hyster b453 (w40za) forklift service repair manual

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    PART NO. 1652525 8000 SRM 1320

  • 2000 SRM 1025 Description of Operation

    General This section covers the troubleshooting and repair procedures for the hydraulic components on the W30/ 40ZA, W25/30/40ZC, and W20/30ZR lift trucks.

    It also includes the remove and install procedures for the solenoid coils used to activate the hydraulic valves.

    For troubleshooting and repairs of the electrical com- ponents, see Electrical System 2200 SRM 1026 and ZAPITM Controllers 2200 SRM 1064.

    Description of Operation The hydraulic system of the W30/40ZA, W25/30/ 40ZC, and W20/30ZR lift trucks includes: • Reservoir • Pump • Check valve • Relief valve • Proportional lowering valve • Lift cylinder(s) • Connecting hoses and tubes

    Based on the model and configuration of the hy- draulic system, it can also include: • Lift valve • Directional valve(s) • Selector valve(s) • Counterbalance valve • Pilot operated check valve • Sideshift cylinder • Tilt cylinders • Reach cylinders • Auxiliary cylinder(s)

    The reservoir contains the hydraulic fluid necessary for the operation of the system. It acts as a heat sink to provide cooling. As the hydraulic oil leaves the reservoir, it is filtered through an internal strainer in the reservoir.

    The hydraulic pump provides the flow of the hy- draulic oil. It moves the oil to activate the cylinders.

    A check valve provides flow of the hydraulic oil in one direction only. In this hydraulic system, it prevents the oil from flowing backwards through the pump.

    A relief valve limits maximum pressure to protect the hydraulic system components.

    The proportional lowering valve is a normally closed valve. When it opens, hydraulic oil from the lift cylin- ders is allowed to return to the reservoir and the forks lower. Rate of flow is regulated by how far the valve opens.

    The lift cylinder(s) rod extends to raise the forks through a series of mast channels and chains.

    The connecting hoses and tubing connect the various hydraulic components in the lift truck to complete the hydraulic circuit.

    The lift valve is used on systems that have more than a lift/lower function. It is a normally closed valve which opens during the lift function. During other functions, such as sideshift, it remains closed to pre- vent flow to the lift cylinders.

    The directional valve(s) is a three position normally closed valve located on the pump. In its normal posi- tion, it blocks the flow of oil to a double acting cylin- der, such as a sideshift cylinder. Activated in one po- sition, it provides flow to extend a cylinder rod. Acti- vated in the opposite position, it reverses flow to the cylinder to retract the cylinder rod.

    The selector valve(s) is a normally closed valve lo- cated on the mast. Selector valves are used to direct the flow from a single pair of hydraulic lines to mul- tiple double acting hydraulic cylinders.

    The counterbalance valve provides free flow in one direction and resistance to flow in the opposite direc- tion. It is located in the tilt circuit to control forward tilt.

    The pilot operated check valve is located in the re- tract circuit and is activated by an auxiliary pres- sure. Its function is to maintain pressure on the rod side of the piston to hold the reach mechanism in the retract position.

    The tilt cylinders rods extend to tilt the forks forward away from the lift truck. The rods retract to tilt the forks back toward the lift truck.

    The reach cylinders rods extend to move the forks away from the lift truck. The rods retract to move the forks back toward the lift truck.


  • Special Precautions 2000 SRM 1025

    The function of the auxiliary cylinder(s) varies based on the optional attachment.


    The hydraulic oil in the system performs the dual function of power transmission and lubrication. Us- ing the correct fluid is essential to proper system operation. See Periodic Maintenance 8000 SRM 1027 for the recommended hydraulic oil.

    The level in the reservoir should be checked first when troubleshooting lifting problems. Low oil lev- els may make it appear that a problem exists with the battery or hydraulic system.


    Adhere to the following precautionary steps to be sure that the hydraulic system remains clean.

    1. Clean the reservoir and pump area to prevent contaminants from entering the hydraulic sys- tem.

    2. Clean (flush) the entire system when a failure is encountered to make sure all contaminants, debris, and foreign objects are removed.

    3. Filter each change of oil to prevent the introduc- tion of contaminants into the system.

    4. Provide continuous protection from airborne con- tamination by keeping the breather cap clean and serviceable.


    Hydraulic system noise may be caused by both im- properly selected oil and loose or damaged system components. • Cavitation - Can be caused by high fluid viscos-

    ity, cold fluid temperatures, or a restriction in the inlet screen or inlet tubing. At startup, low temper- atures can cause pump noises due to cavitation.

    • Aerated hydraulic oil - Results in system noise that is similar to cavitation. Aerated oil is caused by the ingestion of air through the pipe joints of the inlet lines and high-velocity discharge lines, as well as cylinder rod packing. Aeration can also be caused by oil discharging above the fluid level in the hydraulic reservoir. Air does not have suf- ficient time to escape from the fluid while in the reservoir before recycling through the system.

    Special Precautions

    WARNING The capacitor in the transistor controller can hold and electrical charge after the battery is disconnected. To prevent an electrical shock and personal injury, discharge the capacitor before inspecting or repairing any component in the drive unit compartment. Wear safety glasses. Make certain that the battery has been disconnected.

    CAUTION To avoid controller damage, always disconnect the battery, discharge the capacitor, and never put power to the controller while any power

    wires are disconnected. Never short any con- troller terminal or motor terminal to the bat- tery. Make sure to use proper procedure when servicing the controller.

    1. Verify that the key switch is in the OFF position and the battery connector is completely discon- nected.

    2. Discharge the capacitors in the controllers by connecting a 200-ohm, 2-watt resistor across the controller’s B+ and B terminals. DO NOT short across the motor controller terminals with a screwdriver or jumper wire. Remove the 200-ohm, 2-watt resistor before reconnecting the battery. See Figure 1.


  • 2000 SRM 1025 Control Valve

    Figure 1. Discharging the Capacitor

    Legend for Figure 1


    Control Valve

    CAUTION The hydraulic oil must be kept clean to prevent damage to the control valve.

    The control valve is part of the lift pump and mo- tor assembly and is replaceable but not adjustable. When the operator selects a hydraulic function by pressing a button on the control handle, a signal is

    sent to the traction/lift controller, is processed, and is sent to the pump assembly. Lifting speed is con- trolled by varying the pump motor speed. Lower- ing speed is controlled by a proportional electro-hy- draulic valve on the pump assembly.

    The control valve is designed with close tolerances and must be kept clean to work properly.


  • Manual Lowering 2000 SRM 1025

    Hydraulic Reservoir DESCRIPTION

    The hydraulic reservoir is made of a durable, translucent plastic that allows the operator to see how much hydraulic oil is in the reservoir. The reservoir is clamped to the adapter plate on the bottom of the pump and motor assembly in the drive unit compartment or hydraulic unit compartment.

    The reservoir has either a graduated scale or MIN and MAX marks on the side depending on model and should only be filled with hydraulic oil to the graduated scale or MIN mark. See Table 1. There is a fill cap located on the top of the reservoir and a drain plug and O-ring located at the bottom on one side of the reservoir.

    Table 1. Hydraulic Reservoir

    Model Description Reservoir Markings Hydraulic Oil Quantity

    W25/30/40ZC Counterbalance MIN/MAX 11.5 liter (12.2 qt)

    W30/40ZA Straddle Stacker Graduated Scale 11 liter (11.6 qt)

    W20/30ZR Reach Carriage Graduated Scale 11 liter (11.6 qt)

    Manual Lowering

    WARNING Always verify that no one is under or near the lift mechanism or load during the manual lowering procedure. Verify that there are no obstructions beneath the lift mechanism or load. If the mast does not lower when the man- ual lowering valve is activated, deactivate the valve immediately and determine the cause.

    WARNING Failure to return the manual lowering screw to the full clockwise position will cause the forks to lower unexpectedly.

    A provision is provided on the lowering valve to allow manual lowering of the forks if necessary. Manual lowering is accomplished by turning the

    manual override screw counterclockwise with a 7-mm wrench. In this position, the valve will remain open.

    Loosen the manual override screw SLOWLY until the forks begin to lower. Be sure to return the screw to the original position once the manual lowering process is complete by slowly turning the screw until it stop