Remove And Install Charge Pump
1. Thoroughly clean all external surfaces of the main pump and charge pump with solvent and blow dry with compressed air.
2. Remove the hydraulic suction line from the charge pump inlet (1) and immediately cap or plug the openings.
3. Remove the four charge pump mounting bolts (2) that form a rectangular pattern. Do not remove the bolts at the top and bottom, because they hold the segments of the pump together.
| NOTICE |
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There is a spacer (3) in the idler shaft core that can slip out as the charge pump is removed. Do not allow it to fall into the main pump. |
4. Remove the charge pump (4), idler shaft spacer (3) and the gasket (5) from the pump cover.
5. Cover the opening in the main pump.
6. To inspect or replace the charge relief valve, remove the hex plug (6), spring (7) and the poppet (8). Remove the shims (9) from the counterbore of the plug (6).
NOTE: The following steps are for installation of the charge pump.
| NOTICE |
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Do not alter the original shims unless new parts are used. The pressure setting may then have to be adjusted correctly with the use of new shims. |
7. Install poppet (8), spring (7), shims (9) and plug (6). Be sure the shims are placed in hex plug behind the spring. Tighten plug to a torque of 41 to 82 Nm (30 to 60 lb ft).
8. Align the new gasket on the main pump cover so that the small relief valve port is open. Be sure the port in the charge pump is aligned with the port in main pump cover.
9. Rotate the charge pump shaft so its tang (10) aligns approximately with the slot in the end of the main pump drive shaft. Hold the idler spacer (3) in place, and position the charge pump onto the pump cover.
10. Rotate the pump slightly until the tang and slot on the shaft engage and the charge pump is solidly against the main pump cover.
11. Install the four mounting bolts (2) and tighten to a torque of 13.7 to 15 Nm (10 to 11 lb ft).
12. Remove the caps or plugs and reconnect the inlet line back to the charge pump. Tighten the connection to a torque of 19 to 29 Nm (14 to 21 lb ft). Do not exceed this torque specification.
Remove And Install Charge Check Valves
Start By:
a. remove charge pump.
1. The charge check valves (1) are cartridges which are threaded into the pump cover (2). Use a drag link socket to remove the check valves.
NOTE: The charge check valves are interchangeable with each other. It is suggested that they be replaced in pairs.
| NOTICE |
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Be very careful to prevent damage to the O-ring on each cartridge when charge check valve is inserted past the threads in the pump cover. |
2. Install the charge check valves (1) very carefully into the pump cover (2).
3. Tighten the charge check valves to a torque of 41 to 55 Nm (30 to 40 lb ft).
4. After assembly, the check valves must be below the charge pump mounting surface of the pump cover. If not, remove the check valves and determine the cause.
End By:
a. install charge pump
Remove And Install Ground Drive Hydraulic Pump
NOTE: Do not remove a hydrostatic pump on the hunch that it has failed. Low pressure can be caused by several things other than pump failure.
Reference: Before removing the pump, see the Troubleshooting section of the RR-250 and SS-250 Power Train Systems Operation, Testing and Adjusting, Form No. KEBR1237.
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The ground drive transmission shift lever must be in one of the two neutral positions before the engine is stopped and any removal steps started. Failure to do this will mechanically lock transmission in the gear selected, since hydraulic charge pressure is necessary to unlock the shift lever for shifting. Any subsequent procedures to prime and purge the charge and ground drive hydraulic pumps after installation can cause the machine to then move, resulting in possible injury to personnel. |
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1. Remove the pump cover plate and the front plate (1) at the front of the machine.
2. Disconnect the electric wires (2) from the electric displacement control at top of the pump.
3. Mark the hydraulic hoses for identification when reinstalling the ground drive pump (3).
4. Thoroughly clean around the hydraulic hose ends and pump connections, then disconnect all hydraulic lines from the pump that are necessary for pump removal. Cap or plug all openings immediately.
5. Remove the four bolts (5) and separate the drive shaft (4) from the drive hub (6).
6. Remove the cotter pin, slotted nut and washer from the pump shaft.
7. Install a suitable puller and pull drive hub (6) off the pump shaft. Remove the key from the pump shaft keyway.
8. Attach a lifting device to the ground drive pump (3), and remove the four mounting bolts/nuts (7) at the rear of the pump.
9. Pull the pump straight forward and upward until the pump is free of the machine, then lift it away. The pump weighs about 61 kg (135 lbs).
NOTE: The following steps are for installation of the ground drive hydraulic pump.
10. If a new pump is used, inspect the pump for damage in shipping or handling. Install the flange adapters and fittings on the pump. Cap or plug all openings.
11. Inspect all lines, fittings and hoses for burrs or damage. Flush with clean solvent and dry them with clean compressed air.
12. Attach a lifting device to the pump, carefully put the ground drive pump into position in the mounting bracket and install the four mounting bolts/nuts (7) at the rear of the pump.
13. Position the key in the pump shaft keyway, align the drive hub (6) to the key and push the hub onto the tapered shaft.
14. Install the washer and shaft nut onto the pump shaft, lightly oil the shaft threads, and tighten shaft nut using the following procedure:
a. Tighten nut to a torque of 165 to 190 Nm (120 to 140 lb ft).
b. Hit the face of the drive hub with a soft hammer in several places.
c. Tighten the nut again to a torque of 165 to 190 Nm (120 to 140 lb ft).
d. Repeat steps b and c until the nut no longer has rotation when specified torque is applied.
15. Install the cotter pin through the slotted nut and pump shaft.
16. Lift the drive shaft (4) into position on the drive hub (6), and install the four mounting bolts (5) to the drive hub.
17. Connect a tee (10) and a pressure gauge (8) to the charge pressure port (9) as shown. Install the charge pressure line (12) for the transmission shift lock into the tee.
18. Connect all the other hydraulic lines back to the pump, and check the fittings to be sure they are tight.
19. Make sure the hydraulic tank oil level is high enough to prevent air from entering the system.
20. Loosen the charge pump hose at the inlet to the charge pump (11). When the oil appears at the loosened hose, tighten the hose.
NOTE: If gravity feed does not fill the hose to the charge pump or inlet manifold, it must be filled by hand.
21. Remove the line (13) from suction filter (14) and fill the line with filtered ATF Type F oil.
22. Fill the pump case through uppermost case drain opening (15) with filtered ATF Type F oil.
23. Connect the electric wires to the pump electric displacement control valve (16).
24. Disconnect the wiring harness electrical wire from fuel solenoid (17).
NOTE: The travel control lever must be in the neutral position and the rotor clutch lever must be disengaged before the starter motor can be energized.
25. Turn the key on and push start button to crank engine with the starter (engine will not start with fuel solenoid wire disconnected) until the charge pressure reaches 207 kPa (30 psi) or more.
26. Reconnect wire back to fuel solenoid (17).
27. Start the engine and set throttle to lowest idle possible.
28. Check that a charge pressure has been established. Air can be bled from the high pressure lines by cracking (loosening slightly) the two high pressure gauge port plugs at top of pressure manifold assembly (18) on the ground drive hydraulic motor (19).
29. Once charge pressure has been established, increase the engine speed to the maximum. Charge pressure should be 1310 to 1450 kPa (190 to 210 psi) minimum. If the charge pressure is not at the proper value, shut the engine down immediately and determine the cause.
Reference: For troubleshooting procedures, see the Troubleshooting section of the RR-250 and SS-250 Power Train Systems Operation, Testing and Adjusting, Form No. KEBR1237.
30. Start the engine and check that the pump remains in neutral. Increase engine speed to the maximum and check for forward and reverse operation of machine. Charge pressure should remain at 1100 to 1240 kPa (160 to 180 psi) minimum during forward or reverse operation.
Reference: For any necessary adjustment, see Adjusting Pump Neutral in the RR-250 and SS-250 Power Train Systems Operation, Testing and Adjusting, Form No. KEBR1237.
31. Using the travel control lever, continue to cycle the pump slowly from forward to reverse for 15 minutes.
32. Put the travel control lever in neutral, then shut the engine off.
33. Remove the 3450 kPa (500 psi) pressure gauge, transmission shift lock line and the tee, and install the transmission shift lock line (12) back to the pump. Check the hydraulic tank oil level and add oil if necessary.
34. Install front plate (1) and the pump cover plate back to the front of the machine.
Disassemble And Assemble Ground Drive Hydraulic Pump
Start By:
a. remove ground drive hydraulic pump
1. Remove the large retaining ring (1) located on the shaft end of the pump (a Truarc #7 retaining ring pliers may be used). Remove the side of ring opposite the tangs from the groove before the tang side.
2. Remove the aluminum housing (2) by prying the housing toward the end of the shaft (3) until the O-ring is free. The housing is held in place by the friction of the O-ring around its outside diameter.
| NOTICE |
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Handle the bronze sealing ring carefully because it can be damaged easily. |
3. The bronze sealing ring (4) is also held in place by internal O-ring friction. Using hand force only, work the sealing ring free and slide it carefully off the the shaft.
4. Remove the three O-rings.
NOTE: The following steps are for installation of the pump shaft seal. Always use new O-rings when the parts are reinstalled.
5. Lubricate the small O-ring with petroleum jelly and insert O-ring into the I.D. of the bronze sealing ring (4). Lubricate the other small O-ring and insert into the aluminum housing (2).
| NOTICE |
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Protect the parts from any damage by the keyway in the shaft. Wrapping tape around keyway will provide a safe surface for O-ring installation. |
6. With the O-ring facing the pump, slide the bronze sealing ring (4) over the shaft and onto the shaft pilot diameter. Work the O-ring into position using only hand force until it snaps into place.
7. Insert the stationary seal pilot (7) into the aluminum housing (2), locating the notch in the stationary seal over the pin in the aluminum housing. The stationary seal should have a slight spring load due to the springs (5) in the housing.
8. Lubricate the large O-ring (6) and put into position on the housing (2).
NOTE: Make certain all six springs are in place in the aluminum housing before sliding it into position on the shaft.
9. Slide the aluminum housing assembly into position against the bronze sealing ring (4) using hand force only.
10. Compress the aluminum housing to expose the retaining ring groove, and install the retaining ring (1) into the groove with the beveled side out. Install the side opposite the tangs into the groove first, being certain that the retaining ring has snapped completely into its groove.
End By:
a. install ground drive hydraulic pump
Remove And Install Pressure Override Valve
Start By:
a. remove ground drive hydraulic pump
1. Thoroughly clean all external surfaces of the pump and pressure override valve with solvent and blow dry with compressed air.
2. Remove the two hydraulic lines (1) from the valve and cap or plug the openings immediately.
3. Remove the mounting bolts (2) and remove the pressure override valve (3) from the top of the electric displacement control (4).
4. Remove the gasket and O-rings. Cover the opening in the electric displacement control.
NOTE: The following steps are for installation of the pressure override valve.
5. Install the new O-rings and new gasket. Make sure the 1.10 mm (.042 in) orifice is between the pressure override valve and the electric displacement valve.
6. Position the pressure override valve (3) on the top of the electric displacement control (4) and install the mounting bolts (2).
7. Remove the caps or plugs from the openings and install the two hydraulic lines (1).
End By:
a. install ground drive hydraulic pump
Remove Electrical Displacement Control
Start By:
a. remove ground drive hydraulic pump
b. remove pressure override valve
1. Remove the remaining bolts that hold control to the pump housing. Slip the control feedback linkage pin (1) out of the end of the swashplate drag link (2), and remove the control.
2. Remove the case drain fitting (3) from the same side of the pump on which the control was mounted.
| NOTICE |
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Be extremely careful not to drop any components into the pump housing. |
3. Remove the E-ring (4) from the inside end of the connecting pin (5).
4. If necessary, hold the swashplate off neutral to align it with the case drain hole. Remove the pin (5) from the swashplate link arms (6) through the case drain port using a magnet or other tool. Remove the drag link (2).
Install Electrical Displacement Control
| NOTICE |
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Do not install a control with an improper feedback link. A control failure may result, causing pump swashplate to travel to full angle and remain at this position. Do not attempt to install an electrical displacement control on a pump for which it was not originally designed without changing the link-and-ball assembly. Merely changing the swashplate drag link is inadequate. Under no circumstances should a valve originally built for a series 2X pump be used on a series 3X pump. |
1. If a new control is being installed, ensure that it is compatible with the pump. If the control is an MCV104X9XX (control less linkage assembly), use steps (a) thru (d) that follow to install the linkage.
a. Unscrew the bushing (8) from the new control, using care not to damage its O-ring.
b. Install the shaft (6) of the new feedback linkage assembly (1) through the swashplate feedback shaft hole (9). Place the ball (3) in the crosslink ball cavity (2).
c. Lubricate the shaft O-ring (5) and install the bushing over the shaft into the control body. After making sure the feedback shaft (6) extends through the bushing, tighten the bushing to a torque of 13.7 to 20.5 Nm (10 to 15 lb ft).
d. Install the retaining ring (7) in the groove on the shaft.
2. Align one end of the swashplate drag link (10) between the holes in swashplate link arms (11).
| NOTICE |
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Be extremely careful not to drop any components into the pump housing. |
3. Insert the press fit pin (12) through the case drain port to trap the drag link between the swashplate link arms. It will be necessary to tap the pin into place until the head of the pin is against the one arm.
4. Install the retaining ring (13) by forcing it onto the tapered end of pin (12) until it locks into the groove on the pin.
5. Install the three O-rings and the gasket between the control and the pump housing.
6. Install one 1.10 mm (.042 in) orifice between the pressure override valve and the electric displacement valve.
7. Engage the feedback linkage pin (4) of the control into the drag link (10), and swing the control into place against the pump housing. The drag link should be on the cylinder block side of the swashplate.
NOTE: Since most of the mounting bolts that fasten the electric displacement control also fasten the pressure override valve to the pump, do not tighten to final torque until the pressure override control is installed.
8. Install only the short mounting bolts but do not tighten them at this time.
9. After the pressure override valve is installed, install and tighten all the bolts to a torque of 13.7 to 15 Nm (10 to 11 lb ft).
End By:
a. install pressure override valve
b. install ground drive hydraulic pump