Boom Lower Relief Valve Adjustment

TM 10-3930-673-20-2

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

f. Boom Lower Relief Valve Adjustment.

(1)

Connect pressure gage to port.

NOTE

Main relief valve pressure must be

adjusted above normal operating pressure

to permit boom hoist 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 - 5,000 psi (0 - 34475 kPa)

pressure gage to plug port (2).

(c)

Remove acorn nut (3) covering slotted

head adjusting screw.

TR01030

(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 (21374.5 kPa).

(d)

Release hydraulic function lever.

NOTE

Pressure must read between 1,000 - 1,100 psi (6895 - 7584.5 kPa).

(3)

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

(a)

Remove acorn nut (9) covering slotted head adjusting screw.

(b)

Hold adjusting screw and loosen/back off jam nut (10).

18-32