IT38G Series II Integrated Toolcarrier and 938G Series II Wheel Loader Operational Checks (Hydraulic System) Caterpillar


Operational Checks (Hydraulic System)
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1.1. Implement Cycle Times
2.2. Lift Cylinder
3.2. Tilt Cylinder
4.1. Drift Test (Lift and Tilt Cylinder)

------ WARNING! ------

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.

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------ WARNING! ------

Personal injury or death can result from sudden movement of the lift or tilt cylinders.

Sudden movement up or down, can cause the clearance above your head to change rapidly.

Do not stand under the lift arms when testing and adjusting the lift cylinders.

Do not stand under the bucket when testing or adjusting the tilt cylinder.

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Before you perform these procedures, refer to the Service Manual module Troubleshooting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

The following operational checks can be used for the following items:

  • find leakage in the system.

  • determine whether the pilot operated hydraulic controls are functioning correctly.

  • determine whether the pumps or motors are functioning correctly.

  • determine whether the whole work tool system is functioning correctly.

In order for the hydraulic system to function properly, each component in the system must be set to the correct specifications. Some components must be set prior to the testing of other components. A component that is not set properly will have an impact on other components in the system.

Note: The oil in the hydraulic system must be between 54 °C (130 °F) and 82 °C (180 °F). In order to increase the oil temperature, start the engine and operate all the cylinders for at least five cycles.

Implement Cycle Times

Prepare the machine for troubleshooting. Refer to the Service Manual module Troubleshooting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

Lift Cylinder

  1. Ensure that the transmission direction and speed control is in the NEUTRAL position. Start the engine and run the engine at high idle.

  1. Operate the lift cylinder through at least five lift cycles. This will ensure that there is warm oil in the lift cylinders.

  1. Position the work tool so that the bottom of the bucket is flat on the ground. Ensure that the engine is at high idle. Maintain high idle for the duration of the test.

  1. Raise the work tool from the full LOWER position. Record the time from the full LOWER position to the full RAISE position.

  1. Tilt the work tool to the full TILT BACK position.

  1. Lower the bucket from the full RAISE position. Record the time from the full RAISE position to the full LOWER position.

  1. Raise the work tool to the full RAISE position. Move the pilot valve to the FLOAT position. Record the time from the full RAISE position to the full LOWER position.

Table 1
CYCLE TIME FOR THE LIFT CYLINDERS WITH RATED LOAD
938G SERIES II WHEEL LOADER    
Machine Function     Cycle Time    
Raise     6.0 ± 0.4 seconds    
Power Down     3.8 ± 0.5 seconds    
Float     2.1 ± 0.5 seconds    

Table 2
CYCLE TIME FOR THE LIFT CYLINDERS WITH RATED LOAD
IT38G SERIES II INTEGRATED TOOLCARRIER    
Machine Function     Cycle Time    
Raise     6.0 ± 0.4 seconds    
Power Down     3.2 ± 0.5 seconds    
Float     2.8 ± 0.5 seconds    

If the speeds are not correct, refer to the Testing and Adjusting, "Hydraulic System Troubleshooting".

Tilt Cylinder

  1. Ensure that the transmission direction and speed control is in the NEUTRAL position.

  1. Start the engine and run the engine at high idle.

  1. Operate the tilt cylinders through at least five cycles. This will ensure that there is warm oil in the tilt cylinders.

  1. Tilt the work tool to the full TILT BACK position. Raise the work tool to the full RAISE position.

  1. Tilt the work tool from the full TILT BACK position to the full TILT FORWARD position. Record the time from the full TILT BACK position to the full TILT FORWARD position.

  1. Tilt the work tool from the full TILT FORWARD position to the full TILT BACK position. Record the time from the full TILT FORWARD position to the full TILT BACK position.

  1. Lower the work tool to the ground.

Table 3
CYCLE TIME FOR THE TILT CYLINDER WITH RATED LOAD
938G SERIES II WHEEL LOADER    
Machine Function     Cycle Time    
Dumpat maximum lift     1.4 ± 0.5 seconds    
Tilt Back     2.6 ± 0.5 seconds    

Table 4
CYCLE TIME FOR THE TILT CYLINDERS WITH RATED LOAD
IT38G SERIES II INTEGRATED TOOLCARRIER    
Machine Function     Cycle Time    
Dump at maximum lift     3.5 ± 0.5 seconds    
Tilt Back     3.0 ± 0.5 seconds    

If the speeds are not correct, refer to the Testing and Adjusting, "Hydraulic System Troubleshooting".

Drift Test (Lift and Tilt Cylinder)

Prepare the machine for troubleshooting. Refer to the Service Manual module Troubleshooting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

This procedure is done in order to determine the amount of wear that occurs in the lift cylinders and the tilt cylinders.

Note: Perform the following tests with a general purpose bucket on the machine.

  1. Start the engine. Run the engine at high idle.

  1. Operate the lift cylinders through at least five cycles. This will ensure that there is warm oil in the lift cylinder.

  1. Operate the tilt cylinders through at least five cycles. This will ensure that there is warm oil in the tilt cylinder.

  1. Position the work tool in the full RAISE position.

  1. Tilt the bucket forward until the work tool is parallel with the ground.

  1. Reduce the engine speed to low idle. Turn the engine start switch to the OFF position.

  1. Mark the cylinders.

  1. Use a stopwatch to count for five minutes. Measure the drift of the cylinders.

    Table 5
    CYLINDER DRIFT    
    Cylinders     Time     Cylinder Drift    
    Tilt Cylinders     5 minutes     19 mm max    
    Lift Cylinders     5 minutes     13 mm max    

    Note: If the lift cylinder drift and/or the tilt cylinder drift exceeds the maximum, refer to Testing and Adjusting, "Hydraulic System Troubleshooting" for probable causes.

  1. Start the engine and lower the work tool to the ground.

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