Operation and maintenance manual

Section 165-0015
1
SM 2167 Rev 1 10-03
2. Carefully remove wear indicator cap (7) from brake
housing (31).
3. Press in wear indicator pin (9) until it contacts the
discs.
4. The friction discs (26) should be replaced when the
end of the indicator pin (9) is flush with the counterbore
in the brake housing (31).
5. Repeat steps 2 to 4 for the remaining five brake
assemblies.
REMOVAL
Numbers in parentheses refer to Fig. 24, unless
otherwise stated.
WARNINGS
To prevent personal injury and property
damage, be sure wheel blocks, blocking
materials and lifting equipment are properly
secured and of sufficient capacity to do the job
safely.
Hydraulic fluid will remain within the
braking system after engine shutdown. Operate
the treadle valve continuously until the
pressure has dissipated before carrying out any
work on the braking system or serious injury
could result.
Use extreme caution to prevent personal
injury when removing wheels. The exact
procedure must be followed as described in
Section 160-0050, WHEEL, RIM AND TYRE.
Note: Before removing and disassembling brake
assemblies, check the wear of the friction discs. Refer
to 'Disc Assembly Wear Measurement Procedure',
under 'Inspection' in this section, for the maximum
allowable wear limits.
1. Position the vehicle in a level work area, apply the
parking brake and switch off the engine.
2. Turn the steering wheel in both directions several
times to relieve any pressure in the steering circuit.
Operate the treadle valve continuously to relieve any
pressure in the braking system. Block all road wheels.
3. Remove drain plug and drain cooling oil from brake
packs into a clean container. Reinstall plug.
4. Drain oil from hubs and differentials. Refer to
DESCRIPTION AND OPERATION
Numbers in parentheses refer to Fig. 1.
The service brakes are of the enclosed, forced oil-
cooled multiple disc type. The service brakes are
actuated by hydraulic oil as specified in Section 300-
0020, LUBRICATION SYSTEM. DO NOT use BRAKE
FLUID (J 1703). Multiple discs within the brake
assemblies are cooled by brake cooling oil as specified
in Section 300-0020, LUBRICATION SYSTEM.
The brake assembly is bolted to the stub axle and
houses a sandwich of friction discs splined to a hub
rotor. There are six friction discs (26) in each of the
front axle brake assemblies, four in the centre and rear
axle brake assemblies.
When the treadle valve is actuated, hydraulic oil enters
the brake assembly and forces the piston (21) against
the rotating friction discs (26) which react with
stationary stator plates (27). The stator plates (27) are
retained by scalloped tangs at the outside diameter,
which in turn transfers the reaction torque to the rigid
outside housing (31), slowing or stopping wheel
rotation.
In an emergency situation, application of the park/
emergency valve will actuate the service brakes and
the parking brake to bring the machine to a halt. In this
condition, a restriction in the 'Px' line from the brake
manifold valve will slow oil flow from the parking brake
allowing the service brakes to actuate momentarily
ahead of the parking brake.
When the treadle valve or park/emergency brake is
released, hydraulic pressure against piston (21) is
relieved and retractor springs (28) forces the piston (21)
to return to its original position, thus, relieving the
pressure against the brake disc pack.
INSPECTION
Disc Assembly Wear Measurement
Procedure
Note: This measurement should be made prior to
removal and disassembly of the brake assembly to
determine the amount of wear on the brake discs.
Numbers in parentheses refer to Fig. 1.
1. Position the vehicle in a level work area, block all
raod wheels and apply the parking brake. With the
engine running this will apply the service brakes.
BRAKE ASSEMBLY - Oil Cooled Disc Brakes