TM 5-3805-294-23-1
0003
HYDRAULIC SYSTEM - Continued
The pilot pump is a small gear pump that keeps oil moving through the pilot system. It also provides the pressure to
move the spools in the main hydraulic valve and to release the spring applied, hydraulically released, swing and
park brakes.
Reservoir
The hydraulic reservoir is located on the right side of the machine by the fuel tank. The hydraulic reservoir is
pressurized ensuring that hydraulic oil is always supplied to the pumps. Hydraulic oil flows from the hydraulic
reservoir, through a suction screen to pump 1 and pump 2. Pump 1 delivers supply oil to the right control valve and
pump 2 delivers supply oil to the left control valve. Supply oil is routed to the swing, travel, boom, bucket, arm, and
thumb/attachment circuits by valve spools of their respective valve section.
Swing Motor
The swing motor is a fixed displacement axial-piston motor. The swing motor is located at the base of the boom.
The swing motor uses hydraulic pressured from the pumps to make the upper structure rotate. The swing system
has a spring-applied, hydraulically released swing brake. The swing brake engages as soon as the swing controls
are released.
Swing Motor Park Brake
When any dig or swing function is operated, the swing park brake release pilot valve is shifted allowing pilot pressure
oil through the check valve (Figure 11, Item 71) to move the brake piston (Figure 11, Item 72). As brake piston moves,
plate (Figure 11, Item 73) and friction plate (Figure 11, Item 74) disengage, which releases the swing park brake.
75
76
72
77
78
71
73
74
HYEX01686
Figure 11. Swing Motor Park Brake Release.