314D Excavator Hydraulic System Caterpillar

Test

1. Position the machine on level ground.

2. Stop the engine.

3. Release the pressure in the hydraulic system. For more information, refer to Testing and Adjusting, "Hydraulic System Pressure - Release".

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Illustration 1	g01516004
Pump compartment (1) Pressure tap (delivery pressure for drive pump) (2) Pressure tap (delivery pressure for idler pump) (3) Pressure tap (power shift pressure)

4. Connect a 60000 kPa (8700 psi) pressure gauge to pressure tap (1) .

5. Connect a 60000 kPa (8700 psi) pressure gauge to pressure tap (2) .

6. Connect a 6000 kPa (870 psi) pressure gauge to pressure tap (3) . This is used to monitor power shift pressure.

7. Start the engine.

8. Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.

9. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

10. Enter the Service Mode and set the power shift pressure to the specification. Refer to Table 1 for the pressure specification.

    ReferenceRefer to Testing and Adjusting, "Relief Valve (Line) - Test and Adjust".

11. Refer to Table 1 for the pressure settings of the boom cylinder.
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    Table 1

    Relief Valve Pressure Settings
    Cylinder	Cylinder Position	Power shift Pressure and Engine Speed (1)	Relief Pressure Setting
    			Standard	Power Offset Boom
    Boom	Extended	2900 ± 50 kPa (421 ± 7 psi) Engine speed dial "10"	32500 + 1500 - 500 kPa (4714 + 218 - 73 psi)	31900 + 1500 - 500 kPa (4627 + 218 - 73 psi)
    	Retracted	2900 ± 50 kPa (421 ± 7 psi) Engine speed dial "10"	32500 + 1500 - 500 kPa (4714 + 218 - 73 psi)	32500 + 1500 - 500 kPa (4714 + 218 - 73 psi)

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    ( 1 )

    AEC switch OFF

Adjustment (Boom Cylinder Head End)

Illustration 2	g02094233
Cutaway view of boom lowering control valve (4) Line relief valve (left boom cylinder head end) (5) Line relief valve (right boom cylinder head end) (6) Locknut (7) Adjustment screw

Note: In order to adjust relief valve (5) on the right boom lowering control valve, relief valve (4) on the left boom lowering control valve must be temporarily adjusted.

1. Mark the location of adjustment screw (6) on relief valve (4) .

2. Loosen locknut (6) on relief valve (4) on the left boom lowering control valve. Turn adjustment screw (7) clockwise by one quarter turn. Tighten locknut (6) .

3. Move the joystick for the boom to the full BOOM RAISE position (full extension of boom cylinders). Hold the joystick for the boom in this position.

4. Check the pressure in the boom cylinder head end on the pressure gauge at pressure tap (1) .

5. Return the joystick for the boom to the NEUTRAL position.

6. If the pressure gauge reading at pressure tap (1) is not within the specification, adjust line relief valve (5) that is on the right boom lowering control valve.

7. In order to adjust line relief valve (5) , loosen locknut (6) and turn adjustment screw (7) until the pressure gauge reading at pressure tap (1) is within the specification.

   Note: Turn the adjustment screw (7) clockwise in order to increase the pressure. Turn the adjustment screw (7) counterclockwise in order to decrease the pressure.

   Note: Always make final pressure adjustment on pressure rise.

8. Tighten locknut (6) to a torque of 29.5 ± 2 N·m (22 ± 2 lb ft).

9. Loosen locknut (6) on the left boom lowering control valve. Turn adjustment screw (7) counterclockwise by one quarter turn. Tighten locknut (6) .

   Note: In order to adjust relief valve (4) on the left boom lowering control valve, relief valve (5) on the right boom lowering control valve must be temporarily adjusted.

10. Mark the location of adjustment screw (6) on relief valve (5) .

11. Loosen locknut (6) on relief valve (5) on the right boom lowering control valve. Turn adjustment screw (7) clockwise by one quarter turn. Tighten locknut (6) .

12. Move the joystick for the boom to the full BOOM RAISE position. Hold the joystick for the boom in this position and check the pressure gauge reading at pressure tap (1) .

13. Return the joystick for the boom to the NEUTRAL position.

14. If the pressure gauge reading at pressure tap (1) is not within the specification, adjust line relief valve (4) that is on the left boom lowering control valve.

15. In order to adjust line relief valve (4) , loosen locknut (6) and turn adjustment screw (7) until the pressure gauge reading at pressure tap (1) is within the specification.

    Note: Turn the adjustment screw (7) clockwise in order to increase the pressure. Turn the adjustment screw (7) counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

16. Tighten locknut (6) to a torque of 29.5 ± 2 N·m (22 ± 2 lb ft).

17. Loosen locknut (6) on the right boom lowering control valve. Turn adjustment screw (7) counterclockwise by one quarter turn. Tighten locknut (6) .

Adjustment (Boom Cylinder Rod End)

Note: In order to adjust the line relief valve pressure setting for the boom cylinder rod end, a temporary adjustment of the line relief valve for the bucket circuit must be performed. The line relief valve for the bucket is located on top of the main control valve.

Illustration 3	g02094413
Line relief valve (typical example)

1. Loosen locknut (8) on the line relief valve for the BUCKET OPEN function. Turn adjustment screw (9) by one half turn in a clockwise direction. Tighten locknut (8) on the line relief valve for the work tool cylinder.

2. Move the joystick for the work tool to the full BUCKET OPEN position. Hold the joystick for the work tool in this position. At the same time, move the joystick for the boom until the boom is at the full BOOM DOWN position (full retraction of boom cylinders). Hold the joystick for the boom in this position.

3. Check the pressure in the boom cylinder rod end on the pressure gauge at pressure tap (1) .

4. Return the joystick to the NEUTRAL position.

5. If the pressure gauge reading at pressure tap (1) is not within the specification, adjust the boom line relief valve that is on the main control valve.

6. Loosen locknut (8) on the boom line relief valve. Turn adjustment screw (9) until the pressure gauge reading at pressure tap (1) is within the specification.

   Note: Turn adjustment screw (9) clockwise in order to increase the pressure. Turn adjustment screw (9) counterclockwise in order to decrease the pressure.

   Note: Always make final pressure adjustment on pressure rise.

7. Tighten locknut (8) on the boom line relief valve.

8. After completion of line relief valve adjustment for the boom cylinders, return the line relief valve pressure setting of the bucket to the specified pressure setting.

Note: If an appropriate location is not available to fully extend the boom cylinders, exchange the functions of the boom line relief valves. Remove the line relief valve for the boom cylinder head end and the line relief valve for the boom cylinder rod end from the main control valve. Exchange the location of the line relief valves. Adjust the pressure of the boom line relief valve that is now attached in the head end. After completion of line relief valve adjustment, return the respective line relief valves to the original locations.