TM 5-3805-281-24-1
Theory of Operation
WARM-UP CIRCUIT OPERATION
FLOW
TO CONTROL
REGULATOR VALVE BOOM UP
TO PILOT
CONTROLLER VALVE
When the pilot shut-off valve (M) is in the LOCKED
C
B
A
position and the engine is running, pilot oil flows from the
BOOM UP
D PRESSURE
pilot shut-off valve to the flow regulator valve (B) manifold.
SWITCH
CHECK N
The oil is restricted and heated as it flows through the
VALVE
TO CONTROL
orifice (O) at the inlet to manifold. The warm-up oil flows
VALVE BOOM
through the warm-up oil passage, through the check
DOWN
valves (N) and out to the pilot controllers (A), boom pilot
A
E
caps (C and E) and arm pilot caps (G and I).
F CHECK
N
VALVE
At the pilot controllers, warm-up oil flows through the pilot
controllers and out the return port to the pilot shut-off
TO CONTROL
A
valve. Warm-up oil from the pilot controllers (L) flows
VALVE ARM OUT
through the pilot shut-off valve to the solenoid valve
G
VALVE Q
manifold, and then to the hydraulic oil tank. For the boom
SPOOL
up (C) pilot circuit and arm out (G) pilot circuit, warn-up oil
ARM IN
flows to the pilot caps, through orifices to a return
H PRESSURE
P
SENSOR
passage in the pilot caps, and then to the hydraulic oil
ORIFICE
tank. For the arm in (I) pilot circuit, warm-up oil flows to
I
the bottom arm I pilot cap, through a return line, an orifice,
A
TO CONTROL
and then into the hydraulic oil tank. For boom down (E)
N
PILOT
VALVE ARM IN
pilot circuit, warm-up oil flows to the boom II and boom I
O
M SHUT-OFF
pilot caps, through a return line, an orifice, and then into
VALVE
ORIFICE
TO SOLENOID
the hydraulic oil tank. The orifices at the tank connections
VALVE
are used to restrict the flow of pilot oil so the pressure
MANIFOLD
increases enough to shift the valve spools when arm in
J
9025
and/or boom down functions are actuated.
05
13
L
K
In the UNLOCKED position, pilot oil flow to the warm-up
FROM PILOT
FROM PILOT
circuit is blocked at the pilot shut-off valve. When a pilot
CONTROLLERS
PRESSURE
controller is actuated, the check valves (N) block the flow
REGULATING
R PILOT OIL
of pilot oil into the warm-up passage.
VALVE
S WARM-UP OIL
T114602
T WARM-UP CIRCUIT
CED,TX08227,3042 1927MAR981/1
