994F Wheel Loader Hydraulic System Caterpillar

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To prevent personal injury when checks are made while the machine is in operation, make sure only approved personnel are on the machine. Keep other personnel off the machine and in view of the operator. Make sure checks are done in an open area.

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

The test for the implement cycle time is used to verify a complaint about slow speed. This test will also help to determine whether all functions are slow or only one function is slow.

If any functions are slow, the implement cycle times must be checked in order to determine the faulty system. Use the following procedures in order to test the individual implement pumps.

Note: For all cycle time tests, the bucket must be empty.

1. Move the machine to an open area so that the bucket can be fully raised. Park the machine on a smooth, level surface.

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Illustration 1	g01149567

2. Move the steering frame lock into the LOCKED position.

3. Shift the transmission to neutral.

4. Engage the parking brake.

5. Ensure that the hydraulic oil is at the normal operating temperature.

6. Position the bucket so that the bottom of the bucket is flat on the ground.

7. Run the engine to high idle. Maintain high idle for the test.

8. Move the lift control lever to the RAISE position. Hold the lift control lever in the full RAISE position until the lift cylinders reach the full RAISE position. Record the lift time from the ground to the full RAISE position.

   The lift time should be 11 to 12 seconds for the standard machine.

   The lift time should be 11 to 12 seconds for the high lift version.

   The lift time should be 13 to 14 seconds for the super high lift version.

   The lift time should be 13 to 14 seconds for the extended high lift version.

9. Move the bucket to the full RAISE position. Position the bucket to the full RACKBACK position.

10. With the engine at high idle, move the tilt control lever to the full DUMP position. Hold the tilt control lever in this position until the bucket is at the full DUMP position. Record the time to the full DUMP position.

    The time should be 3 to 4 seconds.

11. With the engine at high idle, move the tilt control lever to the full RACKBACK position. Hold the tilt control lever in this position until the bucket is at the full RACKBACK position. Record the time to the full RACKBACK position.

    The time should be 5 to 7 seconds.

12. With the engine at high idle, move the lift control lever to the full LOWER DETENT position. Record the time from the full RAISE position to the lower kickout position at the ground.

    The time should be as follows:

    • 6 to 7 seconds for Standard Lift (SL) and High Lift (HL)

    • 7 to 8 seconds for Extra High Lift (EHL) and Super High Lift (SHL)

If the travel times are not correct, perform the following checks:

1. Check the pump efficiency.

2. Check the setting of the relief valves.

3. Check the makeup valves in the control valve sections.

4. Check the valve stems that are in the control valve sections.

5. Check the piston seals in the cylinders.