990K Wheel Loader Machine Systems Caterpillar

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth, level surface. Lower the work tool to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock.

Specifications

Introduction

The speed of the implements is affected by the amount of oil flow that is produced by the implement pump. Check the implement cycle times in order to determine if there may be a problem with the implement pump.

The implement cycle time can be checked in order to verify a complaint about slow implement speed. This test will also help to determine whether all functions are slow or only one function is slow.

Test Preparation

1. Warm the hydraulic oil to normal operating temperature.

2. Move the machine to a smooth, level surface. Move away from working machines and personnel. Lower the bucket to the ground.

3. Allow only one operator on the machine. Keep all personnel away from the machine or in the view of the operator.

4. Place the transmission into neutral.

5. Engage the parking brake.

6. Place the steering frame lock in the LOCKED position.

Note: Prior to completing any cycle time tests, the pilot pressure must be verified. Refer to Testing and Adjusting, "Pilot Pressure (Pressure Reducing Valve) Test and Adjust" for the machine being serviced.

Test Procedure

Lift Cycle Time

1. Tilt back the bucket. Lower the lift linkage to the full LOWER position.

2. Run the engine at high idle (2010 RPM ± 25).

3. Move the lift control lever to the full RAISE position. Hold the lift control lever in this position until the lift cylinder reaches the end of travel.

4. Record the amount of time that is required for the work tool to travel from the ground to the full RAISE position.

5. The RAISE cycle time should match the times listed below.

Rack Back and Dump Times

Note: This test must be performed with an empty bucket or an equivalent fixture with the appropriate weight.

1. Run the engine at high idle (2010 RPM ± 25).

2. Position the linkage so that the lift arms are at mid position. Ensure that the bucket will not contact the ground and the dump stops are not contacted when dumped.

3. Position the bucket in the full RACK BACK position.

4. Move the tilt control lever to the FULL DUMP position. Hold the tilt control lever in this position until the bucket is against the stop.

5. Release the lever. Record the time.

6. Move the tilt control lever to the full RACK BACK position. Hold the tilt control lever in this position until the bucket is in the FULL DUMP position.

7. Release the lever. Record the time.

8. The RACK and full DUMP cycle times should match the times listed below.