Setting Main Relief Valve - J&M 220 Operating And Maintenance Manual

MODEL 220
HYDRAULIC
IMPACT HAMMER
IV. MAINTENANCE AND ADJUSTMENTS
M. SETTING MAIN RELIEF VALVE
1. Locate main relief valve (P/N 130503) on power unit directional control manifold.
Manifold is located behind the large quick disconnects at the coupler panel.
See page VIII-42 item 6.
2. While holding the valve adjusting screw with a hex key, loosen the adjusting
screw jam nut with an open end wrench.
3. Make an initial adjustment of the screw by turning it approximately 1/8th turn in
the desired direction. (Turning the screw clockwise will increase the pressure
setting. Turning counter-clockwise will decrease pressure.)
CAUTION: NEVER ADJUST THE RELIEF VALVE WHILE THE SYSTEM IS UNDER
PRESSURE.
4. Close all power unit doors.
5. Disconnect the pressure and return (largest) disconnects at the power unit.
6. Start and warm up diesel engine. When engine is warmed up, increase engine
RPM to maximum.
7. While observing the DRIVE pressure gage, turn the FORWARD/REVERSE
switch to FORWARD. The pressure should read 4500 PSI (310 Bar).
8. If the pressure is not correct, repeat steps 3 thru 8.
9. When the desired pressure is achieved, hold the adjusting screw with a hex key
and tighten the adjusting screw jam nut.
IV-9