18-5. MAIN CONTROL VALVE ADJUSTMENT/REPLACEMENT (CONT)
d. Boom Extend Relief Valve Adjustment.
Connect pressure gage to port.
Main relief valve pressure must be
adjusted above normal operating pressure
to permit boom extend relief valve
pressure to be adjusted. Main relief valve
pressure is then returned to normal
operating pressure at end of this
Remove main relief valve plug (1).
Connect 0 to 5000 psi
(0 - 34475 kPa) pressure gage to port (2).
Remove acorn nut (3) covering slotted
head adjusting screw.
Hold adjusting screw and loosen/back off
jam nut (4).
Adjust main relief valve pressure to 3,100 psi (21374.5 kPa).
Engine may be operated at idle or full throttle when performing pressure tests.
Start engine (TM 10-3930-673-10).
Operate boom extend, retract, hoist or lower function until hydraulic oil is passing over relief valve.
Continue to hold hydraulic lever in that position so oil passes over relief valve during relief valve
Turn adjusting screw clockwise (in) until pressure on gage reads 3,100 psi (21734.5 kPa).
Release hydraulic function lever.
Pressure must read between 2,950 - 3,050 psi (20340.25 - 21029.75 kPa).
Read relief valve pressure on gage. If relief valve pressure is not within specifications, adjust as follows:
Remove acorn nut (5) covering slotted head adjusting screw.
Hold adjusting screw and loosen/back off jam nut (6).