c. Main Relief Valve Adjustment.
There are four relief valves on main
control valve. Adjustment of main control
valve is limited to adjustment of relief
Connect pressure gage to port.
Remove main relief valve plug (1) from
Connect 0 - 5,000 psi (0 - 34475 kPa)
pressure gage to port (2).
Start engine (TM 10-3930-673-10).
Engine may be operated at idle or full
throttle when performing tests/
Operate boom hoist, lower, extend, or retract function until cylinder bottoms out and hydraulic oil is passing
over relief valve. Continue to hold hydraulic lever in that position so oil passes over relief valve during relief
Pressure must read between 3,000 - 3,100 psi (20685 - 21374.5 kPa).
Read relief valve pressure on gage. If relief valve pressure is not within specifications, adjust as follows:
Remove acorn nut (3) covering slotted head adjusting screw.
Hold adjusting screw and loosen/back off jam nut (4).
To increase relief pressure, turn adjusting screw clockwise (in). To decrease pressure, turn adjusting screw
When desired relief pressure shows on gage, hold adjusting screw and tighten jam nut (4). Install acorn nut
Shut off engine (TM 10-3930-673-10).
Remove pressure gage.
Remove pressure gage from port (2).
Install main relief valve plug (1).
Install main relief valve plug (1) in port (2).
Replace transmission cover (Para 16-5).