Komatsu 830E-AC Shop Manual page 607

ARMATURE SPEED REAR DISC BRAKES
REAR BRAKES
Each rear wheel service brake assembly consists of
two discs, each with a four piston caliper and a lining
on each side of the disc. Both discs are attached by
adapters to the wheel motor armature.
A constant brake-release clearance between pistons
and linings, and lining and disc, is maintained by an
automatic adjustment feature of the piston subas-
sembly. As the lining wears, the position of grips on a
return pin advances to allow maximum piston force to
be applied to lining. Upon brake release, the piston is
retracted by a return spring for the amount of the pre-
determined clearance.
CALIPER AND DISC
Removal
Do not loosen or disconnect any hydraulic brake
line or component until engine is stopped, key
switch is OFF and drain valves on brake accumu-
lators are opened and steering accumulators are
bled down. Turn steering wheel to be sure steer-
ing accumulator is completely bled down.
1. Park truck in level ground. Block all the wheels
on both sides to prevent the truck from moving.
FIGURE 6-1. BRAKE CALIPER
1. Cap Screws
2. Retainer
3. Caliper
J06025 10/06
4. Crossover Tubes
5. Bleed Plug
Armature Speed Rear Disc Brakes
2. With engine off, key switch OFF, wait 90 sec-
onds for steering accumulators to bleed down.
Open both brake accumulator drain valves.
3. Remove crossover tubes (4, Figure 6-1) from
upper service brake caliper. Remove crossover
tubes on lower brake assembly.
4. Remove two center caliper mount cap screws
(6, Figure 6-2) from outboard caliper and install
two 7/8-9 NC X 14 in. studs.
5. Slowly remove the four remaining caliper mount
cap screws. The brake lining is under spring
pressure, and it will extend out as the cap
screws are loosened. Do not let the brake lining
pull away from the caliper housing.
6. Use small diameter wire and wrap it around the
brake lining and caliper. This will keep the brake
lining from pulling away from the caliper and
over-extending the brake wear adjuster.
NOTE: If the caliper is being removed to be serviced,
it is not necessary to install the wire. If the caliper is
being removed to gain access to other parts, and the
caliper does not need service, the wire must be
installed. If the brake lining pulls away from the
caliper, the caliper must be disassembled to reset the
brake wear adjuster.
7. Remove the caliper half. Each caliper half
weighs approximately 45 kg (100 lbs).
8. Support outer disc (12) and remove disc mount
cap screws (11) and washers. Slide disc from
outboard adapter (10). Shims (7) will be found
between disc and adapter. Remove bushing
(8). Mark all shims so they will be installed in
the same location during assembly.
9. Use small diameter wire and wrap it around the
brake lining and inner caliper half (5).
J6-3