12M Series 2, 140M Series 2 and 160M Series 2 Motor Graders Hydraulic and Steering System Caterpillar

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Hydraulic oil pressure can remain in the hydraulic system on this machine after the engine and pump have been stopped. Serious injury can result if this pressure is not released before any service is done on the hydraulic system. In order to prevent possible injury, release the hydraulic system pressure before working on any fitting, hose, or hydraulic component. Lower all work tools to the ground before service is started. If the hydraulic system must be serviced, tested, or adjusted with the work tool in the raised position, the work tool and lift cylinders must be supported properly. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made.

Reference: Before you perform these procedures, refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".

Specifications

Introduction

The pump control valve for the hydraulic and steering system is attached to the pump for the implement and steering. The pump control valve keeps pump flow at the level that is needed to fulfill the requirements of the hydraulic and steering system.

Required Tools

Illustration 1	g02571852
Tooling (A)

Illustration 2	g02726620
Tooling (B)

Illustration 3	g02111086
Tooling (D)

Note: Tooling (A) or Tooling (B) may be used to perform these tests.

Machine Preparation

1. Move the machine to a smooth horizontal location.

2. Chock the wheels.

3. Start the engine.

4. Operate the engine at low idle. Operate the implement controls for 3 to 10 minutes in order to raise the hydraulic oil temperature to normal operating temperature range.

5. Stop the engine.
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   Illustration 4	g02286437
   Control manifold for the pilot system (1) Control manifold (2) Pressure test port for the pump

6. Remove the dust cover from pressure test port (2). Install Tooling (A) and Tooling (A2) onto pressure test port (2).

Margin Pressure Test

Illustration 5	g02168113
Pump control valve (3) Test port (4) Locknut (5) Adjustment screw for the flow compensator (margin pressure) (6) Adjustment screw for the pressure compensator (pressure cutoff) (7) Locknut

1. Start the engine. Operate the engine at low idle or operate the engine at high idle. This reading is the low pressure standby setting for the implement and the steering system.

2. Once the pressure is reached in step 1, extend the side shift cylinder in one direction until STALL occurs. Extend the side shift cylinder in the opposite direction until STALL occurs. The time from one stall to the other stall should be 14.3 ± 1.9 seconds.

3. If Step 2 is not within the specifications, then proceed to section "Margin Pressure Adjustment".

Margin Pressure Adjustment

Illustration 6	g02286438
Control manifold for the pilot system (1) Control manifold (2) Pressure test port for the pump

Illustration 7	g02168215
Pump control valve (3) Test port (4) Locknut (5) Adjustment screw for the flow compensator (margin pressure) (6) Adjustment screw for the pressure compensator (pressure cutoff) (7) Locknut

Illustration 8	g02173292
View A-A (3) Test port

Illustration 9	g02170973
Pump control valve (3) Test port

1. Connect the low side of Tooling (D) onto pressure test port (3).

2. Connect the high side of Tooling (D) onto pressure test port (2).

3. Start the engine.

4. Operate the engine at low idle. Operate the implement controls for 3 to 10 minutes in order to raise the hydraulic oil temperature to normal operating temperature range.

5. When you obtain the normal operating temperature for the hydraulic oil, operate the engine at high idle.

6. Operate the circle drive and rotate the blade at full speed. The pressure reading should be 2100 ± 100 kPa (305 ± 15 psi).

7. Stop the engine. If the pressure reading is incorrect, loosen locknut (4) on adjustment screw (5). Turn the adjustment screw clockwise in order to increase the setting. Turn the adjustment screw counterclockwise in order to decrease the setting.

8. When you tighten locknut (4) hold adjustment screw (5) secure. Repeat Step 5 through Step 7 until you obtain the correct pressure setting in Step 6.

9. Remove Tooling (D). Replace the dust caps on test port (2) and test port (3).

Adjustment for Signal Network

1. Operate the engine at low idle.

2. Operate the implement controls for 3 to 10 minutes in order to raise the hydraulic oil temperature to the normal operating temperature range.
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   Illustration 10	g02286439
   Control manifold for the pilot system (1) Control manifold (2) Pressure test port for the pump

3. Stop the engine. Remove the dust cover from pressure test port (2). Install Tooling (A) and (A2) onto pressure test port (2).

4. Start the engine and operate the engine at high idle. Stall the cylinder. The correct pressure reading should be 24000 ± 500 kPa (3481 ± 73 psi).
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   Illustration 11	g02170993
   Pump control valve (3) Test port

5. Stop the engine. In order to obtain pump signal pressure, remove the dust cap from pressure test port (3). Install Tooling (A2) onto port (3).

6. Start the engine. Move the joystick control in order to move the blade tip cylinder to the maximum stroke and stall. Read the pressure gauges. The pressure at test port (2) should increase. The pressure at test port (3) should increase.

7. If the pressure at test port (3) increases and the pressure at test port (2) does not increase, replace the pump control valve.
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   Illustration 12	g02170994
   (8) Relief valve (signal) (9) Locknut (10) Adjustment screw for the relief valve (signal)

8. Stop the engine. If the pressure reading is incorrect, loosen locknut (9) on adjustment screw (10). Turn the adjustment screw clockwise in order to increase the setting. Turn the adjustment screw counterclockwise in order to decrease the setting.

9. When you tighten locknut (9) hold adjustment screw (10) secure.

10. If the pressure reading from the gauge on test port (3) is not within the tolerance, adjust the relief valve (signal) (8). The correct pressure reading should be 22050 ± 500 kPa (3198 ± 73 psi).

11. Stop the engine. Remove the pressure gauge from pressure test port (2). Replace the dust cover.

Test for the Signal Resolver

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Illustration 13	g02286440
Control manifold for the pilot system (1) Control manifold (2) Pressure test port for the pump

1. Remove the dust cover from pressure test port (2). Install Tooling (A) onto pressure test port (2).

   Reference: Refer to Testing and Adjusting, "Steering System - Purge" for information on purging the steering system.

2. Start the engine and operate the engine at low idle.
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   Illustration 14	g02173345
   (11) Signal resolver

3. Move the wheel lean cylinder to the end of the stroke and stall the cylinder. The pressure gauge should read 24000 ± 500 kPa (3481 ± 73 psi). Tooling (A) should display the correct pressure reading. Resolver (11) has shifted correctly in order to allow signal oil from the implement system to flow to the pump control valve.

4. Stop the engine.
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   Illustration 15	g03707358

5. Install Tooling (F) into holes, (12) and (13). Be sure not to use the wheel lean function. The wheel lean function may damage Tooling (F).

6. Start the engine and operate at low idle.

7. Move the steering cylinder to the end of the stroke and stall the cylinder. The steering cylinders will stall out on Tooling (F) before the electronic control module automatically reduces steering pressure. The pressure gauge should read 15600 kPa (2263 psi). Tooling (A) should display the correct pressure reading. Resolver (11) has shifted correctly in order to allow steering signal oil to flow to the pump control valve.

8. If the pressure reading does not change between the two different systems, replace the signal resolver (11).

9. Stop the engine. Remove the pressure gauge from pressure test port (2). Replace the dust cover.