TM 5-3805-280-24-1
Theory of Operation
CIRCUIT RELIEF VALVE OPERATION
Q ANTICAVITATION OPERATION
P RELIEF OPERATION
PILOT POPPET E
CHECK VALVE SPRING
F
G PILOT POPPET SPRING
CHECK VALVE D
H SCREW
K RELIEF PRESSURE OIL
C
L OPERATING PRESSURE OIL
FROM WORK
CIRCUIT
M REDUCED PRESSURE OIL
N RETURN OIL
I PISTON SPRING
PISTON B
O LOW PRESSURE OIL
J MAIN POPPET
TO RETURN A
R CIRCUIT RELIEF - ANTICAVITATION VALVE
IT4579
9025
05
During anti-cavitation operation (Q) the check valve (D)
At pressures below the circuit relief setting the main
44
retracts to allow oil to flow from the return passage into
poppet (J) remains closed. In relief operation (P), the
the work circuit. During normal operation the operating
relief valve opens in three steps. In the first step, the
oil pressure (L) on the inner shoulder holds the check
pilot poppet (E) is opened. Flow restriction through the
valve against its seat. This pressure decreases as
hollow piston (B) causes the pressure in the cavity
pressure in the work circuit decreases. The return oil
behind the main poppet to decrease. In the second
pressure (N) on the outer shoulder moves the check
step of relief operation the piston seats against the
valve, main poppet, and piston against the springs to
pilot poppet (E). This further reduces oil flow into the
open the valve.
cavity and greatly decreases the pressure against the
back side of main poppet. The main poppet opens in
the third step of relief operation.
TX,05,GG2146 1910JUL961/1
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