Theory of Operation

Lift/Lower

The lift/lower system consists of an electrically operated hydraulic pump assembly and related components.

The hydraulic pump assembly consists of a positive displacement rotary gear pump with reservoir mounted to an adapter. A DC electric motor is mounted to the opposite side of the pump adapter. An adjustable relief valve, check valve, and a solenoid operated lowering valve are located within the adapter.

With the forks elevated, the normally closed solenoid valve and the check valve prevent hydraulic fluid from returning to the reservoir.

Lift

When the battery is plugged in, the Main ON/OFF switch is ON, the key switch is ON, and the lift button is pressed:

•Lift switch (SW12) closes.

•Lift pump contactor (M2) closes, applying B+ to the lift motor causing the lift pump to operate.

•Hydraulic fluid is drawn through the 100 micron screen in the reservoir into the lift pump.

•As the pump rotates, oil is forced out the pressure port through the lift hose to the lift cylinder. Oil cannot return to the reservoir because of the closed pressure relief valve and closed lowering solenoid valve (SOL).

•Hydraulic pressure in the lift cylinder raises the forks.

Lift cutout switch (SW10) will interrupt power to the lift motor when the forks reach a preset lift limit.

Directional/Speed Control

•When the lift switch is open, the pump contactor coil is de-energized. This stops the lift motor and pump. The forks are held in position by hydraulic fluid trapped in the cylinder by the check valve, the static position of the relief valve, and the closed lowering solenoid (SOL).

The relief valve will open if the hydraulic pressure exceeds the preset limit.

Lower

When the battery is connected, the Main ON/OFF switch is ON, the key switch is ON and the lower button is pressed:

•Lower switch (SW11) is closed, applying B+ to the lowering solenoid (SOL).

•Lowering solenoid opens.

•Hydraulic fluid in the lift cylinder returns to the hydraulic reservoir through the lowering valve and the flow control valve.

•The forks lower.

Directional/Speed Control

The following descriptions assume the battery is charged and connected, the Main ON/OFF switch (SW13) is ON, an d the key switch (SW1) is ON.

The control handle must be in the proper position to close the brake (deadman) switch (SW2) and release the brake. See “Brake (Deadman) Switch” on page5-7. When the brake (deadman) switch is closed, main contactor (M1) is energized.

NOTE: When the control handle is released and the deadman switch opened, the main contactor (M1) will remain energized for several seconds before de-energizing.

Forward

When the twist grip/butterfly control is rotated in the forward direction (tractor first) from neutral:

•Forward directional switch (SW3) is closed and B+ voltage is applied to PMC-12 of the motor controller.

•The resistance across the throttle potentiometer (VR-4 to VR-2) increases from zero ohms to a maximum of 6.5K ohms. Throttle input voltage is then generated at PMC-6 with respect to PMC-7.

•Once the throttle input voltage is above the neutral band threshold the motor controller begins to provide current flow through the drive motor armature at M-. It also provides current flow through the field windings in the proper polarity at S1 and S2.

•The drive wheel begins to rotate in forward direction at a speed proportional to throttle input.

Reverse

When the twist grip/butterfly control is rotated in the reverse direction (forks first) from neutral:

•Reverse directional switch (SW4) is closed and B+ voltage is applied to PMC-11 of the motor controller.

•The resistance across the throttle potentiometer (VR-4 to VR-2) increases from zero ohms to a maximum of 6.5K ohms. Throttle input voltage is then generated at PMC-6 with respect to PMC-7.

•Once the throttle input voltage is above the neutral band threshold the motor controller begins to provide current flow through the drive motor armature at M-. It also provides current flow through the field windings in the proper polarity (S1 and S2).

•The drive wheel begins to rotate in reverse direction at a speed proportional to throttle input.

Emergency Reverse

If the emergency reverse switch (belly button switch) (SW7) is closed with the control handle lowered (SW2 closed) in travel mode, the control system will provide an immediate, rapid acceleration in the reverse (forks-first) direction:

•Emergency reverse switch (SW7) is closed applying B+ voltage to PMC-13.

•Travel inputs (VR, SW 3, SW4) are ignored.

Directional/Speed Control

•The polarity of the field voltage at S1 and S2 is reversed by the motor controller.

•The motor controller provides maximum torque immediately after the emergency reverse switch is closed and current limit is automatically set to the higher plugging value (approximately 300 Amps).

•Maximum reverse travel will continue until the emergency reverse switch is released.

Once the emergency reverse switch is activated, the motor controller inhibits the forward direction. To reset the truck for normal travel, the handle must be cycled to “brake applied” position (SW2 open). Turning the key switch OFF and then ON will also reset the motor controller.

Motor Controller

The basic functions of the motor controller include:

•The direction control section controls the drive motor direction by manipulating the drive motor field polarity according to the directional switch inputs (SW3, SW4).

•The throttle control section controls the drive motor speed and torque by monitoring relative position change of the wiper in the travel potentiometer with respect to the static neutral position. Variable motor speed is accomplished by separate control of field and armature currents.

•The emergency reverse circuitry controls the override of the dir ectional travel control.

•Controls main contactor (M1) operation.

•The diagnostics section continuously monitors the travel circuits for fault conditions and responds appropriately, shutting down travel in some cases.

Maintenance Guidelines

Maintenance Guidelines

Following a regularly scheduled maintenance program:

•Promotes maximum truck performance

•Prolongs truck life

•Reduces costly down time

•Avoids unnecessary repairs

Scheduled maintenance includes:

•Lubrication

•Cleaning

•Inspection

•Service

Perform all of the scheduled checks and maintenance during the suggested intervals. The intervals given in this guide are based on normal operating conditions. When operating under abnormal or severe conditions, perform these services more often as required to keep the unit in good operating condition.

See “Lubrication Equivalency Chart” on page A-2. Refer to the manufacturer’s supplements for components not listed on the following pages.

Daily

Perform the daily checks and report any faults or abnormal conditions to your supervisor.

Item

Daily or Eight Hour Checklist

Check cleanliness and exterior condition. See “Battery Exterior Cleaning” on page 6-9. Check the charge. Check the weight.

Battery

General Operation

Check the connector. Make sure all powered functions shut down when disconnected. Make sure the battery is properly installed. Check the “free play” of the battery. Make sure the battery does not move more than 0.5 in. (12.7 mm).

Check that the horn operates when you press the horn button. (Battery must be connected and the Main ON/OFF switch must be ON.)

Check the speed and directional controls. Check the steering operation. Check the lifting and lowering functions. Check the operation of the emergency reverse button. Note any unusual noise during operation, and report it to your supervisor or maintenance personnel.

Brake

Verify the drive motor does not run while the brake is applied. Check that the control handle returns to the vertical position when released.

Decals

Warning/Safety/Operational decals must be in place and legible. Notify your local authorized Raymond Dealer if any decal is defective.

Hydraulic SystemCheck for oil leaks.

Wheels/Tires

Check the condition of the drive wheel and load wheels. Remove any steel chips and foreign material to prevent damage to the wheels.

Check for gouging and chunking of the surface. If damaged, report to your supervisor or maintenance personnel.

Every Two Months or 250 Operating Hours

Every Two Months or 250 Operating Hours

Perform daily checks plus the following:

Grease Fittings

Lubricate all grease fittings. See “Grease Fittings” on page 4-7.

Forks Check the lift limit switch for lift motor cut-out. Adjust if necessary.

Lubrication PointsLubricate all le vers, shafts and linkage points.

Lift Cylinder

Hydraulic System

Check the lift cylinder for leaks. Replace cylinder if necessary. See “Hydraulic Cylinder” on page 6-74.

Check for proper fluid level with the forks fully loweredwithin 1 in. (25.4 mm) of filler plug. Add fluid if necessary. See “Lubrication Equivalency Chart” on page A-2.

Check hydraulic connections and mountings. Check the tightness of the pump and motor hardware. Check hoses, tubes and fittings for leaks. Replace hoses or seals. Clean the fill/vent plug. See “Hydraulic Unit” on page 6-77.

General Check for loose hardware. Tighten if necessary. Check the tightness of the drive unit mounting bolts. Tighten if necessary.

Visually inspect all cables for damage. Replace if necessary. See “Power Cables” on page 6-16.

Electrical System

Drive Wheel

Drive Unit

Motor Brushes

Brake (Deadman) Switch

Check for electrical shorts to frame. See “Checking for Shorts from Battery to Truck Frame” on page 5-4.

Check the tightness of the retaining nut on the drive wheel mounting. Tighten to 250 ft. lbs. (339.2 Nm).

Check for oil leaks. If leaks are found, check the oil level. If the oil level is low, determine the cause. See “Drive Unit” on page 6-57.

Check and lubricate the transmission pivot bearing. See Figure4-2.

Check the condition of brushes, springs and holders. Check that the brush length exceeds the minimum length. Drive motor - 0.62 in. (15.7 mm)

Hydraulic pump motor - 0.5 in. (12.7 mm)

Check adjustment. See “Brake (Deadman) Switch” on page 6-27.

Load Wheel Check and lubricate the load wheel bearings and linkage. See “Grease Fittings” on page 4-7.

Raymond® Walkie Pallet Truck Maintenance Manual

Scheduled Maintenance

Every Two Months or 250 Operating Hours

Item Every Two Months or Every 250 Hours

Brake Check the brake shoes for wear. Replace if necessary. See “Brake” on page 6-43.

Battery System Clean the battery and the truck. See “Battery Exterior Cleaning” on page 6-9.

PDMM-0100 Issued: 5/21/01

4-5

Annually or Every 1500 Operating Hours

Perform the Every Two Month checks plus the following:

Annually or Every 1500 Hours

Drive Housing Change the oil in the drive housing. See “Drive Housing Lubrication” on page6-62.

Grease Fittings

How to Use This Chapter

How to Use This Chapter

This chapter uses a set of “decision-tree” charts designed to take you from a symptom to a specific sequence of tests in order to isolate a failing component.

•Use the TS1: START TROUBLESHOOTING on page 5-27 to guide you to the individual symptom chart you need.

•Once you’re familiar with the symptoms listed, you may instead simply look up the symptom chart from the List of Troubleshooting Charts on page 5-25

As you work with a troubleshooting symptom chart, you may be instructed to test various electrical connector pins.

Every time you complete a troubleshooting procedure, be sure to follow the steps in the END1: End of Troubleshooting Procedure on page 5-30

If the troubleshooting symptom charts do not isolate the problem, or if the symptoms are not consistent or repeatable, go to GEN1: General Troubleshooting on page 5-28. This chart will help you approach the problem in a systematic and logical manner.

Each chart begins with an oval-shaped symbol containing the title and symptom. Charts are identified as H for Hydraulic and T for Travel. The logic generally flows top to bottom and left to right. A symbol shaped like a baseball home plate means the chart is continued on another page (either a continuation of the current chart, or a different chart). Continuation charts have a suffix number added. A continuation chart begins with a circle-shaped symbol containing the chart number and suffix.

For example, look at Chart H-3 on page 5-38 . One logic path is continued on Chart H-3-2, which is the next page. Another logic path from Chart H-3 goes to the END1: End of Troubleshooting Procedure on page 5-30.

Raymond® Walkie Pallet Truck Maintenance Manual

Electrical Troubleshooting Guidelines

Many problems are caused by a faulty or dirty battery. Make sure the battery is clean. Check the electrolyte level and state-of-charge. See “Battery” on page6-8. Be sure to block the truck whenever a troubleshooting procedure requires turning the key switch ON. This will avoid accidents caused by unexpected truck travel.

Caution

Unless otherwise directed, disconnect the battery connector when you check electrical circuits or components with an ohmmeter. Electrical curren t can damage the ohmmeter.

Save time and trouble by looking for simple causes first.

Visually inspect all wiring and electrical components for:

•Loose connections or connectors

•Loose or broken terminals

•Damaged terminals, blocks, or strips.

•Broken wiring and shorted conditions (especially those that are close to metal edges or surfaces)

Use an ohmmeter to check for wiring continuity and shorts.

For information on pin, connector, and harness connections, see “Wiring Harness” on page6-17 and see “Electrical Connector Locator Chart” on page5-12.

Checking for Shorts from Battery to Truck Frame

Checking for Shorts from Battery to Truck Frame

1.Turn the key switch OFF and disconnect the battery connector.

2.Use a voltmeter set on a 50 volt DC scale.

3.Attach the voltmete r leads as follows:

•Negative (-) lead to an unpainted, grounded surface on the truck frame

•Positive (+) lead to the positive battery terminal,

4.The voltmeter should show no more than 3 volts.

5.Now attach the voltme ter leads as follows:

•Negative (-) lead to the negative battery terminal

•Positive (+) lead to an unpainted, grounded surface on the truck frame

6.The voltmeter should show no more than 3 volts.

7.If you get more than a three volt reading in Step 4 or 6: a.Remove the battery from the truck. See “Battery” on page 6-8. b.Thoroughly clean the battery. See “Battery Exterior Cleaning” on page6-9. c.Reinstall the battery. d.Repeat steps 2 through 6 to see if this has eliminated the problem. e.If excessive voltage is still found, have the battery checked for internal leakage.

Checking for Shorts from Components to Truck

Checking for Shorts from Components to Truck Frame

1.Turn the key switch OFF and disconnect the battery connector.

2.Use an ohmmeter and measure the resistance to an unpainted, grounded surface on the frame at B+, B-, and all fuses. See Figure5-2.

A resistance reading of less than 1000 ohms indicates a serious short to frame. If this condition exists, locate the source of low resistance or short to frame using step 6. Do not continue until this condition is corrected.

3.Remove the battery from the truck. See “Battery” on page 6-8.

4.Connect the battery lead to the truck.

5.Use an ammeter to measure the leakage current to an unpainted, grounded surface on the frame at B+, B-, all fuses and all motors. If the current is less than 0.001 ampere (1mA), the truck system passes. If the current exceeds 1mA, go to step 6.

6.To find the cause of the low resistance, disconnect the power cables from each motor or major sub-assembly one at a time, to determine if that item is causing the low resistance.

Hydraulic Troubleshooting Guidelines

When you check voltage at solenoids, make sure hydraulic lines and components are fully installed.

Use an ohmmeter to check for wiring continuity to solenoids. Use an ammeter to check for proper current to soleno ids and contactor coils (refer to specific component tests).

Caution

Unless otherwise directed, disconnect the battery connector when you check electrical circuits or components with an ohmmeter. Electrical curren t can damage the ohmmeter.

Visually inspect all hydraulic lines and components for:

•Leaking connections or connectors

•Loose or broken fittings

•Damaged tubing, hoses, vents, or seals

Definitions

Acceleration Rate

The time required for the controller to increase from 0% to 100% duty cycle (PWM) when a continuous 100% throttle request is applied. Acceleration rate is an adjustable parameter within program mode. See “Motor Controller Parameter Settings (User Access Only)” on page 5-21.

Brake (Deadman) Switch

The switch (also known as deadman switch) (SW2) that must be closed to allow truck travel. The switch is activated by the control handle position. The switch acts to protect against travel while the brake is applied. The handle must be positioned betw een 10° of vertical and 10° of horizontal in order for the brake (deadman) switch to be closed, allowing travel. See Figure5-3.

Continuity

A continuous and uninterrupted path between two or more locations in an electrical circuit, typically having a resistance of less than 1 ohm.

Creep Speed

Creep speed is activated when a direction is first selected. It is the speed at the minimum throttle setting (minimum PWM). See “Pulse Width Modulation” on page 5-9. The output maintains creep speed un til the throttle is rotated out of the throttle minimum setting (10% of throttle). Creep speed is adjustable from 0–10% PWM duty cycle. The factory default value is 0%.

Current Limiting

A protective function of the motor controller which prevents excessive current levels from damaging drive components. The controller has adjustable current limit parameters for the drive current, brake (plugging) current, field current maximum, and field current minimum.

Emergency Reverse

Emergency Reverse is activated when the emergency reverse switch (“Belly Button” switch) is pressed while the brake is released and the keyswitch (SW1) is ON. After the “Belly Button” (BB) switch is released, normal controller operation is not resumed until neutral (no direction) is selected or until the brake is cycled (brake, then brake release). However, repeatedly pressing the BB switch will reactivate the emergency reverse function each time.

Fault Codes

The motor controller provides fault information by flashing fault codes via the status LED built into the controller cover. See “Fault Codes” on page5-13.

High Pedal Disable (HPD)

The HPD feature prevents the truck from being started while the throttle is applied. The motor controller can be programmed to have HPD based on either the brake (deadman) switch or key switch input. The Model 101 is Type “1” (only key switch input required prior to 25% throttle).

Neutral Braking

The automatic process by which the drive motor creates torque opposite to the direction of travel when the throttle is returned to neutral with the control arm in travel position. This is a programmable parameter (Neutral Braking). See “Motor Controller Parameter Settings (User Access Only)” on page 5-21.

Open Circuit

A lack of a continuous path between two or more electrical connections. Usually greater than one megohm resistance.

Definitions 5-8

Overtemperature (Motor Controller)

Overtemperature (Motor Controller)

Overtemperature of the motor controller is 185°F (85°C) and above. At overtemperature the drive current limit is linearly decreased from full set current down to zero.

NOTE: Plugging strength is not decreased at any overtemperature level.

Overvoltage Cutoff

Overvoltage protection resets the internal microprocessor, zeros out the pulse width modulation, and shuts down the controller. Controller operation resumes when the voltage is brought within the acceptable range. The cutoff voltage and re-enable voltage are set at the factory and are not adjustable.

Plugging (Plug Braking)

The process by which the drive motor creates torque opposite to the direction of travel proportional to the throttle command opposing the current travel direction. The braking (plugging) current limit is a programmable parameter and is normally set higher than the drive current limit. This parameter is factory preset and not user adjustable.

Pulse Width Modulation

Pulse Width Modulation (PWM), also called “chopping,” controls the speed of the motor by switching the battery voltage applied to the motor on and off very quickly.

Ramp Shape

The ramp shape (acceleration) is the relationship between the speed/directional control rotation and truck response (PWM output). It is adjustable (throttle map parameter) so you can provide the proper feel for each truck.

Ramp shape number refers to the PWM output at half throttle, as a percentage of its full range.

Overtemperature (Motor Controller)

Sequencing Delay

Sequencing delay allows the brake (deadman) switch to be momentarily opened within a set time (sequency delay), thus preventing inadvertent activation of high pedal disable (HPD) or static return to off (SRO). See “Static Return To Off (SRO)” on page 5-11 or High Pedal Disable (HPD) on page 5-8. This feature is useful in applications where the brake (deadman) switch may bounce or be momentarily cycled during operation.

Short Circuit or “Short”

A short circuit is an unspecified path in a circuit that provides unwanted full or partial continuity between two or more locations in an electrical circuit.

Example: Two insulated wires are physically next to each other and the insulation has been worn off each of the wires. Because the conductors inside each wire are now touching each other, there is a short circuit.

Example: A power cable from the battery to a junction post in the truck has had the insulation worn away. Because the wire conductors are touching the tractor frame, there is a short circuit of the battery cable.

Speed Limiting

The controller can limit the maximum speed: •“Max speed” parameter limits the maximum PWM for both directions of travel. This is a programmable parameter. See “Motor Controller Parameter Settings (User Access Only)” on page 5-21.

Walkie Pallet Truck Maintenance Manual

Static Return To Off (SRO)

The SRO feature prevents the truck from being started (direction selected) prior to the release of the brake (brake [deadman] switch closed). SRO checks sequencing of the brake (deadman) switch input and KSI relative to the direction input. The brake (deadman) switch must be activated before the speed/directional control is rotated. If a direction is selected before or simultaneously (within 50 milliseconds) with the brake input, the motor controller will not command travel.

Tractor

The body section of the truck that contains the motors, drive unit, controls, and handle.

Undertemperature

When the controller is operating at less than -25°C (-13°F), current limit is reduced to about one-half of the set current resulting in reduced travel speed.

Undervoltage Cutback

Undervoltage protection automatically disables the controller output if the battery voltage is detected below the undervoltage point at startup, or when the battery voltage is pulled below the undervoltage point by an external load. The undervoltage cu tback point is set at the factory and is not adjustable.

Troubleshooting Raymond® Walkie Pallet Truck Maintenance Manual

Electrical Connector Locator Chart

Electrical Connector Locator Chart

Refer also to electrical schematics located in the Appendix and wiring harness component procedures.

Connector Function or Routing Location

PMC1Connector on motor controller Motor controller

JP2 Handle functions In control handle

JP3 Travel functions (C.S. only) In control handle

JP6 Travel functions In control handle

JP9 Meters (Options) By key switch

JPS1Splice for brake switch circuitsIn control handle

Table 5-1:Electrical Connector Locator Chart