Boom Reduced Leakage Valve
Bypass Shut-Off Valve
To prevent boom down drift caused by leakage from
To combine supply oil flow from right control valve
the cylinders back through control valve.
neutral passage with supply oil flow in left control
valve power passage before auxiliary valve.
Sticking or stuck check valve or pilot valve. No pilot
Auxiliary function attachment does not operate at
control signal to shift pilot spool.
No pilot control signal to shift spool.
If check valve does not open, boom cannot be
If spool seized open, auxiliary function attachment
lowered. If check valve is stuck open, boom drifts
does not operate at specified speed.
down. Boom down speed is slow or jerky if check
If spool seized in close position and all control lever in
valve sticking or does not open fully.
neutral, system relief valve is relieving. Front pump
control pressure is at maximum.
If seized partially open and all control lever in neutral,
front pump delivery pressure is higher than rear pump
Monitor No. 1 Front pump control pressure, No. 3
Front pump delivery pressure, and No. 4 Rear pump
Description of Operation
See Arm Rod End and Boom Reduced Leakage
See Bypass Shut-Off Valve Operation in Group
Valves Operation in Group 9025-05.