Valve Adjustments
Setting hydraulic pressure is a complex operation and should be performed only after
satisfying the following conditions.
1. Warm the hydraulic oil to 130° F in normal conditions.
NOTE: If the normal hydraulic operating temperature is substantially above or
below 130° F use that value instead.
2. Be sure the correct engine speed is used as the relief valve setting will vary with the
flow rate.
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.
NOTE: Some machines are equipped with auxiliary winch plumbing even though an
auxiliary winch is not installed. on these machines you must follow the procedure for
setting the auxiliary winch relief valve.
THIS MACHINE USES A PRESSURIZED HYDRAULIC RESERVOIR. THE
PRESSURE MUST BE RELEASED BEFORE ANY HYDRAULIC LINE OR
CONNECTION IS OPENED.
Failure to do so will result in substantial loss of oil and may cause personal injury. The
pressure is relieved by turning the reservoir cap counterclockwise to the first stop. DO NOT
turn the cap beyond the first stop until all pressure has been released. This will cause the
cap to be blown off the reservoir with sufficient force to cause personal injury. DO NOT
place any portion of your body above the reservoir cap while relieving pressure or removing
cap.
BOOM HOIST & MAIN RELIEFS
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. Lower the boom completely and continue to boom down with the engine running at
full governed rpm. The relief setting should b 4500 psi. If necessary, adjust relief valve.
Service / Parts
243REVISED:
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