Wet Disc Brake Assembly (Front And Rear); Operation - Komatsu 930E-2 Shop Manual

The oil cooled, wet disc brake assemblies mounted on
the front and rear wheels are similar in design. The rear
wheel brakes differ from the front in their mounting
arrangement only. The rear brake assembly requires
an adapter hub (1, Figure 5-1) for installation on the
wheel motor wheel hub.
Each disc brake assembly consists of the following
basic components:
• Ten friction discs
• Nine separator plates
• Two damper discs
• Piston assembly
• Stationary ring gear
• Rotating inner gear
• Floating ring oil seal assembly

OPERATION

The ring gear (4, Figure 5-1) is internally splined to
retain the dampers (8) and separator plates (12). The
separator plates are alternately placed between the
friction faced discs (7) which are splined to the inner
gear (6). The inner gear mounts directly to the wheel
hub on the front wheel brakes. On the rear, the inner
gear requires an adapter hub which mounts on the
wheel hub on the wheel motor.
The inboard side of the assembly contains the piston
(9) which is activated by hydraulic pressure supplied
by the dual relay valves (controlled by the brake valve).
As hydraulic pressure is applied, the piston moves to
compress the rotating friction faced discs against the
stationary steel discs. The friction forces generated
resist the rotation of the wheels. As hydraulic pressure
increases, friction forces are increased and wheel
rotation is slowed until maximum force is reached and
the wheel is stopped.
The complete brake disc pack is cooled by hydraulic
oil. The low pressure cooling circuit is completely
isolated from the high pressure, piston apply circuit.
Cooling oil flows from the hydraulic tank to the hoist
pump, through the hoist circuit high pressure filters,
through the hoist valve, and into the brake housings.
A parallel circuit from the hoist valve outlet is con-
nected to relief valves at the hydraulic tank which limit
brake cooling circuit pressure to 35 psi (241 kPa). Oil
routed to the front brakes passes through the oil cooler
before entering the front brake housings. In addition,
the brake cooling oil provides lubrication for the front
wheel bearings. Oil exiting the brake housings returns
to the hydraulic tank.
J05018 03/01
WET DISC BRAKE ASSEMBLY
Disc Brake Assembly
FIGURE 5-1. WET DISC BRAKE ASSEMBLIES
1. Hub Adapter (Rear Only)
2. Capscrew & Lockwasher
3. Socket Head Screw
(Temporary)
4. Ring Gear
5. Capscrew & Hardened
Washer
6. Inner Gear
7. Friction Disc
8. Damper
9. Piston Assem-
bly
10. Seal Carrier
11. Back Plate
J5-1