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336
80-160
Service / Parts
Hydraulic System
Pressure Settings-Pumps & Valves
Setting hydraulic pressure is a complex operation and should be performed only after satisfying the
following conditions.
1. Warm the hydraulic oil to greater than 80° F.
2. Always check pressure settings at maximum engine speed in PTO mode.
3. Be certain to calibrate the pressure gauge used. Gauge calibration can be lost if the gauge is
subjected to pulsating pressure for a few seconds. The gauge must have a proper snubber to read
center of pump pressure ripple or erroneous readings will result.
MAINTENANCE CHECKS
All the relief valve maintenance checks are conducted an a SEMI-ANNUAL BASIS. Check the relief
valves and make the necessary adjustments by the following procedures.
The relief valves used on this hydraulic crane have a screw type adjustment. If it is determined that the
valve is out of adjustment, follow this general adjustment procedure.
PUMP ADJUSTMENT
1. Check / Adjust Standby Pressure
BOOM HOIST & WINCH MAIN PRESSURE SETTING PROCEDURE
Check the boom relief settings as follows:
1. Operate the boom over relief to warm the oil if necessary.
2. Attach a calibrated pressure gauge to test port on the inlet pressure port at the valve bank.
3. Raise the boom completely and continue to boom up with the engine running at full governed rpm.
The gauge reading at location (3) should be 4500 psi. If necessary, adjust item (6) Load Sense (LS)
pressure adjustment screw. (See chart below).