554 and 574 Forwarders Power Train Power Train Charge System Pressure - Test - 574 Forwarder (1FM434-UP) Caterpillar

The following procedure can be used as a first step in order to check the performance of the drive loop. If there is excessive internal leakage in a component of the drive loop, the machine may experience a loss of rimpull.

Illustration 1	g00932407
Charge pressure shown monitored by the IQAN.

The charge pressure is monitored by the IQAN system. The IQAN Monitoring and Control System should be initially used in order to check the performance of the charge pressure. The following test should only be performed if the reading from the IQAN is suspect. In order to display the screen that is shown in Illustration 1, press the right arrow key once when at the main operation screen.

Reference: For more information about IQAN, refer to System Operation, RENR6127, "IQAN Monitoring and Control System".

The Forwarder uses a power train pump to provide oil flow to the drive loop. A charge pump is mounted on the power train pump.

The charge pump provides makeup oil flow to the power train pump. Charge pump oil prevents cavitation in the power train pump.

Illustration 2	g00916687
Power Train Pump (1) Oil line (drive loop) (forward). (2) Charge pressure relief valve. (3) Oil line (drive loop) (reverse). (4) Charge pump. (5) Relief valve (cold oil start-up).

The oil pressure in the charge system is controlled by relief valve (2). Relief valve (2) will open when the oil pressure in the charge system exceeds 2300 kPa (334 psi).

Relief valve (5) protects the charge system from cold oil or restrictions in the charge system. Relief valve (5) will open when the oil pressure exceeds 3000 kPa (435 psi).

1. Remove the cover that is located on the right side of the machine.

2. Start the engine.

3. Read the charge pressure on the IQAN display. The pressure reading should not exceed 23 bar. The charge pressure should not drop below 12 bar.

Show/hide table



Illustration 3	g00917445
Location of Valve Bank (underneath cab) (6) Parking brake valve. (7) Wire connector.

4. Disconnect wire (7) from parking brake valve (6) .

   This prevents the parking brake from disengaging.

5. Install the cover that is located on the right side of the machine.

6. At the main menu of the IQAN display, press the right arrow key. The following window will appear.

7. Allow the machine to warm up. Ensure that the hydraulic oil is at normal operating temperature.

8. Place the direction selector switch in the FORWARD position. Place the machine in HIGH speed.

9. Slowly depress the accelerator pedal until the accelerator pedal is on the floor. Note the pressure reading on the IQAN display. The pressure reading should not drop below 12 Bar.

   Note: In order to prevent damage to the power train pump, do not hold down the accelerator pedal to the floor for more than 10 seconds.

10. Place the direction selector switch in the REVERSE position. Place the machine in HIGH speed.

11. Slowly depress the accelerator pedal until the accelerator pedal is on the floor. Note the pressure reading on the IQAN display. The pressure reading should not drop below 12 Bar.

    Note: In order to prevent damage to the power train pump, do not hold down the accelerator pedal to the floor for more than 10 seconds.

12. Release the accelerator pedal and stop the engine.

13. Perform Steps 14 and 15 if the charge pressure dropped below 12 Bar in either the FORWARD position or the REVERSE position.

    If the charge pressure dropped below 12 Bar, there is excessive leakage in the power train pump or the power train motor.

    Steps 14 and 15 will isolate the test to the power train pump.

Show/hide table



Illustration 4	g00916687
Power Train Pump (1) Oil line (drive loop) (forward). (2) Charge pressure relief valve. (3) Oil line (drive loop) (reverse). (4) Charge pump. (5) Relief valve (cold oil start-up).

14. Disconnect oil lines (7) and (8). Use covers (A) and rectangular seals (B) to block ports "P2(S)" and "S(P2)" on the power train pump.

    Note: When high pressure oil flows from the "P2(S)" port, the machine travels forward. When high pressure oil flows from the "S(P2)" port, the machine travels backward.

15. Repeat Step 2 through Step 12.

    If the charge pressure dropped below 12 Bar in either direction, there is excessive leakage in the power train pump.

    If the charge pressure was within specifications, perform the procedures in Systems Operation, "Hydrostatic Drive System Performance - Test".