R1600G Load Haul Dump Hydraulic System Relief Valve (Line) - Test and Adjust Caterpillar

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth, level surface. Lower the work tool to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock.

Machine Preparation

Note: Start the engine. Run the engine at high idle. Operate the joystick control lever and move all the cylinders to increase the temperature of the hydraulic oil to normal operating temperature.

Illustration 1	g00913554
(1) Rod end line relief valve for the tilt cylinder (2) Head end line relief valve for the auxiliary cylinder (3) Head end line relief valve for the tilt cylinder (4) Rod end line relief valve for the auxiliary cylinder (5) Main control valve (6) Main relief valve

Note: In order to set a line relief valve, the main relief valve setting must be higher than the setting for the line relief valve. Refer to Table 2 for the main relief valve setting. Refer to Table 3 for the line relief valve settings.

If the main relief valve pressure setting is above the setting of the line relief valve, proceed to the function that is being tested.

If the main relief valve setting is below the setting for the line relief valve, temporarily increase the main relief valve setting.

Reference: For additional information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine that is being serviced.

Note: Holding the joystick control lever for more than 5 seconds while the pressure is at the relief setting may cause rapid heating of the hydraulic oil.

Testing Line Relief Valves (Tilt)

1. Release the pressure from the hydraulic system.

   Reference: Refer to Systems Operation, Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

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   Illustration 2	g00912770
   Tilt cylinder (7) Pressure tap (for the rod end of the tilt cylinder)

2. Connect an 8T-0858 Pressure Gauge to pressure tap (7).

3. Start the engine. Raise the lift arms so that the bucket will clear the ground in the full DUMP position.

4. Run the engine at low idle. Hold the joystick control lever in the full DUMP position.

5. Record the pressure reading from the pressure gauge that is connected to pressure tap (7).

   If the pressure reading does not agree with the value in Table 3, proceed to "Adjusting the Line Relief Valve".

   If the pressure reading agrees with the value in Table 3, proceed to Step 6.

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   Illustration 3	g00912771
   Tilt cylinder (8) Pressure tap (for the head end of the tilt cylinder)

6. Stop the engine.

7. Release the hydraulic system pressure.

   Reference: Refer to Systems Operation, Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

8. Remove the pressure gauge from pressure tap (7). Install an 8T-0860 Pressure Gauge to pressure tap (8).

   Note: The main relief valve has a lower setting than the tilt cylinder head end line relief valve. In order to set the line relief valve, temporarily increase the main relief valve setting.

   Reference: For additional information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine that is being serviced.

9. Start the engine.

10. Run the engine at low idle. Hold the joystick control lever in the full TILT BACK position.

11. Record the pressure reading from the pressure gauge that is connected to pressure tap (8).

    If the pressure reading does not agree with the value in Table 3, proceed to "Adjusting the Line Relief Valve".

    If the pressure reading agrees with the value in Table 3, proceed to "Remove Test Equipment".

Testing Line Relief Valves (Auxiliary)

1. Release the pressure from the hydraulic system.

   Reference: Refer to Systems Operation, Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

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   Illustration 4	g00913102
   Auxiliary cylinder manifold (9) Plug (for the head end of the auxiliary cylinders)

2. Remove plug (9) and install a pressure tap. Connect an 8T-0860 Pressure Gauge to the pressure tap.

   Note: The main relief valve has a lower setting than the auxiliary cylinder head end line relief valve. In order to set the line relief valve, temporarily increase the main relief valve setting.

   Reference: For additional information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine that is being serviced.

3. Start the engine.

4. Run the engine at low idle. Hold the joystick control lever in the full EJECT position.

5. Record the pressure reading from the pressure gauge that is connected to the pressure tap.

   If the pressure reading does not agree with the value in Table 3, proceed to "Adjusting the Line Relief Valve".

6. If the pressure reading agrees with the value in Table 3, release the pressure from the hydraulic system.

   Reference: Refer to Systems Operation, Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

7. Remove the test gauge and pressure tap. Install plug (9) and proceed to Step 8.
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   Illustration 5	g00913103
   Auxiliary cylinder manifold (10) Plug (for the rod end of the auxiliary cylinders)

8. Remove plug (10) and install a pressure tap. Connect an 8T-0860 Pressure Gauge to the pressure tap.

   Note: The main relief valve has a lower setting than the auxiliary cylinder rod end line relief valve. In order to set the line relief valve, temporarily increase the main relief valve setting.

   Reference: For additional information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine that is being serviced.

9. Start the engine.

10. Run the engine at low idle. Hold the joystick control lever in the full RETRACT position.

11. Record the pressure reading from the test gauge that is connected to the pressure tap.

    If the pressure reading does not agree with the value in Table 3, proceed to "Adjusting the Line Relief Valve".

12. If the pressure reading agrees with the value in Table 3, release the pressure from the hydraulic system.

    Reference: Refer to Systems Operation, Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

13. Remove the test gauge and pressure tap. Install plug (10) and proceed to "Remove Test Equipment".

Adjusting the Line Relief Valve

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Illustration 6	g00913104
Line relief valve (11) Adjusting screw (12) Locknut

1. Refer to Illustration 1 for the location of the line relief valves.

2. Loosen locknut (12). Turn adjusting screw (11) clockwise to increase the relief valve setting.

3. Turn adjusting screw (11) counterclockwise to decrease the relief valve setting.

4. After adjusting screw (11) is turned for an adjustment, tighten locknut (12) to a torque of 50 ± 7 N·m (37 ± 5 lb ft).

5. Test the relevant line relief valve pressures. Refer to "Testing Line Relief Valves (Tilt)" or "Testing Line Relief Valves (Auxiliary)".

Remove Test Equipment

1. Set the main relief valve to the pressure in Table 2.

   Reference: For information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine that is being serviced.

2. When the pressure settings are correct, stop the engine and release the pressure from the hydraulic system.

   Reference: Refer to Systems Operation, Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

3. Remove the test equipment.