953D, 963D and 973D Track-Type Loaders Machine Does Not Move Caterpillar


Machine Does Not Move
`
1.1. Probable Causes
2.2. The Parking Brake Is On
3.2. The Operator Presence Detection System Has A Problem
4.2. The Engine RPM Is Set Too Low
5.2. The Pump Control is Suspect
6.2. The Control Lever Is Not Calibrated Properly
7.2. Contamination Of The Hydraulic Oil
8.2. Insufficient Pressure Oil To The Brakes
9.2. Hystat System Pressure Is Not Correct
10.2. Failed Brake Components
11.2. Brake Control Valve Is Not Releasing
12.2. The Pump Has Too Much Wear
13.2. The Drive Coupler Has Failed

Probable Causes

  • The parking brake is ON.

  • The operator presence detection system has a problem.

  • The engine rpm is set too low.

  • The pump control is suspect.

  • The control lever is not calibrated properly.

  • Contamination of the hydraulic oil

  • Insufficient pressure oil to the brakes

  • Hystat system pressure is not correct

  • Failed brake components

  • Brake control valve is not releasing

  • The pump has too much wear.

  • The drive coupler has failed.

The Parking Brake Is On

Refer to Troubleshooting, "Brake Does Not Release" in this manual.

The Operator Presence Detection System Has A Problem

Check the sensors on the machine to make sure the are operating properly. The sensors monitor the arm rest, seat and brake pedal positions. Refer to Operation and Maintenance Manual, "Operation Information" for your machine for more information.

The Engine RPM Is Set Too Low

Increase the engine rpm setting. Guidelines for checking the engine rpm refer to the Testing and Adjusting manual for the engine in your machine.

The Pump Control is Suspect

Check the pump for contamination. Make sure that the "Flow Rate" for the hydraulic control valve is adjusted correctly. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.

Check the current that is applied to the solenoid valve. Make sure that the solenoid valve is functioning correctly.

If necessary, repair the solenoid or replace the solenoid valve.

Note: DO NOT ADJUST THE MINIMUM OR MAXIMUM STOPS

The Control Lever Is Not Calibrated Properly

Be sure that the control lever position sensor is calibrated properly. Refer to Testing and Adjusting, "Hystat Operator Control Calibrations" for your machine.

Contamination Of The Hydraulic Oil

If the symptom is not active or if the symptom is intermittent, oil contamination may be the problem.

Change the hydraulic oil. Change the oil filter element and clean the screens.

Insufficient Pressure Oil To The Brakes

Insufficient pressure oil to the brakes is a probable cause of the symptom.

The brakes are engaged by spring force. The brakes are released by pressure oil which is sent from the brake control solenoid to the brakes.

Reference: Refer to Testing and Adjusting, "Brake Pedal - Test" for your machine.

Hystat System Pressure Is Not Correct

Check the system pressure.

Reference: Refer to Testing and Adjusting, "Hydrotatic Pump and Motor Efficiency Test" for your machine.

Expected Results

  • The system pressure is correct.

Results

  • OKAY: The system pressure is correct. The brake pressure is not correct. Inspect the brake control valve. Proceed to "Brake Control Valve Is Not Releasing".

  • NOT OKAY: The system pressure is not correct. The cause of the problem may be due to a problem in the charge system or the pump. Refer to the appropriate troubleshooting procedures.

Failed Brake Components

Disassemble the brakes and check the following components of the brakes for failure:

  • seals

  • splines

  • friction discs

  • brake plates

Replace any damaged components, if necessary.

Calibrate the brakes. Refer to Testing and Adjusting, "Calibration" for your machine.

Brake Control Valve Is Not Releasing

  1. Disassemble the brake control valve and inspect the valve for damage.

    1. Repair the components and/or replace the components, if necessary.

    2. Calibrate the brakes. Refer to Testing and Adjusting, "Calibration" for your machine.

    3. Recheck the brake pressure. Refer to Testing and Adjusting, "Brake Pedal - Test" for your machine.

      Expected Results

      • The brake pressure is correct.

      • The original problem is resolved.

      Results

      • OKAY: Stop.

      • NOT OKAY: If no problems with the brake control valve were observed then the probable causes that were analyzed in this procedure did not identify the cause of the problem.

The Pump Has Too Much Wear

Check the swash plate and make sure it is operating properly. If the swash plate is functioning properly then check the pump components for wear. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.

The Drive Coupler Has Failed

Check to see if there will be no pressure. If there is no pressure, check the condition of the drive coupler. Repair or replace as needed.

Information System:

953D, 963D and 973D Track-Type Loaders Implement Movement Without Request
953D, 963D and 973D Track-Type Loaders Hydraulic Cylinder Drift
973K Track-Type Loader Systems Piston Pump (Hydrostatic)
3516B Engine for 994F and 994H Wheel Loaders Electronic Service Tool Does Not Communicate
953D, 963D and 973D Track-Type Loaders Implement Cycle Time Is Slow for One Implement
953D, 963D and 973D Track-Type Loaders Implement Cycle Time Is Slow for All Implements
953D, 963D and 973D Track-Type Loaders Implement Droops Before Raising
Identification and Installation of Cambered Pivot Shafts{4153}
2009/08/10 Diagnostic Publications for the Systems of the Hydraulic Electronic Unit Injector (HEUI) have been Updated {1100, 1126, 1250, 1251, 1261, 1290}
2009/08/31 Diagnostic Process for Fuel Rail Pressure Sensor {127A, 1439}
2009/08/31 Diagnostic Process for Fuel Rail Pressure Sensor {127A, 1439}
D11T Track-Type Tractor Machine Systems Ladder Hinge - Assemble
C7.1 Industrial Engine Engine Valve Lash - Inspect
Procedure to Apply Dielectric Grease to the Horn (Cruise Control) Contact Ring{4310}
973K Track-Type Loader Systems Motor Control Valve (Hydrostatic) (Displacement)
2009/08/24 New Fuel Injection Lines {1251, 1252}
953D, 963D and 973D Track-Type Loaders Steering Hesitates
953D, 963D and 973D Track-Type Loaders Steering Is Harsh
973K Track-Type Loader Systems Flushing Valve
953D, 963D and 973D Track-Type Loaders Machine Moves Slowly
C4.4 Industrial Engine Before Starting Engine
C4.4 Industrial Engine After Stopping Engine
C4.4 Industrial Engine System Pressure Release
C27 and C32 Engines for Caterpillar Built Machines Electronic Unit Injector - Test