R1700G Load Haul Dump Hydraulic System 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	g01249808
(1) Main control valve (2) Head end line relief valve for the tilt cylinder (3) Rod end line relief valve for the tilt cylinder (4) Auxiliary control valve (5) Main relief valve (6) Head end line relief valve for the auxiliary cylinder (7) Rod end line relief valve for the auxiliary cylinder

Note: To correctly 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, it will be necessary to temporarily increase the main relief valve setting.

ReferenceFor additional information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

Note: Do not move the joystick control lever fully for more than five seconds while the pressure is at the relief setting. This may cause rapid heating of the hydraulic oil.

Testing Line Relief Valves (Tilt)

1. Release the pressure from the hydraulic system.

   ReferenceRefer to Systems Operation, Testing and Adjusting, "System Pressure - Release".

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Illustration 2	g01249814
(8) Pressure tap (rod end of the tilt cylinder) (9) Pressure tap (head end of the tilt cylinder)

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

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

4. Increase the engine to high idle rpm. 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 (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 Step 6.

6. Stop the engine.

7. Release the hydraulic system pressure.

   ReferenceRefer to Systems Operation, Testing and Adjusting, "System Pressure - Release".

8. Remove the pressure gauge from pressure tap (8). Install an 8T-0860 Pressure Gauge to pressure tap (9) .

   Note: The main relief valve has a lower setting than the tilt cylinder head end line relief valve. To correctly set the line relief valve, the main relief valve setting must be temporarily increased.

   ReferenceFor additional information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

9. Start the engine.

10. Increase the engine to high 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 (9) .

    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.

   ReferenceRefer to Systems Operation, Testing and Adjusting, "System Pressure - Release".

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Illustration 3	g01249819
Auxiliary cylinder manifold (10) Plug (head end of the auxiliary cylinders)

2. Remove plug (10). Install 6V-4143 Quick Connect Coupler and connect a 8T-0860 Pressure Gauge .

   Note: The main relief valve has a lower setting than the auxiliary cylinder head end line relief valve. To correctly set the line relief valve, the main relief valve setting must be temporarily increased.

   ReferenceFor additional information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

3. Start the engine.

4. Increase the engine to high 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.

   ReferenceRefer to Systems Operation, Testing and Adjusting, "System Pressure - Release".

7. Remove the pressure gauge. Proceed to Step 8.

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Illustration 4	g01249820
Auxiliary cylinder manifold (11) Plug (rod end of the auxiliary cylinders)

8. Remove plug (11). Install 6V-4143 Quick Connect Coupler and connect a 8T-0860 Pressure Gauge .

   Note: The main relief valve has a lower setting than the auxiliary cylinder rod end line relief valve. To correctly set the line relief valve, the main relief valve setting must be temporarily increased.

   ReferenceFor additional information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

9. Start the engine.

10. Increase the engine to high idle rpm. 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.

    ReferenceRefer to Systems Operation, Testing and Adjusting, "System Pressure - Release".

13. Remove the pressure gauge. Proceed to "Remove Test Equipment".

Adjusting the Line Relief Valve

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Illustration 5	g01249828
Line relief valve (12) Adjusting screw (13) Locknut

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

2. Loosen locknut (13). Turn adjusting screw (12) clockwise to increase the relief valve setting.

3. Turn adjusting screw (12) counterclockwise to decrease the relief valve setting.

4. After adjusting screw (12) is turned for an adjustment, tighten locknut (13) to a torque of 50 ± 7 N·m (37 ± 5 lb ft).

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

Remove Test Equipment

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

   ReferenceFor information on setting the main relief valve, refer to Systems Operation, Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

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

   ReferenceRefer to Systems Operation, Testing and Adjusting, "System Pressure - Release".

3. Remove the test equipment.