120H, 12H, 135H, 140H, 143H, 14H, 160H, 163H and 16H Motor Graders Secondary Steering System Caterpillar


Hydraulic System

Usage:

120H 124
If no electrical problems were found in the Testing and Adjusting, "Electrical System Troubleshooting" section, proceed with the following tests.


Illustration 1g00927062

(1) Steering cylinders

(2) Steering metering unit

(3) Hydraulic tank and filter

(4) Implement and steering pump

(5) Check valve

(6) Check valve

(7) Combination valve

(8) Relief valve

(9) Check valve

(10) Pump

(11) Electric Drive




Illustration 2g00922990

(12) Secondary steering test switch




Illustration 3g00922724

Rear compartment on left side of machine

(13) Battery disconnect switch




Illustration 4g00922535

Instrument Panel

(14) Action light

(15) Panel for the indicator lights

(16) Warning light

(17) Monitoring panel

General Test Procedures

  1. Turn battery disconnect switch (13) to the ON position.

  1. Turn the engine start switch to the ON position.

    Note: The secondary steering system will not function unless both of these switches are in the ON position.

  1. Warning light (16) and action light (14) should flash until the engine is started. Warning light (16) should stay on for three seconds and electric drive (11) should run for three seconds.

    Note: This three second period is referred to as the three second powerup test.

  1. When warning light (16) is on, the operator should be able to steer with a normal amount of effort.

  1. Start the engine. After the engine is started, warning light (16) turns off and action light (14) turns off.

  1. Turn off the engine. Turn the engine start switch to the ON position. Warning light (16) should flash and action light (14) should also flash. Hold the secondary steering test switch (12) in the TEST position. Electric drive (11) should run. The status light in secondary steering test switch (12) should turn on. The operator should be able to steer with a normal amount of effort.


    NOTICE

    The seconday steering motor should remain on for no more than two minutes. This time period should be sufficient to safely steer the machine to a stop. After the machine has come to a stop, turn the engine start switch to the OFF position. This will turn off the secondary steering system. Prolonged use of the secondary steering system will cause the secondary steering motor to overheat. Overheating will cause damage to the components of the secondary steering motor.


  1. With the engine at low idle, perform the following steps:

    • Depress the transmission modulator pedal.

    • Depress the brake pedal.

    • Put the transmission direction and speed control in the highest gear.

    • Release the transmission modulator pedal.

    This procedure will stall the engine. After the engine has stalled the following conditions will occur:

    • Warning light (16) flashes.

    • Action light (14) flashes.

    • Electric drive (11) starts running.

    The operator should be able to steer the machine with a normal amount of effort.

The following steps should be used to troubleshoot any problems.

Problem

The operator is unable to steer the machine with a normal amount of effort and the following conditions occur:

  • The engine start switch is in the ON position.

  • Secondary steering test switch (12) is held in the TEST position.

  • Electric drive (11) runs.

  • Pump (10) operates.

Probable Cause

  • Check valve (9) is sticking.

Check valve (9) is installed on the combination valve. Check valve (9) should unseat when pump (10) is pumping hydraulic oil. The sticking of check valve (9) inhibits the flow of the hydraulic oil from pump (10) to steering metering unit (2) .

Replace check valve (9) .

Problem

The primary steering system does not function. The secondary steering system functions properly.

Probable Cause

  • Check valve (6) has failed open. Check valve (6) is mounted in combination valve (7) .

Replace check valve (6) .

Problem

The effort to steer the primary steering system and the effort to steer the secondary steering system is significantly different.

Probable Cause

  • Relief valve (8) has failed.

Perform the steps in the Testing and Adjusting, "Relief Valve (Secondary Steering) - Test" section.

Caterpillar Information System:

2002/12/02 The Lines for the Hoist Cylinders Have Been Updated in Order to Protect the Hoist Valve {5057}
R2900 Load Haul Dump Starting the Engine
R2900 Load Haul Dump Computerized Monitoring System - Self Test
120H, 12H, 135H, 140H, 143H, 14H, 160H, 163H and 16H Motor Graders Secondary Steering System Electrical System
AP-655C and BG-2255C Asphalt Pavers Machine Systems Introduction (Auxiliary System)
3500 and 3500B High Displacement Engines for Caterpillar Built Machines Auxiliary Water Pump - Install
IT28G Integrated Toolcarrier and 924G, 924GZ, 928G and 930G Wheel Loaders Brake Accumulator - Check
Field Installation of the 222-5721 Cab Heater and Mounting Gp {7304} Field Installation of the 222-5721 Cab Heater and Mounting Gp {7304}
120H, 12H, 135H, 140H, 143H, 14H, 160H, 163H and 16H Motor Graders Secondary Steering System General Information
TH220B, TH330B, TH340B, TH350B, TH355B, TH360B, TH460B, TH560B and TH580B Telehandlers MID 039 - CID 1832 - FMI 02
TH220B, TH330B, TH340B, TH350B, TH355B, TH360B, TH460B, TH560B and TH580B Telehandlers MID 039 - CID 1830 - FMI 02
120H, 12H, 135H, 140H, 143H, 160H and 163H Motor Graders Operational Checks
IT38G Series II Integrated Toolcarrier and 938G Series II Wheel Loader Operational Checks (Steering System)
TH220B, TH330B, TH340B, TH350B, TH355B, TH360B, TH460B, TH560B and TH580B Telehandlers MID 039 - CID 1833 - FMI 02
2002/11/25 A Front Mounted Liquid Level Gauge for the Hydraulic Oil Tank is Available {7479}
776D, 777D and 777D HAA Off-Highway Truck/Tractors Air System and Brakes Brake Hydraulic System
3500 and 3500B High Displacement Engines for Caterpillar Built Machines Auxiliary Water Pump - Disassemble
D350E Series II and D400E Series II Articulated Trucks Power Train Final Drive and Wheel
2002/09/02 The Thumb Switch on the Propel Lever is not Functional {3209, 5462}
793C XQ Off-Highway Truck and 793C Off-Highway Truck Engine Supplement Modular Front End - Install
2002/08/26 Special Instruction, REHS1329 , "Field Installation of the Radio Installation Group for Utility Cabs" is Available {7301, 7338}
950G Series II Wheel Loader, 962G Series II Wheel Loader and IT62G Series II Integrated Toolcarrier Power Train Torque Converter
3500 and 3500B High Displacement Engines for Caterpillar Built Machines Auxiliary Water Pump - Assemble
2002/09/02 Correction to Custom Product , "140G All Wheel Drive (AWD) Motor Grader" {1000, 7000}
Back to top
The names Caterpillar, John Deere, JD, JCB, Hyundai or any other original equipment manufacturers are registered trademarks of the respective original equipment manufacturers. All names, descriptions, numbers and symbols are used for reference purposes only.
CH-Part.com is in no way associated with any of the manufacturers we have listed. All manufacturer's names and descriptions are for reference only.