330D Forest Machine Hydraulic System Caterpillar

Note: The main relief valve should have a 1000 kPa (145 psi) pressure difference between heavy lift mode and standard lift mode.

1. Position the machine on level ground and stop the engine.

2. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".

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Illustration 1	g01266656
Pump compartment (1) Pressure tap (pressure for drive pump) (2) Pressure tap (pressure for idler pump) (3) Pressure tap (power shift pressure)

3. Attach a 60000 kPa (8700 psi) pressure gauge to pressure tap (1) .

4. Start the engine.

5. 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.

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Illustration 2	g01267081

6. Set heavy lift switch (A) to the ON setting. Make sure that the indicator light is on.

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

8. Raise the boom until the boom cylinder rods are at full extension.

9. Check the pressure setting of the heavy lift at pressure tap (1) .

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

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Illustration 3	g01241161
(4) Main relief valve (5) Locknut for the heavy lift (6) Adjustment screw for the heavy lift (7) Locknut for the main relief valve (8) Adjustment screw for the main relief valve

Note: When the main relief setting is adjusted, the setting for heavy lift is not affected. When adjustment screw (8) is turned counterclockwise in order to decrease the main relief setting the pressure difference between the main relief setting and setting for heavy lift will increase. When adjustment screw (8) is turned clockwise in order to increase the main relief setting the pressure difference between the main relief setting and setting for heavy lift will decrease.

Note: When the setting for heavy lift is increased, the main relief setting is also increased. When the setting for heavy lift is decreased, the main relief setting is also decreased.

11. The relief valve pressure setting for heavy lift should be 36000 ± 500 kPa (5220 ± 73 psi). If the relief valve pressure setting for heavy lift is not within the specification, adjust the relief valve pressure setting for heavy lift.

    1. Loosen locknut (5) in order to adjust the relief valve for the heavy lift. Adjust the pressure by turning adjustment screw for the heavy lift (6) until the pressure gauge reading at pressure tap (1) is 36000 ± 500 kPa (5220 ± 73 psi).

       Note: Turning adjustment screw (6) clockwise increases the pressure. Turning adjustment screw (6) counterclockwise decreases the pressure.

       Note: Always make final pressure adjustments on pressure rise.

    2. Tighten locknut (5) to a torque of 70 ± 10 N·m (50 ± 7 lb ft).

       Note: Confirm the heavy lift pressure by raising the boom until the boom cylinder rods are at full extension.

12. Set heavy lift switch (A) to the OFF setting. The indicator light should not be illuminated.

13. Open the bucket until the bucket cylinder rod is at full retraction.

14. Check the main relief valve pressure setting at pressure tap (1) .

15. Return the joystick for the bucket to the NEUTRAL position.

16. The main relief valve pressure setting should be 35000 ± 500 kPa (5075 ± 72 psi). If the main relief valve pressure setting is not within the specification, adjust the main relief valve pressure setting.

Note: During adjustment of screw (8) , do not allow screw (6) to move.

17. In order to adjust the main relief valve, loosen locknut (7) and turn adjustment screw (8) until the pressure gauge reading at pressure tap (1) is 35000 ± 500 kPa (5075 ± 72 psi).

    Note: Turning adjustment screw (8) clockwise increases the pressure. Turning adjustment screw (8) counterclockwise decreases the pressure.

    Note: Always make final pressure adjustments on pressure rise.

18. Tighten locknut (7) to a torque of 50 ± 10 N·m (37 ± 7 lb ft).

Note: If the pilot line for heavy lift prevents proper adjustment of the relief valve settings, the line can be removed in order to make the adjustments. The machine will need to be off and the hydraulic system pressure will need to be released in order to remove the pilot line for heavy lift. Before starting the machine and checking the pressure settings, adjust the relief valves and reconnect the pilot line.

Temporary Setting of the Main Relief Valve

Note: In order to adjust line relief valve pressure settings, the main relief valve must be temporarily adjusted to a higher setting since the line relief valve pressure settings are higher than the main relief valve pressure setting.

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Illustration 4	g01267081

1. Set the heavy lift switch (A) to the ON setting. Make sure that the indicator light is ON.

2. The main relief valve pressure setting should be 36000 ± 500 kPa (5220 ± 73 psi) when the heavy lift mode is on. If the main relief valve is not within the specification, adjust the main relief valve pressure setting to the correct pressure specification before performing Step 3. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust (Heavy Lift)".

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Illustration 5	g01200818
(4) Main relief valve (5) Locknut for the heavy lift (6) Adjustment screw for the heavy lift (7) Locknut for the main relief valve (8) Adjustment screw for the main relief valve

3. Loosen locknut (5) .

4. Turn screw (6) clockwise by a half turn. Tighten locknut (5) while screw (6) is secured.

5. Perform the desired steps for Testing and Adjusting the line relief valves.

6. Reset main relief valve pressure setting to the normal operating condition. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust (Heavy Lift)".