554 and 574 Forwarders Power Train Power Train Drive Loop Speed - Test and Adjust Caterpillar


Power Train Drive Loop Speed - Test and Adjust
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1.1. Testing Procedure for Minimum Current
2.1. Adjusting Procedure for Minimum Current
3.1. Testing and Adjusting Procedure for Maximum Current

The machine has a hydrostatic drive loop. The drive loop is a closed loop circuit.

The drive loop uses hydraulic oil from the power train pump. The IQAN controls the oil flow from the power train pump to the power train motor.

The power train pump has a maximum current setting and a minimum current setting for the forward direction and the reverse direction.

When you first move the accelerator pedal from the neutral position, no current flows from the pedal. If you move the pedal slightly more the "minimum current" will flow from the pedal.

Note: The initial movement will release the parking brake and the oscillation lock.

The "minimum current" should be adjusted so that the machine does not move during the initial movement of the accelerator pedal. When the accelerator pedal is pushed slightly more the machine should begin to move.

If the "minimum current" is too high, the machine will jump when you move the accelerator pedal. If the "minimum current" is too low the accelerator pedal must be moved excessively in order to begin the movement of the machine.

When the accelerator pedal reaches the end of travel, the maximum current will flow from the accelerator pedal. The "maximum current" should be adjusted so that the maximum speed of the machine corresponds to maximum travel of the accelerator pedal.

If the maximum current is set too high, the accelerator pedal will not move all the way to reach maximum speed. If the maximum current is set too low, the machine will not move at maximum speed.

Testing Procedure for Minimum Current

Note: This test must be performed when the engine is on and while the machine is driven.

This test ensures that the machine begins to move soon after you press the accelerator pedal. The minimum current setting of the proportional solenoid on the power train pump controls when the power train motor begins to send oil through the drive loop.

  1. If your machine has chains or tracks that are mounted on the tires, remove the chains or the tracks.

  1. Ensure that the hydraulic oil in the system is at normal operating temperature.

  1. Start the engine. Move the machine to a smooth level surface. Be sure that all wheels are on the ground. Place the bogie float switches in the FLOAT position.

  1. Place the operating mode switch in the OPERATION MODE position.

  1. Turn the speed potentiometer to 100 percent.

  1. Perform step 7 in order to test the drive loop in the forward direction. Perform step 8 in order to test the drive loop in the reverse direction.

  1. Forward:

    1. Place the speed selector switch in the FORWARD position. Then, slowly depress the accelerator pedal.

      The machine should begin to move when the following conditions are met.

      • The accelerator is pressed and a click in the accelerator pedal is heard.

      • The accelerator pedal is pressed further.

      The click is from the neutral switch on the accelerator pedal. The switch sends the signal to the IQAN to release the parking brake and the oscillation lock.

    1. Perform Step 8 if the following conditions are met.

      • The click was heard.

      • The accelerator pedal was pressed further.

      • The machine began to move slightly.

    1. If the conditions in Step 7.b were not met, refer to "Adjusting Procedure for Minimum Current" for adjustment procedures.

  1. Reverse:

    1. Place the speed selector switch in the REVERSE position. Then, slowly depress the accelerator pedal.

      The machine should begin to move when following conditions are met.

      • The accelerator is pressed and a click in the accelerator pedal is heard.

      • The accelerator pedal is pressed further.

      The click is from the neutral switch on the accelerator pedal. The switch sends the signal to the IQAN to release the parking brake and the oscillation lock.

    1. Park the machine and stop the engine, if the following conditions are met.

      • The click was heard.

      • The accelerator pedal was pressed further.

      • The machine began to move.

    1. If the conditions in Step 8.b were not met, refer to "Adjusting Procedure for Minimum Current" for adjustment procedures.

Adjusting Procedure for Minimum Current

The following procedure uses the IQAN to adjust the minimum current to the power train pump.

Note: The current adjustment through the IQAN DG (Display unit) are locked at the factory in order to avoid unauthorized adjustment. In order to unlock the adjustment menu, a PC must be used that has the IQANtalk software loaded onto the PC. It is recommended to lock the adjustment menu when the adjustment procedure is completed in order to prevent unauthorized adjustment.

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




    Illustration 1g00686440

    IQAN DG Unit (Operation Menu)

    (1) Arrow key. (2) Arrow key. (3) Arrow key. (4) Arrow key. (5) Menu key. (6) Function key.

  1. At the operation menu of the IQAN DG unit, press menu key (5) and then press arrow key (4) .

  1. The IQAN screen is now displaying "Maintenance" next to the function key "F3". Press the function key "F3".

  1. The IQAN screen is now displaying "GOV Setup" next to the function key "F1", "Transm lowgear" next to the function key "F2", and "Transm highgear" next to the function key "F3".



    Illustration 2g00686160

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

  1. Press function key "F2" in order to view the maximum and minimum current settings for the "Transm lowgear". Press function key "F3" in order to view the maximum and minimum current settings for the "Transm highgear".

    "Transm lowgear" is the maximum and minimum current settings for first speed. "Transm highgear" is the maximum and minimum current settings for second speed and third speed (1FM1-433).

  1. In order to change the current settings, perform steps 5.a through 6.

    1. Press function key "F2".

    1. Press arrow key (1) or press arrow key (2) in order to decrease the current setting. Press arrow key (3) or press arrow key (4) in order to increase the current setting.

      Note: Arrow keys (1) and (4) will change the current value in small increments. Arrow keys (2) and (3) will change the current value in large increments.

      If the current setting is decreased, the machine will begin to move sooner. The initial speed will be lower as a result. If the current setting is increased the machine will begin to move later. The initial speed will be higher as a result. If the current is set too low, the accelerator pedal must be moved an excessive amount in order to move the machine. If the current is set too high, the machine will be jerky.

  1. Repeat the procedure "Testing Procedure for Minimum Current".

Testing and Adjusting Procedure for Maximum Current

This test ensures that the setting of output speed of the power train motor is correct when the accelerator pedal reaches the end of travel.

When the 554 Forwarder or the 574 Forwarder is shifted to first speed or second speed, the maximum speed setting of the power train motor is 3800 rpm. When the 574 Forwarder is shifted to third speed, the maximum speed setting of the power train motor is 2850 rpm.

Note: The rpm reading for the power train motor is displayed on the IQAN screen as "Pwr Train Mtr".

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.

  1. Start the engine. Move the machine to a smooth level surface. Be sure that the machine is at the lowest level. If your machine has chains or tracks that are mounted on the tires, remove the chains or the tracks.

  1. Ensure that the hydraulic oil in the drive loop is at normal operating temperature.

  1. Place the machine in first speed, second speed, or third speed. Place the operating mode switch in the ROADING MODE position.

  1. Perform step 5 in order to test and adjust the drive loop in the forward direction. Perform step 6 in order to test and adjust the drive loop in the reverse direction.

  1. Forward:



      Illustration 3g00686440

      IQAN Terminal (Main Menu)

      (1) Arrow key. (2) Arrow key. (3) Arrow key. (4) Arrow key. (5) Menu key. (6) Function key.

    1. At the main menu of the IQAN display, press menu key (5) and then press arrow key (4) .

    1. The IQAN screen is now displaying "Maintenance" next to the function key "F3". Press the function key "F3".

    1. The IQAN screen is now displaying "GOV Setup" next to the function key "F1", "Transm lowgear" next to the function key "F2", and "Transm highgear" next to the function key "F3".



      Illustration 4g00686160

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

    1. Press function key "F2" in order to view the maximum and minimum current settings for the "Transm lowgear". Press function key "F3" in order to view the maximum and minimum current settings for the "Transm highgear".

    1. Set the "Max Curr Fwd" to 340 mA for the power train pump. This current setting is 20 mA below the maximum current setting that is required to fully upstroke the power train pump.

    1. Road the machine on a hard, level surface. When possible, use a paved road.

    1. Press the accelerator pedal to the floor. Read the speed of the power train motor that is displayed on the IQAN screen.

    1. If the rpm reading is low, increase the maximum current setting. If the rpm reading is high, decrease the maximum current setting.

    1. Repeat Steps 5.f through Steps 5.h until the rpm reading of the power train motor is at the proper speed.

  1. Reverse:



      Illustration 5g00686440

      IQAN Terminal (Main Menu)

      (1) Arrow key. (2) Arrow key. (3) Arrow key. (4) Arrow key. (5) Menu key. (6) Function key.

    1. At the main menu of the IQAN display, press menu key (5) and then press arrow key (4) .

    1. The IQAN screen is now displaying "Maintenance" next to the function key "F3". Press the function key "F3".

    1. The IQAN screen is now displaying "GOV Setup" next to the function key "F1", "Transm lowgear" next to the function key "F2", and "Transm highgear" next to the function key "F3".



      Illustration 6g00686160

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

    1. Press function key "F2" in order to view the maximum and minimum current settings for the "Transm lowgear". Press function key "F3" in order to view the maximum and minimum current settings for the "Transm highgear".

    1. Set the "Max Curr Rev" to 340 mA for the power train pump. This current setting is 20 mA below the maximum current setting that is required to fully upstroke the power train pump.

    1. Road the machine on a hard, level surface. When possible, use a paved road.

    1. Place the speed selector switch in the REVERSE position. Press the accelerator pedal to the floor. Read the rpm of the power train motor that is displayed on the IQAN screen.

    1. If the rpm reading is low, increase the maximum current setting. If the rpm reading is high, decrease the maximum current setting.

    1. Repeat Steps 6.f through Steps 6.h until the rpm reading of the power train motor is at the proper speed.

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