325D Material Handler Hydraulic System Caterpillar

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

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Illustration 1	g01221037
Pump compartment (1) Pressure tap (delivery pressure for drive pump) (2) Pressure tap (delivery 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.

Testing Procedure for the Main Relief Valve (Heavy Lift)

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

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Illustration 2	g01278759
Switch panel (9) Heavy lift switch

1. Set heavy lift switch (9) to the ON position for the test. The indicator light should be illuminated.

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

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

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

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

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

Testing Procedure for the Main Relief Valve (Standard Lift)

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Illustration 3	g01201390
Switch panel (9) Heavy lift switch

1. Set heavy lift switch (9) to the OFF position for the test. The indicator light should not be illuminated.

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

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

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

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

6. The main relief valve pressure setting should be 35000 ± 500 kPa (5075 ± 73 psi). If the main relief valve pressure setting is not within the specification, adjust the main relief valve pressure setting.

Adjusting Procedure for the Main Relief Valve

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Illustration 4	g01278759
Switch panel (9) Heavy lift switch

1. Set the heavy lift switch (9) to the ON setting. Make sure that the indicator light is on.

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

Note: When the main relief setting is adjusted the heavy lift setting 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 heavy lift setting 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 heavy lift setting will decrease.

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

2. The relief 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 the heavy lift.

   1. Loosen locknut (5) in order to adjust the relief valve for heavy lift. Adjust the pressure by turning the heavy lift adjustment screw (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 the locknut (5) to a torque of 50 ± 10 N·m (37 ± 7 lb ft).

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

3. Set heavy lift switch (9) to the OFF setting. The indicator light should not be illuminated.

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

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

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

7. The main relief valve pressure setting should be 35000 ± 500 kPa (5075 ± 73 psi). If the main relief valve pressure setting is not within the specification, adjust the main relief valve pressure setting.

8. 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 ± 73 psi).

   Note: Always make final pressure adjustments on pressure rise.

   Note: Ensure that adjustment screw (heavy lift) (6) does not turn when the adjustment of screw (8) is performed.

9. Tighten the locknut (7) to a torque of 69 ± 10 N·m (51 ± 7 lb ft).

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.

1. Set the heavy lift switch 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). 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".

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Illustration 6	g01186845
(4) Main relief valve (5) Locknut (heavy lift) (6) Adjustment screw (heavy lift) (7) Locknut (main relief valve) (8) Adjustment screw (main relief valve)

3. Loosen locknut (5) and turn adjustment screw (6) clockwise for one half turn. Tighten locknut (5) to the specified torque.

   Note: Always make final pressure adjustments on pressure rise.

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

5. After the completion of the adjustment of the line relief valves, loosen locknut (5) and turn adjustment screw (6) counterclockwise for one half turn. Tighten locknut (5) to the specified torque.