PISTON ASSEM. 7D2653 - Caterpillar

Preparation - Filling and Flushing
Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.Note: Permit only one operator on the machine. Keep all other personnel away from the machine or in the sight of the operator.
Place the steering and transmission control lever in the NEUTRAL position.
Engage the parking brake.
Lower the attachments to the ground.
Stop the engine.
Turn the key to the ON position, but do not start the engine.
Verify that the implement shutoff control is not activated.
Move the control levers through the full range of travel several times. This will relieve any pressure that may be present in the implement hydraulic system.
Make sure that the pressure in the entire hydraulic system has been released.Procedure - Filling the Hydrostatic System
Illustration 2 g06022996
Remove tube (1).
Fill the pump case through the case drain port with clean hydraulic oil that is used in the hydraulic tank. Fill the pump to the bottom threads of the case drain port.
Install tube (1).
Illustration 3 g06023148
Remove cover (2).
Connect Tooling (B) to service tool connector (E1).
Start the engine and run the engine at LOW IDLE.
Illustration 4 g02724483
Both loop pressures should be a minimum of 2000 kPa (290 psi) within 10 seconds after you start the engine.
If the pressure is low, stop the engine.
Check the hydraulic oil level. Add hydraulic oil, if necessary.
Determine the cause of the low pressure and repair the cause.
Repeat Step 6 through Step 10 until the loop pressure is correct.
If the engine is still running, stop the engine.
Illustration 5 g01356813
Use Caterpillar Electronic Technician (ET) to perform the transmission stall test. Select the “Diagnostics” option from the Cat ET menu. Then, select “Diagnostic Tests” from the drop-down menu. Select the “Transmission Stall” from the selection menu. Follow the instructions that are provided.
Start the engine.
Increase engine speed to 1100 rpm.
Move the speed and direction control to the FORWARD position.
Slowly, increase the max speed setting until both loop pressures reach 10000 5000 kPa (1450 725 psi). Maintain this pressure for 90 30 seconds to fill the motor case.
Return the speed and direction control to the NEUTRAL position.
Decrease engine speed to LOW IDLE.
Engage the parking brake.
Exit the stall test in Cat ET.
Stop the engine.
Check the hydraulic tank level. Add hydraulic oil, if necessary.Procedure - Calibration After Pump/Motor Replacement
Illustration 6 g03112719Note: Perform steps 1 and 2 to both sides of the machine.
Remove bolts (4) and cover (5).
Remove sun gear (6).Note: The thread in shaft (9) is M16 X 2 - 6H.
Use Cat ET to calibrate the pumps and the motors. Refer to Testing and Adjusting, "Calibration".
Continue with the flushing procedure.Procedure - Flushing the Hydrostatic System
Illustration 7 g03112719Note: Perform steps 1 and 2 to both sides of the machine.
Remove bolts (4) and cover (5).
Remove sun gear (6).Note: The thread in shaft (9) is M16 X 2 - 6H.
Start the engine.
Disengage the parking brake.
Select the lowest max speed setting.
Increase engine speed to HIGH IDLE.
Move the speed and direction control to the FORWARD position for 60 30 seconds.
Move the speed and direction control to the NEUTRAL position