953D, 963D and 973D Track-Type Loaders Machine Movement Is Unstable Caterpillar


Machine Movement Is Unstable
`


Illustration 1g01953851

  1. Check for the symptom.

  2. Determine that the symptom is active.

  3. Complete this procedure only if the symptom is active.


    Illustration 2g01677296
    General location of the pump's "X1" and "X2" ports on the 953D and the 963D machines


    Illustration 3g01960653
    General location of the right side pump on the 973D machines


    Illustration 4g01983733
    General location of the pump's "X1" and "X2" ports on the 973D machines

  4. View pressure increases on the charge oil for the Forward/Reverse solenoids of the hydrostatic pumps.

    Make sure that the spool is not sticky. Place the machine on stands. Attach pressure gauges to "X1" and "X2" ports of the hydrostatic pumps. While the tracks are slowly moving, slowly increase the speed range. The pressure at gauges "X1" and "X2" should slowly increase. This should be a smooth transition.

  5. Recalibrate the control lever.

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

  6. Conduct recalibration of the pumps.

    Guidelines for checking the calibrations of the pumps refer to Testing and Adjusting, "Calibration" for your machine.

  7. Check EPOR sensor.

    Check the EPOR sensor in ET for an erratic signal. Recalibrate sensor if needed.

  8. Inspect the pumps control valve and screens.

    Be sure to check electronic pressure control spool for and damaged or contaminations including the edge filters, screens, swashplate, rod and springs.

  9. Inspect the pumps actuator piston and the bore

    Make sure the pumps actuator piston is operating properly. Check the pump bore for any roughness.



    Illustration 5g01622175

  10. View pressure increases on (M1) port of the hydrostatic motors.

    Make sure that the spool is not sticky. Place the machine on stands. Attach pressure gauges to (M1) ports of the hydrostatic motors. While the tracks are slowly moving, slowly increase the speed range. The pressure at gauges (M1) should slowly increase. This should be a smooth transition.

  11. Check the speed sensor.

    Check the status of the speed sensors in ET. Refer to Testing and Adjusting, "Speed Sensor - Adjust" for your machine. Replace the sensors, if necessary.

  12. Conduct recalibration of the motors.

    Guidelines for checking the calibrations of the motors refer to Testing and Adjusting, "Calibration" for your machine.

  13. Recalibrate the EPOR sensor.

    Recalibrate the EPOR sensor using ET. Replace the sensor, if necessary.

  14. Inspect the motor's electronic pressure control valve.

    Inspect the pressure control valve, edge filters, swashplate, springs, and pump controls.

  15. Inspect the motor's actuator piston and the bore for roughness.

    Results

    • OKAY: proceed to step 16.

    • NOT OKAY: Repair the problem and proceed back to step 10.

  16. Conduct a recalibration of the pumps and motors.

    Guidelines for checking the calibrations of the pump and motor refer to Testing and Adjusting, "Calibration" for your machine.

Information System:

953D, 963D and 973D Track-Type Loaders Hydraulic System Hesitates
2009/10/01 A New Slip Joint Group Improves Service Life of the Drive Shaft {3251}
D7E Track-Type Tractor Hydraulic, HVAC, and Electrical Systems Implement Droops Before Raising
C9.3 Tier 4 Final Engines Diesel Particulate Filter Has High Ash Load
IT38H Integrated Toolcarrier and 938H Wheel Loader Declaration of Conformity
966H and 972H Wheel Loaders Declaration of Conformity
953D, 963D and 973D Track-Type Loaders Hydraulic System Pressure Is Low
C13, C15, and C18 Tier 4 Interim Engines ARD Temperature Is Low
Procedure to Improve the Starting Capability on 627G and 637G Wheel Tractor-Scrapers{0645, 1456, 1920, 7620}
2010/02/03 A New "B" Pin Bearing Has Been Designed for the Bucket of Medium Wheel Loaders that Are Used As Steel Mill Machines Working in Severe Applications {6107, 7000}
D7E Track-Type Tractor Hydraulic, HVAC, and Electrical Systems Implement Movement Without Request
C15 and C18 Engines for Caterpillar Built Machines Flywheel - Remove and Install
953D, 963D and 973D Track-Type Loaders Machine Top Speed Is Not Obtained
953D, 963D and 973D Track-Type Loaders Hydrostatic Drive Is Sluggish
2012/04/09 Improved Friction Disc and Software for the Torque Converter Impeller Clutch on 988H Wheel Loaders {3101, 7610, 7620}
2010/01/06 A New Lip Seal for the Final Drive Is Now Used {4050, 4052}
2009/07/27 Improved Procedure for the Retention of the Identification Film for the Roll Over Protective Structure (ROPS) and Falling Object Protective Structure (FOPS) {7323, 7325, 7405, 7557}
D7E Track-Type Tractor Hydraulic, HVAC, and Electrical Systems Implement Hydraulic Force Is Low
2009/09/28 New Software Released For AccuGrade Office {5267, 7220}
2009/07/27 New Air Lines and a New Air Motor Are Now Used to Improve the Capability of the Cold Start {1450, 1451, 1462, 1466}
621G Wheel Tractor-Scraper Maintenance Interval Schedule
627G Wheel Tractor-Scraper Maintenance Interval Schedule
613G Wheel Tractor-Scraper Maintenance Interval Schedule
D7E Track-Type Tractor Hydraulic, HVAC, and Electrical Systems Implement Cycle Time Is Slow for All Implements