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The main component of the valve is an adjustable
spring loaded plunger that when it is pushed off from
its seat by the oil pressure, the oil flows back into
the reservoir. See figure 1-4. Turning the adjustment
nut clockwise increases the amount of oil pressure
required to open the valve, and turning it counter-
clockwise decreases the amount of oil pressure.
(See adjustment section for specification.)
1-2. Component Operation
a. Motor/Pump Operation
The motor/pump assembly is a gear type pump that
provides the oil pressure and volume for the entire
hydraulic system. The pump has an inlet side and
an outlet side. The inlet side is connected to the
reservoir which provides the oil supply. The reservoir
has a very fine mesh screen strainer which prevents
foreign material from entering the oil system.
The output line of the pump is connected to the main
oil galley which is internal and common to all the
hydraulic mini-valves and pressure relief valve. Also,
common to the hydraulic mini-valves and pressure
relief valve is an oil galley that internally connects
to the oil reservoir to provide a return path for the
hydraulic oil. See figure 1-2.
Figure 1-4. Pressure Relief Valve Functioning
Figure 1-3. Pressure Relief Valve Not
Functioning
Figure 1-2.
b. Pressure Relief Valve
This device provides an alternate oil path back to
the reservoir when the hydraulic cylinders reach
the end of their stroke and the pump continues to
run. If this path were not provided, the pump motor
would stall because the oil cannot be compressed.
The pressure relief valve is directly connected to
the mini-valve bodies and shares both the common
internal main pressure oil galley, and the return
oil galley that internally connects to the reservoir.
See figure 1-3.
041905.021mj
MAIN PRESSURE
OIL GALLERY (internal)
MINI-VALVES
OIL RESERVOIR
PUMP
OUTLET
PUMP
INLET
PRESSURE
RELIEF VALVE
MOTOR/PUMP
ASSEMBLY
MAIN RETURN
OIL GALLERY
(internal)
050305.06
PRESSURE RELIEF
ADJUSTMENT NUT
PRESSURE
GAUGE
SPRING
LOADED
PLUNGER
PRESSURE
RETURN
050305.07
PRESSURE RELIEF
ADJUSTMENT NUT
PRESSURE
GAUGE
SPRING
LOADED
PLUNGER
OIL LINE
FROM
PUMP
OIL RESERVOIR
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