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Hydraulic oil pressure can remain in the hydraulic oil system on this machine after the engine and pump have been stopped. Personal injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent personal injury, refer to the procedure in Testing and Adjusting Manual, "Release of Pressure in the Hydraulic System". When possible, the bucket must always be lowered to the ground with the cutting edge rotated to the ground before service is started. When it is necessary for the boom to be in the raised position while tests or adjustments are done, be sure that the boom, stick and bucket have correct support. Be sure the swing parking brakes and the travel parking brakes are on and the brake release lines are disconnected and plugged. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made. |
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Note: The main relief valves are considered to be a factory set valve. The main relief valves are set at 4825 ± 350 kPa (700 ± 50 psi).
Prior to checking the main relief valves, check the signal relief valves and the line relief valves.
- Operate the engine at high idle (1830 ± 10).
- Stall an implement function with the engine at high idle and measure the engine speed.
- The main relief valves are correctly functioning if an engine speed of 1785 rpm is obtained.
- Proceed to the next step if an engine speed of 1785 is not obtained.
- Replace the main control valves with 6E-4816 Main Control Valve Plug Gp .
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Illustration 1 | g00812509 |
Location of main relief valves |
- Repeat step 2.
- Replace the main relief valves if an engine speed of 1785 rpm is obtained.
- The problem may be the margin relief valve or some other leak to the hydraulic tank if the engine speed is less than 1785 rpm.