How to Release System Pressure on a Caterpillar 320D2 Excavator
Perform the following steps to release hydraulic pressure from multiple hydraulic circuits in the main hydraulic system.
1. Park the machine on level ground.
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2. Fully retract the boom cylinder linkage. Adjust the bucket position so that the bucket is parallel to the ground. Lower the boom until the bucket is level with the ground. Refer to Figure 1.
3. Turn off the engine.
4. Turn the engine start switch to the ON position, but do not start the engine.
5. Place the hydraulic start control lever in the LOAD position.
6. Move only the operating handle or pedal of the hydraulic circuit requiring servicing to the full range position. This will release only the high pressure in that hydraulic circuit. This will also release any pressure that may be present in the pilot hydraulic circuit. Note: If the hydraulic circuit requiring servicing requires an operating switch, activate the corresponding operating switch on the hydraulic circuit.
7. Place the hydraulic start control lever in the LOAD position.
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8. Start the engine.
9. Place the hydraulic start lever in the unlocked position. Do not move any handles or pedals out of neutral during this step. Do not activate any switches during this step.
10. Move the hydraulic start lever back to the locked position.
11. Turn off the engine.
12. Repeat steps 4 through 11 for the other hydraulic circuits requiring maintenance.
13. After releasing the hydraulic pressure in each target hydraulic circuit, place the hydraulic start lever in the locked position.
14. Turn the engine start switch to the off position.
15. Slowly loosen the filler cap on the hydraulic oil tank to release pressure. The filler cap should remain loose for at least 45 seconds. This will release any pressure that may be present in the return hydraulic circuit. https://127.0.0.1/sisweb/sisweb/techdoc/techdoc_print_page.jsp?returnurl=/sis... Friday, October 26, 2018
16. Tighten the filler cap on the hydraulic oil tank to the specified torque.
17. The pressure in the multi-hydraulic circuits requiring maintenance has now been released, and the lines and components can now be disconnected or removed from these hydraulic circuits.
