TM 5-3805-280-24-1
Theory of Operation
SYSTEM RELIEF AND POWER BOOST VALVE OPERATION
FIRST
ADJUSTING A
O PUMP SUPPLY OIL
PLUG
P PILOT OIL
TOP NUT B
Q RETURN OR
PRESSURE
SECOND
FREE OIL
ADJUSTING C
PLUG
BOTTOM NUT D
E PISTON
LEFT CONTOL
F VALVE HOUSING
PILOT POPPET
G
SPRING
H PILOT POPPET
MAIN POPPET
I
SPRING
J MAIN POPPET
K RETURN PASSAGE
9025
05
L POWER PASSAGE
42
M DIGGING
N POWER BOOST
R SYSTEM RELIEF AND POWER BOOST VALVE
T102821
oil flows out faster than oil can flow through the orifice
The function of system relief and power boost valve
in poppet. The main poppet is pushed open to relieve
(R) is to limit the main hydraulic system operating
pressure oil to the return passage.
pressure. The system relief and power boost valve is a
pilot-operated, poppet-type relief valve with a piston
For power boost operation (N), pilot oil (P) from the
(E).
power boost solenoid valve pushes the piston (E)
down increasing the pressure setting of the pilot
When the pump supply oil in the power passage (L)
poppet spring (G). The main hydraulic system can now
pressure exceeds the relief valve setting, pilot poppet
operate at a higher operating pressure for
(H) is pushed off its seat letting oil behind main poppet
approximately 8 seconds.
(J) flow to the return passage (K). A pressure
difference is created across the main poppet because
TX,05,GG2155 1929MAY981/1
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