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Parts Section 5-29
Hydraulic inspection.
Install 3 pressure gauges, on the valve inlet (use M port, or tee into hose supplying oil
from the pump to the inlet), on the workport that is not operating, and on the LS port.
With the spools in Neutral
Gear pump – P should be approximately 200 psi, LS = 0, workport – pressure on
cylinder or function.
LS pump – P should equal pump standby pressure, LS = 0, workport – pressure on
cylinder or function.
Pressure Comp pump – P should equal pump standby pressure, LS = 0, workport –
pressure on cylinder or function.
Gear pump – P should be approximately 200 psi higher than LS, LS should equal
workport, workport – pressure on cylinder or function.
LS pump – P should be LS + standby, LS should equal workport, workport – pressure
on cylinder or function.
Pressure Comp pump – P should equal pump standby pressure, LS should equal
workport, workport – pressure on cylinder or function.
Operate one spool, measure pressures with function at end of travel or stop
Gear pump – P should equal valve relief setting or workport shock valve setting. LS
should equal workport. Workport should equal relief setting or workport shock valve
setting.
LS pump – P should equal valve relief setting, pump max pressure setting, or
workport shock valve setting. LS should equal workport. Workport should equal relief
setting, pump max pressure setting, or workport shock valve setting.
Pressure Comp pump – P should equal pump standby pressure, LS should equal
workport. Workport should equal pump standby pressure or workport shock valve
setting.
Operate more than one spool.
Gear pump – P should approximately 200 psi higher than LS. LS should equal
highest workport pressure. Workport – pressure on cylinder or function.
LS pump – P should be LS + standby pressure. LS should equal highest workport
pressure. Workport – pressure on cylinder or function.
Pressure Comp pump. P should equal pump standby pressure. LS should equal
highest workport pressure. Workport – pressure on cylinder or function.
Possible hydraulic problems.
Cylinder leak.
LS signal leaking to tank before reaching pump LS port.
Hydraulic system or pump not supplying flow to valve.
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