M318 Excavator Hydraulic System Caterpillar

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Illustration 1	g00530074
The pressure tap is located in the battery compartment. (1) Attachment circuit pressure

1. Prior to any adjustment, refer to the "Preparations" section in Testing and Adjusting, "Operational Checks".

2. Connect a 25000 kPa (3600 psi) pressure gauge to pressure tap (1) .

3. Run the engine in high idle.

4. Lower the left console.

Test and Adjust for the Line Relief Valves

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Illustration 2	g00530074
The pressure tap is located in the battery compartment. (1) Attachment circuit pressure

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Illustration 3	g00530076
Pilot manifold (2) Line relief valves (medium pressure)

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Illustration 4	g00530160
Pilot manifold (3) Relief valve (medium pressure)

1. To check the setting of the two line relief valves for the medium pressure at pressure tap (1), increase the pressure setting of relief valve (3). Remove the plug from relief valve (3) and tighten the adjusting screw in order to increase the pressure setting.

2. Operate the medium pressure attachment. Check the pressure at pressure tap (1). When the pressure stops increasing, Check the pressure at pressure tap (1). Refer to Testing and Adjusting, "Specifications" for the correct line relief valve pressure for the medium pressure function.

3. Reset the relief valve to the proper specification.

4. Check the line relief valve in both directions (left and right).

5. To adjust the pressure on the line relief valve, remove the cover and loosen the locknut on line relief valve (2) .

   Note: Always make the final pressure adjustment on the pressure rise.

6. When the adjustments are complete, tighten the locknut for the adjustment screw to the proper torque and place the cover on the adjusting screw.

7. Once the line relief valves are adjusted to the recommended setting, relief valve (3) must be adjusted.

Test and Adjust for the Relief Valve

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Illustration 5	g00530074
The pressure tap is located in the battery compartment. (1) Attachment circuit pressure

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Illustration 6	g00530160

1. Operate the medium pressure attachment against the end position of the cylinder. Check the pressure at pressure tap (1). Refer to Testing and Adjusting, "Specifications" in this manual for the correct pressure setting.

2. To adjust the pressure setting on the relief valve, remove the plug from relief valve (3). While the attachment is operated, turn the adjustment screw until the pressure at pressure tap (1) is correct.

   Note: Always make the final pressure adjustment on the pressure rise.

3. When the adjustments are complete, tighten the plug for the adjusting screw to the proper torque.