TM 9-4940-568-20
5-6
5-3.
DESCRIPTION AND DATA (Continued)
c. Hydraulic System. The FRS hydrualic
pump supplies hydraulic oil to the crane at a
flow rate of up to 12 gallons per minute. This
flow of hydraulic oil is directed and controlled
by several valves on the crane. Opening these
valves sends a signal back to FRS
variable-displacement hydraulic pump, using
the pump to stroke up and deliver to the
crane’s hydraulic cylinders. Here, hydraulic oil
pressure builds until great enough to move the
hydraulic cylinders. Relief valves prevent this
pressure from becoming too great. The relief
valves release extra pressure and send it back
to the hydraulic reservoir on the FRS system.
Unwanted movement of the crane is prevented
by holding valves mounted on the crane’s
boom.
All hydraulic oil eventually flows back to the
FRS hydrualic reservoir through a return line.
There, the hydraulic oil is cooled. The
hydraulic oil is then drawn into the hydraulic
pump, through the filter and begins the cycle
again.
(1) OUTRIGGER EXTENSION CYLINDERS.
The two outrigger extension cylinders
hydraulically extend or retract the
extension beams.
(2) OUTRIGGER JACK CYLINDERS. The
two hydraulic jack cylinders are used
together with the outrigger beams to give
the crane greater stability for handling
loads.
OUTRIGGER
JACK
CYLINDERS
OUTRIGGER
JACK
CYLINDERS
OUTRIGGER
EXTENSION
CYLINDERS
OUTRIGGER
EXTENSION
CYLINDERS
