TM 5-3805-281-24-1
Theory of Operation
supply oil flows through the groove (I) to the park
The propel brakes are a wet type multi-disk brake. The
brake pressure reducing valve. The pressure reducing
brakes are spring applied and hydraulically released.
valve operates to reduce the supply oil pressure.
The brakes are released whenever the propel function
Reduced pressure oil flows to the brake piston (C) to
is actuated. The brakes are applied by a disk spring
move it against the disk spring (B) force and releases
(B) whenever the propel control valve spools are in
the park brake. Oil not used to release the park brake
neutral. The plates in the brake pack (D) are
flows through the orifice in the reducing valve spool
connected to the motor housing. The disks are
and into the propel motor housing (F).
connected to and rotate with the drive shaft (E). The
disk spring pushes against the piston to squeeze the
When propel pilot controllers are returned to neutral,
plates and disks together to keep the machine from
supply oil is blocked by the valve spools and the
moving.
propel motor work ports are open to the control valve
return passage. The counterbalance valve (G) returns
When the propel pilot controllers are actuated the
to its neutral position causing the machine to slow and
propel valve spools route supply oil to the bottom work
then stop (dynamic braking). The pressure reducing
port of propel motor for forward travel or the top work
valve (A) is shifted by its spring. The disk spring (B)
port for reverse travel. The supply oil flows into the
pushing against the brake piston (C) forces the oil to
chamber (J) at the end of counterbalance valve (G). At
flow through the orifice in the reducing valve and into
the same time supply oil moves the park brake release
the propel motor housing (F). The delay caused by the
shuttle valve (H) to route supply oil to the park brake
oil flowing through the orifice is enough to slow
pressure reducing valve (A) but is blocked by the
engagement to ensure that park brake is only fully
counterbalance valve. When supply oil pressure
applied after the machine has stopped.
increases enough to shift the counterbalance valve,
9025
05
94
CED,TX08227,3103
1923APR982/2
6-93
