Boom Extend Relief Valve Adjustment

TM 10-3930-673-20-2

18-5. MAIN CONTROL VALVE ADJUSTMENT/REPLACEMENT (CONT)

d. Boom Extend Relief Valve Adjustment.

(1)

Connect pressure gage to port.

NOTE

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

procedure.

(a)

Remove main relief valve plug (1).

(b)

Connect 0 to 5000 psi

(0 - 34475 kPa) pressure gage to port (2).

(c)

Remove acorn nut (3) covering slotted

TR01028

head adjusting screw.

(d)

Hold adjusting screw and loosen/back off

jam nut (4).

(2)

Adjust main relief valve pressure to 3,100 psi (21374.5 kPa).

NOTE

Engine may be operated at idle or full throttle when performing pressure tests.

(a)

Start engine (TM 10-3930-673-10).

(b)

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

adjustment.

(c)

Turn adjusting screw clockwise (in) until pressure on gage reads 3,100 psi (21734.5 kPa).

(d)

Release hydraulic function lever.

NOTE

Pressure must read between 2,950 - 3,050 psi (20340.25 - 21029.75 kPa).

(3)

Read relief valve pressure on gage. If relief valve pressure is not within specifications, adjust as follows:

(a)

Remove acorn nut (5) covering slotted head adjusting screw.

(b)

Hold adjusting screw and loosen/back off jam nut (6).

18-28