Yale Pallet Stacker: MPB040-E [B827], MPW045-E [B802] Workshop Service Manual

Maintenance :$/,( +<'5$8/,& 6<67(06 MPB040E [B827]; MPW045E [B802] PART NO. 524154894 1900 YRM 1018 Yale

SAFETY PRECAUTIONS MAINTENANCE AND REPAIR • When lifting parts or assemblies, make sure all slings, chains, or cables are correctly fas- tened, and that the load being lifted is balanced. Make sure the crane, cables, and chains have the capacity to support the weight of the load. • Do not lift heavy parts by hand, use a lifting mechanism. • Wear safety glasses. • DISCONNECT THE BATTERY CONNECTOR before doing any maintenance or repair on electric lift trucks. • Disconnect the battery ground cable on internal combustion lift trucks. • Always use correct blocks to prevent the unit from rolling or falling. See HOW TO PUT THE LIFT TRUCK ON BLOCKS in the Operating Manual or the Periodic Maintenance section. • Keep the unit clean and the working area clean and orderly. • Use the correct tools for the job. • Keep the tools clean and in good condition. • Always use YALE APPROVED parts when making repairs. Replacement parts must meet or exceed the specifications of the original equipment manufacturer. • Make sure all nuts, bolts, snap rings, and other fastening devices are removed before using force to remove parts. • Always fasten a DO NOT OPERATE tag to the controls of the unit when making repairs, or if the unit needs repairs. • Be sure to follow the WARNING and CAUTION notes in the instructions. • Gasoline, Liquid Petroleum Gas (LPG), Compressed Natural Gas (CNG), and Diesel fuel are flammable. Be sure to follow the necessary safety precautions when handling these fuels and when working on these fuel systems. • Batteries generate flammable gas when they are being charged. Keep fire and sparks away from the area. Make sure the area is well ventilated. NOTE: The following symbols and words indicate safety information in this manual: WARNING Indicates a condition that can cause immediate death or injury! CAUTION Indicates a condition that can cause property damage!

Walkie Hydraulic Systems Table of Contents TABLE OF CONTENTS General ................................................................................................................................................................ 1 Operation ............................................................................................................................................................. 1 Lifting a Load................................................................................................................................................... 1 Lowering a Load.............................................................................................................................................. 1 Hydraulic Lines................................................................................................................................................ 2 Hydraulic Oil .................................................................................................................................................... 2 Cleanliness...................................................................................................................................................... 3 Sound Level .................................................................................................................................................... 4 Hydraulic Unit ...................................................................................................................................................... 4 Remove ........................................................................................................................................................... 4 Special Precautions ........................................................................................................................................ 5 Install ............................................................................................................................................................... 5 Hydraulic Pump ................................................................................................................................................... 6 Remove ........................................................................................................................................................... 6 Install ............................................................................................................................................................... 6 Hydraulic Pump Reservoir ................................................................................................................................... 8 Remove ........................................................................................................................................................... 8 Install ............................................................................................................................................................... 8 Hydraulic Cylinder ............................................................................................................................................... 9 Remove ........................................................................................................................................................... 9 Repacking ....................................................................................................................................................... 10 Install ............................................................................................................................................................... 10 Relief Valve Adjustment ....................................................................................................................................... 11 Troubleshooting ................................................................................................................................................... 13 Lift Assemblies ................................................................................................................................................ 13 Hydraulic Cylinders ......................................................................................................................................... 13 Hydraulic Pump ............................................................................................................................................... 14 This section is for the following models: MPB040E [B827]; MPW045E [B802] ©2002 Yale Materials Handling Corp. i

1900 YRM 1018 Operation General The hydraulic system provides the force required to lift the loads on all motorized lift trucks. The hydraulic system on the motorized lift truck consists of the following individual components: • Pump Motor Assembly • Hydraulic Pump Assembly • Solenoid Lowering Valve • Pilot Relief Valve • Lift Cylinder • Reservoir The hydraulic pump and motor assemblies are mechan- ically joined together as a compact unit combining the reservoir, pump, and motor together as a single assembly. The pump is located inside of the hydraulic tank and coupled to the motor by an adapter plate, coupler drive, and four capscrews. Hydraulic unit servicing is best performed by removing the unit from the truck to a clean work area. Operation LIFTING A LOAD To raise a load the lift button must be depressed. De- pressing this switch will activate the pump motor. This torque is transferred to the pump from the motor through the motor shaft and shaft coupling. Hydraulic oil is pumped through the system as the pump begins to operate. A vacuum created inside of the pump draws oil out of the reservoir through the suction line. Air which is drawn into the reservoir through the breather displaces the pumped oil allowing it to be sent through the system. See Figure 1, Figure 2, and Figure 3. If the breather is clogged or blocked the ability of the system to lift a load will be greatly reduced. As oil is pushed out of the pump, it passes through a one-way check valve to the lift cylinder. The check valve prevents oil from flowing back to the pump when lifting ceases, holding the lift cylinder in the raised position until lowered. The piston will begin to lift the load when fluid pressure acting against it is high enough to overcome the weight of the load at rest on the forks/platform. When the piston is fully extended to the end of its stroke or if the load is too heavy, pressure will continue to build until the rated pressure needed to operate the relief valve is reached. When this occurs, the relief valve, which is normally closed, is forced back against its spring creating a path for the fluid to flow back to the reservoir. Once relief valve pressure is reached, hydraulic oil will continue to be diverted from the lift cylinder to the reservoir until the lift button is released or electrical power is interrupted. LOWERING A LOAD A load is lowered by depressing the lower button. When the lower button is depressed, electric current is sent to the normally closed solenoid lowering valve which causes it to change position and open a path for the trapped hydraulic oil to flow from the cylinder back to the reservoir. Figure 1. Hydraulic Schematic 1 Lowering Solenoid Valve To Lift Cylinder Check Valve Suction Line Pilot Operated

Operation 1900 YRM 1018 1. HYDRAULIC POWER UNIT 2. CAPSCREW 3. WASHER 4. LOCKWASHER 5. CAPSCREW 6. FITTING 7. HOSE 8. TUBE 9. FITTING 10. ADAPTER 11. FITTING 12. LIFT CYLINDER 13. SPACER PLATE Figure 2. Hydraulic System - 12 Volt HYDRAULIC LINES 1. All hydraulic lines must be thoroughly cleaned before installation. 2. When making repairs, use the least number of fit- tings and connections to minimize flow resistance and the possibility of leakage. HYDRAULIC OIL The hydraulic oil in the system performs the dual func- tion of the power transmission and lubrication. Using the correct fluid is essential to proper system operation. Refer to the Lubrication Charts for the recommended hydraulic oil to be used. Check the reservoir level when troubleshooting lifting problems. Low oil levels will make it appear that a prob- lem exists with the battery or hydraulic system. 2

1900 YRM 1018 Operation 1. HYDRAULIC POWER UNIT 2. CAPSCREW 3. WASHER 4. LOCKWASHER 5. CAPSCREW 6. FITTING 7. HOSE 8. TUBE 9. FITTING 10. ADAPTER 11. FITTING 12. LIFT CYLINDER Figure 3. Hydraulic System - 24 Volt CLEANLINESS Adhere to the following precautionary steps to insure that the hydraulic system remains clean. 1. Flush the entire system when a failure is encoun- tered to make sure all paint, metal chips, welding shot, and debris are removed. 2. Filter each change of oil to prevent the introduction of contaminants into the system. 3. Provide continuous protection from airborne con- tamination by keeping the breather clean and ser- viceable. 3

Hydraulic Unit 1900 YRM 1018 SOUND LEVEL Hydraulic system noise is caused by both improperly selected oil and loose or damaged system components. • Hydraulic oil with high or moderately high viscosities - At startup, temperatures can cause pump noises due to cavitation and also impedes the release of trapped air. Air does not have sufficient time to purge itself from the fluid while in the reservoir before recycling through the system. • Aerated Hydraulic Oil - Results in system noise that is similar to cavitation. Aerated oil is caused by the in- gestion 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 dis- charging above the fluid level. Hydraulic Unit REMOVE WARNING Batteries are heavy and can cause personal injury. Use care to avoid injury. Do NOT put hands, arms, feet, and/or legs between the battery and a solid object. Make sure the capacity of the crane and spreader bar is greater than the weight of the battery. The weight of the battery is normally shown on the battery case. The maximum battery weight is shown on the lift truck nameplate. The spreader bar must NOT be made of metal or it must have in- sulated straps. WARNING Put blocks under each side of the truck under the drive unit frame. Position blocks on both sides of the load wheels. The blocks must prevent the lift truck from falling and causing personal injury or property damage. WARNING The capacitor in the transistor controller can hold an electrical charge after the battery is disconnected. To prevent electrical shock and personal injury, discharge the capacitor before inspecting or repairing any component in the drive unit compartment. Wear safety glasses. Make certain the battery has been disconnected. Refer to Steering Mechanism 1600 YRM 1004. CAUTION Make certain the hydraulic cylinder is fully col- lapsed. 1. Remove the drive unit compartment cover. 2. Disconnect the battery. Use a spreader bar and lifting device to remove the battery. Do not let the battery move from side to side. Make sure the battery cables have clearance. 3. Raise the drive wheel off the floor and put blocks under both sides of the drive unit frame. 4. Drain the hydraulic oil from the hydraulic unit into an appropriate container. 5. Tag and disconnect all of the electrical wires from the hydraulic unit. 6. Remove the hydraulic lines from the hydraulic unit. 7. Loosen and remove the three capscrews attaching the hydraulic unit to the frame. Remove the hydraulic unit and place in a clean work area. 4

1900 YRM 1018 Hydraulic Unit SPECIAL PRECAUTIONS WARNING To avoid personal injury and prevent electrical shock, perform the following steps before perform- ing any troubleshooting and/or adjustments, and connecting or disconnecting a handset or PC. CAUTION To avoid controller damage always disconnect the battery. Discharge the capacitor, and never put power to the controller with any power wire disconnected. Never short any controller terminal or motor terminal to battery. Make sure to use proper procedure when servicing the controller. CAUTION To avoid controller damage always disconnect the battery. Discharge the capacitor, and never put power to the controller with any power wire disconnected. Never short any controller terminal or motor terminal to battery. Make sure to use proper procedure when servicing the controller. Refer to Steering Mechanism 1600 YRM 1004. 1. Block the lift truck so that the drive wheels are off the floor. See Periodic Maintenance 8000 YRM 1009 - How to Put Lift Truck on Blocks. 2. Turn the key switch to the OFF position and unplug the battery. 3. After key-off, the capacitors in the unit remain charged for several minutes. To discharge the capacitors, connect a 200-ohm (2-3W) resistor between +BATT and -BATT on the controller. Hold for 5 seconds. 4. Tag and disconnect all electrical wires to the hydraulic unit. 5. Disassemble and plug the hydraulic lines to the hydraulic unit. INSTALL 1. Align the hydraulic unit with the mounting holes in the frame and install the three capscrews. Tighten the hydraulic unit mounting capscrews to 49 N•m (36 lbf ft). 2. Install the hydraulic lines to the hydraulic unit. 3. Connect all the electrical wires to the hydraulic unit. 4. Remove the blocks and lower the lift truck to the floor. 5. Remove the breather and add the recommended hydraulic oil until the oil level reaches the full level mark. Replace the breather. If too much hydraulic oil is added, the oil will leak from the breather during operation. 6. Install the battery and connect the battery. Operate the lift truck until the hydraulic oil reaches operating temperature. Add additional oil if necessary. Check for hydraulic oil leaks. 7. Install the drive unit compartment cover. Test the operation of the lift truck prior to returning the truck to service. 5 A is is

Hydraulic Pump 1900 YRM 1018 Hydraulic Pump REMOVE 1. Remove the hydraulic unit from the lift truck. Refer to the section Hydraulic Unit in this manual. 2. Clean the reservoir and pump area to prevent contaminants from entering the hydraulic system. 3. Remove the capscrews retaining the reservoir to the hydraulic unit. Tap around the perimeter to break the seal and separate the reservoir from the motor assembly. 4. Remove the spring retaining screw from the suction tube. 5. Remove the suction tube and strainer by pulling down and out. 6. Remove the four capscrews retaining the pump to the drive motor. 7. Disassemble the pump assembly and coupling from the adapter. INSTALL NOTE: The hydraulic unit includes four separate kits as shown in Figure 4. 1. Clean and lubricate all components using clean hydraulic oil. 2. Replace all o-rings and seals within the unit. 3. Grease the coupler and coupler cavity with the motor resting with the adapter plate up. Align the pump mounting holes with the holes in the motor. Ensure that the tank is seated into the motor. 4. Install the four capscrews and tighten to 13.6 to 16.3 N•m (10 to 12 lbf ft). 5. Install the O-rings into the pump cavities. Apply grease to the return tubes. Insert tubes into pump cavities and O-rings. Grease the suction tube and insert into locking device with hole. Install and tighten the spring retaining screw to secure the suction tube. 6. Remove the retainer and replace the O-ring. Lightly grease the O-ring before installation. 7. Align the reservoir so the hose connections will be in the same position as they were prior to removal. Install the four capscrews to retain the reservoir. 8. Install the hydraulic unit. Refer to Hydraulic Unit, Install, this section. 9. Remove the breather and fill the reservoir with the recommended oil. See the section Capacities and Specifications 8000 YRM 1010. Add oil until the oil is up to the full mark. If too much oil is added, the oil will leak from the breather during operation. If too much oil has been added, drain the excess or use a suction device to remove some of the oil. 10. Run the pump for 5 seconds and energize the lowering valve at the same time so that oil gets through the pump body and valve at 0.0 psi. Operate the forks up and down three or four times to remove air from the system. Operate the lift truck until the hydraulic oil reaches operating temperature. Remove the breather and check the hydraulic oil level. Add additional oil if necessary. Check for hydraulic oil leaks. 11. Install the drive unit compartment cover. Test the operation of the motorized hand truck before returning the truck to service. 6

Yale Pallet Stacker: MPB040-E [B827], MPW045-E [B802] Workshop Service Manual

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