CLARK FORKLIFT HT200 Hydrostatic Drive TECHNICAL TECHNICAL TRAINING MANUAL

HT200 Hydrostatic Drive

TECHNICAL TRAINING Copyrighted Material Intended for CLARK dealers only Do not sell or distribute

Copyrighted Material Intended for CLARK dealers only Do not sell or distribute

Contents

About this Class...........................................................................................

Safety............................................................................................................

Section 1. Introduction to Hydrostatic Drive..............................................

System Description...........................................................................

Microprocessor...................................................................................

LED Indicators..................................................................................

Dia-3 Tester.......................................................................................

Sensors, Switches, and Actuators.....................................................

System Drawing................................................................................

Electrical Components......................................................................

Section 2. Programming the Susmic Dia-3.................................................

DIA-3 Quick Reference......................................................................

Sensor Set-up Settings......................................................................

Sensor Error Codes...........................................................................

Sensor Check Codes...........................................................................

Programming Procedures..................................................................

Susmic-Dia 3 Operation Manual Version ........................................

Custom Adjustments of Driving Characteristics Version 6.4.........

Custom Adjustments of Driving Characteristics Version 6.3.........

Sensor and Actuator Error Diagnosis..............................................

Sensor Check Procedw·e....................................................................

Section 3. Troubleshooting...........................................................................

Using Dianostic LEDs.......................................................................

Driving Behavior Abnormal..............................................................

Does Not Reach Maximum Speed....................................................

Section 4. Hydraulic System........................................................................

Hydrostatic Transmission Specifications........................................

System Drawing................................................................................

Hydraulic Schematic.........................................................................

Pump Components............................................................................

Adjusting Charge Pressures.............................................................

Adjusting Main Pressures................................................................

Towing a Disable Vehicle..................................................................

Start-Up Procedures..........................................................................

Section 5. Component Removal and Replacement.....................................

Hydrostatic System Plumbing..........................................................

Drive Axle..........................................................................................

Hydrostatic Pump.............................................................................

Pump Mounting.................................................................................

Axle General Arrangement...............................................................

Engine Adjustments..........................................................................

Engine Idle Speed Adjustment.........................................................

Maximum Governor Speed Adjustment...........................................

2 3 4 4 5 6 7 8 9 10 18 18 18 19 19 20 25 43 43 56 58 67 67 69 70 72 73 74 75 76 77 78 80 80 82 82 83 84 85 86 87 87 87

©Copyright Clark Material Handling Company 1998.

Copyrighted Material Intended for CLARK dealers only Do not sell or distribute

Hydrostatic Drive page 1

About this class

Welcome to Class HT-200: Clark Hydrostatic Drive System This class consists of five major sections.

•

Hydrostatic Drive Introduction

•

Programming the Control

•

Troubleshooting

•

Hydrostatic Pump and Motors

•

Hydrostatic Components

The purpose of this class is to introduce you to the Hydrostatic Drive system. This class will explain how to maintain, program, and troubleshoot the electrical control, the Susmic Dia 3.

Maintenance and adjustment of the hydraulic elements of the system will also be discussed.

The maintenance procedures will prevent most types of premature failures while the troubleshooting procedures provide a means whereby a particular component can be isolated as the problem when failures do occw·.

Important Refer to the service manual for the truck you are working on for additional information.

Hydrostatic Drive page 2

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About Safety

The following messages may be used to emphasize important information:

Note This message is used when special information, instructions or identification is required relating to procedures, equipment, tools, pressures, capacities and other special data.

Important This message is used when special precautions should be taken to ensure a correct action or to avoid damage to or malfunction of the truck or a component.

CAUTION This message is used as a reminder of safety practices. which can result in personal injury if proper precautions are not taken.

WARNING This message is used when a hazard exists which can result in injury or death if proper precautions are not taken.

DANGER

This message is used when an extreme hazard exists which will result in death or serious injury of proper precautions are not taken.

Only trained and authorized personnel shall be permitted to maintain, repair, adjust, and inspect industrial trucks. Work should be performed in accordance with the manufacturer's specifications.

WARNING Always be sure to follow all safety precautions. Before you take any action, determine whether it could result in injury to yourself or a by stander. Refer to Clark service manuals for a complete listing of safe maintenance practices and for procedures to perform safe lifting, jacking and blocking of the lift truck.

Note Properly ventilate work area, vent exhaust fumes, and keep shop clean and floor dry.

Before working on truck: Raise drive wheels off of floor and use blocks or other positive truck positioning devices.

Operation of the truck to check performance must be conducted in an authorized, safe, clear area.

Park truck on a hard, level, and solid sw.-face, such as a concrete floor with no gaps or breaks. Put upright in vertical position and fully lower the forks or attachment. Put all controls in neutral. Turn key switch OFF and remove key. Apply the parking brake and block the wheels. Make sure there is sufficient overhead clearance for raising the upright.

Clark recommends for companies with multiple hydrostatic trucks that all the trucks be set with the same driving parameters so they drive the same.

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Hydrostatic Drive page 3

Section 1. Hydrostatic Drive System Introduction

In the hydrostatic drive truck, power is transmitted to the drive wheels by hydraulic-powered motors, rather than by gears and clutches.

The hydrostatic truck's conventional spark-ignited or diesel engine rotates a hydraulic pump, the "hydrostatic drive pump," that supplies fluid to two hydraulic motors in the drive axle. Each motor drives a drive wheel.

The hydraulic fluid is drawn from the same sump that supplies the load handling system. [Incidentally, the pump for the load-handling system (main hydraulic pump) is mounted on, and mechanically driven by, the hydrostatic drive pump.]

The hydrostatic drive pump is a variable displacement axial piston pump. Pump out­ put volume and direction of flow are governed by the pump's swashplate. The angle at which the swashplate is tilted controls the length of the piston strokes as the pistons rotate past inlet'outlet ports. Swashplate angle is controlled by an electrical displace­ ment control (EDC). The EDC hydraulically varies the angle of the swashplate in response to the electrical signal level received from the computer.

The fluid displaced by the drive pump flows through external plumbing to the radial piston drive motors in the drive axle. The volume and direction of the fluid determines the speed and direction of the truck. Each drive motor is connected to an axle shaft that drives an axle end and wheel identical to those used on the standard truck.

Parallel circuitry to the drive motors allows a speed differential between the motors when the truck is cornering.

The diagram below shows the flow of information into and out of the computer that controls the drive system, the SUSMIC DIA 3 microprocessor. The inputs consist of signals from the various sensors and switches that are affected by positioning of the truck's manual controls.

Tilt Switch

Parking Brk Switch

Aux1&2 Switches

Acc. Pedal Sensor

Eng. Actuator Engine Speed Sensor Sensor

Brake Pedal Sensor

COMPUTER (SUSMIC -DIA 3 MICRO-PROCESSOR)

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Hydrostatic Drive page 4

Engine Actuator

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Throttle

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Electrical Displacement Control

Drive Pump

Lift Lever Sensor

The signals from the switches consist of either an open or closed circuit. The signal from the engine speed sensor consists of pulses ranging from 0 to 9.9 kHz (cycles per second), increasing as engine speed increases. The signals from the other sensors con­ sists of 0 to 5-volt levels that vary according to the position of the associated control.

The outputs consists of electrical power to the engine actuator and to the EDC. Zero to 12 volts are supplied to the engine actuator and 0 to 100 mA are supplied to the EDC. As the truck operates, the computer monitors the positions of the various manual controls in order to sense the desired performance; while at the same time, the com­ puter monitors engine speed and engine actuator position in order to sense the actual performance.

To make the actual performance match the desired performance, the computer varies the engine throttle position via the engine actuator and the drive pump output via the EDC. The system can be diagnosed and adjusted with a diagnostic conti·ol, usually the SUSMIC-DIA 3 tester, that connects to the SUSMIC DIA 12 computer.

Hydrostatic Drive Microprocessor The hydrostatic drive system in the Clark CGC 20/25/30H, the CGP 20/25/30H, and the CDP 20/25/30H is controlled by a microprocessor. The microprocessor is mounted on the left side frame rail in the engine compartment. The microprocessor has a program loaded in it which analyzes the data inputted from the sensors and switches located on the truck. From this data, the engine speed and the displacement of the pump are controlled to provide drive capabilities and higher engine speeds for the mast functions.

Computer

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Hydrostatic Drive page 5

The memory of the microprocessor cannot be damaged by using the DIA-3 service tester or by disconnection of the battery. The internal components can be damaged or the memory can be affected by electric arcs so disconnection of the microprocessor from the wire harness prior to welding is required.

LED Indicators

Located on top of the microprocessor are four light emitting diodes (LED's), two green, one yellow, and one red. Looking down on the microprocessor in the truck, the rear most LED is green and indicates the 12 volt power from the trucks electrical system. If this LED is dim or not illuminated when the ignition switch is on, then a connection or low voltage problem exists.

The next LED is also green and it indicates the microprocessor's internal 5 volt power supply. If this LED is dim or not illuminated when the ignition switch is on and the first LED is illuminated, than an internal problem with the microprocessor exists. This condition is not serviceable at the dealership.

The LED third from the rear is yellow and indicates when the program is running. It flashes slow, (approximately once per second), when the program is running and fast if the program is not running.

The forward most LED is red and indicates when an error condition exists. When the truck is in an en-or mode, the truck is programmed to not allow driving until the error is corrected.

The DIA-3 diagnostic instrument must be used to diagnose and con-ect the en-or.

Red Error Indication - , , Yellow-Application Status·

__

Green-5 Volt Power Supply Green-12 Volt

Power Supply

Hydrostatic Drive page 6

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Programming

The Susmic Dia 3 computer can be programmed using a lap-top computer or the Dia 3 Tester. This class will supply you with the information needed to use the Dia 3 tester.

Sus:mic Dia-3 Diagnostic Tool Part # 4334183 The Susmic Dia-3 tester is used to communicate with the microprocessor which con­ trols the hydrostatic drive system. When using the Dia-3 tester the instruction manual must be followed precisely.

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Connecting the Tester

Plug the tester harness into the truck's test harness plug located under the floor plate.

Enter/Save

Note The Susmic Dia-3 is a sensitive electronic service tool and must be handled with care. Protect tool from water, shock, and dust.

Battery Life

The Dia-3 tester uses 2 AA batteries. You should experience the following approximate battery life when using the Dia-3 tester; Zink-20 min.

Akaline-250 min.

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Lithium-550 min.

Hydrostatic Drive page 7

Sensors Switches, and Actuators A series of sensor, switches, and actuators are used to allow the computer to monitor and control driving conditions.

Directional Switches Signals the computor when the direction lever is moved to the forward or reverse posi­ tion.

Brake Pedal Sensor The brake pedal sensor sends a variable signal to the computer as the pedal is de­ pressed.

Accelerator Pedal Sensor The accelerator pedal sensor sends a variable signal to the computer as the pedal is depressed.

Lift Lever Sensor The Lift lever sensor sends a variable signal to the computer as the lever is moved to the lift position.

Tilt and Aux. Lever Switches Signals the computer that the tilt or aux. hydraulic lever has been actuated.

Parking Brake Switch Signals the computer that the parking brake is released.

Engine Speed Sensor (PPU) The engine speed sensor sends a variable signal to the computer as engine RPMs in­ crease or decrease. This is how the computer monitors engine RPMs. Engine (Thottle) Actuator Recieves signals from the computer to control the engine RPMs by increasing or de­ creasing engine thottle position.

Electrical Displacement Control (EDC) Recieves signals from the computer to control the swashplate position in the hydro­ static pump which in turn, controls the amount and direction of hydraulic flow to the drive motors.

Hydrostatic Drive page 8

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