Hydraulic Pump Pressure Relief Valve; Troubleshooting - prime mover smx45 Master Service Manual

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2.2. Hydraulic Pump Pressure Relief Valve

The hydraulic system is protected by a relief valve installed in
the adapter body. The relief valve is set by the manufacturer
to open at specific pressure (3000 psi [20684 kPa]). There is
no need to ever adjust the relief valve on this truck.

3. Troubleshooting

NOTE! Proper care and cleanliness should be
observed in servicing to insure oil does not
become contaminated with dirt or other
foreign material. Contaminants can be
drawn into pump so as to stick or score
pump which will cause failure of pump
assembly.
If the hydraulic pump assembly does not operate properly,
the following preliminary checks should be made:
1. Proper oil level
2. All electrical connections tight
3. Battery fully charged
When checking voltage at contactors, make sure hydraulic
lines and components are fully installed.
When possible, keep the main ON/OFF switch OFF and
battery connector disconnected.
After the preliminary check is accomplished, install a 0-5000
psi (0-34473 kPa) pressure gauge in the 0.375 inch (9.525
mm) NPTF outlet port near the relief valve in the adaptor. The
installation of a pressure gauge is required to insure proper
observation of what is occurring in the unit during trouble
shooting. Start pump and raise lift cylinder to its upper limit
stops to develop maximum pressure of the unit, which will
normally be passing all flow over a relief valve. Pressure
gauge should be reading the set pressure of the relief valve.
Remove pressure on hydraulic system by actuating the
solenoid operated lowering valve.
Normal trouble that may occur with pump assembly have
been grouped under three headings: Failure to (A) Raise (B)
Hold (C) Lower load. One or more of the listed trouble
Master Service Manual 2006-08-08
F-code Section
PT S6.0
Hydraulic System
Version no T-code
001 SMX
C-code
6000
259