554 and 574 Forwarders Power Train Caterpillar

Description of Test

Do not perform the following test until you have performed the procedures in Testing and Adjusting, RENR3028, "554 Forwarder and 574 Forwarder Power Train", "Power Train Charge System Pressure - Test".

The following procedure is used in order to determine whether the power train pump or the power train motor has excessive internal leakage.

Preparation for Testing

1. Tilt the cab.

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Illustration 1	g00686130
Location of Power Train Pump (underneath cab) (1) Pressure tap. (2) Power train pump.

2. Connect a 0 to 2000 kPa (0 to 290 psi) pressure gauge to pressure tap (1). Pressure tap (1) is located on the right side of the power train pump.

   The pressure reading at pressure tap (1) is stroking pressure.

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Illustration 2	g00686143
Location of Valve Bank (underneath cab) (3) Parking brake valve. (4) Wire connector.

3. Disconnect wire (4) from parking brake valve (3) .

   This prevents the parking brake from disengaging.

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Illustration 3	g00686145
Location of Pressure Sensors (underneath cab) (5) Oil line (drive loop) (forward). (6) 574 Forwarder Oil line (drive loop) (reverse). (6a) 554 Forwarder Oil line (drive loop) (reverse).

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Illustration 4	g00686151
Components from Table 1 (5) Oil line (drive loop) (forward). (6) 574 Forwarder Oil line (drive loop) (reverse).

4. Disconnect oil lines (5) and (6) .

   Assemble the components that are shown in Illustration 4.

   Connect oil lines (5) and (6) to tee (C) .

   This will allow you to read the drive loop pressure in forward and reverse direction.

5. Connect a 0 to 50000 kPa (0 to 7250 psi) pressure gauge to each pressure tap.

6. Tilt down the cab.

Test

1. Start the engine. Increase the engine speed to 1500 rpm with the engine speed potentiometer. Turn the machine speed potentiometer to 0.

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Illustration 5	g00686160
IQAN Screen (Current settings to the proportional solenoids on the power train pump)

2. Set the minimum current of the drive loop to 170 mA and the maximum current of the drive loop to 360 mA. If the minimum current is set higher than 170 mA, the drive loop pressure will increase too fast for the test procedure.

   Note: The current settings of the power train pump are locked at the factory. A PC that is equipped with IQANtalk software must be used to unlock these current settings for adjustment.

3. Move the direction selector switch to the FORWARD position and the speed selection switch to SECOND speed.

4. Depress the accelerator pedal halfway.

5. Very slowly turn the machine speed potentiometer until the pressure reading of the drive loop reaches 5000 kPa (725 psi). Record the stroking pressure from pressure tap (1) .

6. Continue to turn the machine speed potentiometer until the pressure reading of the drive loop reaches 35000 kPa (5100 psi). Record the stroking pressure from pressure tap (1) .

7. Release the accelerator pedal.

8. Move the direction selector switch to the REVERSE position and the speed selection switch to SECOND speed. Repeat Step 4 through 7.

   Note: The difference between the two stroking pressures should not be more than 120 kPa (17 psi).

9. Stop the engine.

10. If the difference between the two pressure readings is out-of-range, perform Step 11 through Step 13.

11. Tilt the cab.

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Illustration 6	g00685851
Location of Power Train Pump (underneath cab) (7) Oil line (drive loop) (forward). (8) Oil line (drive loop) (reverse).

12. Disconnect oil lines (7) and (8). Use covers (E) and rectangular seals (F) to block ports "P(S)" and "S(P)" on the power train pump.

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

13. Tilt down the cab and repeat Step 1 through Step 8.

    Note: The difference between the two stroking pressures should not be more than 60 kPa (9 psi). If the difference between the two pressure readings is within the correct range, the source of the leakage is most likely from the power train motor.