Specification SPECIFICATION E806‑2 3

0.78

Canopy

lb

8090

Cab

lb

―

lb

2120

Bucket Capacity (with BOC) Empty

Loader

Weight

yd

Operating Weight Engine

KUBOTA

D1503‑M‑DI‑T‑E2B‑WLHF‑6

40.6HP/2800min‑1 41.2PS/2800rpm A： Overall

Length

in

186.8

in

66.5

ROPS Canopy

in

103.5

Cab

in

―

D： Wheel Base

in

74.8

E： Tread

in

49.6

F： Ground Clearance

in

11.6

G： Dumping Clearance

in

98.4

H： Dumping Reach

in

36.0

B： Overall Width

(Width

C： Overall Height

Over

Bucket)

R1： Turning Radius

Center of Outside Wheel

in

126.8

R2： Turning Radius

Bucket Outside Edge

in

154.3

Travel Speed

Forward/Reverse

mph

10.2/10.2

Transmission Speeds

Forward/Reverse

―

2/2

％(degree）

30

degree

41

―

15.5/60‑18‑8PR

Max. Grade of Hill Climb Articulation Angle Tire Size

q *

$

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GENERAL ／ Specification ENGINE Item

Unit Engine Model

Description KUBOTA D1503-M-DI-T-E2B-WLHF-6 4-cycle Diesel, water cooled/with Turbo charger

Type Number of Cylinders - Bore x Stroke

in

3-3.27Ｘ3.64

Total Displacement

gal

0.4

Type of Combustion Chamber

Re-entrant Type (Direct Injection)

Rated Output / Rated Speed

ｋｗ（ＰＳ）／ｒｐｍ

30.3(41.2)±5％／2800±25

High Idle Speed/Low Idle Speed

ｒｐｍ

3000±50／1050 0〜＋50

Max. Torque / Engine Speed

Ｎ・ｍ（ｋｇf・ｍ）／ｒｐｍ

122.6（12.5）±5%／1700〜1900

Injection Order

1-2-3

Rotating Direction

Counterclockwise (Viewed from Flywheel)

Injection Nozzle Type

P Nozzle

Injection Pump Type

PFR3K Type Pump (Posh 3K Type Mini Pump)

Injection Pressure

Ｍｐａ（ｋｇｆ／c㎡）

First：18.6 MPa (190 kgf/cm2) Second：22.6 MPa (230 kgf/cm2)

Injection Timing

TC-6.0°〜-7.5°(-7.0〜-8.5°p）

Compression Ratio

20.5

Fuel Required Fuel Consumption

Diesel Oil ｇ／ｋｗ・ｈ（ｇ／ｐｓ・ｈ）

263(194)±10%

Cooling System

Pressurized Radiator Type (with Coolant Pump, Forced Circulation)

Lubricating System

Forced Lubrication with Trochoid Pump

Lubricant Required

Grade CD or higher, 10W-30

Lubricant Capacity

gal

1.5

Coolant Capacity

gal

0.4(Only Engine)

Air Cleaner

Cyclone Type, Paper Filter

Regulator

IC Type (with Built-in Alternator)

Dimensions of Engine (L x W x H)

in

23.58.x 20.24.x 25.31

Dry Weight

lb

375

Starting System

Starter Motor Type (with glow plugs)

Starter Motor

Ｖ−ｋｗ

12-1.4

Alternator

Ｖ−ｋｗ

12-0.48

Battery

Ｖ−Ａｈ

12-52(Warm Location) 12-64(Cold Location)

１ ‑32

GENERAL ／ Specification ＨＳＴ PUMP（YUKEN ／ Serial No. 1001 〜 4499） MODEL

PVK２５FRAU１２３９S１００７

PUMP TYPE

Variable-displacement axial piston pump

Drive System

Engine crankshaft direct connection

Delivery

０〜２７．５ ｒｅｖ

Max Pressure to be used

４２ Ｍｐａ

Low pressure relief valve set

３８．２ Ｍｐａ

Control devlce

ＡＵ Control

Weight

３９．３ ｋｇ

Charging pump

Gear Pump

ＨＳＴ PUMP （UCHIDA ／ Serial No. 4501 〜） MODEL

Ａ４ＶＧ２８DA

PUMP TYPE

Variable-displacement axial piston pump

Drive System

Engine crankshaft direct connection

Delivery

０〜２８ ｒｅｖ

High pressure relief valve

３８．５ Ｍｐａ

Low pressure relief valve

２．５ Ｍｐａ

Control devlce

DA Control

Weight

３６ ｋｇ

Charging pump

Gear Pump

１ ‑33

GENERAL / Component Layout MAIN COMPONENT LOCATION

1-Bucket 2-Bucket Link 3-Bell Crank 4-Bucket Cylinder 5-Control Valve 6-Hydraulic Oil Tank 7-Oil Filter 8-HST Filter 9-Brake Reserve Tank 10-Monitor Panel

11-Steering Wheel 12-Loader Control Lever 13-Awning 14-HST Pump 15-Operator's Seat 16-Battery 17-Radiator 18-Engine 19-Oil Cooler 20-Air Cleaner

21-Coolant Reserve Tank 22-Water Separater 23-Fuel Filter 24-Fuel Pump 25-Muffler 26-Rear Axle 27-Rear Propeller Shaft 28-Reduction 29-Solenoid Valve 30-Fuel Tank

１ ‑34

31-HST Motor 32-Master Cylinder 33-Orbitrol 34-Steering Cylinder 35-Lift Arm Cylinder 36-Front Propeller Shaft 37-Wheel 38-Front Axle 39-Lift Arm

GENERAL / Component Layout ENGINE

1-Water temperature gauge sending unit 2-Alternator 3-Starter motor 4-Engine oil pressure switch 5-Engine stop solenoid 6-Glow plugs

１ ‑35

GENERAL / Component Layout ELECTRICAL COMPONENT LOCATION 1

1-Horn 2-Headlamp 3-Combination Lamp 4-Fuse Box 5-Combination Lamp Switch 6-Shift Lever 7-Battery 8-Back Buzzer 9-Reverse Light

10-Combination Lamp 11-Fuel Pump 12-Fuel Sending unit 13-Solenoid Valve 14-Bucket Positioner Proximity Switch

１ ‑36

GENERAL / Component Layout ELECTRICAL COMPONENT LOCATION 2

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1-Monitor Panel 2-Travel mode selector switch 3-Starter Switch 4-Parking Brake Switch 5-Starter Relay 6-Glow relay 7-Slow blow fuse 65A 8-Battery relay 9-Glow timer 10-Flasher unit 11-Relay 4 (Parking brake)

12-Relay 1 (Monitor light check) 13-Relay 2 (Monitor light check) 14-Relay 3 (Parking brake) 15-Brake lamp switch 16-Solenoid valve (forward) 17-Water temperature gauge sending unit 18-Air cleaner indicator 19-Solenoid valve (back) 20-1st-speed fixing solenoid

１ ‑37

GENERAL / Component Layout ELECTRICAL COMPONENT LOCATION 3

1-Turn signal indicator pilot lLight 2-Air cleaner warning light 3-Alternator (Charging) warning light 4-Drive mode indicator light 5-Engine oil pressure warning light 6-Engine pre-heat pilot light 7-Turn signal indicator pilot lLight 8-Brake oil level warning light 9-Hour meter

10-Fuel level gauge 11-Engine water temperature gauge 12-Parking brake pilot light

１ ‑38

GENERAL / Component Layout HST PUMP （YUKEN Serial No. 1001 〜 4499）

1-Main pump 2-Charging pump 3-Inching valve ASSY 4-Solenoid valve [Y] for Forward 5-Solenoid valve [Z] for Reverse

6-High pressure relief valve 7-Low pressure relief valve

HST PUMP （UCHIDA Ser-al No. 4501 〜）

1-Main pump 2-Charging pump 3-Solenoid valve [A] for Forward 4-Solenoid valve [B] for Reverse 5-High pressure relief valve

6-Low pressure relief valve 7-DA valve

１ ‑39

GENERAL / Component Layout REDUCTION

1-Reduction Gear Case 2-Bolt 3-Cover 4-Bleeder 5-Plug

6-Flange 7-Plug 8-Plug 9-Plug 10-HST Motor

１ ‑40

SECTION 2 SYSTEM − CONTENTS − Fuel System Outline........................................................2-42 Water separator..........................................2-43 Fuel filter....................................................2-43

Hydraulic System Outline........................................................2-44 HST Circuit ................................................2-46 HST oil filter................................................2-50 Brake Circuit...............................................2-51 Steering Circuit...........................................2-53 Hydraulic Circuit.........................................2-56

Electrical System Outline........................................................2-59 Main Circuit.................................................2-61 Pre-heating Circuit......................................2-62 Charging Circuit..........................................2-64 Start and Stop Circuit..................................2-65 Monitor Lamp Circuit..................................2-66 Gauge Circuit..............................................2-67 Traveling System Circuit.............................2-68 Light Circuit.................................................2-75 Horn Circuit.................................................2-76 Auto-leveler Circuit.....................................2-76

(Blank)

S Y S T E M ／ Fuel System OUTLINE The Fuel system consists of the Fuel tank, fuel filter, water separator filter, and fuel piping.

・Ｆuel Ｔank The fuel tank is located at the left side of the rear frame and the fuel hoses (feed and return) are connected to the engine.Also, the fuel sender unit is installed on the fuel tank and the fuel tank level is indicated on the fuel gauge on the meter panel. ・Fuel Piping Fuel oil is sucked up from the fuel tank ① by the fuel pump ③ and through the water separator ② .The fuel is discharged from the fuel pump ③ is filtered by the fuel filter ④ and send to the injection pump ⑤ .The injection pump ⑤ increases the fuel pressure and distributes the fuel to the injection nozzle ⑥ of each cylinder through which the fuel is injected into the cylinder. The surplus fuel in injection nozzle ⑥ returns to the fuel tank through return hose ⑦ .If the air enters in the fuel piping, the starter switch is turned on, the air can be bled through the return circuit. (Automatic air bleeding system).

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２ ‑42

1-Fuel tank 2-Water separator 3-Fuel pump 4-Fuel filter 5-Injection pump 6-Injection nozzle

S Y S T E M ／ Fuel System ・Water Separator Filter The water separator filter separates water in the fuel. However, if it is used for a long time, foreign substances, etc may cause clogging.

Clean it periodically.

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S Y S T E M ／ Hydraulic System

OUTLINE（YUKEN Serial No. 1001 〜 4499）

The hydraulic system consists of the steering circuit, hydraulic circuit, HST circuit, and brake circuit. ＜ Hydraulic Circuit ＞

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S Y S T E M ／ Hydraulic System

OUTLINE（UCHIDA Serial No. 4501 〜）

The hydraulic system consists of the steering circuit, hydraulic circuit, HST circuit, and brake circuit. ＜ Hydraulic Circuit ＞

S Y S T E M ／ Hydraulic System ＨＳＴ Circuit（ Serial No. 1001 〜 4499） ・The HST piping is divided roughly as: suction circuit (A), charging pump circuit (B), HST high-pressure circuit (C), pilot pressure circuit (D) and lubrication/cooling/return circuit (E).The casing of the HST pump ① and HST motor ④ are filled with oil discharged from the charging pump ② .The oil cools each part and flows to the oil cooler ⑥ . The oil is cooled by the oil cooler ⑥ and returns to the oil tank ⑤ .In the main body, the first speed fixing solenoid valve ⑦ is connected to the inching valve ⑧ using the hydraulic hose in the system pressure control pilot circuit.

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㧮 㧯 1-HST pump 2-Charging pump 3-HST oil filter 4-HST motor

5-Oil tank 6-Radiator (Oil cooler)

２ ‑46

S Y S T E M ／ Hydraulic System ＨＳＴ Circuit（Serial No. 4501 〜） ・The HST piping is divided roughly as: suction circuit (A), charging pump circuit (B), HST high-pressure circuit (C), pilot pressure circuit (D) and lubrication/cooling/return circuit (E).The casing of the HST pump ① and HST motor ④ are filled with oil discharged from the charging pump ②. The oil cools each part and flows to the oil cooler ⑥ . The oil is cooled by the oil cooler ⑥ and returns to the oil tank ⑤ .In the main body, the first speed fixing solenoid valve ⑦ is connected to the inching valve ⑧ using the hydraulic hose in the system pressure control pilot circuit.

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㧮 1-HST Pump 2-Charging pump 3-HST Oil Filter 4-HST Motor 5-Oil Tank

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㧰 6-Radiator AS (Oil Cooler) 7-Middle speed fixing solenoid valve 8-Inching valve

２ ‑47

S Y S T E M ／ Hydraulic System ＨＳＴ Circuit（ Serial No. 1001 〜 4499）

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① High-pressure relief valve ② Low-pressure relief valve ③ Main pump discharge rate ④ Charging pump discharge rate

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Charging Pump ・The tandem gear pump which consists of the main pump and the charging pump. It is installed to the HST pump and turns together with the engine.The charging pump supplies oil to the HST highpressure closed circuit and automotive control circuit, and it sends oil to the parking brake for releasing. The oil discharged from the charging pump is sent to the inching valve assembly through the HST oil filter.

２ ‑48

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S Y S T E M ／ Hydraulic System HST Oil Filter ・The oil from the charging pump flows into the case ④ through the inlet port and it is filtered by the element ① . Then the oil flowing out of the outlet port goes to the inching valve assembly.When the element ① is clogged, the pressure at the inlet rises and the difference in pressure between the inlet and outlet becomes 0.34MPa or over, the by-pass valve (1) opens and the oil flows from the inlet to the outlet without flowing through the element ① .

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２ ‑50

S Y S T E M ／ Hydraulic System Brake Circuit（ Serial No. 1001 〜 4499） ・Service brake The service brake uses wet disk brake equipped to the input shaft in the reduction gear box. This hydraulic brake system consists of the brake pedal (1), brake fluid reservoir (2), master cylinder (3) and piping.This master cylinder (3) is a single type and the brake hydraulic line is single circuit system. ・Inching mechanism The brake pedal (1) is linked with the HST pump (inching valve) by the inching link. When either right or left pedal (1) is depressed, the machine is stopped, using the wet disk brake after the inching function (HST brake function) is performed by the operation of the inching lever.

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1-Brake Pedal 2-Brake Oil Tank 3-Master Cylinder 4-Brake Lamp Switch

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２ ‑51

S Y S T E M ／ Hydraulic System Brake Circuit（Serial No. 4501 〜） ・Service brake The service brake uses wet disk brake equipped to the input shaft in the reduction gear box. This hydraulic brake system consists of the brake pedal (1), brake fluid reservoir (2), master cylinder (3) and piping.This master cylinder (3) is a single type and the brake hydraulic line is single circuit system. ・Inching mechanism The inching valve lever is coupled to the brake pedal by a link.When the brake pedal ① is pressed (either left or right) the reduction gear box builtin type wet disk brake stops the vehicle after the operation of the HST pump inching mechanism (HST brake function).

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1-Brake Pedal 2-Brake Oil Tank 3-Master Cylinder 4-Brake Lamp Switch 5-Brake oil level switch

6-Brake oil level warning lamp 7-Bleeder (For Air Bleeding) 8-Inching valve 9-Reduction Gear AS

２ ‑52

S Y S T E M ／ Hydraulic System Steering Circuit（Serial No. 1001 〜 4499） ・The steering system mainly consists of the steering wheel, power steering ass'y, steering cylinder and hydraulic oil piping. When the steering wheel is turned (by hand) the power steering ass y directly installed to the steering shaft in the steering column assembly is turned and pressurized hydraulic oil is sent to the steering cylinder to turn the machine.

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5-Check Valve 6-Steering Cylinder

２ ‑53

S Y S T E M ／ Hydraulic System Steering Circuit（Serial No. 4501 〜） ・The steering system mainly consists of the steering wheel, power steering ass'y, steering cylinder and hydraulic oil piping. When the steering wheel is turned (by hand) the power steering ass y directly installed to the steering shaft in the steering column assembly is turned and pressurized hydraulic oil is sent to the steering cylinder to turn the machine.

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5-Check Valve 6-Steering Cylinder 7-Check Valve

２ ‑54

S Y S T E M ／ Hydraulic System Steering Piping ・The hydraulic oil is drawn up from the oil tank by the main pump. Then the hydraulic oil is sent to the power steering assembly and it is distributed to the steering circuit and main circuit.The steering hydraulic circuit uses a load sensing system, so when the steering wheel is turned, the amount of oil corresponding to the amount of steering wheel turning is sent to the power steering assembly and remaining oil is sent to the main circuit.The oil sent to the power steering assembly is then fed to the steering cylinder to steer the machine in accordance with the steering wheel operation.The hydraulic oil flows out from the steering cylinder returns through the power steering assembly, filtrated by the return filter and finally to the oil tank.

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S Y S T E M ／ Hydraulic System Hydraulic Circuit（Serial No. 1001 〜 4499） ・The main hydraulic system mainly consists of the main pump, control valve, hydraulic oil tank, return filter, lift cylinder, tilt cylinder and the hydraulic piping. By operating the work control lever, the hydraulic oil flow from main pump is controlled via the control valve to operate the work as desired.

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S Y S T E M ／ Hydraulic System Hydraulic Circuit（Serial No. 4501 〜） ・The main hydraulic system mainly consists of the main pump, control valve, hydraulic oil tank, return filter, lift cylinder, tilt cylinder and the hydraulic piping. By operating the work control lever, the hydraulic oil flow from main pump is controlled via the control valve to operate the work as desired.

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S Y S T E M ／ Hydraulic System Hydraulic Circuit ・The oil discharged from the main pimp is divided to the main hydraulic circuit and the steering circuit by the VP-valve is in the power steering assembly.The oil discharged from the main pump is sent to the main control valve and it returns to the oil tank through the return filter when the tilt plunger and lift plunger are in the neutral position.When the shovel control lever is moved, the tilt plunger and/or lift plunger of the main control valve is operated to send the oil discharged from the main pump to the tilt cylinder and/or lift cylinders for operating the shovel equipment.

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S Y S T E M ／ Electric OUTLINE The electrical system is broadly divided into the main circuit, monitor circuit and travel system circuit.

・Main Circuit （１）Electric Power Circuit: supplies electric power to all electrical systems on the machine. （２）Preheat Circuit: assists engine start in cold weather. （３）Charging Circuit: recharges the batteries. （４）Starting Circuit: starts the engine.

Engine Stop Circuit: stops engine by operating the engine stop motor. ・Monitor Lamp Circuit （１）Displaying the machine operating conditions (monitor display, monitor controller, sensors, and switches.) （２）Gauging circuit: Displaying engine water temperature and remaining fuel quantity on the meter panel ・Travel System Circuit （１）Consisting of the parking brake circuit (parking brake switch, parking brake solenoid valves) and the FNR selection circuit (FNR switch, FNR solenoid valve). ・Other circuits （１）Lighting control circuit Turing on/off each lamp (headlamps, turn signal lamps, rear combination lamps, backup lamp) （２）Horn circuit: Activate the horn. （３）Automatic leveler circuit: Turning on/off the proximity switch of the automatic leveler system (mechanism to keep the bucket level).

２ ‑59

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S Y S T E M ／ Electric ・Main Circuit The battery negative terminal is grounded to the vehicle frame.

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S Y S T E M ／ Electric ・Pre-heat Circuit（Starter Switch「HEAT」） (1)When the key switch is set to "HEAT", the glow relay is activated and the current goes to the glow plugs.

(2)In the other line, the current turns on the glow lamp on the meter panel through the glow lamp timer.

(3)The glow lamp is turned off 5 seconds later by the glow lamp timer and indicates the completion of preheating.

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S Y S T E M ／ Electric ・Pre-heat Circuit（Starter Switch「START」） (4)When the key switch is set to "START", the current goes from key switch terminal "C" to the glow lamp timer through the shift lever to activate the glow relay. The current then goes to the glow plugs.

(5)In the other line, the current passes to the glow lamp on the meter panel through the glow lamp timer and turns on the glow lamp.

(6)After the engine was started, the key switch is returned to "ON".At the same time, the activated circuit of the glow relay is opened, then the glow plugs turn off.

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S Y S T E M ／ Electric ・Charging Circuit (1)After the engine starts and the key switch is released, the key switch is returned to the ON position.

With the key switch ON, terminal B is connected to terminals BR and ACC in the switch.

(2)When the engine rotates, the alternator is also rotated, starting to generate electricity.

(3)The current from alternator terminal B is routed to the batteries via the battery relay, recharging the batteries. At the same time, the current is supplied to the head lights and work lights via the fuse box.

The current from alternator terminal N is routed to the controller in the monitor. When charging operation is normal, the controller turns the alternator indicator OFF.

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S Y S T E M ／ Electric ・Engine Start Circuit (1)Starter Switch: "ON → START" operation.

The electric current from C of starter switch is sent to coil of starter relay through neutral switch of the shift lever, so the starter relay is closed. At the same time, the positive current from battery relay runs through the starter relay to the starter motor to start the starter motor.

(2)Starter Switch "ON → START" operation while the engine is running When the engine is running, as the terminal L on the alternator is not grounded (alternator monitor light turned off) the current does not go to the coil of the starter relay, so the starter relay is in open condition. Therefore, the starter motor is not activated.

・Engine Stop Circuit (1)Starter Switch "ON" The positive current from the fuse box is sent to the coil of engine stop solenoid, and the engine is running.

(2)Starter Switch "OFF" The current from fuse box to the engine stop solenoid is cut off, and engine is stopped.

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S Y S T E M ／ Electric ・Traveling System Circuit 1.Shift lever: [N] → [F] When the parking brake is released, the electric current is sent from fuse to the parking brake solenoid and the sift lever through the relay (4).When the shift lever is changed from [N] to [F], the current goes to the [F] solenoid on the HST pump.

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S Y S T E M ／ Electric 2.Shift lever: [N] → [R] When the parking brake is released, the electric current is sent from fuse to the parking brake solenoid and the sift lever through the relay (4).When the shift lever is changed from [N] to [R], the current goes to the [R] solenoid on the HST pump.

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S Y S T E M ／ Electric 3.Travel mode selector switch: [AUTO] The electric current from the fuse maintains the automatic speed circuit without making the current pass to the firstgear fixing solenoid on the HST motor. On the other hand, the current passing to the meter panel turns on the "Rabbit" monitor light.

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4.Travel mode selector switch: [LOW] The electric current from the fuse goes to the firstgear fixing solenoid on the HST motor and activates it. On the other hand, the current passing to the meter panel, turns on the "Tortoise" monitor light.

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S Y S T E M ／ Electric 5.Parking brake circuit (1)Before engine start (Starter switch is in "ON" position) Current from the fuse ③ goes to:Terminal b of relay[1] → terminal c → coil → terminal g → terminal L of alternator → ground, then relay[1] is switched from b-e to b-a.

At the same time current from the fuse ① goes to:Terminal b of relay[4] → terminal e → Parking monitor light → ground, parking monitor light turns on.

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(2)After engine is started. ・Parking brake switch is in "ON"(Applied) position.

The circuit between ground and terminal L of alternator is opened, when the alternator is charging.

Current from the fuse ③ goes to:Terminal b of relay[1] → terminal e → terminal 1 of parking brake switch.

At the same time current from the fuse ① goes to:Terminal b of relay[4] → terminal e → parking monitor light → ground, the parking monitor light is on.

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Current from the fuse ③ goes to:Terminal b of relay[1] → terminal e → terminal 1 of parking brake switch.

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・Parking brake switch is operated in "OFF" position.

Current from fuse③ goes to:Terminal b of relay[1] →terminal e →terminal 1 of parking brake switch → terminal 2 → terminal 5.

Current from terminal 5 of parking brake switch goes to relay [3] and [4] separately.

One goes to: Terminal b of relay[3] → terminal e → parking brake solenoid → ground, then parking break is released. Another one goes to: Terminal c of relay[4] → coil → terminal g → ground, then parking monitor light turns off.

Another one goes to: Terminal c of relay[4] →coil → terminal g →ground, then parking monitor light turns off.

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２ ‑73

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S Y S T E M ／ Electric (3)After resetting the parking brake switch to "OFF"(automatic return). ・Once the parking brake switch is set to "OFF", the relay[4] stays on by the current from fuse ① . ・Parking brake switch is switched in "ON" position.

Current from terminal c of relay[4] goes to: Terminal 5 of parking brake switch → terminal 6 → terminal c of relay[3] → coil → ground, then relay[3] is switched from b-e to b-a. and parking brake is applied. At the same time, current from terminal c of relay[4] goes to: Terminal b of relay[3] → terminal a → parking monitor light turns on.

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・Parking Brake Switch is switched from "ON" to "NEUTRAL".

Current for the coil of relay[3] is cut off, then parking monitor light turns off.

At the same time, current from terminal c goes to:terminal b of relay[3] → terminal e → parking brake solenoid → ground, then parking brake is released .

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２ ‑74

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SECTION 3 COMPONENT OPERATION − CONTENTS − Hydro-Static Transmission .........................3-78 HST Pump（YUKEN）......................................3-79 HST Pump（UCHIDA）....................................3-89 HST Motor(YUKEN）.....................................3-107 HST Motor（UCHIDA）...................................3-112 Axle..............................................................3-119 Service Brake...............................................3-122 Parking Brake...............................................3-124 Wet Brake Asembly in Rduction Gear Box...3-127 Master Cylinder............................................3-128 Orbitrol.........................................................3-129 Control Valve................................................3-134 Main pump....................................................3-147 Return Filter..................................................3-148

３ ‑77

(Blank)

COMPONENT OPERATION ／ HST Pump Hydro-Static Transmission HST is a hydraulic driving unit where the engine's power is transmitted to the wheels by the hydraulic pressure.

The machine's HST is equipped with a combination of variable-displacement pump and variable-displacement motor.

The engine's mechanical power is converted to hydraulic power using the pump. This hydraulic power is reconverted to mechanical power by the motor and transmitted to the wheels. HST functions both as clutch and transmission and the nonstage conversion is available using the hydraulic control.

Basically, HST has a system where low-speed and high-pressure oil is used and the oil is circulated in the closed circuit consisting of pump and motor.

The HST is controlled by the following three factors: By controlling the above three factors properly, the machine can travel smoothly.

Oil Discharge → Machine speed Direction of oil flow → Machine moving forward and reverse.

Oil Pressure → Driving Force

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The direction of the pump input shaft rotation is always the same. The direction of flow of oil discharged from the pump changes according to tilting of the swash plate and, thereby, the direction of motor output shaft rotation changes.

In other words, the machine moves forward or backward according to the direction of swash plate tilting. Further, gear shifting (or speed changing) is done by changing the motor cylinder block tilting angle.

３ ‑78

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COMPONENT OPERATION ／ HST Pump ・ＨＳＴ ＰＵＭＰ（YUKEN ／ Serial No. 1001 〜 4499） The HST pump is the swash plate type axial piston pump with automotive control. The cylinder block ⑤ , with nine pistons in total, is connected to the shaft ⑭ using a spline; and the main pump ② and charging pump ① are connected to it through the coupling ③ .

To the HST pump, the AU controller ⑧ which is the center of the automotive control, and the neutral hold mechanism, and the inching valve ⑮ , which controls the pilot pressure for the automotive control, are all integrated into the HST pump.

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３ ‑79

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COMPONENT OPERATION ／ HST Pump ・ＨＳＴ Pump（YUKEN ／ Serial No. 1001 〜 4499）

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1-Charging pump 2-Main pump 3-Coupling 4-Port plate (valve plate) 5-Cylinder Block 6-Piston 7-Cradle (Swash plate) 8-AU control section Neutral hold Section

9-Spacer 10-Pin (B) 11-Pin (C) 12-Pin (A) 13-Needle bearing 14-Shaft 15-Inching valve 16-High-pressure relief valve 17-Low-pressure relief valve

３ ‑80

COMPONENT OPERATION ／ HST Pump ・AU controller（YUKEN ／ Serial No. 1001 〜 4499） 1.The electromagnetic selector valve ① for forward and reverse is equiped to the AU controller. When electric current is sent to solenoid ② , the spool of the selector valve is operated and the pilot pressure generated in the inching valve sends pressurized oil to the right or left pressure chamber of the piston ③.

2.The pilot pressure controls the stroke of the piston ③ against force of the spring ⑦ which is installed in the piston ③ .

3.When the piston ③ is moved, the cradle is tilted through the spacer ④ and the pin ⑤ . When the cradle is tilted, the pump discharges oil.

4.The amount of oil discharging by the pump is decided by the stroke of the piston ③ . The adjusting screw ⑧ limits the stroke of the piston ③ and decides the maximum amount of oil discharge by the pump.

・Neutral holder（YUKEN ／ Serial No. 1001 〜 4499） 1.Holding the neutral position is done by force of spring ⑦ which is installed in the piston ③ .

2.The adjusting screw ⑨ is equipped to adjust the piston ③ to the neutral position.

㪮㪘㪩㪥㪠㪥㪞 DO NOT re-adjust neutral position in the field.

Because it must be adjusted on test bench.

The AU controller and the neutral holder are not independent of each other, but they are combined system.

３ ‑81

COMPONENT OPERATION ／ HST Pump ・AU controller、Neutral holder（YUKEN ／ Serial No. 1001 〜 4499）

When the electric current is sent to the solenoid Y, the pump discharges oil from the port P. And when the electric current is sent to the solenoid Z, the pump discharges oil from the port S.

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9-Adjusting screw (Neutral adjustment)

３ ‑82

COMPONENT OPERATION ／ HST Pump ・Horsepower control mechanism（YUKEN ／ Serial No. 1001 〜 4499） 1.This HST pump uses the horsepower control mechanism using the hydraulic power working on the rotary components.

The following describes the horsepower control mechanism.

2. When the pump is rotating in the direction of the arrow the cradle receives the reaction force from the high-pressure piston side. The nine pistons are rotating and 4 or 5 pistons are at the high-pressure side. The reaction force from those pistons works on the cradle. When the pistons are rotating, the resultant reaction force of each piston works as if drawing a figure of eight (8) as shown in the figure.

The mean position of the resultant force is shown as G. 3.The deviated position of G from the shaft center is shown as δ.

The resultant force on G is increased with the discharging oil pressure and reduces the tilt angle of the cradle. The force that is reducing tilt angle of cradle is decided by the formula (resultant force x eccentric amount (δ)).

The decrease of the cradle tilt angle indicates a decrease in the pump's discharge. It mean the horsepower control is starting

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３ ‑83

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COMPONENT OPERATION ／ HST Pump 4.The eccentric quantity (δ) can be adjusted by changing the port plate phase angle. The phase angle is changed by turning the eccentric bolt towards A or B within the range of ± 90 degrees. When the eccentric bolt is turned ± 90 degrees, the phase angle of port plate is changed about ± 2 degrees.

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When the eccentric bolt is turned towards A, the eccentric amount (δ) is increased and when the eccentric bolt is turned towards B the amount (δ) is decreased. Within this range, it can be adjusted.

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5.The cradle's reaction to the resultant force x eccentric amount (δ) is decided by the piston area, the spring force in the piston, and the pilot pressure on the piston. To match the engine output and HST pump input the pilot pressure is adjusted because the area and spring force of the piston are both fixed.

When the pilot pressure is low, the pressure point starting the horsepower control is moved to the low-pressure side and when the pilot pressure is high, it is moved to the high-pressure side.

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３ ‑84

COMPONENT OPERATION ／ HST Pump ・Inching valve assembly（YUKEN ／ Serial No. 1001 〜 4499） 1.The oil from the charging pump enters from port A and divides into two, going to the orifice ④ of the pressure control valve spool ① and the orifice of the valve body ② .

2.When the oil sent to the pressure control valve spool ① passes through the orifice ④ a different pressure is created before and after the orifice because the different pressure moves the spool ① to the spring ③ side against the spring force.

3.The valve body ② functions as the variable orifice.

When the variable orifice ⑩ is closed, all the oil goes from the charging pump to the pressure control valve spool ① . When the variable orifice ⑩ is fully opened, all the oil goes from charging pump to port B through the valve Body ② . In this case, pilot pressure is not created. his function is connected with brake pedal of the machine, and is using as the inching control.

4.The oil from port B joins the oil from port D through the relief valve ⑧ and returns to the oil tank through the pump drain port.

5.The pilot pressure ( ΔPc) is led to port C to control the pump discharge quantity. The pilot pressure from port C goes to the piston chamber which controls the pump discharge, through the electromagnetic selector valve.

6.The pump speed changes the proportionally charging pump's discharge so that the engine speed is sensed after it has been converted to the charging pump's discharge.

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３ ‑85

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COMPONENT OPERATION ／ HST Pump ・Pilot pressure creating mechanism（YUKEN ／ Serial No. 1001 〜 4499）

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The spool is pushed to the left because of the spring force and the port C which creates pilot pressure is closed.

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3.The spool begins to move when the engine speed has gone beyond low idle speed. The opening of the control section is then increased and pilot pressure is created (point X). The point X is decieded by setting load of the spring ③ -1. The spring load setting is adjusted by the shims.

３ ‑86

COMPONENT OPERATION ／ HST Pump 4.When the engine speed is increased, a differential pressure before and after the orifice ④ , the spool ① is moved to the right and the opening of the control section is increased, so that the pilot pressure is increased, as shown in the figure. The spring ③ -2 determines the pilot pressure gradient. Adjusting the smaller spring set load creates the pilot pressure characteristics to gain horsepower and yield optimum characteristics.

・HST pump characteristic curve（YUKEN ／ Serial No. 1001 〜 4499）

Eng.rpm-HST control pressure kg/cm2 25

MPa

20

1.96

15

1.47

10

0.98

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1000

1500 Ｅｎｇ.rpm

３ ‑87

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COMPONENT OPERATION ／ HST Pump ・Low-pressure relief valve（YUKEN ／ Serial No. 1001 〜 4499） The oil sent from the inching valve assembly acts on the port (A), pushes out the valve stem (1) at a pressure of 1.57MPa or over and flows into the casing through the port (B) to hold the pressure in the low-pressure circuit.

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Relieving 1.The oil from the high-pressure port (A) acts on the difference in area between the two parts having the diameters D and d. (D>d).

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Sucking When the pressure in the high-pressure port (A) is lower than the pressure in the low-pressure port (B), the valve body (2) opens and the oil in the low-pressure port (B) flows to the highpressure port (A) to prevent cavitation.

３ ‑88

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COMPONENT OPERATION ／ HST Pump ・HST Pump（UCHIDA ／ Serial No. 4501 〜） The HST pump is the swash plate type axial piston pump with automotive control (DA control). The cylinder block with nine pistons in total is connected to the drive shaft using a spline; and the main pump is connected to it. The charging pump is built-in in the HST pump and it connected to the drive shaft to replenish the oil in the closed travel circuit and for piloting the automotive control.

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３ ‑89

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３ ‑90

COMPONENT OPERATION ／ HST Pump ・High-pressure relief valve This valve determines the maximum pressures in the closed circuit and protects the high-pressure circuit. It also has an anti-void unit, which refills the oil to low-pressure side from the drain circuit directly to prevent the cavitation.

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< When relieved> The force of high pressure circuit [A] is larger than the spring force due to the spring (6), thus press down the poppet (7) to the position shown in the figure and the oil in the high pressure circuit [A] will be drawn into the charging circuit [B].

３ ‑91

COMPONENT OPERATION ／ HST Pump <When bypassed > When the force generated by the low pressure circuit [A] plus the spring force (3) becomes smaller than the force generated by the charging circuit [B], the valve sheet (8) is pressed up to the position shown in the figure and the oil in the charging circuit [B] will be drawn into the low pressure circuit [A].

<When towing (engine stops)> The poppet (7) is pressed down to the position shown in the figure by tightening the rod (1), the oil in the high pressure circuit [A] will be drawn into the charging circuit [B].

３ ‑92

COMPONENT OPERATION ／ HST Pump ・Low-pressure relief valve This valve controls the charging pressure. During the machine operation, it is always working. The relieved oil goes through the HST pump housing then goes to the HST motor, oil cooler and oil tank for their lubrication and cooling.

・HST pump characteristic curve（UCHIDA ／ Serial No. 4501 〜）

25

2.45

20

1.96

15

1.47

10

0.98

5

0.49

0 500

1000

1500

2000

[ min-1 ]

３ ‑93

2500

0 3000

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COMPONENT OPERATION ／ HST Pump ・DA control system（UCHIDA ／ Serial No. 4501 〜） （１）Features ① The discharging direction can be changed by using the solenoid valve.The travel direction can be changed the forward and reverse easily by the switch. ② The discharge amount is controlled according to the engine speed. Only the accelerator operation can continuously control the machine speed. ③ Torque Fixing Control. When the load is increased, engine overload is prevented by controlling the oil discharge amount.

（２）DA valve The gear pump is connected to the HST pump for charging and piloting. The gear pump discharge is increased or decreased according to the engine speed. The flow rate is led to the charge circuit through the orifice on the full flow DA valve. Using as an indicator the differences in pressures caused at the front and rear of the orifice, according to the flow rate change, the DA valve decompresses the charging pressure and generates the pilot pressure. It means that the pump tilt is controlled along with the pressure almost in proportion to the engine speed.

A certain volume, which is directly proportional to the engine speed, of oil will be drawn from the charging pump into the charging circuit [C] through the port [A]. DA valve can be activated with signals which indicate the spring force by the spring (4) and the pressure difference between foreand-aft the orifice (6) to reduce the pressure of the charging circuit [C] and generate a control pressure in the control circuit [B].

1-Control cartridge 2-O-ring 3-Adjusting screw 4-Adjusting Spring 5-Differential piston 6-Orifice

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３ ‑94

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３ ‑95

COMPONENT OPERATION ／ HST Pump <Idling> The pressure difference between fore-and-aft the orifice (6) is small since the output volume of the charging pump is small, thus the differential piston (5) will be located at the position shown in the figure. Hence, low control pressure due to reduction in section between the charging circuit [C] and the control circuit [B] will be drawn into the control circuit [B].

<High Idle> The pressure difference between fore-and-aft the orifice (6) becomes larger since the output volume of the charging pump is large, thus the differential piston (5) will be pressed up to the position as shown in the figure. Hence, high control pressure will be drawn into the control circuit [B].since the section area of the passage between the charging circuit [C] and the control circuit [B] will becomes large.

３ ‑96

COMPONENT OPERATION ／ HST Pump （３）DA control system

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18-Swash plate 19-Slide ring Ａ-DA valve, primary (from charging pump) Ｂ-DA valve, secondary (to control circuit) Ｃ-DA valve, secondary (to charging circuit) Ｄ-DA valve drain Ｅ-Tilt piston (x1) Ｆ-Tilt piston (x2)

３ ‑97

COMPONENT OPERATION ／ HST Pump Neutral position

３ ‑98

COMPONENT OPERATION ／ HST Pump <Forward driving> When the shift lever is set at [F], the solenoid valve [a] (10) is energized, which press the control piston (13) connected to the solenoid valve upward to the position shown in the figure, and the oil in the control circuit generated by the DA valve (3) will be drawn into the tilt piston right chamber [F]. As a result, a hydraulic force directly proportional to the pressure of the control circuit [B] is applied to the tilt piston (14) and the tilt piston (14) will move downward to the position shown in the figure. The swash plate (18) is connected to the tilt piston (14) through the slide ring (19), and the HST pump discharges the oil to the forward drive circuit.

３ ‑99

COMPONENT OPERATION ／ HST Pump <Backward drive> When the shift lever is set at [R], the solenoid valve [b] (9) is energized, which press the control piston (13) connected to the solenoid valve downward to the position shown in the figure, and the oil in the control circuit [B] generated by the DA valve (3) will be drawn into the tilt piston left chamber [E]. As a result, a hydraulic force directly proportional to the pressure of the control circuit [B] is applied to the tilt piston (14) and the tilt piston (14) will move upward to the position shown in the figure. The swash plate (18) is connected to the tilt piston (14) through the slide ring (19), and the HST pump discharges the oil to the backward drive circuit by rotating counterclockwise shown in the figure.

３ ‑100

COMPONENT OPERATION ／ HST Pump (4)Tilting mechanism of the swash plate The tilt piston is connected to the pin on the swash plate (tile plate). The springs are built into the tilt piston and the spring force works to return the tilt piston to neutral (zero discharge). The control pressure is led to the tilt piston decides the tilt piston position and pump discharge amount.

The relation of the solenoid and the pressure discharge port and travel direction

[The relation of the solenoid and the pressure discharge port and travel direction] Acting solenoid

Discharge port

Pilot pressure measuring ports

Solenoid (a)

Ａ (Forward)

Ｘ２

Solenoid (b)

Ｂ (Reverse)

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３ ‑101

COMPONENT OPERATION ／ HST Pump %QPVTQN RTGUUWTG 2 UQN D

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３ ‑102

COMPONENT OPERATION ／ HST Pump ・Recovering force from tilt and spark-advance（UCHIDA ／ Serial No. 4501 〜） Hydraulic power works on the swash plate through the piston. The control plate's high and low changing point is set so that the angle is advanced into the rotation direction: therefore the application point on the high-pressure section, worked on the piston, slightly deviates from the supporting point of the swash plate. Because of the deviation between the supporting and application points a recovering power from the tilt is generated. (referred as Recovering Power from the tilt or Self-Recovering Power) The eccentric pin at the adjusting screw end is connected with the control plate groove. The spark advance of the control plate has been adjusted (by turning the adjusting screw) by HST manufacturer in the bench test before the delivery.

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３ ‑103

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COMPONENT OPERATION ／ HST Pump ・Inching function（UCHIDA ／ Serial No. 4501 〜） The inching valve is separated from the HST pump to which it is connected by the brake link and rod.When the brake pedal is depressed, the linked lever is turned and it turns the spool so that the oil flow in the spool is connected to the oil flow between the P-port and T-port.

Because the DA pilot pressure is linked to the P port, when the oil is drained in the oil tank the pilot pressure is lowered so as to reduce the pump tilt.

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This function is used when the machine is to be controlled at a low speed while the engine speed is increased and the speed of working equipment is increased.

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３ ‑104

COMPONENT OPERATION ／ HST Pump ・Automatic speed change function（UCHIDA ／ Serial No. 4501 〜） The pilot pressure in relation to the engine speed is linked from the DA valve to the tilt piston on the side selected by the solenoid valve. When the engine is running in low idling the pilot pressure is lower than the spring force in the tilt piston so that the pump is set to neutral and the machine is stopped. When the engine speed increases the control pressure also increases and the spring is under pressure, which inclines the pump. It means that the discharged quantity varies with the engine speed so that speed control is continuously available by use of the accelerator.

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・Torque control function（UCHIDA ／ Serial No. 4501 〜） When the pressure increases, the recovery of the swash plate tilt is increased and the swash plate tilt angle is reduced. This is an approximate torque fixing control. As the torque set is based on the pilot pressure, and the balance between the spring force of the tilt piston and the recovery force from the swash plate tilting, the set torque varies with the engine speed.

If the engine is loaded beyond its torque, then the engine speed tries to reduce from N1 to N2.

When the engine speed is reduced, the HST pump input torque also reduces and the HST pump tilt angle is balanced at a point appropriate to the engine's torque. It means that when the load increases, the engine speed slightly decreases and the HST pump automatically performs the tilt angle control without stopping the engine effectively adjusting to the engine torque.

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３ ‑105

COMPONENT OPERATION ／ HST Pump ・Middle speed fixing solenoid valve（UCHIDA ／ Serial No. 4501 〜） When the [AUTO] mode is selected, the DA pilot pressure in the HST pump is connected to the X port on the HST motor. When the [LOW] mode is selected, the decompressed charging pressure from the G port is supplied to the X port at a fixed rate. Because of that the HST motor tilt angle is fixed at the middle and the maximum speed is reduced.

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３ ‑106

COMPONENT OPERATION ／ HST Motor ・HST Motor（YUKEN ／ Serial No. 1001 〜 4499） This HST motor is a bent axis type axial piston motor and the variable-displacement type in which the displacement can be changed in two steps. The bent axis type features that the cylinder block tilts with respect to the shaft. By sending the pressurized oil from charging pump to the chamber A or B of the piston ⑥ , the maximum, middle or minimum cylinder block ⑩ tilting angle can be obtained.

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1-Nut 2-Shaft 3-Push rod 4-Piston assembly 5-Port plate (Valve plate) 6-Piston 7-Pin 8-Set screw 9-Bush

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10-Cylinder block 11-Body 12-Piston (for middle-speed control) 13-System pressure control valve 14-Electromagnetic selector valve

３ ‑107

COMPONENT OPERATION ／ HST Motor ・System pressure control valve（YUKEN ／ Serial No. 1001 〜 4499） １．Two kinds of pressurized oil are supplied from the HST pump to the system pressure control valve. ① Pilot Pressure to change the motor displacement - Connect to Port "G". It is connected from port "V" on the HST pump. ② Pilot Pressure (DPc) to control the system pressure - Connect to Port "H". It is connected from port "Q" on the HST pump. ２．When the engine speed is low; A spring force is given to the right side of the spool, and the pilot pressure, which is used for the pump discharge rate control, is given to the left side of the spool. When the engine speed is low, the pilot pressure is also low. The spring force is stronger than the pilot pressure, so that the spool is moved to the left. When the spool is in this position the HST motor capacity becomes large. Therefore, when the engine speed is low the motor capacity is large. 㪧㫆㫉㫋㩷䌈 㪧㫆㫉㫋㩷䌇

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３．When the Engine Speed is High; ৻ㅦ⁁ᘒ As the engine speed increases, the pilot pressure rises gradually. When the pilot pressure rises, the force pressing the spool to the spring side also rises. As the force of the pilot pressure increases, the spool moves to right side. And then circuit of the chamber A is connected to drain port through the spool and port G is connected to chamber B to change HST motor capacity to small. After the spool position has been changed to the right side, the small HST motor capacity is maintained even though the engine speed is further increased.

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３ ‑108

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COMPONENT OPERATION ／ HST Motor ４．System pressure control (Automatic speed change control) The check valve selects the higher pressure from the two sides in the main circuit pressure, and is led to the end of the pin built in the spool. When high pressure acts on the pin, the spool is moved to the left. When the HST motor capacity position is smaller position and the main circuit pressure is higher, the spool moves to the left side by acting high pressure to the pin. Then the capacity of the HST motor becomes large.

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５．When the motor capacity changes from small to large the main circuit pressure is affected by the pilot pressure (ΔPc) which itself changes with the engine speed. The higher the engine speed (pilot pressure), the higher the main circuit pressure to change the capacity of the HST motor.

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６．In order to adjust the engine speed when the engine capacity is changed from large to small, the tension of the spring is set by using the adjusting screw.

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３ ‑109

COMPONENT OPERATION ／ HST Motor ・HST motor first-speed control （YUKEN ／ Serial No. 1001 〜 4499） The electromagnetic selector valve controls the direction of pilot pressure which is into port "G" to choose automatic shift mode or middle speed fixing mode.

The following shows the hydraulic circuit.

When the electromagnetic valve is turned OFF, the HST motor is functioned as automatic shift mode. When it is turned ON, the pilot pressure goes to the middle speed control piston, and then the HST motor changes to middle speed fixing mode.

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３ ‑110

COMPONENT OPERATION ／ HST Motor ・Solenoid OFF Condition (Automatic shift mode)（YUKEN ／ Serial No. 1001 〜 4499）

・Solenoid ON Condition (Middle speed fixing mode)（YUKEN ／ Serial No. 1001 〜 4499）

３ ‑111

COMPONENT OPERATION ／ HST Motor ・ＨＳＴ Motor（UCHIDA ／ Serial No. 4501 〜） Motor Start-up The direction of the drive shaft's rotation is determined by whether the pressure-raised oil is connected to the port A or to port B. When the pressure-raised oil is led to the cylinder block, where the seven pistons are circularly located with a movable condition, the piston presses and rotates the drive shaft. A single piston a stroke takes a cycle, and it sucks and discharges the oil. The drive shaft is smoothly rotated by the continuous motion from the seven pistons. Because part of the hydraulic oil force works on the piston becomes the torque, when the tilt angle is larger, the torque is large.

Also, when the tilt angle increases the volume of sucked oil is large, so the drive shaft speed is reduced.

The control plate is connected to the control piston through the connecting rod and the tilt angle is changed by the position of the control piston.

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３ ‑112

COMPONENT OPERATION ／ HST Motor ・Description of Pilot Pressure Proportion Control (HD Control) Operation （UCHIDA ／ Serial No. 4501 〜） The oil on each high-pressure side (A or B) is fed to the smaller diameter side (ring section) of the control piston through the check valve, which presses the rotary group to maximum tilting angle.

The oil at each high-pressure side is also led to the primary side of the control bush. The secondary side of the control bush is connected to the larger diameter side of the control piston through the cut-off valve (describe later). So when the pilot pressure led from the X-port becomes higher than the initial load of the adjusting spring, then the pilot piston is moved to the spring side and the oil passage on the primary and secondary sides of the control bush is opened and highpressure oil enters the larger diameter side of the control piston. The control piston is then moved to the minimum tilt side (qmin) direction and the torque reduces and the shaft speed increases because the volume of motor has become smaller.

As above indicated, the movement of the control piston changes the tilt angle: and when the control piston is moved in the qmin direction, the feed-back spring is correspondingly compressed.

The thrust from the pilot pressure is now balanced by the feed-back spring force. That closes the oil passages on the primary and secondary sides of the control bush and keeps the tilt angle appropriate to the pilot pressure.

When the pilot pressure decreases the feed-back spring force exceeds it, so the pilot piston is pushed upward. Therefore, the secondary side of the control bush is led to the tank, and the oil in the larger diameter side of the control piston is returned to the tank.

Thus the tilt angle becomes larger, because of the oil pressure on the smaller diameter side of the control piston and the feed-back spring force, and it is changed to an angle which will be appropriate for the pilot pressure.

・Fixed Pressure Control（UCHIDA ／ Serial No. 4501 〜） The pressure on the primary side of the control bush is also connected to the cut-off valve and is opposed against the cut-off pressure adjusting spring. When the high-pressure oil in the main circuit exceeds the set pressure of cutoff spring, the spool is moved and the oil on the larger diameter side of the control piston is returned to the tank. Then, as the motor tilts to maximum angle, the input torque is increased and the raised main circuit pressure is temporarily controlled.

At that time the main circuit pressure is so controlled that the pressure is fixed until the motor is tilted to the maximum tilt side. When the load is further increased and the main circuit pressure is higher than the cut-off set pressure, the motor is fixed to the maximum tilt.

３ ‑113

COMPONENT OPERATION ／ HST Motor ・ＨＤ Controller（UCHIDA ／ Serial No. 4501 〜）

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10-Back-up ring 11-O-ring 12-Cutoff valve 13-Adjust spring 14-Set screw Ａ-Control bush (Primary port) Ｂ-Control bush (Secondary port) Ｃ-Control piston (Smaller diameter side: Ring section) Ｄ-Control piston (Larger diameter side)

３ ‑114

COMPONENT OPERATION ／ HST Motor ・ＨＤ Controller（When vehicle stops (idling) ）（UCHIDA ／ Serial No. 4501 〜） In this case, the hydraulic force due to the pilot pressure [Px] is smaller than the force due to the springs (3) and (4). Thus the pilot piston (1) is located at the position shown in the figure to block the primary side of the control bush [A]. In addition, the cut-off valve (12) moves to the position as shown in the figure to relief the pressure of the larger diameter side of the control piston [D], because the hydraulic force of the primary side of the control bush [A] which is applied to the cut-off valve (12) is smaller than the force due to the spring (13). As a result, the hydraulic force due to the pressure of the smaller diameter side of the control piston [C] is applied to the control piston (5), thus the control piston (5) is held at the large tilt side shown in the figure.

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３ ‑115

COMPONENT OPERATION ／ HST Motor ・ＨＤ Controller（1st gear drive ）（UCHIDA ／ Serial No. 4501 〜） In this case, the hydraulic force due to the pilot pressure [Px] is larger than the force due to the springs (3) and (4). Thus the pilot piston (1) is located at the position shown in the figure to transfer the pressure of the primary side of the control bush [A] to the secondary side of the control bush [B]. In addition, the cut-off valve (12) moves to the position as shown in the figure to transfer the pressure of the secondary side of the control bush [B] to the larger diameter side of the control piston [D], because the hydraulic force of the primary side of the control bush [A] which is applied to the cut-off valve (12) is smaller than the force due to the spring (13). As a result, three forces, hydraulic force due to the difference in section area between large [D] and small [C] diameters of the control piston (when driving with the 1st gear, the pressure at the primary side of the control bush is approx. 50 % of that for automatic drive)", Hydraulic force due to the pilot pressure [Px] , and the sng force due to the spring (4), are applied to the control piston (5), and it is moved to a certain location where these forces are balanced. ※ In the 1st gear drive, the pressure in the primary side of the control bush [A] is approximately 50 % of that in the case of automatic drive.

３ ‑116

COMPONENT OPERATION ／ HST Motor ・ＨＤ Controller（Automatic drive ）（UCHIDA ／ Serial No. 4501 〜） In this case, the hydraulic force due to the pilot pressure [Px] is larger than the force due to the springs (3) and (4). Thus the pilot piston (1) is located at the position shown in the figure to transfer the pressure of the primary side of the control bush [A] to the secondary side of the control bush [B].In addition, the cut-off valve (12) moves to the position as shown in the figure to transfer the pressure of the secondary side of the control bush [B] to the larger diameter side of the control piston [D], because the hydraulic force of the primary side of the control bush [A] which is applied to the cut-off valve (12) is smaller than the force due to the spring (13).As a result, a hydraulic force due to the difference in section area between large [D] and small [C] diameters of the control piston is applied to the control piston (5), and it is moved to the side of small tilt shown in the figure.

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３ ‑117

COMPONENT OPERATION ／ HST Motor ・ＨＤ Controller（Maximum towing force ）（UCHIDA ／ Serial No. 4501 〜） In this case, the hydraulic force due to the pilot pressure [Px] is larger than the force due to the springs (3) and (4). Thus the pilot piston (1) is located at the position shown in the figure to transfer the pressure of the primary side of the control bush [A] to the secondary side of the control bush [B].In addition, the cut-off valve (12) moves to the position as shown in the figure to block the pressure of the secondary side of the control bush [B] and relief the pressure of the larger diameter side of the control piston [D], because the hydraulic force of the primary side of the control bush [A] which is applied to the cut-off valve (12) is larger than the force due to the spring (13).As a result, the hydraulic force due to the pressure of the smaller diameter side of the control piston [C] is applied to the control piston (5), thus the control piston (5) is moved to the large tilt side shown in the figure.

３ ‑118

COMPONENT OPERATION ／ AXLE ・Axle The axle consists of the axle tube, differential unit, final reduction and axle shaft, and wheels are installed to the axle shafts.

The power from the reduction gear box is transmitted to the front and rear axles through the propeller shafts. Within the axle assembly, the power is transmitted to the differential unit and branches to right and left and then to the axle shafts to drive the wheels through the final reduction assembly. Refer to "Power Train 1".

The front axle is fixed to the front frame by bolts. For the rear axle, a cradle pin support system is equipped, where the rear axle is supported by the rear frame using the axle supports at the front and rear sections.

The rear axle therefore oscillates the motion of the machine in accordance with the unevenness of the road surface, using the cradle pin at the front and rear as an axis.

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３ ‑119

COMPONENT OPERATION ／ AXLE ・Differential The differential turns the power from the reduction gear box in the rectangular direction and decreases the speed of the power to increase the torque. Further, when the machine swings or it travels on the rough road surface, the differential changes the left and right wheel speeds so that the machine can move smoothly.

Operation principle of differential When the machine travels in a beeline under the condition that the road surface on which the left and right wheels move are equal or when the load to be applied to the left and right wheels are equal, the same torque acts on the left and right side gears (2) within the differential case (4), the pinion (1) turn together with the differential case (4) and the left and right wheels turn at the same speed.

On the other hand, when the loads to be applied to the left and right wheels are different, for example, in swinging, the torque acting on the left and right side gears (2) are different and thereby each pinion (1) revolves round the side gear (2) of which the resistance is greater while it turns on the spider (5) to drive the other side gear (2) for performing the differential action.

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３ ‑120

COMPONENT OPERATION ／ AXLE ・Final Gear The torque from differential is transmitted to the final gear through the sun gear (3). The speed is reduced to increase the torque and then the torque is transmitted to the wheel.

Operation planetary gears The sun gear (3) meshes with the three planetary gears (5) and the planetary gears (5) mesh with the internal gear (6). The three planetary gears (5) are installed to the gear case (7) by the shafts (4) and the internal gear (6) is held to the housing through the pins.

When the torque from the differential rotates the sun gear (3), the planetary gears (5) rotate on the internal gear (6) while they rotate on the shafts (4). The rotation of the planetary gears (5) on the internal gear (6) drives the shaft (4) together with the gear case (7) to rotate the wheel.

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３ ‑121

COMPONENT OPERATION ／ BRAKE ・Service brake Service brake is operated 1.When the brake pedal (1) (either right or left) is depressed, the inching valve (2) operates to stop the HST pump from sending oil. Consequently the driving force is cut and the braking force is created. (HST Braking Function) 2.When the brake pedal (1) is further depressed, the push rod (3) operates to push the piston of the master cylinder (4). The oil pressure created by the piston is sent to the chamber (5) and pushes the piston (6) of brake assembly in the reduction gear box.

3.The service brake piston (6) is therefore moved, and the wet disk brakes (7) are pressed to create thte braking force.

The stop lamp switch (8) is also turned ON and so the stop lamp is turned ON.

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３ ‑122

COMPONENT OPERATION ／ BRAKE ・Service brake is released 1.When the brake pedal (1) is released (either right or left), the push rod (3) is returned to its original position and a piston in the master cylinder (4) is also returned to upward. Consequently the brake oil pressure in the chamber (5) is released.

2.The service brake piston (6) becomes free and the brake disks (7) are released.

3.At the same time, the HST pump inching valve (2) lever is returned to its original position and the inching (HST brake) function is released.

4.The stop lamp switch (8) is turned OFF and so the stop lamp is turned OFF.

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３ ‑123

COMPONENT OPERATION ／ BRAKE ・Parking brake The parking brake and the service brake use the same wet disk brake. It consists of HST charging hydraulic circuit (hydraulic pressure source) and electrical circuits including the parking brake switch and parking brake solenoid valve .

The parking brake switch on the right hand side of the meter panel operates the parking brake. ＜ Parking brake is applied ＞ 1.When the parking brake switch (9) is pushed to turn it on, the hydraulic oil in the parking brake cylinder chamber (11) is drained by the parking brake solenoid valve (10).

2.The parking brake piston (12) is moved to the left due to force of the spring (13) and the wet disk brake is applied through the service brake piston (6).

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３ ‑124

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COMPONENT OPERATION ／ BRAKE ＜ Parking brake is released ＞ 1.When the parking brake switch (9) is pushed to turn it off, pressurised oil is sent from HST inching valve to the parking brake cylinder chamber (11) by the parking brake solenoid valve.

2.he force of pressure raised oil in the chamber (11) overcomes the force of the spring (13) and moves the parking brake piston (12) to the right. Consequently the service brake piston becomes free and releases the wet disk brake (7).

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３ ‑125

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COMPONENT OPERATION ／ BRAKE ・How to Toe How to tow a vehicle (in an emergency) The parking brake is released by pressure raised oil. Therefore, when the engine is not running the parking brake cannot be released, because oil pressure to release parking brake is not created.

When the engine cannot be operated and the machine is to be towed, the parking brake can be released manually.

㪚㪘㪬㪫㪠㪦㪥 Do not tow a vehicle by compulsory (manual) release of the parking brake except in an emergency.

1.Remove the bolt ① (M10 x L55).

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The parking brake piston is pulled and it becomes released position so the vehicle can be moved.

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・Short circuit of HST pump hydraulic circuit 1.Loosen relief valves (2 locations) three times to cause short circuit between the high and low pressure sides.

㪚㪘㪬㪫㪠㪦㪥 Do not loosen more than three times to avoid oil leaks.

３ ‑126

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COMPONENT OPERATION ／ BRAKE ・Wet Bake Asembly in Rduction Gear Box In the reduction brake box, the wet brake assembly is equipped to the input shaft. It is used in both the service brake and parking brake operations.

Wet brake natural lubrication mechanism In this mechanism, oil in the reduction gear box splashes through the seal retainer ⑦ oil hole (section B) and lubricates the brake section.

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1-Cap 2-Piston housing 3-Wave spring 4-Brake disk 5-Brake plate 6-Brake housing 7-Seal retainer 8-End plate

9-Service brake piston 10-Disk hub 11-Spring 12-Input shaft 13-Parking brake piston

３ ‑127

COMPONENT OPERATION ／ BRAKE ・Master Cyinder The master cylinder is operated by the brake pedal and pressurized brake oil is sent to the wet disk brake in the reduction gear box.

This master cylinder has a brake oil reservoir.

㪮㪘㪩㪥㪠㪥㪞 Use the specified mineral brake oil in the reservoir of the master cylinder. DO NOT use automotive type brake oil (vegetable oil).

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３ ‑128

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COMPONENT OPERATION ／ Orbitrol ・Orbitrol（Power steering） The use of the steering wheel (turning it by hand) changes the oil passage using the power steering ass'y and the pressurized hydraulic oil caused by above makes the steering operation easy.

The power steering assembly consists of the control valve section and rotor section. When the steering wheel is turned, the spool in the power steering is turned to change the oil passage; this directs the oil to the steering cylinder. The rotor section is equipped under the control valve. In an emergency, it can be used as a hand pump to steer the machine manually.

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３ ‑129

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COMPONENT OPERATION ／ Orbitrol When the steering wheel is turned, the spool (4) also turns through the steering shaft, which makes an angular displacement in relation to the sleeve (3) to switch the oil passages. The oil is transferred to the steering cylinder through the rotor (1), where the sleeve (3) is rotated using the rotation of the rotor (1) which is transferred via the drive (2) and the pin (5). When the number of rotation of the sleeve (3) comes to that of the spool (4), the sleeve closes the oil passage and stops. In other words, the sleeve (3) performs a rotation which is identical to that of steering wheel (spool) in a continuous manner, which is referred to as steering operation. ・Emergency steering The power steering ass'y（Orbitrol）also acts as an emergency steering mechanism by which the steering operation is performed even when no pressurized oil supplied due to the defective pump or the engine stop.

・VP (Priority) valve The VP valve is a priority valve built in the power steering ass'y. This valve distributes the oil discharged from the main pump to the steering system and the shovel equipment.Also, the VP valve has a relief valve for the steering hydraulic circuit.

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・Load sensing valve When the steering wheel is in neutral position or the steering relief valve operates, most of the oil discharged from the main pump is sent to the shovel unit. When the steering wheel is turned, the amount of oil corresponding to the steering wheel turning is sent to the steering system and remaining oil is sent to the shovel equipment.

・Dynamic signal system The dynamic signal system is employed, where the LS line check valve and the CF line check valve are built in. Therefore kickback to the steering wheel can be prevented.

３ ‑130

COMPONENT OPERATION ／ Orbitrol ・Operation in neutral The oil discharged from the main pump is transferred to the port P. The oil, moreover, flows from the spool (8), through the LS check valve, the spool (4), the tank port T, and the return filter, to the oil tank.

At this time, the spool of the priority valve shifts to the right due to the force balance between the orifice and the control spring, thus almost the all oil discharged from the pump goes through the EF port.

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３ ‑131

COMPONENT OPERATION ／ Orbitrol ・Right turn When the steering wheel is turned right, the oil passage in the power steering ass y will shift as shown in the figure. The oil discharged from the main pump flows at first through two passages, one runs from the spool (8) to the spool (4) and the other runs from the LS check valve to the spool (4), then they merge with each other and go to the steering cylinder through the rotor (1). At this time, the spool of the priority valve shifts to the left due to the force balance between the orifice and the control spring. The displacement of the spool (4) is determined by the rotating angle of the steering wheel. An oil quantity corresponding to the rotating angle is fed to the steering wheel, and the remaining oil is fed to the control valve.

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３ ‑132

COMPONENT OPERATION ／ Orbitrol ・When relief valve activated When the steering cylinder reaches the stroke ends or the setting pressure predetermined by the relief valve (9) but it is tried to be turned further, the relief valve (9) initiates its operation. The oil discharged from the main pump flows to the tank through the orifice in the sleeve (8) and the relief valve.

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３ ‑133

COMPONENT OPERATION ／ Control Valve ・Control Valve The control valve consists of the inlet section (7), lift plunger section (2), tilt plunger section (3) and outlet section (1). It is a 2-plunger valve which controls the direction of the flow and the pressure of the oil discharged from the main pump to operate the bucket and lift arm. ・Relief valve This control valve equips main relief valve (4), which is installed in inlet section. The main relief valve (4) controls the pressure in the shovel circuit to 20.6 MPa maximum.

The overload relief valves are installed to the cylinder port which connects with the rod and the bottom side of the tilt cylinder. When a great external force is applied to the bucket and an excessively high pressure is created in the tilt cylinder through the link, the overload relief valves (5) operate at a pressure of 22.6 MPa to prevent each device from being damaged. Each overload relief valve also acts as a check valve. ・Detent mechanism As a detent mechanism for this valve, an electromagnetic detent (auto-leveler) is equipped to the tilt plunger section.

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1-Outlet section 2-Lift plunger section 3-Tilt plunger section 4-Main relief valve 5-Overload relief valve 6-Anti-void valve 7-Inlet section 8-Electromagnetic Detent

A1-To rod side of tilt cylinder (Bucket dump) A2-To rod side of lift cylinder (Lift arm lowering) B1-To bottom side of tilt cylinder (Bucket tilt back) B2-To bottom side of lift cylinder (Lift arm raising) P-From pump T-To oil tank (to return filter)

３ ‑134

COMPONENT OPERATION ／ Control Valve ・Operation The control lever changes the passage of the oil by sliding each spool and sends the pressurized oil from the VP valve to the selected tilt cylinder or lift cylinder.

The detent mechanism is equipped to the lift spool. So when the control lever is moved to the "FLOAT" position, the control lever is automatically held and the spool not returned to "NEUTRAL" even when the hand is released from the level.

The electromagnetic detent mechanism is equipped to the tilt spool. So when the control lever is moved to the "TILT BACK" position from the condition in which the bucket is dumped, the control lever is electrically held and the spool not returned to "NEUTRAL" until the bucket automatic leveler is actuated even when the hand is released from the lever.

When the control lever is moved to other positions, the control lever returns automatically to the "NEUTRAL" position.

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COMPONENT OPERATION ／ Control Valve ・Oil flow in TILT plunger section NEUTRAL position of the TILT and LIFT sections １．As the spools of the the tilt and lift sections are in the "NEUTRAL", the cylinder ports at both A (Rod side) and B (Bottom side) are closed by the spools. ２．The oil is sent to the control valve that passes from the inlet section through the neutral passage (3) of the tilt section and lift section, then it goes out from the drain passage (4) to the oil tank.

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３ ‑136

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COMPONENT OPERATION ／ Control Valve TILT BACK

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１．When the control lever is moved to "TILT BACK" position, the tilt spool is moved as shown in the figure. ２．Because of this movement, the spool closes the neutral circuit (3), and the pressurized oil opens the load check valve (1). Then the pressurized oil is sent to the bottom side of the tilt cylinder through the port B1. ３．Further, the oil from the rod side of the tilt cylinder is sent to the oil tank through the port A1 and the drain passage (4).

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1-Load check valve 2-Oil discharged from the pump 3-Neutral passage to the lift section 4-Drain passage to the oil tank

３ ‑137

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COMPONENT OPERATION ／ Control Valve DUMP

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１．When the control lever is moved to "DUMP" position, the tilt spool is moved as shown in the figure. ２．Because of this movement, the spool closes the neutral circuit (3), and the pressurized oil opens the load check valve (1). Then the pressurized oil is sent to the rod side of the tilt cylinder through the port A1. ３．Further, the oil from the rod side of the tilt cylinder is sent to the oil tank through port B1 and the the drain passage (4).

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３ ‑138

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COMPONENT OPERATION ／ Control Valve ・Oil flow in LIFT plunger section NEUTRAL position of the TILT and LIFT sections １．As the spools of the the tilt and lift sections are in the "NEUTRAL", the cylinder ports at both A (Rod side) and B (Bottom side) are closed by the spools. ２．The oil is sent to the control valve that passes from the inlet section through the neutral passage (3) of the tilt section and lift section, then it goes out from the drain passage (4) to the oil tank.

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３ ‑139

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COMPONENT OPERATION ／ Control Valve ・Oil flow in LIFT plunger section RAISE positions １．When the control lever is moved to "RAISE" position, the tilt spool is moved as shown in the figure. ２．Because of this movement, the spool closes the neutral circuit (3), and the pressurized oil opens the load check valve (1). Then the pressurized oil is sent to the bottom side of the lift cylinder through the port B2. ３．Further, the oil from the rod side of the lift cylinder is sent to the oil tank through the port A2 and the drain passage (4).

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３ ‑140

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COMPONENT OPERATION ／ Control Valve ・Oil flow in LIFT plunger section LOWER positions １．When the control lever is moved to "LOWER" position, the tilt spool is moved as shown in the figure. ２．Because of this movement, the spool closes the neutral circuit (3), and the pressurized oil opens the load check valve (1). Then the pressurized oil is sent to the rod side of the lift cylinder through the port A2. ３．Further, the oil from the rod side of the lift cylinder is sent to the oil tank through port B2 and the the drain passage (4).

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３ ‑141

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COMPONENT OPERATION ／ Control Valve ・Oil flow in LIFT plunger section FLOAT position １．When the control lever is pressed down from the "LOWER" to "FLOAT" position, the lift spool is moved as shown in the figure. ２．Because of this movement the neutral circuit (3) is opened and the pressurized oil flows as in the neutral condition. Also both the cylinder ports A2 and B2 are connected to the low-pressure oil passage. Therefore the lift arm is freely moved up and down according with any uneven surface of the road. At that time, the oil flows freely through the low pressure oil passage in the control valve so that the oil discharged from the rod side of the lift cylinder is sent to the bottom side and the oil discharged from the bottom side of the lift cylinder is sent to the rod side.

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３ ‑142

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COMPONENT OPERATION ／ Control Valve ・Detent operation Lift plunger section １．When the control lever is pushed forward to set it in the "FLOAT" position, the lift spool (1) is fully pulled. At the same time the detent pin (2) installed to the spool end is moved and 4-pieces of the detent balls (3) are dropped into the groove on the detent sleeve (4). ２．As the detent balls (3) are pushed by the detent spring (5), the lift spool (1) is held in "FLOAT" position and the detent mechanism is activated. ３．When the detent operation is cancelled, pull the control lever. The detent ball (3) exits the groove and the detent operation is cancelled.

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Tilt plunger section １．For the detent mechanism on the tilt spool section, an electromagnetic detent mechanism has been equipped. For the electric circuit, the current goes from the battery to the proximity switch on the auto-lever through the coil assembly (4) in the tilt section. ２．When the bucket is tilted forward from the level position, the proximity switch is closed and acts the coil assembly (4). ３．When the control lever is moved fully to the "TILT BACK" direction, the tilt spool is pressed in to the end. At the same time the pin (2) attached to the spool end is pressed in, so that the plate (3) touches the coil (4). Therefore the tilt spool (1) position is held and the detent mechanism is activated. ４．When the detent operation is cancelled, operate the control lever manually to cancel.

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３ ‑143

COMPONENT OPERATION ／ Control Valve ・Relief valve This control valve has one main and two port relief valves. The main relief valve is equipped between the neutral passage in the inlet section and the low-pressure passage. The 2-port relief valves are equipped, one is between the rod side of the tilt cylinder port and the low-pressure passage, another one is between the bottom side of tilt cylinder port and the low-pressure passage.

Main Relief Valve The main relief valve is located in the circuit between port P (the pump side port) and port T (the hydraulic oil tank side port) and prevents the loader circuit pressure from increasing more than the set pressure.

The oil pressure in port P acts on pilot poppet (8) via orifice (2) in main poppet (1) and orifice (7) in sleeve (6). If the oil pressure in the loader circuit increases more than the set pressure by spring (9), pilot poppet (8) opens so that a small quantity of the pressure oil flows to port T through the outer diameter of sleeve (3). Then, a differential pressure arises between port P and spring chamber (5) as orifice (2) is provided. If the differential pressure increases so that main poppet (1) is pushed to the right by a force greater than spring (4) force, main poppet (1) opens, allowing the pressure oil to flow from port P directly to port T. When the oil pres-sure in port P decreases, main poppet (1) is closed again by spring (4) force.

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３ ‑144

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COMPONENT OPERATION ／ Control Valve Overload Relief Valve The overload relief valve is located in the circuit be-tween the cylinder and port T (hydraulic oil tank side port) and prevents the circuit oil pressure from being increased excessively even if the cylinder is forcibly moved by external force.

The oil pressure in the cylinder acts on pilot poppet (5) through the passage in poppet valve (1). If the oil pressure increases more than the set pressure by spring (6), pilot poppet (5) opens so that a small quantity of the pressure oil flows to port T through the outer diameter of sleeve (3). Then, a differential pressure arises between the cylinder side port and chamber (4). Then, poppet valve (1) is pushed to the right so that main poppet (2) opens, allowing the pressure oil to flow from the cylinder side port to directly port T. In addition, this overload relief valve draws hydraulic oil from port T (hydraulic oil tank side) when the cylinder circuit pressure becomes negative, preventing the occurrence of cavitation in the cylinder circuit (Anti-void valve)

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３ ‑145

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COMPONENT OPERATION ／ Control Valve ・Anti-void valve When a negative pressure is created on the rod side of the lift cylinder, the anti-void valve refill the rod side directly with the oil in the tank port.

Operation １．The oil from the cylinder port HP is sent into the anti-void valve through the hole in the poppet (1).The poppet (1) is positioned as shown due to the difference in area between (A) and (B).

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㧝 ２．When the pressure in the cylinder port HP is lower than in the tank port LP, the poppet (1) moves to the right due to the difference in area between (A) and (B).At this time, sufficient oil flows to the cylinder port HP from the tank port LP to prevent a cavitation in the cylinder.

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３ ‑146

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COMPONENT OPERATION ／ Main pump ・Main Pump The main pump is a double gear pump with the main pump coupled with the charging pump. This pump, installed to the HST pump via the coupling, rotates with the engine. The main pump doubles as a steering pump. The main pump sucks up hydraulic fluid from the hydraulic fluid tank and supplies it to the orbitroll (VP valve). Hydraulic fluid is split into the main hydraulic circuit and steering hydraulic circuit by the orbitroll (VP valve). With the main charging pump operated, the hydraulic fluid in the hydraulic fluid tank fills the space made of the gear bottom and inside walls of housings (9) and (17) by suction power generated when the drive gear (1) engaged with the driven gear (8) and drive gear (15) engaged with driven gear (18) rotate. The hydraulic fluid is pushed out to the discharge side when engagement of gears starts again. The main pump, to prevent oil leaks from the clearance between gears and side plates by high pressure, uses bushings (7) and (16) to achieve pressure balance and make the clearance smaller by leading discharge pressure to surfaces of the bushings (7) and (16), resulting in increased pump efficiency (volume efficiency).

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COMPONENT OPERATION ／ Main pump ・Return Filter The return filter is installed in the return circuit to the oil tank to remove fine dust including in the oil, which could not be removed by the suction strainer. The oil returning from the steering circuit and shovel circuit enters the cartridge through the inlet port, passes through the filter, and is sent to the oil tank through the outlet port.

If the pressure in the inlet port increases and the pressure difference from the outlet port becomes 0.14Mpa when the filter clogged or the oil temperature is low, the bypass valve is opened and the oil is sent directly from the inlet port to the outlet port without passing through the filter.

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３ ‑148

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SECTION 4 OPERATIONAL PERFORMANCE TEST − CONTENTS − Introduction OPERATIONAL PERFORMANCE TEST.................4-150 PREPARATION FOR PERFORMANCE TESTS..........4-151

Wheel Loader Test Engine Speed ............................................4-152 Engine Compression Pressure.....................4-153 Valve Clearance...........................................4-154 Nozzle...........................................................4-156 Travel Speed................................................4-158 Service Brake Capacity................................4-160 Parking Brake Capacity................................4-161 Hydraulic Cylinder Cycle Time......................4-162 HYDRAULIC CYLINDER CYCLE TIME.......4-164 Control Lever and Pedal Stroke....................4-165 Main Relief Valve Set Pressure....................4-166 Steering Relief Set Pressure.........................4-167 HST Main Pressure......................................4-168 Performance Standard Table........................4-172

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OPERATIONAL PERFORMANCE TEST / Introduction OPERATIONAL PERFORMANCE TEST Measurement of performance is a work to keep track of the function levels of each part in a quantitative manner.

Kinds of Tests 1. Base machine performance test is to check the operational performance of each system such as engine, travel, and hydraulic cylinders.

2. Hydraulic component unit test is to check the operational performance of each component such as hydraulic pump, motor, and various kinds of valves.

Purpose of Performance Tests 1. To comprehensively evaluate each operational function by comparing the performance test data with the standard values.

2. According to the evaluation results, repair, adjust, or replace parts or components as necessary to restore the machine's performance to the desired standard.

3. To economically operate the machine under optimal conditions.

Performance Standards Performance Standard is shown in tables to evaluate the performance test data.

Precautions for Evaluation of Test Data 1. To evaluate not only that the test data are correct, but also in what range the test data are.

2. Be sure to evaluate the test data based on the machine operation hours, kinds and state of work loads, and machine maintenance conditions.

The machine performance does not always deteriorate as the working hours increase.

However, the machine performance is normally considered to reduce in proportion to the increase of the operation hours. Accordingly, restoring the machine performance by repair, adjustment, or replacement shall consider the number of the machine's working hours.

Term definitions Definition of "Performance Standard" 1. Operation speed values and dimensions of the new machine.

2. Operational performance of new components adjusted to specifications. Allowable errors will be indicated as necessary.

Operational performance limit 1. A condition in which to perform general operations is difficult 2. A condition in which repair/adjustment work is difficult to carry out 3.A condition in which repair/adjustment is impossible Thus, an appropriate maintenance operation is required before it reaches the operational limit, from the viewpoint of machine availability and maintenance cost.

４ ‑150

OPERATIONAL PERFORMANCE TEST / Introduction PREPARATION FOR PERFORMANCE TESTS Observe the following rules in order to carry out performance tests accurately and safely.

THE MACHINE 1. Repair any defects and damage found, such as oil or water leaks, loose bolts, cracks and so on, before starting to test.

2. A condition in which repair/adjustment is impossible Thus, an appropriate maintenance operation is required before it reaches the operational limit, from the viewpoint of machine availability and maintenance cost.

TEST AREA 1. Select a hard and flat surface.

2. Secure enough space to allow the machine to run straight more than 50 m (164 ft), and to make a steering.

3. Please keep sufficient space for steering.

4. Please prepare apparatuses・instruments suitable for the desired measurements.

5. If required, rope off the test area and provide signboards to keep unauthorized personnel away.

6.Please prepare weights for measurement or equivalent heavy objects

4. Avoid polluting the machine and the ground with leaking oil. Use oil pans to catch escaping oil. Pay special attention to this when removing hydraulic piping.

MAKE PRECISE MEASUREMENT 1.Accurately calibrate test instruments in advance to obtain correct data.

2. Carry out tests under the exact test conditions prescribed for each test item.

3. Repeat the same test and confirm that the test data obtained can be produced repeatedly.

Use average values of measurements if necessary.

4.Please exert any efforts to improve your measurement skills.

７ §Well communicate with one after another in advance with cues, before a collaborative operation is performed.

PRECAUTIONS 1. Before starting to test, agree upon the signals to be employed for communication among coworkers. Once the test is started, be sure to communicate with each other using these signals, and to follow them without fail.

2. Operate the machine carefully and always give first priority to safety 3. While testing, always take care to avoid accidents due to landslides or contact with highvoltage power lines. Always confirm that there is sufficient space for full swings.

４ ‑151

OPERATIONAL PERFORMANCE TEST / Engine Engine Speed Summary: 1. Measure the engine speed.

Measure the engine speed before performing all 㪥㪦㪫㪜

other tests to check that the engine speed meets specification. Because, if the engine speed is not adjusted correctly, all other performance data will be unreliable.

Preparation: 1. Install speed pickup (1) on injection pipe (2).

2. Warm up the machine until the engine coolant temperature reaches 50 ℃ (122 °F) or more, and hydraulic oil temperature is 50 ± 5 ℃ (122 ± 9 °F).

Make sure that when the engine is running

㪥㪦㪫㪜 at the slow idle or at the fast idle, governor

lever (4) touches stopper bolt (3) or stopper bolt (5) respectively beforehand.

Measurement: 1. Measure the slow and fast idle speeds.

2. Start the engine. Select the parking brake switch, accelerator pedal, and FNR shift lever positions as shown below.

3. Measure the engine speeds while operating the accelerator pedal.

4. Repeat measurement three times and calculate the average values.

Evaluation: Refer to the Performance Standard Table Remedy: Refer to the Troubleshooting

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４ ‑152

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OPERATIONAL PERFORMANCE TEST / Engine Engine Compression Pressure Summary: 1. Measure compression pressure in the cylinders to check for a decline in engine power.

2. Check exhaust gas color. Keep track of engine oil consumption.

3. Check for any abnormalities in the intake system including the air cleaner.

Preparation: 1. Confirm that valve clearances are within specifi-cations.

2. Charge the batteries properly.

3. Warm up the engine until the coolant temperature is in the operating range.

4. Stop the engine. Remove the glow plugs from each cylinder.

5. Install an adapter and pressure gauge in the glow plug hole. (Securely install it so that air does not leak.)

Measurement: 1. Rotate the starter to crank the engine.

Measure the compression pressure in each cylinder.

2. Repeat measurement three times for each cylinder and calculate the average values.

Evaluation: Refer to the Performance Standard Table Remedy: Refer to the Troubleshooting

４ ‑153

OPERATIONAL PERFORMANCE TEST / Engine Valve Clearance Summary: 1. Perform measurement when the engine is cold.

2. Before starting work, clean the head cover mounting area to prevent contaminating the engine.

Preparation: 1. Locate top dead center (TDC) in the compression stroke.

Align the 1.4TC mark on the crank pulley with the pointer on the timing gear case.

Piston No.1 (or piston No.4) is now positioned at TDC in its compression stroke.

2. Remove the head cover (after cleaning).

3. When both the intake and exhaust valves on cylinder No.1 are closed, piston No.1 is positioned at the TDC in its compression stroke. (When both the intake and exhaust valves are closed on cylinder No.4, piston No.4 is positioned at TDC in its compression stroke.) Start measurement from cylinder No.1 or No.4 positioned at the TDC in its compression stroke.

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Measurement: 1. Insert a feeler gauge into the clearance between the rocker arm and the valve stem end to measure the valve clearance.

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４ ‑154

OPERATIONAL PERFORMANCE TEST / Engine 2. When measurement is started from cylinder No.1, perform the same measurement to all

cylinder No.4, perform the same measurement to all valves indicated with

valves indicated with mark ● in the following table after measuring cylinder No.1. (When measurement is started from

mark ○ in the following table after measuring cylinder No.4.)

No.1

Cylinder No. Valve Location When measurement is started from cylinder No.1 When measurement is started from cylinder No.4

No.2

I

E

I

●

●

●

No.3 E

I

No.4 E

I

E

○

○

● ○

○

3. After rotating the crank shaft 360 ?, align the TDC mark with the pointer. Then, continue measuring the other valves in the same manner.

Evaluation: Refer to the Performance Standard Table Adjustment: Please perform the adjustment with a procedure similar to the measuring method, if it has not standard dimensions.

1. Loosen the adjusting screw lock nuts for the rocker arms. Insert the feeler gauge set of the standard size, and adjust the adjusting screws.

2. After adjusting, retighten the lock nut to specification. Recheck the valve clearance after tightening the lock nut.

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４ ‑155

OPERATIONAL PERFORMANCE TEST / Engine Nozzle Summary: 1. Check the injection pressure and the spray pattern with a nozzle tester.

2. Before starting the check, clean the nozzle holder mounting area to prevent contaminating the engine.

Preparation: 1. Remove the nozzle holders.

Remove all nozzle holders and fuel injection pipes from the engine.

2. Attach the nozzle holder.

Attach the nozzle holder removed from the engine to the nozzle tester.

Measurement: 㪚㪘㪬㪫㪠㪦㪥 Never touch the spray directly. The fuel spray from the nozzle may penetrate the skin and can cause gangrene. If fuel penetrates into the blood stream, contact a doctor immediately as it may cause blood toxicosis.

1. Injection Pressure Check After attaching the nozzle holder to the nozzle tester, strongly make several strokes of the tester to inject fuel. Then, while operating the tester at approx. 60 times a minutes, measure the fuel injection pressure. If adjustment is required, loosen the lock nut and adjust the pressure by turning the adjusting screw. Turn the screw clockwise to increase the pressure, and counterclockwise to decrease the pressure.

2. Spray Pattern Check After attaching the nozzle holder to the nozzle tester, strongly make several strokes of the tester to check the spray pattern. For this test, avoid using the pressure gauge. 㪠㪤㪧㪦㪩㪫㪘㪥㪫

Use only clean diesel oil.

４ ‑156

OPERATIONAL PERFORMANCE TEST / Engine Evaluation: 1. Standard Injection Pressure Refer to the Performance Standard Table

Normal 2. Spray pattern ・Large-size spray should not be visible to the naked eye. ・During initial injection stage, fine size spray should be injected intermittently. ・Sideways spray should not be visible. ・No drips should be found after injection. ・Injection spray angle must be normal.

Abnormal

Adjustment: ・If adjustment is required, loosen the lock nut and adjust the pressure by turning the adjusting screw.

Turn the screw clockwise to increase the pressure, and counterclockwise to decrease the pressure. ・After adjusting, retighten the lock nut.

４ ‑157

OPERATIONAL PERFORMANCE TEST /System performance Travel Speed Summary: Measuring travel time checks overall performance of the travel driving system (between the HST pump and the HST motor).

Preparation: 1. Inflate all tires to equal air pressure: Air Pressure: 220 kPa(2.2 kgf/cm2)

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2. Prepare a level and solid test track 20 m (65 ft) straight with an extra length of 20 m (65 ft) on both ends for acceleration and deceleration.

3. Hold the empty bucket 0.4 m (1.3 ft) above the ground with the lift arm.

4. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F) 5. Please also sufficiently warm up the oils for axle and reduction.

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４ ‑158

OPERATIONAL PERFORMANCE TEST /System performance Measurement:

CAUTION:Avoid measurement in reverse travel operation, as it is too dangerous.

1. Measure in each mode (slow and fast).

2. Select the switch positions as follows: 3.Start traveling the machine from the acceleration zone with the FNR shift lever in the forward position and the accelerator pedal at full stroke.

Measure the time (sec) required to travel 20 m (65 ft) in each travel mode.

4.Repeat the measurement three times in both travel modes and calculate the average value.

5.Covert the measured value to the value in km/h unit using the following formula: Measure Value = S (sec) Converted Value = A (km/h) A = (20 × 3600)/(S × 1000)

Evaluation: Refer to the Performance Standard Table Remedy: Refer to Troubleshooting

４ ‑159

OPERATIONAL PERFORMANCE TEST /System performance Service Brake Capacity Summary: 1. Overall performance of the service brake is checked.

2. The service brake capacity test is a maintenance item. Be sure to perform this test.

3. In regards to braking performance, the distance required for stoppage is specified in accordance with the regulation for special small vehicle, Load Vehicles Act - Safety Criteria.

Preparation: 1. Inflate all tires to equal air pressure: Air Pressure:220 kPa(2.2 kgf/cm2) 2. Prepare a dry surface test track 50 m (164 ft) straight. Set a brake apply position along the test track.

3. Hold the empty bucket 0.4 m (1.3 ft) above the ground with the lift arm.

4. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

Measurement:

CAUTION:Avoid measurement in reverse travel operation, as it is too dangerous.

1.Measure in the fast speed mode.

2.Start traveling the machine from the acceleration zone with the FNR shift lever in the forward position and the accelerator pedal at the full stroke. Drive the machine at 15 km/ h (9.3 mph).

3. Step on the right (service) brake pedal at the brake apply position.

4.After the machine stops, measure the distance from the brake apply position to the front tire ground contact position.

5.Repeat measurement three times and calculate the average value.

Evaluation: Refer to the Performance Standard Table Remedy: Refer to Troubleshooting

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４ ‑160

OPERATIONAL PERFORMANCE TEST /System performance Parking Brake Capacity Summary: 1. The parking brake capacity is measured on the specified slope.

2. The parking brake capacity test is a maintenance item. Be sure to perform this test.

3. In regards to parking brake, its performance on slope with 20 % (11.31 degrees) inclination is specified in the regulation for special small vehicle, Load Vehicles Act - Safety Criteria.

Preparation: 1. After climbing the slope, turn the parking brake switch ON. 2. Stop the engine.

3. After the machine stops, put a mark line on a tire and the slope surface.

4. 5 minutes later, measure distance from the mark line on the slope surface to the marked tire.

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Evaluation: Refer to the Performance Standard Table

４ ‑161

OPERATIONAL PERFORMANCE TEST /System performance Hydraulic Cylinder Cycle Time Summary: 1. Overall hydraulic cylinder system (between the loader steering pump and all hydraulic cylinders) performance is checked by measuring the cycle time of the lift arm, bucket, and steering cylinders.

2. The bucket should be empty.

Preparation: 1. Position the front attachment as follows: （１）When measuring the lift cylinder: Lower the lift arm so that the bucket bottom is parallel to the ground surface.

Lift Cylinder （２）When measuring the tilt cylinder: Raise the lift arm to the maximum height position.

（３）When measuring the steering pump: Hold the front attachment in the traveling position with the bucket empty.

2. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

４ ‑162

Tilt Cylinder

OPERATIONAL PERFORMANCE TEST /System performance Measurement: 1. Accelerator Pedal:Full Stroke(Engine at Fast Idle),Parking Brake Switch:ON,FNR Shift Lever:N(Neutral) 2. Operate each cylinder as follows (including the cushion stroke range): (1) When measuring the lift cylinder: While moving the lift arm lever full stroke, measure the time required to raise or lower the lift arm. In addition, measure the time required to lower the lift arm from the maximum raised position to the ground with the lift arm lever in the FLOAT position.

(2) When measuring the tilt cylinder: While moving the tilt lever full stroke, measure the time required to tilt or dump the bucket.

(3) When measuring the steering pump: While turning the steering wheel full stroke, measure the time required to fully steer the machine from the right to the left and vice versa.

3.

Repeat measurement three calculate the average value.

times

and

Evaluation: Refer to the Performance Standard Table Remedy: Refer to Troubleshooting

４ ‑163

OPERATIONAL PERFORMANCE TEST /System performance Dig Function Drift Summary: 1. The measurement should be performed on the machine with the standard front attachment (standard bucket).

2. When measuring the dig function drift just after cylinder replacement, operate each cylinder full stroke to purge any trapped air prior to measuring.

Preparation: 1. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

Measurement: 1. Stop the engine.

2. After 5 minutes, measure the lift arm and tilt cylinder retractions and the amount of the bucket drift.

3. Repeat measurement three times and calculate the average value.

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Evaluation: Refer to the Performance Standard Table

A1 − A2 ＝ Lift cylinder retractions

Remedy: Refer to Troubleshooting

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A1 − A2 ＝ Tilt cylinder retractions

４ ‑164

OPERATIONAL PERFORMANCE TEST /System performance Control Lever And Pdal Stroke Summary: 1. Each control lever and pedal stroke, and turning numbers of the steering wheel are measured.

2. Lever and pedal strokes should be measured at the top of each lever grip. Measure the pedal stroke from the neutral position to the stopper at the pedal center.

3. When lever stroke has play in neutral, measure the distance from the center of the play to the stroke end.

Preparation: 1. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

Measurement: 1. Stop the engine.

2. Measure the stroke of the lift arm, bucket, or FNR shift lever from each lever neutral position to the stroke end at the top of the lever grip.

3. Measure the pedal stroke from the neutral position to the stroke end at the top face of the pedal.

4. Measure how many turns are needed when the steering wheel is rotated from the right stroke end to the left stroke end or vice versa.

5. Take the measurements of straight stroke distances.

6. Repeat each measurement three times and calculate the average value.

Evaluation: Refer to the Performance Standard Table

４ ‑165

OPERATIONAL PERFORMANCE TEST /System performance Main Relief Valve Set Pressure Summary: The main relief pressure (set pressure of the main relief valve on the control valve) of the loader circuit is measured.

Preparation: 1. Stop the engine.

2. Push the pressure release button on the hydraulic oil tank to release air pressure.

3. Install the oil pressure gauge to the outlet port for the tilt cylinder.

4. Start the engine. Check the pressure gauge connection for any oil leaks.

5. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

Measurement: 11.Accelerator Pedal:Full Stroke(Engine at Fast Idle),Parking Brake Switch:ON,FNR Shift Lever:N(Neutral) 2. Slowly operate each control lever of the lift arm and bucket. Move each cylinder to the stroke end to relieve each function. Measure the pressure while each function is relieving.

3. Repeat each measurement three times and calculate the average value.

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Adjustment: After loosening the lock nut, turn the adjusting screw.

1. Loosen the lock nut.

2. Turn the adjusting screw.

Tightening (turn right): Oil pressure increase Loosen (turn left): Oil pressure decrease 3. Tighten the lock nut.

4. Recheck the set pressure after adjustment.

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Evaluation: Refer to the Performance Standard Table

NOTE: If the measured relief pressures in all circuits are lower than specification, the probable cause may be a reduction in the set pressure of the main relief valve. If the measured relief pressure is different in only a particular circuit, the probable cause is other than the main relief valve.

４ ‑166

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OPERATIONAL PERFORMANCE TEST /System performance Steering Relief Set Pressure Summary: The relief pressure in the steering circuit is measured.

1. Stop the engine.

2. Push the pressure release button on the hydraulic oil tank to release air pressure.

3. Install the oil pressure gauge to the outlet port for the steering cylinder.

4. Start the engine. Check the pressure gauge connection for any oil leaks.

5. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

Measurement: 1.Accelerator Pedal:Full Stroke(Engine at Fast Idle),Parking Brake Switch:ON,FNR Shift Lever:N(Neutral) 2. Turn the steering wheel to either right or left stroke end to relieve the steering pressure.

3. Repeat each measurement three times and calculate the average value.

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Evaluation: Refer to the Performance Standard Table

４ ‑167

OPERATIONAL PERFORMANCE TEST /System performance HST Main Pressure Summary: Measure the AU control pressure of the HST pump Preparation: 1. Stop the engine.

2. Install the oil pressure gauge to the Q2 port of HST pump.

3. Install the tachometer to the engine.

4. Start the engine. Check the pressure gauge connection for any oil leaks.

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5. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

Measurement: 1. Measure the AU control pressure for the engine speed.

Evaluation: Refer the performance curve of HST pump.

HST pump DA control pressure Summary: Measure the AU control pressure of the HST pump 1. Stop the engine.

2. Install the oil pressure gauge to the PS port of HST pump.

3. Install the tachometer to the engine.

4. Start the engine. Check the pressure gauge connection for any oil leaks.

5. Maintain the hydraulic oil temperature at 50 ±

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5 ℃ (122 ± 9°F).

Measurement: 1. Measure the ＤA control pressure for the engine speed.

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Evaluation: Refer the performance curve of HST pump.

４ ‑168

OPERATIONAL PERFORMANCE TEST /System performance HST pump low-pressure relief pressure (YUKEN） Summary: Measure the oil pressure in the low-pressure (charging) circuit.

Preparation: 1. Stop the engine.

2. Install the oil pressure gauge to the G port of HST pump.

3. Start the engine. Check the pressure gauge connection for any oil leaks.

Measurement: 1.Accelerator Pedal:Full Stroke(Engine at Fast Idle),Parking Brake Switch:ON,FNR Shift Lever:N(Neutral) 2. Repeat each measurement three times and calculate the average value.

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Evaluation: Refer the performance curve of HST pump.

HST pump low-pressure relief pressure (UCHIDA)

Summary: Measure the oil pressure in the low-pressure (charging) circuit.

Preparation: 1. Stop the engine.

2. Install the oil pressure gauge to the V port of HST pump.

3. Start the engine. Check the pressure gauge connection for any oil leaks.

Measurement: 1.Accelerator Pedal:Full Stroke(Engine at Fast Idle),Parking Brake Switch:ON,FNR Shift Lever:N(Neutral) 2. Repeat each measurement three times and calculate the average value.

Evaluation: Refer the performance curve of HST pump.

４ ‑169

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OPERATIONAL PERFORMANCE TEST /System performance HST pump high-pressure relief pressure (YUKEN)

Summary: Measure the oil pressure in the high-pressure circuit.

Preparation: 1. Stop the engine.

2. Install the oil pressure gauges to the ports of HST pump.

Port A: Forward Port B: Backward 3. Put the bucket on a tough wall made of concrete or equivalent, to lock the vehicle in position.

4. Start the engine. Check the pressure gauge connection for any oil leaks.

5. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

Measurement: 1. Change the shift lever to Forward.

2. Gradually increase the engine speed up to the maximum speed (full stroke), then measure.

3. Repeat the above procedure for backward.

Evaluation: Refer to the Performance Standard Table

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４ ‑170

OPERATIONAL PERFORMANCE TEST /System performance HST pump high-pressure relief pressure (UCHIDA)

Summary: Measure the oil pressure in the high-pressure circuit.

Preparation: 1. Stop the engine.

2. Install the oil pressure gauges to the ports of HST pump.

Gauge port MA: Forward Gauge port MB: Backrward 3. Put the bucket on a tough wall made of concrete or equivalent, to lock the vehicle in position.

4. Start the engine. Check the pressure gauge connection for any oil leaks.

5. Maintain the hydraulic oil temperature at 50 ± 5 ℃ (122 ± 9°F).

Measurement: 1. Change the shift lever to Forward.

2. Gradually increase the engine speed up to the maximum speed (full stroke), then measure.

3. Repeat the above procedure for backward.

Evaluation: Refer to the Performance Standard Table

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４ ‑171

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OPERATIONAL PERFORMANCE TEST / Standard This table lists the performance standard table.

Description

Unit

Standard Performance

Note

Engine Speed Slow Idle Speed

ｒｐｍ

950〜1100

Fast Idle Speed

ｒｐｍ

2600〜2750

Engine Compression Pressure(After warming up operation)

kPa(PSI)

3.2〜3.7（469〜540）

Valve Clearance (IN, EX)

in

0.01

Nozzle Injection Pressure

MPa(PSI)

22.6（3271）

Fast Speed

MPH

9.32〜9.94

Slow Speed

MPH

4.97±0.31

Service Brake Capacity

in

78.74

Parking Brake Capacity

in/5 min

With the engine coo

Travel Speed

0

Hydraulic Cylinder Cycle Time Lift Arm Raise

sec

5.0±0.5

Lift Arm Lower

sec

3.2±0.3

Lift Arm Float

sec

3.0

Bucket Tilt

sec

1.4±0.3

Bucket Dump

sec

1.2±0.3

Right Steering (Engine Slow/Fast Idle)

sec

≦2.1/≦1.7

Left Steering (Engine Slow/Fast Idle)

sec

≦1.8/≦1.4

Lift Arm Cylinder

in

≦0.31

retractions

Bucket Cylinder

in

≦0.35

retractions

Lift Arm Lever (Raise)

lbf

≦54

Lift Arm Lever (Lower)

lbf

≦54

Lift Arm Lever (Lower Detent/Release Detent)

lbf

≦97/≦39

Bucket Lever (Tilt)

lbf

≦54

Bucket Lever (Dump)

lbf

≦54

FNR Shift Lever

lbf

≦22

Accelerator Pedal

lbf

≦22

Dig Function Drift (mm/5 min)

Control Lever and Pedal Operating Force

４ ‑172

OPERATIONAL PERFORMANCE TEST / Standard Description

Unit

Standard Performance

Note

Lever and Pedal Stroke Lift Arm Lever

in

2.76

Lift Arm Lever (Float)

in

4.33

Bucket Lever

in

2.36

FNR Shift Lever

in

1.57

Accelerator Pedal

deg

48.5〜33.6

Service Brake Pedal

deg

≦55

Steering Wheel (Turn Right/ENG̲MAX)

rev

4.5

End〜End

Steering Wheel (Turn Left/ENG̲MAX)

rev

3.2

End〜End

Main Relief Valve Set Pressure Lift Arm Relief

MPa(PSI) 20.6±1.0(2986±142)

Bucket Relief

MPa(PSI) 20.6±1.0(2986±142)

Steering Relief Set Pressure

MPa(PSI) 17.2±1.0(2489±142)

HST pump pressure relief pressure (HST pump manufactured by YUKEN, 1001 to 4499) high-pressure relief pressure

MPa(PSI) 38.2±2.7(5546±398)

low-pressure relief pressure

MPa(PSI)

1.57(228)

HST pump pressure relief pressure (HST pump manufactured by UCHIDA, 4501 and subsequent) high-pressure relief pressure

MPa(PSI) 38.5±2.7(5588±398)

low-pressure relief pressure

MPa(PSI)

４ ‑173

2.5(363)

SECTION 05 TROUBLESHOOTING − CONTENTS − Diagnosing Procedure INTRODUCTION.......................................5-175 DIAGNOSING PROCEDURE....................5-176 FAILURES Failures on Engine.....................................5-178 Failures on system performance ..............5-179 ENGINE.......................................................5-180 SYSTEM PERFORMANCE A: Driving performance .............................5-189 B: Braking performance ............................5-219 C: Steering performance ...........................5-227 D: Operation performance .......................5-232

(Blank)

TROUBLESHOOTING / Diagnosing Procedure INTRODUCTION Each troubleshooting section group is presented in an orderly fashion so as to make the inspecting and trou-bleshooting procedures easy to follow.

Use the trouble-shooting section to guide you in locating the source of any problems that may arise.

The troubleshooting section consists of 3 groups: DiagnosingProcedure,Engine,System performance.

・Diagnosing Procedure ・Engine This is used to perform fault diagnostics possibly caused from engine associated parts.

Refer the engine workshop manual for detailed information on engine parts diagnostics. ・System performance Used if a failure exists in regards to the system performance Ex) Slow driving speed

５ ‑175

TROUBLESHOOTING / Diagnosing Procedure DIAGNOSING PROCEDURE These six basic steps are essential for efficient troubleshooting.

1. Study the system Study the machine's technical manuals to know what the system construction and functions are, how it works, and what the system component specifications are.

Fuse failure is often caused by a fine crack in the fuse.

Such fine cracks are very hard to detect by visual inspection. Be sure to check for fuse failures only with a tester.

2. Ask operator Get the full story and history from the operator. ・Operating Conditions: Find out what type of work the machine has been applied to and if the machi-ne has been operated correctly. ・Trouble Occurrence Time: Check when the ma-chine had the trouble, i.e. morning, etc. ・Symptom: Check what the character of the trouble was, and if the trouble appeared suddenly or was getting worse gradually.

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・Past Record of Failure: Check if the machine had any other trouble previously and which parts have been repaired or replaced before.

3. Perform Essential Inspection Before starting the troubleshooting, perform the daily maintenance points as described in the Operator's Manual.

Check the electrical system for any failures such as low battery voltage, loose connections, blown fuses. Any electrical system failure may affect the machine control performance, resulting in overall malfunction of the machine.

If the troubleshooting is started without noticing a blown fuse, the results of the troubleshooting may reach an incorrect conclusion, causing the loss of a lot of time.

５ ‑176

TROUBLESHOOTING / Diagnosing Procedure 4. Inspect Symptom Reproduce the trouble on the machine and inspect the actual status of the trouble yourself.

If the trouble is not reproducible, reconfirm what the process of trouble occurrence was taken. In addition, check for any incomplete connections of the wire harnesses in more detail.

5. Perform Troubleshooting Systematically

CAUTION:Never attempt to disconnect harnesses or hydraulic lines while the engine is running. The machine may malfunction or pressurized oil may spout, possibly resulting in personal injury. Be sure to stop the engine before disconnecting harnesses or hydraulic lines.

Check each component operational performance in accordance with Troubleshooting A in this section.

6. Find Out Cause of Trouble Before starting repair work, reconfirm if the conclusion obtained by troubleshooting is reasonable or not.

Take corrective measures against the original source of the trouble.

Take care to avoid consequent malfunctions due to improper repair work.

５ ‑177

TROUBLESHOOTING / FAILURES Engine Troubleshooting

１．Starter does not operate.

２．Engine starts hard.

３．Unsmooth operation while idling.

４．Lack of power under heavy load.

５．Too much black smoke in exhaust gas.

６．Engine overheats.

７．Abnormal noise from engine.

８．Excessive engine oil consumption.

９．Excessive fuel consumption.

５ ‑178

TROUBLESHOOTING / FAILURES Failures on system performance A: Drivin g performanc e 1.Machine can be moved neither in forward nor reverse direction 2. Machine can be moved only in forward or reverse direction 3. Drop in moving speed 4. Movement speed is normal in "work mode" (LOW) but top speed is not reached in "travel mode" (AUTO).

5. Poor traction 6.Machine travels when engine is running at low idle speed 7.HST fluid level lowers rapidly 8.Oil leakage from axle or reduction gearbox 9.Abnormal noise or inability to travel

B: Braking pe rforman ce 1. Poor braking 2. Parking brake does not function 3. Parking brake drags

C: Ste erin g performanc e 1. Steering is impossible or hard 2. Machine pulls to one side

D: Operation performance 1. Lift arm fails to rise or is slow to rise.

2. Lift arm exclusively lowers (drifts) when control valve is in "Hold (Neutral)" position 3. Lift cylinder does not generate enough force to raise front wheels off ground 4. Lift arm drifts quickly at specific position 5. With load in bucket, lift arm lowers momentarily, then rises when lift lever is moved from "Hold (Neutral)" to "Raise" position.

6. Bucket tilt-back motion is slow or tilt-back force is insufficient

7. Bucket tilts forward with control valve in "Hold (Neutral)" state (front wheels cannot be raised off ground) 8. Bucket drifts quickly at specific position 9. Bucket sways during travel 10. Too large control lever operating resistance

５ ‑179

TROUBLESHOOTING / Engine Troubleshooting

１．Starter does not operate.

Faulty battery

Battery

Faulty charging system

Open circuit or poor contact Loosen connection or corrosion ofterminals

Wiring

Faulty starter switch Faulty safety relay Faulty battery ground

Troubleshooting

２．Engine starts hard.

Fuel system

Injection pump

Sticking plunger Malfunctioning delivery valve Faulty operation of control rack Loose control pinion Faulty operation of feed pump

No fuel in fuel tank

Insufficient fuel

Air in fuel system

Others

Water in fuel Clogged fuel filter Loose fuel pipe connection Clogged fuel hose Cracked or loose injection pipe Clogged breather hose of fuel tank

５ ‑180

TROUBLESHOOTING / Engine Troubleshooting

２．Engine starts hard.

Fuel system Improper injection timing injection

Worn tappet roller and cam

Too low injection start

Faulty nozzle and nozzle holder Sticky needle valve

Poor spray of fuel setting

Weak or broken nozzle spring

Engine

Burned valve Seized or worn valve stem Broken valve spring

Too low compression pressure

Improper valve clearance Wear of cylinder, piston and piston ring

Sticky or broken piston ring Blowby through cylinder head gasket Others

Faulty engine control mechanism Faulty preheating system

５ ‑181

TROUBLESHOOTING / Engine Troubleshooting

３．Unsmooth operation while idling.

Fuel system

Broken plunger spring Injection pump

Faulty operation of control rack Malfunctioning delivery valve Faulty operation of governor Faulty adjustment of idling spring Faulty operation of feed pump

Irregular fuel injection

Others

Air in fuel system Water in fuel Loose connection of fuel pipe Clogged breather hose of fuel tank Improper injection timing Sticky needle valve Poor spray of fuel

Weak nozzle spring Carbon deposition in injection nozzle

Irregular injection start pressure

Faulty nozzle and nozzle holder

Engine

Too low compression pressure (Refer to the problem item "Engine starts hard.")

Others

Faulty engine control mechanism

５ ‑182

TROUBLESHOOTING / Engine Troubleshooting

４．Lack of power under heavy load.

Fuel system

Injection pump

Worn or seized plunger Faulty operation of control rack Malfunctioning delivery valve Faulty operation of governor Faulty operation of feed pump Irregular injection of fuel

Others

Air in fuel system Water in fuel Loose connection of fuel pipe Clogged breather hose of fuel tank Improper injection timing

Worn tappet roller and cam

Sticky needle valve Poor spray of fuel

Weak nozzle spring Carbon deposition in injection nozzle Too low compression pressure (Refer to the problem item "Engine starts hard.")

Engine

Others

Insufficient intake air

Clogged air cleaner

Faulty exhaust system

Clogged muffler

５ ‑183

TROUBLESHOOTING / Engine Troubleshooting

５．Too much black smoke in exhaust gas.

Fuel system Worn or sticky plunger Broken plunger spring

Irregular or excessive fuel injection

Faulty operation of delivery valve Faulty operation of control rack

Worn tappet roller and cam

Improper injection timing

Loose tappet adjusting bolt

Sticky needle valve Poor spray of fuel

Weak nozzle spring Carbon deposition in injection nozzle

Too low injection start pressure setting

Loose nozzle adjusting screw Too low compression pressure (Refer to the problem item "Engine starts hard.")

Engine

Other Insufficient intake air

Clogged air cleaner

５ ‑184

TROUBLESHOOTING / Engine ６．Engine overheats.

Troubleshooting

Cooling system Worn water pump seal Worn or seized plunger Cooloant leakage

Broken hose and pipe or loose clamp Damaged cylinder head gasket

Faulty operation of water pump Clogged radiator Faulty cooling system components

Faulty radiator cap Faulty thermostat Loose or damaged fan belt Scale in coolant passage

Excessive injection of fuel Improper injection timing Fuel system

Poor spray of fuel Too low injection start pressure setting

Poor circulation of engine oil

Lubrication system

Malfunctioning oil cooler

Carbon deposition in combustion chamber

Others

Clogged muffler Too much load

５ ‑185

TROUBLESHOOTING / Engine Troubleshooting

７．Abnormal noise from engine.

Improper injection timing Irregular injection of fuel Knocking noise

Too high injection start pressure setting Poor spray of fuel Poor ignition Too low compression pressure (Refer to the problem item "Engine starts hard.")

Worn cylinder and piston Seized or broken piston and piston ring Worn connecting rod small end bushing and piston pin Worn or broken crank pin and connecting rod bearing

Rapping noise

Worn or damaged crankshaft journal and journal bearing

Too large axial play of crankshaft and camshaft Loose flywheel and crankshaft pulley Worn tappet and cam Excessive valve clearance

Worn or damaged alternator and water pump bearings

Continuous rattling

Wear or poor tooth contact of timing gears Loose or damaged fan belt

５ ‑186

TROUBLESHOOTING / Engine Troubleshooting

８．Excessive engine oil consumption.

Lubrication system Loose oil filter and/or defective O-ring

Oil leakage

Loose oil pan and/or defective gasket Loose oil pipe connection or cracked pipe

Loose oil pipe connection k d

Worn cylinder liner and piston Oil remains unscraped by piston ring

Worn, broken or sticking piston ring Clogged oil hole in piston and oil ring Clogged breather pipe

External oil leakage

Oil leakage

Worn valve stem and valve guide Defective valve stem oil seal

Defective gasket and oil seal

５ ‑187

TROUBLESHOOTING / Engine Troubleshooting

９．Excessive fuel consumption.

Fuel system Worn or seized plunger Broken plunger spring

Irregular or excessive injection of fuel

Malfunctioning of delivery valve Faulty operation of control rack

Worn tappet roller and cam

Improper injection timing

Loose tappet adjusting bolt

Sticky of needle valve Poor spray of fuel

Weak nozzle spring Carbon deposition in injection nozzle

Too low injection start pressure setting

Loose nozzle adjusting screw Too low compression pressure (Refer to the problem item "Engine starts hard.")

Engine

Others

Overheating (Refer to the problem item "Engine overheats.")

Insufficient intake air

Clogged air cleaner

５ ‑188

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-1．Machine can be moved neither in forward nor reverse direction

（１）Insufficient hydraulic fluid in tank

Check hydraulic fluid level.

1.Park the machine on a level ground.

2.Lower the bucket or attachment flat on the ground.

3.With the engine stopped, check that fluid level on the level gauge is between the upper and lower limit marks.

.GXGN )CWIG 7RRGT .KOKV Too low hydraulic fluid level

Normal hydraulic fluid level

.QYGT .KOKV Repair leaky locations, then refill the tank with fluid.

（２）Clogged in suction strainer

Remove the suction strainer ① in the hydraulic fluid tank and check it for clogging.

Ԙ

Clogged

Not clogged

Check the HST filter element ②and hydraulic fluid filter element ③ for foreign materials that cause clogging of the suction strainer ①.

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Clean the suction strainer

Repair hydraulic cylinder(s) and hose(s). （Metal fragment includ-ing copper particles）

Repair the hydraulic pump. （Fragment of ny-lon and/or rubber）

５ ‑189

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A- １．Machine can be moved neither in forward nor reverse direction

（３）Deteriorated, emulsified or improper type of fluid

Perform fluid check.

1. Is fluid deteriorated and browned?

2. Has fluid been mixed with water and emulsified?

3. Does fluid trap air (from intake system) and show white?

4. Is fluid of specified characteristics (especially viscosity) used? (Refer to the Operation and Maintenance Manual.)

Oil is inappropriate.

Oil is normal.

Change oil.

（４）Worn spline and broken coupling of HST pump

Check that the shovel and steering system operate.

Fail to operate

Operate

ԙ HST pump's drive shaft ① spline is worn and coupling ② is broken.

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Replace the drive shaft and coupling.

５ ‑190

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A- １．Machine can be moved neither in forward nor reverse direction

（５）Faulty operation or poor adjustment of brake (inching) pedal linkage

Check that the inching valve lever is in the "close" position. （ＨＳＴ ＰＵＭＰ／ＹＵＫＥＮ） 1. With the engine stopped and the brake (inching) pedal ① released, check that the inching valve lever ② is in contact with the stopper ("close" position).

Note: Make sure that the inching lever is always in the "close" position when the pedal is not depressed.

Lever not in the "close" position

Lever in the "close"

Repair and adjust the linkage.

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5VQRRGT

５ ‑191

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A- １．Machine can be moved neither in forward nor reverse direction

（５）Faulty operation or poor adjustment of brake (inching) pedal linkage

Check that the inching valve lever is in the "close" position. （ＨＳＴ ＰＵＭＰ／ＵＣＨＩＤＡ） 1. With the engine stopped and the brake (inching) pedal ③ released, adjust stopper 3 to make measurement A becomes 205 ± 2 mm.

Note: Make sure that the inching lever is always in the "close" position when the pedal is not depressed.

Lever not in the "close" position

Lever in the "close"

Repair and adjust the linkage.

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ԙ ５ ‑192

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A- １．Machine can be moved neither in forward nor reverse direction

（６）Faulty parking brake solenoid and parking brake switch (brakes drag)

Measure the terminal voltage of parking brake solenoid.

1. After starting the engine, place the parking switch in the "RESET" operation.

2. Check that the shift lever is locked in the neutral position.

3. Disconnect the parking brake solenoid connector.

4. While turning the parking brake switch from "ON" to "OFF", measure the terminal voltage (make measurement on the machine side connect with the parking brake monitor lamp turned off).

Standard valu e: Voltage １０．９５〜１４．４ V

Out of standard

Standard value

① Parking brake switch is faulty. ② Relay [3] is faulty. ③ Connector and/or ground connection are in poor contact.

① Parking brake solenoid is faulty.

Replace faulty part(s)

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５ ‑193

TROUBLESHOOTING /SYSTEM PERFORMANCE A- １．Machine can be moved neither in forward nor reverse direction

Troubleshooting

（７）Drop in AU control pressure（ＨＳＴ ＰＵＭＰ／ＹＵＫＥＮ）

Measure the AU control pressure of the HST pump. （ＨＳＴ ＰＵＭＰ／ＹＵＫＥＮ） 1. Connect an oil pressure gauge to the Q2 port (φ6 flareless tube fitting 1/4) of the HST pump.

2. Install a tachometer to the engine.

3. Measure the AU control pressure at certain engine speeds.

4. Standard value Refer to the characteristic graphs below. 㧼㨏 %QPVTQN 2TGUUWTG 㧽㧞 2QTV

Below standard value

Normal

Ａ-1.（8） Drop in low-pressure relief valve pressure

Ａ-2.（3） Measure the oil pressure in high-pressure circuit.

Eng.rpm-HST control pressure kg/cm2

MPa

25

2.45

20

1.96

15

1.47

10

0.98

5

0.49

0 0

500

1000

1500 Ｅｎｇ.rpm

５ ‑194

2000

2500

3000

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A- １．Machine can be moved neither in forward nor reverse direction

（７）Drop in ＤＡ control pressure（ＨＳＴ ＰＵＭＰ／ＵＣＨＩＤＡ）

Measure the AU control pressure of the HST pump. （ＨＳＴ ＰＵＭＰ／ＵＣＨＩＤＡ） 1. Connect an oil pressure gauge to the PS port (G 1/4) of the HST pump.

2. Install a tachometer to the engine.

3. Measure the AU control pressure at certain engine speeds.

4. Standard value：Refer to the characteristic graphs below

Below standard value

Normal

Ａ-1.（8） Drop in low-pressure relief valve pressure

Ａ-2.（3） Measure the oil pressure in high-pressure circuit.

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25

2.45

20

1.96

15

1.47

10

0.98

5

0.49

0 500

1000

1500

2000

[ min-1 ]

５ ‑195

2500

0 3000

[ MPa ]

[ kgf/cm2 ]

Eng.rpm-HST control pressure (AUTO mode)

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A- １．Machine can be moved neither in forward nor reverse direction

（８）Drop in low-pressure relief valve pressure

Measure the pressure in the low-pressure (charging) circuit. （ＨＳＴ ＰＵＭＰ／ＹＵＫＥＮ） 1. Remove the hose ①, adapter ② and O-ring ③, then install an oil pressure gauge to the V port.

2. Read the oil pressure gauge while running the engine at the maximum speed.

3. Standard value

１．５７ＭＰａ（１６ｋｇｆ／ｃｍ 2 ） Note: Measure the pressure with the fluid at an operating temperature (approximately 40 - 60°C).。

Out of standard value

Standard value

Remove the low-pressure relief valve and check its seat surface for presence of foreign matter, damage and sign of sticking.

Replace faulty part(s).

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５ ‑196

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-2. Machine can be moved only in forward or reverse direction

（１）Faulty shift lever or electrical wiring。

Measure the terminal voltage of the forward and reverse.

5QNGPQKF XCNXG (QTYCTF

1. After starting the engine, move the parking switch to the "RESET" position.

2. Disconnect the forward and reverse solenoid connector.

3. Place the shift lever in the neutral position and set the parking brake switch to the "OFF" position (to make measurement on the machine harness side connector with the parking brake monitor lamp turned off).

4. Place the shift lever in the "Forward" position, and measure the voltage.

5QNGPQKF XCNXG 4GXGTUG

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Stan dard value : Voltage 10 .95 〜 14 .4 V 5. Place the shift lever in the "Reverse" position, and measure the voltage.

51. 4

Stan dard value : Voltage 10 .95 〜14 .4 V 51. ( %QPPGEVQT *56 2WOR

Standard value

Out of standard value

① The solenoid on the side showing standard voltage is faulty.

① Shift lever is faulty. ② Relay [3] is faulty. ③ Parking brake switch is faulty.

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Replace faulty parts.

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５ ‑197

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-2. Machine can be moved only in forward or reverse direction

（２）Faulty operation of forward or reverse solenoid valve

Perform operation check of the solenoid valve（YUKEN) 1. Insert and push a long, round stick B into the hole A(inside diameter: 6 mm) in the solenoid valve.

2. The solenoid valve is normal if reaction force of the spring D is felt and the piston C moves inward by 2.8 mm and it returns smoothly on release of the force on the stick.

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Normal

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Replace the solenoid valve.

５ ‑198

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-2. Machine can be moved only in forward or reverse direction

（３）Measurement of high-pressure circuit pressure（YUKEN）

Measure the high-pressure circuit pressure of the HST pump.

1. Connect an oil pressure gauge to the port A ("forward").

2. Measure the oil pressure in the high-pressure circuit in accordance with the descriptions in the measurements of performance.

3. Refer Performance standard list for standard value.

Lower pressure than standard value

Standard value

Faulty high-pressure relief valve

Inspect the HST motor.

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５ ‑199

TROUBLESHOOTING /SYSTEM PERFORMANCE A-2. Machine can be moved only in forward or reverse direction

Troubleshooting

（３）Measurement of high-pressure circuit pressure（UCHIDA）

Measure the high-pressure circuit pressure of the HST pump.

1. Connect an oil pressure gauge to the port MA ("forward").

2. Measure the oil pressure in the high-pressure circuit in accordance with the descriptions in the measurements of performance.

3. Refer Performance standard list for standard value.

Lower pressure than standard value

Standard value

Faulty high-pressure relief valve

Inspect the HST motor.

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５ ‑200

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-2. Machine can be moved only in forward or reverse direction

（４）Faulty high-pressure relief valve

Remove and check the high-pressure relief valve.

1. Check the high-pressure relief valves for looseness or other defects in installation.

(If a valve is loose, the fluid in high-pressure circuit leaks into low-pressure circuit resulting in a drop in the high-pressure circuit pressure.)

2. If no defect is found in the installation, remove the high-pressure relief valve and check the valve for presence of foreign matter on the valve seats ① and ②.

3. Interchange the "forward" and "reverse" high-pressure relief valves and check whether the abnormal condition change.

4. Replace the high-pressure relief valves with new ones, and check whether the abnormal condition recurs.

Abnormal

Normal

Repair or replace the highpressure relief valve(s).

Inspect HST motor assembly.

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５ ‑201

*KIJ RTGUUWTG TGNKGH XCNXG

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-3. Drop in moving speed

C h e c kin g m o vin g spe e d W h e n a u se r c o m plain s th at th e m ac h in e c an n o t m o ve at fu ll spe e d, first m e asu re th e m o vin g spe e ds in th e wo rk m o de (fixe d in th e 1 st ge ar) an d th e n in th e trave l m o de (AUT O) fo r bo th th e fo rward an d re ve rse dire c tio n s in o rde r to de te rm in e wh e th e r th e u se r fe e ls th e m ac h in e to be to o slo w alth o u gh th e spe e ds are n o rm al o r th e ve h ic le is tru e ly to o slo w du e to s o m e m alfu n c tio n .

M e asu re th e drivin g spe e d in ac c o rdan c e with th e de sc riptio n in th e m e asu re m e n ts o f syste m pe rfo rm an c e .

T o o slo w spe e d in all m o de s

W o rk m o de : stan dard spe e d T rave l m o de : m axim u m spe e d is n o t re ac h e d

In su ffic ie n t e n gin e po w e r

D raggin g brake s (se rvic e , parkin g)

Stan dard spe e ds

N o rmal

（ １） In su ffic ie n t e n gin e pow e r (lac k of spe e d) Me asu re th e e n gin e maximu m spe e d w ith n o load an d th e spe e d w ith th e sh ove l lifte d.

Me asu re th e maxim u m n o- load e n gin e spe e d in ac c o rdan c e w ith th e de sc ription in th e se c tion o f m e asu re me n ts o f e n gin e pe rfo rman c e , 「 En gin e spe e d」 ．

B e low stan dard valu e

Stan dard valu e

Fin d ou t c au se s fo r to o lo w spe e d e ve n w ith n o lo ad on th e e n gin e .

Me asu re m e n t of spe e d w ith sh o ve l raise d

1 . Ac c e le rator lin kage is fau lty, so th e m axim u m spe e d position c an n n ot be re ac h e d e ve n if th e pe dal is fu lly de pre sse d.

2 . Th e fu e l filte r an d air filte r are c logge d.

3 . Th e fu e l pu m p an d n ozzle s are fau lty.

4 . Th e re are oth e r fau lts in th e e n gin e .

1 .Lift arm to th e h igh e st positio n 2 .Me asu re th e e n gin e spe e d du rin g o pe ratio n of th e sh ove l main re lie f valve by ke e pin g th e le ve r in th e " Raise " position .

3 .Re fe r Pe rfo rman c e stan dard list for stan dard valu e .

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B e low stan dard valu e

Stan dard valu e

D raggin g brake s (se rvic e , parkin g)

Re pair th e e n gin e

５ ‑202

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-4. Movement speed is normal in "work mode" (LOW) but top speed is not reached in "travel mode" (AUTO).

（１）Faulty mode selector switch or electrical wiring（YUKEN） Check that, when the mode selector switch is changed from "work mode" to "travel mode", the "tortoise" lamp in the meter panel goes off and the " rabbit" lamp illuminates.

Abnormal

Normal

Measure the terminal voltage of the mode selector solenoid.

1. Disconnect the connector ① of the mode selector solenoid valve.

2. Measure the voltage between terminals of the machine side harness connector of the connector ①, when the starter switch is set to "ON" and the mode selector switch is set to the "travel mode."

3. Standard value: 0 V In normal condition, voltage is present when the mode selector switch is set to the "work mode" and no voltage is present when it is set to the "travel mode".

Check and replace the selector switch.

Voltage is present

Standard value (no voltage)

Faulty wiring between mode selector switch and mode selector solenoid

Faulty operation of mode selector solenoid valve

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５ ‑203

TROUBLESHOOTING /SYSTEM PERFORMANCE A-4. Movement speed is normal in "work mode" (LOW) but top speed is not reached in "travel mode" (AUTO).

Troubleshooting

（１）Faulty mode selector switch or electrical wiring（ＵＣＨＩＤＡ） Check that, when the mode selector switch is changed from "work mode" to "travel mode", the "tortoise" lamp in the meter panel goes off and the "rabbit" lamp illuminates.

Abnormal

Normal

Measure the terminal voltage of the mode selector solenoid.

1. Disconnect the connector ① of the mode selector solenoid valve.

2. Measure the voltage between terminals of the machine side harness connector of the connector ①, when the starter switch is set to "ON" and the mode selector switch is set to the "travel mode."

3. Standard value: 0 V In normal condition, voltage is present when the mode selector switch is set to the "work mode" and no voltage is present when it is set to the "travel mode"

Check and replace the selector switch.

Voltage is present

Standard value (no voltage)

Faulty wiring between mode selector switch and mode selector solenoid

Faulty operation of mode selector solenoid valve

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TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-4. Movement speed is normal in "work mode" (LOW) but top speed is not reached in "travel mode" (AUTO).

（２）Faulty operation of mode selector solenoid valve

Check operation of the solenoid valve 1. Insert and push a long, round stick ② into the hole ① (diameter: 6 mm) in the solenoid valve.

2. Check that, when the starter switch is turned ON and the mode selector switch is moved from the "travel mode" position (AUTO) to the "work mode" position (LOW), the inside piston ③ moves inward.

3. Set the mode selector switch to the "travel mode" position, and push the piston ③ with the stick ②.

4. The solenoid valve is normal if a reaction force of the spring ④ is felt and the piston ③ moves inward by 2.8 mm and returns smoothly on release of the force on the stick.

5. If the piston ③ does not move or its movement is not smooth, the spool is stuck with foreign matter.

Ԙ

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/QFG 5GNGEVQT 5QNGPQKF 8CNXG

Faulty

Normal

Repair or replace solenoid valve.

Inside leakage or sticky movement of the HST motor system pressure control section

５ ‑205

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-4. Movement speed is normal in "work mode" (LOW) but top speed is not reached in "travel mode" (AUTO).

（２）Faulty operation of mode selector solenoid valve

Check operation of the solenoid valve 1. Check that the spool ① is not sticking.

Ԙ

Faulty

Normal

Repair or replace solenoid valve.

Inside leakage or sticky movement of the HST motor system pressure control section

５ ‑206

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-4. Movement speed is normal in "work mode" (LOW) but top speed is not reached in "travel mode" (AUTO).

（３）Internal leakage or sticky movement of HST motor system pressure control section

If no abnormalities are found in all the preceding checks and still the full speed (15 km/h) is not reached in the "travel mode", the inclination of the motor's swash plate is not switched to the small capacity position (small-torque, high-speed position) from the large capacity position (large-torque, low-speed position).

1. The 1st gear fixing control piston ① is sticking 2. The piston ② is sticking.

3. The system pressure control valve is internally leaking or the spool ③ is sticking.

4. The orifice ④ is clogged.

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Faulty

Replace HST motor assembly.

５ ‑207

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-5. Poor traction

（１）Internal leakge and sticky movement of HST motor system pressure control section

If no abnormalities are found in all the preceding checks and still the traction of the machine is poor, the incli-nation of the motor's swash plate is not switched to the large capacity position (large-torque, low-speed position) from the small capacity position (small-torque, high-speed position).

Faulty HST motor

Troubleshooting

A-6.Machine travels when engine is running at low idle speed

（１）Engine low idle speed is too high.

Measure the low idle speed of the engine.

Measure the engine low-idling speed in accordance with the description in the section of measurements of engine performance, Engine speed.

Refer Performance standard list for standard value.

Above standard value

Standard value

1. Adjustment of the accelerator linkage is faulty, so its lever does not come in contact with the minimum speed stopper even when the accelerator pedal is released.

2. Foreign matter jammed in the accelerator pedal prevents it from returning fully.

3. The accelerator linkage is rusted and/or sticking.

Poor air bleeding of HST system or damage to AU control section

/KPKOWO 5RGGF 5VQRRGT

５ ‑208

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

A-6.Machine travels when engine is running at low idle speed

（２）Poor air bleeding of HST system or damage to AU control section

1. If the machine travels with the shift lever in the "neutral" position, check the hydraulic fluid (pay attention to viscosity).

2. If the machine travels only momentarily just after engine start with the shift lever in the "neutral" position, bleed air out of the HST system. Air may remain in the system when the hydraulic fluid filter or its element is replaced, the HST pump or motor is repaired, or the HST piping and hoses are replaced. If such replacement or repair is not a cause, air may have entered the system from loose connection of the HST piping and hoses; check the connnectors and tighten the fittings as necessary.

3. If, even after air bleeding, the machine travels with the shift lever in the "neutral" position, damage to the AU control section and/or faulty neutral control section are assumed to be the cause.

Proceed to "Faulty HST pump".

Troubleshooting

A-7.HST fluid level lowers rapidly

（１）Faulty HST motor rear oil seal, or internal leakage of parking brake

If the hydraulic fluid level lowers and the reduction oil is discharged together with air from the breather, the hydraulic fluid may have leaked into the reduction gear due to faulty HST motor oil seal, or hydraulic fluid is internally leaking after flowing through the parking brake control system due to damaged parking brake piston in the reduction gear.

Caution: Repair the faulty sections immediately as operating the machine with insufficient oil will cause serious accidents possibly resulting from seizure or sticking-up of the MST pump and motor.

５ ‑209

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-8.Oil leakage from axle or reduction gearbox

（１）Oil leakage from around nut ② of front axle drive pinion ①

Excessive play in spline coupling between drive pinion ① and input flange ③

Faulty O-ring ④ of splined section

Remove the nut ② and turn the input flange ③ by hand to check the spline coupling for excessive

Excessive play.

Replace the drive pinion ① or input flange ③.

No excessive play.

Replace the O-ring ④

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５ ‑210

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-8.Oil leakage from axle or reduction gearbox

（２）Oil leakage from oil seal at input flange ③ of front axle

Faulty oil seal ⑤ or worn seal rubbing surface of input flange ③

Worn or damaged bearings ⑥ and ⑦

Turn the input flange ③ by hand, and check the flange for excessive play.

Excessive play

No excessive play

Replace the bearings ⑥ and ⑦.

Replace the oil seal ⑤ or input flange ③.

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５ ‑211

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-8.Oil leakage from axle or reduction gearbox

（３）Oil leakage from around nut ② of front axle drive pinion ①

Faulty oil seal ①

Worn or damaged bearings ③ and ④

Remove the wheel and move the drive shaft ② flange by hand to check for excessive play in axial and circumferential directions.

Excessive play

No excessive play

Replace the bearings ③ and ④.

Replace the oil seal ①

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Ԛ Ԙ ５ ‑212

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-8.Oil leakage from axle or reduction gearbox

（４）Oil leakage from around nut ② at reduction gearbox output flange ①

Excessive play in spline coupling between shaft ③ and output flange ①

Faulty O-ring ④ at splined section

Remove the nut ② and turn the output flange ① by hand to check the spline coupling for excessive play.

Excessive play

No excessive play

Replace the shaft ③ or output flange ①.

Replace the O-ring ④

Ԙ ԙ

５ ‑213

ԛ

Ԛ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-8.Oil leakage from axle or reduction gearbox

（５）Oil leakage from oil seal ⑥ / ⑦ of output flange ① / ⑤

Faulty oil seals ⑥ / ⑦ or worn seal rubbing surface of output flange ① / ⑤

Worn or damaged of bearing ⑧ / ⑨

Turn the output flange ① or ⑤ by hand to check the flange for excessive play.

Excessive play

No excessive play

Replace the bearing ⑧ / ⑨.

Replace the oil seal ⑥ / ⑦ or output flanges ① / ⑤.

Ԙ ԝ ԟ

５ ‑214

Ԡ

Ԟ Ԝ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-9.Abnormal noise or inability to travel

（１）Lack of oil in axle housing or its deterioration

Remove the axle housing level plug ① to check for the oil level. Also sample the oil by removing the drain plug ② and check it for contamination, emulsification (entry of water)

Abnormal

Normal

Refill the axle housing to the specified level, or change oil. （For the specified axle oil, refer to the Operation and Maintenance Manual.）

Ԙ

ԙ

５ ‑215

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-9.Abnormal noise or inability to travel

（２）Lack of oil in reduction gear box or its deterioration

Remove the reduction gear box level plug ① to check for the oil level. Also sample the oil by removing the drain plug ② and check it for contamination, emulsification (entry of water) and viscosity.

Lack of oil or deterioration

Refill the reduction gear box to the specified level or change oil. （For specified oil, refer to the Operation and Maintenance Manual.）

Oil level too high

Normal

If the oil level is excessive, remove the drain plug ② to reduce oil to the specified level. Then, operate the machine to check whether the oil level rises again.

Oil level too high

Ԙ

ԙ

Hydraulic fluid is leaking into the reduction gear box due to faulty HST motor rear oil seal ③ or faulty brake piston O-ring ④.

Perform repair immediately if the HST motor rear oil seal is faulty. Operating the machine with a faulty rear oil seal leads to significant reduction of hydraulic fluid and ultimately to serious accidents possibly resulting from seizure and sticking-up of the HST pump and ｍotor, dragging brakes, seizure and premature wear of brake disks.

Ԛ

５ ‑216

ԛ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-9.Abnormal noise or inability to travel

Improper angle of propeller shaft

Excessive play in the spline coupling ② of propeller shaft or worn and damaged universal joint ①

Visually check that the universal joint ① is mounted at a correct angle.

Remove the propeller shaft assembly and check the spline coupling ② for excessive play, or check the universal joint ① for wear and damage.

Incorrect angle

Correct angle.

Replace faulty parts.

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4GFWEVKQP IGCT VQ TGCT CZNG LQKPV

５ ‑217

Ԙ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ａ-9.Abnormal noise or inability to travel

Worn or damaged inner parts of front and rear axles

Worn or damaged inner parts of reduction gear box

Drain and collect oil to check for presence of foreign matter (fragments and metal particles from gears and bearings)

Foreign matter is present

Replace faulty parts.

If noise-producing location (front axle, rear axle, or reduction gear box) cannot be identified, use the following method.

1. Jack up the machine and support it with stands.

2. Remove the propeller shaft ① (reduction gear to front axle) and move only the rear wheels. If no abnormal noise is heard, there will be a problem in the front axle.

3. If abnormal noise still exists in step 2 above, install the propeller shaft ①, remove the propeller shaft ② (reduction gear box to rear axle), then move only the front wheels. If no abnormal noise is heard, there will be a problem in the rear axle.

If abnormal noise still exists, there will be a problem in the reduction gear box.

4GCT #ZNG

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５ ‑218

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

B-1. Poor braking

（１）Fluid leakage from brake piping

Check the fluid level in the brake fluid tank. If the level is too low, check the brake piping for leakage.

Too low brake fluid level

Normal brake fluid level

External fluid leakage

No external fluid leakage.

Repair leaky locations and refill the tank with brake fluid

Refill the tank with brake fluid to the specified level.

Air is in the brake system.

Operate the service brakes, then check the fluid level in the tank.

Fluid level remains

Fluid level lowers

Internal leakage to the reduction gear box

If fluid decreases quickly although there is no external fluid leakage, there is internal fluid leakage into the reduction gear box.

1. Worn or damaged brake piston O-ring ① and parking brake piston O-rings ②, ③ 2. Worn and damaged piston rubbing surface

Replace O-ring and other faulty parts.

５ ‑219

ԙ

Ԙ Ԛ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｂ-1. Poor braking

（ ２） Air in brake system

De press the brake pe dal an d c he ck w he the r it fe els spon gy.

Spongy

N ot spon gy

B le ed the brake syste m.

（３）Faulty master cylinder

Ch ec k th at th e pedal stops wh en the brake pe dal is depresse d.

If th ere is in tern al leakage in th e master cylinde r, the pedal does n ot stop if th e pedal is depre ssed strongly.

Cau se s of intern al leakage in th e master c ylinde r are : ① Worn or damaged cu p ① ② Worn or damaged bore su rface of c ylin der C a u t io n : I f t h e c u p ② is f a u lty , f lu id w ill le a k e x te r n a lly .

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Th ere is inte rn al le akage .

Th ere is no in ternal leakage.

Repair or replace th e master c ylinde r.

５ ‑220

TROUBLESHOOTING /SYSTEM PERFORMANCE Ｂ-1. Poor braking

Troubleshooting

（４）Abnormal noise during braking.

Deterioration of brake and reduction gear fluid, use of improper fluid Deterioration of brake and reduction gear fluid, use of improper fluid Check the brake and reduction gear fluid. As the brakes of this machine are of a wet, built-in type, use of a deteriorated or non-recommended fluid (of different viscosity) in the brake system and reduction gear causes poor braking, abnormal noise and abnormal wear of components.

Deterioration of fluid, mix-ture with water, use of non-recommended

Normal

Reduction gear fluid smells a burn

Change fluid （５）Worn or damaged of brake disks and plates

Worn or damaged of brake disks ① and plates ②, or damaged to rubbing surface of brake piston

Service limit

ԙ Ԙ

ＮＯ．

Item

Standard value

Service limit

①

Brake disk

２．２５ ｍｍ

１．９ ｍｍ

②

Brake plate

１．６

１．４ ｍｍ

ｍｍ

Replace faulty parts.

Caution: Abnormal or premature wear of brake disks ① and plates ② may be caused by dragging brakes.

５ ‑221

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｂ-2. Parking brake does not function

（１）Parking brake does not function both when the engine is stopped and when it is running.

Worn or damaged brake disks ① and plates ②。

Refer to 1-B （５）

（２）Parking brake functions when the engine is stopped but does not when the engine is running even with the parking brake switch in the "ON" position.

Faulty parking brake solenoid valve, parking switch and/ or relay If the parking brake does not function at all with the engine ru nning and the parking brake switch in the "ON" position, the following defects may be the cause.

1. If the parking solenoid is energized under the above-mentione d condition, faulty switch, relay or harness may be the cause.

2. The parking solenoid valve is stuck in the released condition .

Caution: If both the conditions in items 1 and 2 above are normal, the parking brake oil pressure measured at the location shown in illustration on the right should be 0 k g f / c m 2 .

2CTMKPI $TCMG 1KN 2TGUUWTG /GCUWTGF CV VJG .QECVKQP

2CTMKPI 5QNGPQKF 8CNXG

Repair or replace faulty parts.

５ ‑222

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｂ-3. Parking brake drags

（１）Faulty parking brake control electrical system

Measure the terminal voltage of the parking brake solenoid.

1. After starting the engine, place the parking switch in the "RESET" position.

2. Check that the shift lever is locked in the neutral position.

3. Disconnect the parking brake solenoid connector.

4. While turning the parking brake switch from "ON" to "OFF", measure the terminal voltage (make measurement on the machine side connector with the parking brake monitor lamp turned off).

Stan dard valu e : Vo ltage 1 0 .9 5 〜 1 4 .4 V

)4

$

%QPPGEVQT

0 V or below operating voltage

2CTMKPI 5QNGPQKF 8CNXG

Normal

Parking brake solenoid is faulty.

1. Parking brake switch is faulty.

2. Relay is faulty.

3. Connector and/or ground connection are in poor contact.

Replace faulty part(s).

５ ‑223

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｂ-3. Parking brake drags

（２）Faulty parking brake control hydraulic system

Measure the parking brake oil pressure (charging pressure).

1. Disconnect the hose ② and adapter ① at the lower part of the HST pump (below inching valve) and connect an oil pressure gauge.

2. Start the engine and read the oil pressure gauge.

3. Measure the pressure with the hydraulic fluid warmed to an operating temperature (40 〜 60°C).

Parking brake release oil pressure

１． ５７ MPａ（１６Ｋｇｆ／ｃｍ2）

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Below the release oil pressure

Above the release oil pressure

Charging pump circuit is faulty.

Measure the release oil pressure on the parking brake solenoid side ③

５ ‑224

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｂ-3. Parking brake drags

（３）Faulty parking brake control hydraulic system

Measure the parking brake oil pressure on the parking brake solenoid side.

1. Disconnect the parking solenoid valve hose ② and 90-degree elbow ③, then connect an oil pressure gauge.

2. Start the engine, place the parking switch in the "RESET" position, and read the oil pressure gauge.

3. Measure the pressure with the hydraulic fluid warmed to an operating temperature (40 〜 60°C).

Parking brake release oil pressure

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１．５７ MPａ （ １６Ｋｇ ｆ／ｃｍ2）

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Below the release oil pressure

Sticking parking brake solenoid

Replace the parking brake solenoid

５ ‑225

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｂ-3. Parking brake drags

（４）Seizure of brake disks and plates

Disassemble the parking brake and check the brake disks ① and plates ② for seizure and bend.

Service limit

ԙ Ԙ

ＮＯ．

Item

Item

Service limit

①

Brake disk

２．２５ ｍｍ

１．９ ｍｍ

②

Brake plate

１．６

１．４ ｍｍ

Replace faulty parts.

５ ‑226

ｍｍ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｃ-1.Steering is impossible or hard

Me asure th e ste e rin g time .

Wh e n a u se r c omplain s th at stee rin g th e mac h ine is h ard, first m e asu re th e time re qu ire d for ste e rin g. Th e n de te rmin e w h e th e r th e u se r fe e ls ste e rin g h ard (slow ) alth ou gh the syste m is n ormal or it is re ally h ard (slow ) du e to malfu n c tion .

Me asu re the ope ratin g time of h ydraulic cylin de rs in acc ordan c e with th e de scription in th e se c tion of me asu reme nt of syste m pe rforman c e .

1 . Plac e th e mac h in e in a trave l position on a le ve l, pave d su rf ac e w ith th e parkin g brake re le ase d.

2 . Warm the h ydrau lic flu id to an ope ratin g te mpe ratu re (4 0 - 6 0 ° C).

3 . Make th e buc ke t e mpty.

4 . Ch e c k tire s for c orre ct in flation pre ssure s. Air Pre ssu re :2 20 kPa(2 .2 kgf/ c m2 ) 5 . With th e mac h in e u n de r th e above c on dition s an d the e n gin e ru n n in g at th e maximu m spe e d, me asu re th e time re qu ire d to ste e r th e w h e els from th e le ft stop to th e right stop an d from th e righ t stop to th e le ft stop.

Re fe r Pe rforman c e stan dard list for stan dard valu e .

Above stan dard valu e

Stan dard valu e

N ormal

A- 1 (1 ). Flu id in h ydrau lic flu id tan k is in su ffic ie n t.

A- 1 (2 ).Su c tion strain e r is c logge d.

５ ‑227

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｃ-1.Steering is impossible or hard

（２）Too low steering main relief valve pressure

Measure the steering pressure.

Measure the steering relief pressure in accordance with the description in the section of measurements of system performance.

Refer Performance standard list for standard value.

Below standard value

Repair or replace the main pump.

Standard value

Normal 1KN 2TGUUWTG 2QTV

（３）Damaged to piston seals in steering cylinder

Check steering cylinder for internal leakage.

1. Turn the steering wheel to the right, keep it in close contact with the stopper on the frame, then stop the engine.

2. Disconnect the hose ① from the cylinder rod end of the steering cylinder, and install the plug ② on the end of the hose ①.

3. Start the engine, accelerate it to the maximum speed, and continue applying a right turning force to the steering to allow pressurized fluid to flow to the cylinder bottom.

4. If fluid leaks out of the cylinder port ③, piston seals in the cylinder may be damaged.

ԙ

Ԙ

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Fluid leaks.

Fluid does not leak.

Repair the steering cylinder.

Normal

５ ‑228

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｃ-1.Steering is impossible or hard

（４）Faulty orbit-roll (sticking or worn spool and sleeve)

Measure the force required to turn the steering wheel.

1. Place the machine in a travel position on a level, paved surface, and release the parking brake.

2. Make the hydraulic fluid to an operating temperature (40 - 60°C).

3. Make the bucket empty.

4. Under this condition, measure the forces required to turn the steering wheel for both when the engine is running at a low idling speed and when it is running at the maximum speed. At the same time, check for any irregularity in the required turning force (sticking).

Refer Performance standard list for standard value.

Measure the amount of slip of the steering wheel.

1. Turn the steering wheel to the right or left until it makes a close contact with the stopper on the frame stopper (stroke end).

2. Continue turning the steering wheel further; the steering wheel will be made to rotate while slipping due to the internal leakage that takes place in the orbit-roll.

Measure the number of turns the wheel make in a minute.

Standard value The standard value for a new machine is 3.5 turns per minute. If the number of turns is 1.5 times the standard value, the internal leakage is excessive, so the steering system must be repaired.

Above standard value

Repair or replace orbitroll.

5RTKPI $CNCPEG

５ ‑229

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｃ-1. Steering is impossible or hard

（５）Faulty operation of priority valve

Disassemble and check the priority valve.

Faulty operation of the priority valve may be caused by the following: 1. Sticking spool ①

Ԙ

2. Clogged orifice ②

ԙ

3. Weak spring ③

Repair or replace the priority valve.

５ ‑230

Ԛ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｃ-2. Machine pulls to one side

（１）Faulty orbit-roll (sticking and worn of spool and sleeve)

（２） Damaged to piston seals in steering cylinder

Refer to the items 1-Ｃ （3） and （4）

（３）Loose steering cylinder mounting pins and/or center pin

Check for looseness.

Check for looseness.

（４）Unevenly worn or inflated tires

Check for abnormal wear of a certain tire, too low tire inflation pressure (blowout) and use of tires of nonrecommended sizes.

Replace pins and bushings.

５ ‑231

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-1. Lift arm fails to rise or is slow to rise.

Measure rising time of lift arm When a user complains that the lift arm is slow to rise, first measure the time required for the lift arm to rise to the specified height in order to determine whether the user feels the lift arm motion to be slow or it is really slow due to malfu nction.

1. Measure the time required to move up the lift arm from ground level to the maximum height, in accordance with the description in the section of measurement of system performance.

5GE

Note: 1. The values shown above are standard values for new mach ines. With machines that have been operated for some time, the time will be slightly longer than

Much longer than the standard time

Standard time

（１）Too low fluid level in hydraulic fluid tank

Normal

５ ‑232

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-1. Lift arm fails to rise or is slow to rise.

（ １） T o o lo w flu id le ve l in h ydrau lic flu id tan k 7RRGT NKOKV

C h e c k th e flu id le ve l in th e h ydrau lic flu id tan k 1 . Park th e ve h ic le o n a le ve l gro u n d.

2 . Lo w e r th e bu c ke t o r attac h m e n t flat o n th e gro u n d.

3 . Sto p th e e n gin e an d c h e c k th at th e flu id le ve l is be tw e e n th e u ppe r an d lo w e r lim its.

N o rm al h ydrau lic flu id le ve l

.QYGT NKOKV

T o o lo w h ydrau lic flu id le ve l

Ԙ C avitatio n n o ise fro m th e pu m p

Re pair le aky lo c atio n s, th e n re fill th e h ydrau lic flu id tan k.

Ԛ

（ ２） C lo gge d su c tio n strain e r

Re m o ve th e su c tio n strain e r ① in th e h ydrau lic flu id tan k an d c h e c k fo r c lo ggin g. #V VJG TKIJV QH VJG OCEJKPG 㧛WPFGT VJG HNQQT RNCVG

C lo gge d

Also c h e c k th e H ST lin e filte r e le m e n t ② an d h ydrau lic flu id filte r e le m e n t ③ fo r pre se n c e o f fo re ign m atte r th at c au se s c lo ggin g o f th e su c tio n strain e r ①.

C le an th e su c tio n strain e r.

N o t c lo gge d

ԙ

0GCT VJG TGCT HTCOG EGPVGT RKP

Alu m in u m o r o th e r m e tal flake s

Fragm e n ts o f n ylo n o r ru bbe r

Re pair th e h ydrau lic pu m p.

Re pair th e h ydrau lic c ylin de r an d h o se .

５ ‑233

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-1. Lift arm fails to rise or is slow to rise.

（３）Poorly adjusted control link

Measure the stroke distances of the control valve spools.

(NQCV OO .QYGT OO *QNF OO 4CKUG

&WOR OO *QNF OO 6KNV

Check that the spools move by the distances corresponding to the standard values when the control lever is moved from the "hold (neutral)" position to each position.

6KNV 5RQQN

Below standard value

Standard value

Adjust or repair the control link.

Repair the control valve.

.KHV 5RQQN

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%QPVTQN .GXGT

%QPVTQN %CDNG Ԙ

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6KNV 5RQQN

５ ‑234

.KHV 5RQQN

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-1. Lift arm fails to rise or is slow to rise.

（４）Drop in shovel main relief valve pressure or faulty main pump

Measure the shovel control valve main pressure.

Measure the main relief pressure in accordance with the description in the section of measurement of system performance.

Standard main oil pressure value：２０．６MPａ（２１０ kgf／ｃｍ2）

Drop in main pressure

Adjust the relief valve set pressure or replace the valve.

1KN 2TGUUWTG 2QTV

6KNV %[NKPFGT Oil pressure does not rise even after the abovementioned

Adjust the overload relief valve, or repair or replace the main pump.

2TGUUWTG &GETGCUG

2TGUUWTG +PETGCUG

.QEM 0WV /CKP 4GNKGH 8CNXG

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５ ‑235

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-1. Lift arm fails to rise or is slow to rise.

（５）Faulty operation of priority valve

Disassemble and inspect the priority valve incorporated in the orbitroll.

Check the spool ① for sticking and the orifice ② for clogging.

Normal

Spool is sticking and/or orifice is clogging.

Clean or replace faulty parts.

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５ ‑236

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-1. Lift arm fails to rise or is slow to rise.

（６）Damaged to piston seals in lift cylinder

Check the lift cylinder for internal leakage.

1. Tilt back the bucket and lower the lift arm to the lowest position.

2. Disconnect the hose ① from the cylinder bottom. Close the disconnected end of the hose ① with the plug ② to prevent fluid from spouting from th e hose.

3. Start the engine and move the control lever to the "Lower" po sition to apply pressure to the piston rod (cylinder head) end.

Caution: Be careful not to let the control lever move into th e "Float" position from the "Lower" position.

4. If fluid flows out of the cylinder port ③ , the cause can be determined to be damaged to piston seals in the cylinder.

Repair the lift cylinder.

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５ ‑237

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-1. Lift arm fails to rise or is slow to rise.

（７）Broken couplings and worn splines in HST pump and main pump

If the lift arm does not operate at all when the shovel control lever or steering wheel is operated, start the engine to check whether the travel system (HST system) is normal.

Faulty travel operation

Normal

Worn spline of the coupling ① in the main pump or broken coupling ② or worn spline in the HST pump

Repair or replace faulty parts.

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５ ‑238

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TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-2. Lift arm exclusively lowers (drifts) when control valve is in "Hold (Neutral)" position Measure the amount of the lift arm drift.

When a user complains that the lift arm lowers with the control valve in the "Hold Neutral)" position, first check that the amount of the drift is within the standard value (normal).

1. Measure the natural depression distance of hydraulic cylinder in accordance with the description in the section of measurement of system performance.

2. Refer Performance standard list for standard value.

Much larger than standard value

Within the standard value

Normal

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５ ‑239

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-2. Lift arm exclusively lowers (drifts) when control valve is in "Hold (Neutral)" position

（１）Damaged to piston seals in lift cylinder

Check the lift cylinder for internal leakage.

1. Tilt back the bucket, then lower the lift arm to the lowest position.

2. Remove the hose ① from the cylinder bottom end and close the disconnected end of the hose ① with the plug ② to prevent oil from spouting from the hose.

3. Start the engine and move the control lever to the "Lower" position to apply pressure to the piston rod (cylinder head) end.

Caution: Be careful not to let the control lever move into the "Float" position from the "Lower" position.

4. If oil flows out of the cylinder port ③, the cause can be determined to be damaged piston seals in the cylinder.

Repair the lift cylinder.

Ԛ ԙ Ԙ

５ ‑240

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-2. Lift arm exclusively lowers (drifts) when control valve is in "Hold (Neutral)" position

（２）Faulty oil-tightness of control valve lift spool

Disassemble and inspect the control valve.

1. If there are dents, scratches, rust and corrosion on the surfaces of the spool ① and housing ②, rectify them with a #2000 emery paper or oil stone.

2. If they are beyond repair, replace the section assembly.

Repair the control cylinder or replace the section assembly.

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５ ‑241

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TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

D-3.Lift cylinder does not generate enough force to raise frontwheels off ground

（１）Faulty operation of antipode valve

If drift of the lift cylinder is normal but the cylinder cannot generate a force enough to raise and hold the front wheels off the ground, remove the antipode valve and inspect it.

1. If the poppet seal surface ② of the antipode valve ① is in poor contact with its seat, pressure oil in the piston rod side flows directly to the drain circuit through the antipode valve, so that the lift cylinder cannot generate power to raise and hold the front wheels off the ground.

Clean or replace antipode valve.

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５ ‑242

Ԙ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

D-4. Lift arm drifts quickly at specific position

（１）Bulged or scratched cylinder tube

Measure the inside diameter of the cylinder tube at several locations to check for a bulge. Also check the rubbing surface for dents and scratches.

Standard inside diameter：７０ｍｍ

Repair or replace the cylinder tube.

%[NKPFGT )CWIG

５ ‑243

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

D- ５．リフトアームを上昇させる時一旦下がってから上昇する。

（１）Faulty operation of load check valve

If drift of the lift arm is normal but the lift arm momentarily lowers and then starts to rise when the lift lever is moved to the "Raise" position with the bucket loaded, remove and check the load check valve for the lift position. １．When the load check valve is normal, fluid can flow in the directions indicated by arrows →, but not in the directions indicated by ２．Therefore, even if the pressure P1 acting on the lift cylinder piston becomes greater due to the load on the bucket than the pump pressure P2, the lift arm does not lower. ３．However, if the poppet seat ① surface is damaged, foreign matter is jammed, the poppet is sticking or the springs ② is damaged, the fluid on the P1 side flows to the P2 side, causing the lift arm to lower momentary.

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Clean or replace the load check valve.

５ ‑244

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

D-6. Bucket tilt-back motion is slow or tilt-back force is insufficient Measure the bucket tilt-back time.

When a user complains that the bucket tilt-back motion is too slow, first measure the tilt-back time to determine whether the user feels the movement to be slowalthough the system is normal or it really moves too slowly due to malfun ction.

1. Measure the time required to move the bucket from maximum dump (forward tilt) position to maximum tilt back (backward tilt) when the lift arm is at the maximum height, in accordance with the description in the section of measurement of system performance.

5GE

Note: Values shown above are standard value for brand-new vehicle. These values may be degraded when the vehicle has been used for certain period.

Much longer than the standard

Standard time

Normal

（１）Too low fluid level in fluid tank

（２）Clogged suction strainer

（３）Excessive play in control linkage, poor adjustment

（４）Too low shovel main relief valve opening pressure or faulty main pump

（５）Faulty operation of priority valve

５ ‑245

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

D-6. Bucket tilt-back motion is slow or tilt-back force is insufficient

（１）Damaged tilt cylinder piston seals

Check the tilt cylinder for internal leakage.

1. Lower the lift arm to the lowest position and tilt back the bucket.

2. Disconnect the hose ① from the piston rod end (cylinder head) and close the disconnected end of the hose ① with the plug ② to prevent oil from spouting from the hose.

3. Start the engine and place the control lever in the "Tilt-back" position to apply oil pressure to the cylinder bottom end.

4. If oil flows out from the cylinder port ③, the cause can be determined to be damaged piston seals in the cylinder.

Repair the tilt cylinder.

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6KNV $CEM

５ ‑246

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

D-6. Bucket tilt-back motion is slow or tilt-back force is insufficient

（２） Too low overload relief valve opening pressure

Measurement of overload relief valve opening pressure １． Connect an oil pressure gauge to the oil pressure check port ① of the tilt cylinder to measure the main relief valve opening pressure. Adjust the pressure if necessary according to the procedure below.

Sta nd a r d v a lue of ma in p r essur e ２ ０ ．６ Ｍ Ｐ ａ （２ １ ０ ｋｇｆ／ ｃ ｍ 2） 1KN 2TGUUWTG 2QTV

２．Screw in the adjusting screw to increase the set pressure of the main relief valve ①. If the pressure does not rise with the adjusting screw turned down, the oil pressure gauge indicates the set pressure of the overload relief valve ② on the piston rod end.

First measure and adjust the set pressure of the overload relief valve, then adjust the set pressure of the main relief valve ① to the standard value.

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３．Lower the bucket flat on the ground, disconnect the tilt cylinder hoses ④ and ⑤ from the cylinder and interchange the hoses. (Connect the hose ④ to the cylinder bottom end and the hose ⑤ to the rod end.)

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Ca ut ion : With the hoses connected as mentioned above, if the control lever is placed in the "Dump" position, the bucket makes a "Tilt-back" motion; if the lever is placed in the "Tilt-back" position, the bucket makes a "Dump" motion.

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Screw in the adjusting screw to increase the set pressure of the main relief valve ① while holding the control lever in the "Tilt-back" position (the bucket makes a "Dump" motion).

When the pressure does not rise with the adjusting screw turned down, the oil pressure gauge indicates the set pressure of the overload relief valve ③ on the cylinder bottom end.

First measure and adjust the set pressure of the overload relief valve, then adjust the set pressure of the main relief valve ① to the standard value. After these adjustments, interchange the tilt cylinder hoses ④ and ⑤ again to restore them to the original condition. ４．Standard set pressure for overload relief valves ② and ③

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2TGUUWTG +PETGCUG

2TGUUWTG +PETGCUG 2TGUUWTG &GETGCUG

２ ２ ．５ Ｍ Ｐ ａ（ ２ ３ ０ ｋｇ ｆ／ ｃ ｍ 2）

５ ‑247

2TGUUWTG &GETGCUG

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/CKP 4GNKGH 8CNXG /2C㧔 MIH 㨏ট㧕

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

D-6. Bucket tilt-back motion is slow or tilt-back force is insufficient

5. If the measurements of the overload relief valve pressures in steps 1 to 3 are all the same and lower than the standard main relief valve opening pressure, the causes may be the following.

Faulty main relief valve

Faulty main pump

Faulty or poorly adjusted overload valves ② and ③

6. If the measurements of the overload relief valve opening pressure in steps 1 and 2 are the same, and they are lower than the standard main relief valve pressure, and the overload relief valve pressures measured in step 3 is equal to the standard pressure, then the cause may be the following.

Faulty or poorly adjusted overload valve ②

＜Adjusting method＞ (1) Make preparations ready for an overload relief valve ② pressure measurement using an oil pressure gauge as described in step 2.

(2) Loosen the lock nut ⑥ of the overload relief valve ②.

(3) While reading the oil pressure gauge, turn the adjusting screw ⑦ with a hexagonal wrench so that the reading becomes equal to the standard pressure.

Turn clockwise to raise the pressure.

Turn counter-clockwise to lower the pressure

Standar d set pressure：２２．５ＭＰａ（２３０ｋ ｇｆ／ｃｍ2） Caution: Never turn the adjusting screw quickly as the relief valve is very sensitive. ・Hold the adjusting screw ⑦ with a hexagonal wrench when securing it with the lock nut ⑥. ・Measure the overload relief valve opening pressure again to make sure that the pressure conforms to the standard pressure. ・Adjust the pressure of the main relief valve to the standard pressure.

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1XGTNQCF 4GNKGH 8CNXGԙ‫ޔ‬Ԛ

５ ‑248

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

D-6. Bucket tilt-back motion is slow or tilt-back force is insufficient

7. If the measurements of the overload relief valve opening pressure in step 1 and 3 are the same, and they are lower than the standard main relief valve pressure, and the overload relief valve pressure measured in step 2 is equal to the standard pressure, then the cause may be the following.

Faulty or poorly adjusted overload valve ③ ＜Adjusting method＞ (1) Make preparations ready for overload relief valve ③ pressure measurement using an oil pressure gauge as described in step 3.

(2) Loosen the lock nut ⑥ of the overload relief valve ③.

(3) While reading the oil pressure gauge, turn the adjusting screw ⑦ with a hexagonal wrench so that the reading becomes equal to the standard pressure.

Turn clockwise to raise the pressure.

Turn counter-clockwise to lower the pressure.

Standard set pressure ：２２．５ＭＰａ（２３０ｋｇｆ／ｃｍ2） Caution: Never turn the adjusting screw quickly as the relief valve is very sensitive. ・Hold the adjusting screw ⑦ with a hexagonal wrench when securing it with the lock nut ⑥. ・Measure the overload relief valve opening pressure again to make sure that the pressure conforms to the standard pressure. ・Adjust the set pressure of the main relief valve to the standard pressure.

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1XGTNQCF 4GNKGH 8CNXGԙ‫ޔ‬Ԛ （４）Restore the tilt cylinder hoses ④ and ⑤ to the original condition by interchanging their connection.

8. If the overload relief valve pressure measurement in step 2 is higher than the standard pressure, adjust the overload relief valve ② in accordance with step 6.

9. If the overload relief valve pressure measurement in step 3 is higher than the standard pressure, adjust the overload relief valve ③ in accordance with step 7.

５ ‑249

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-7. Bucket tilts forward with control valve in "Hold (Neutral)" state (front wheels cannot be raised off ground) Measure the amount of drift of the bucket.

When a user complains that the bucket tilts forward spontaneously with the control valve in a "Hold (Neutral)" state, first check that the amount of the forward tilt is within the standard amount (normal).

1. Measure the natural depression distance of hydraulic cylinder in accordance with the description in the section of measurement of system performance.

2. Refer Performance standard list for standard value.

Much larger than the standard

Within the standard value

Check the tilt cylinder for internal leakage.

Normal

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５ ‑250

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting Ｄ-7. Bucket tilts forward with control valve in "Hold (Neutral)" state (front wheels cannot be raised off ground)

（１）Ch eck th e tilt cylinder for in ternal leakage .

Ch eck th e tilt cylinder for in ternal leakage .

1. Lower the lift arm to the lowest position and tilt back the bucket.

2. Disconnect the hose ① from the piston rod end (cylinder head) and close the disconnected end of the hose ① with the plug ② to prevent oil from spouting from the hose.

3. Start the engine and place the control lever in the "Tilt-back" position to apply oil pressure to the cylinder bottom end.

4. If oil flows out from the cylinder port ③ , the cause can be determined to be damaged piston seals in the cylinder. ԙ

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Repair th e tilt c ylinder. Ԛ

（２）Poor oil- tigh tne ss of overload relief valve

Chec k the overload relief valve for oil-tightn ess.

1 . Ch eck th at the fron t wh eels can be raised an d he ld off the grou nd by the tilt c ylin der.

2 . If fore ign matter is jammed into the overload relie f valve or the valve is in poor contac t with its se at, pre ssure fluid in th e piston rod e nd flow s directly to th e tank circ uit via the overload relie f valve, so the tilt cylinde r rod cannot be he ld in an extended position (front wh eels gradu ally low er).

3 . As the overload relie f valve s in the piston rod end an d cylin der bottom end are the same, fu nctionality of both the valves can be che cke d by in terc han gin g th em.

4 . If oil- tigh tness of th e c ylinder bottom end ove rload relief valve is de fec tive , th e b u c k e t s p o n t a n e o u s ly tilt s f o rw a rd . If oil-tightness of the piston rod en d overload relie f valve is defe ctive, th e f ro n t w h e e ls c a n n o t b e r a is e d a n d h e ld o f f th e g ro u n d . $QVVQO 'PF

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O il-tightn ess of the ove rload re lief valves is normal.

O il-tightness of the overload re lief valves is defe ctive.

Cle an or re place the ove rload re lief valve(s).

５ ‑251

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting Ｄ-7. Bucket tilts forward with control valve in "Hold (Neutral)" state (front wheels cannot be raised off ground)

（３）Defective oil-tightness of control valve tilt spool

Disassemble and inspect control valve.

1. If there are dents, scratches, rust and corrosion on the surface of the spool ① and housing ②, rectify them with a #2000 emery paper or oil stone.

2. If they are beyond repair, replace the section assembly.

Repair the control valve or replace the section assembly.

Ԙ

５ ‑252

ԙ

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-8. Bucket drifts quickly at specific position

（１）Bulged or scratched cylinder tube

Measure the inside diameter of the cylinder tube at several locations to check for a bulge. Also check the rubbing surface for dents and scratches.

Standard inside diameter： ７０ｍｍ %[NKPFGT )CWIG

Repair or replace the cylinder tube.

Troubleshooting

Ｄ-9. Bucket sways during travel

（１ ）D a m a ged tilt cy linder piston sea ls

R efer to problem item 6(1).

（２ ） Too low setting of ov erloa d relief v a lv e opening pressure

R efer to problem item 6(2).

（３ ）D efectiv e oil-tightness of ov erloa d relief v a lv e

R efer to problem item 6(2).

（４ ） D efectiv e oil-tightness of control v a lv e tilt spool

R efer to problem item 6(3).

（５ ）W orn shov el linka ge pins a nd bushings

R epla ce pins a nd bushings.

５ ‑253

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-10. Too large control lever operating resistance

Measure the forces required to operate the control lever When a user complains that the shovel control lever is hard to move, first check for the forces required to operate the control lever.

1.Measure the lever stroke in accordance with the description in the section of measurement of system performance.

2. Refer Performance standard list for standard value. *1.& &7/2 6+.6

Much larger than the standard value

Within the standard value

*1.& .19'4

4#+5'

(.1#6

Normal

（１）Too large movement resistance of cable

Separate the cable from the control valve by loosening the nut ①, then operate control lever.

Operating force is small.

Operating

Operating force is very large.

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Repair or replace the control cable. .KHV 5RQQN

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５ ‑254

TROUBLESHOOTING /SYSTEM PERFORMANCE Troubleshooting

Ｄ-10. Too large control lever operating resistance

（２）Sticking control valve spools

Measure the operating force of each spool.

Using a push-pull gauge, measure the operating force of each spool.

1. Tilt spool (Hold/Neutral) 2. Tilt spool (full stroke: Tilt, Dump) 3. Lift spool (Hold/Neutral) 4. Lift spool (full stroke: Raise, Lower) 5. Float release (detent release) Refer Performance standard list for standard value.

Much larger than the standard values

Disassemble and inspect the control valve.

５ ‑255

Within the standard values

Normal

(Blank)

No. SEW-603-MAE Issued:

October, 2006

INTERNATIONAL MARKETING DIVISION:

1-15-5, Nishi-shimbashi, Minato-ku, Tokyo 105-0003, Japan FAX: JAPAN +81-3-35918152, 3-35918153

All rights reserved

X-0610002(OS) Printed in Japan