Case 1838 Uni-Loader SkidSteer Repair Manual

Manuals: Service Manual
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Manual Extract Pressure Test
1 . Connect a 400 PSI (28 bar) pressure gauge to the test port in the elbow at the hydraulic filter outlet port.

2. If the hydraulic oil is not at operating temperature run the engine at full throttle and hold the bucket control lever in the Rollback position for 30 seconds. Then return the bucket control lever to Neutral for 15 seconds. Repeat this cycle until the temperature of the oil is at least 125° F (52° C).

3. Continue to run the engine at full throttle. Read the pressure gauge and record the Charge Pressure reading. Stop the engine.
4. The pressure must be 130 to 150 PSI (9.0 to 10.3 bar) minimum at full throttle.
5. If the pressure is correct, go to Step 9. If the pressure is not correct check the Neutral System pressure at the gear pump, see Section 8002, Page 6.

6. If the Neutral System pressure is correct go to step 7. If the Neutral System pressure is not correct: A Check that the hydraulic lines are routed correctly so all of the gear pump flow returns to the hydraulic filter to provide charge oil to the piston pumps.

8. Check the gear pump efficiency with a flow meter. See Section 8002 for procedure.

7. If the Neutral System pressure is correct and the charge pressure is low, remove and inspect the parts of the charge relief valve. Connect the CAS10192 vacuum pump with the CAS-1871 adapter to create a vacuum in the hydraulic reservoir to hold the oil when the charge relief is removed.

8. If the parts of the charge relief are good, add shims from the shim kit. A shim 0.010 inches (0.25 mm) in thickness will increase the charge pressure 7 PSI (0.5 bar). Repeat steps 3 and 4 until the pressure is correct.

9. When the charge pressure is correct in Neutral, do the following steps:

IMPORTANT: It is recommended for the following test that the machine be raised up on supports until the tires are above the floor. This is a safety procedure if the parking latch pins fail to hold.

10. Start and run the engine at low idle. Raise the seat bar and slowly move the direction control levers into FORWARD until the pins for the parking latch engage each drive sprocket.

11. Increase the engine speed to full throttle. Slowly move the direction control levers forward to load the piston pumps without decreasing the engine speed. Read the pressure gauge. The pressure must be within 25 PSI (1. 7 bar) of the pressure in step 3.

12. Repeat step 11 in REVERSE. The pressure must be within 25 PSI (1. 7 bar) of the pressure in step 3.
13. If the pressure is not correct in steps 11 and 12, there is too much leakage in the hydrostatic system. Disassemble and inspect the piston pump, and drive motor.