12M Series 3, 140M Series 3 and 160M Series 3 Motor Graders 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.

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	g02118318
Tooling (A)

Illustration 2	g01623868
Tooling (B)

Illustration 3	g02111086
Tooling (D)

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

Machine Preparation

Reference: Before you perform these procedures, refer to Testing and Adjusting, "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 of 60° ± 5°C (140° ± 9°F).

5. Stop the engine.
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   Illustration 4	g03603616
   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 (B) and Tooling (B2) 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	g03603616
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	g03639997
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).

Load Sense Pressure Test

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	g03640018
   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 (B) and (B2) 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 24115 + 400 − 1035 kPa (3500 + 58 − 150 psi).
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   Illustration 11	g03639988
   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 (B2) 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	g03640021
   (4) Relief valve (signal) (5) Locknut (6) Adjustment screw for the relief valve (signal)

8. Stop the engine. If the pressure reading is incorrect, loosen locknut (5) on adjustment screw (16). 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 (5) hold adjustment screw (6) secure.

10. If the pressure reading is not within the tolerance, adjust the relief valve (signal) (4). The correct pressure reading should be 22050 ± 500 kPa (3200 ± 72 psi).

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

Test for the Shuttle Valve

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Illustration 13	g03639633
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 (B) 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	g03639638
   The shutoff valve contains the shuttle valve (3) Shutoff Valve

3. Move the wheel lean cylinder to the end of the stroke and stall the cylinder. The pressure gauge should read 24000 ± 500 kPa (3450 ± 100 psi). Tooling (B) should display the correct pressure reading. The shuttle valve has shifted correctly in order to allow signal oil from the implement system to flow to the pump control valve.

4. Move the steering cylinder to the end of the stroke and stall the cylinder. The pressure gauge should read 12600 kPa (1825 psi). Tooling (B) should display the correct pressure reading. The shuttle valve has shifted correctly in order to allow steering signal oil to flow to the pump control valve.

5. If the pressure reading does not change between the two different systems, replace the shuttle valve.

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

Test and Adjust the Steering Load Sense Valve

Reference: Before you perform this adjustment, refer to Testing and Adjusting, "Machine Preparation".

Machine Preparation

1. Move the machine to a smooth horizontal location.

2. Chock the wheels.

3. Lower all of the implements.

4. Shut off the engine and verify that all pressure has been removed from the Hydraulic and Steering System.

5. Assemble tooling (F).
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   Illustration 15	g03861543

6. Remove elbow (H) and retain for reassembly. Install tooling (F) where elbow (H) was removed.

7. Install digital pressure indicator group (B) onto tooling (F).
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   Illustration 16	g03861542

8. Install bolts and washers (G) into the locations shown in Illustration 16.
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   Illustration 17	g03639726
   The implement and steering pump is mounted to the engine on the left side of the machine.

9. Remove the dust cover and Install the test gauge on pressure tap (2).

10. Start the engine and operate at low idle.

11. Align the left-hand joystick control so that the joystick control will match the steering angle of the front wheels.

12. Move the left-hand joystick control all the way to the left and hold for 30 seconds. Check the pressure reading on the gauge. The pressure reading should be 17000 ± 500 kPa (2465 ± 72 psi).

Adjustment procedure

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Illustration 18	g03861544

1. If the pressure is incorrect adjust the steering load sensing relief valve. Loosen lock nut (2) and turn stem (1) clockwise to increase the pressure. Turn stem counter clockwise to decrease the pressure.

2. Hold the stem (1) and tighten the lock nut (2) to 12 ± 2 N·m (106 ± 18 lb in) after the proper setting is achieved.
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   Illustration 19	g03861543

3. Remove digital pressure indicator group (B) and tooling (F). Then reinstall elbow (H) that was retained.