Operation and maintenance manual

Section 170-0030
SM 2166 Rev 1 10-03
1
PARKING BRAKE - Actuator
DESCRIPTION AND OPERATION
WARNING
Use only hydraulic oils meeting specifications
outlined in Section 300-0020, LUBRICATION
SYSTEM. Do Not use Brake Fluid (J 1703). Use
of improper fluids is destructive to rubber
components of brakes resulting in loss of
braking and possible catastrophic failure.
The actuator is a spring on/fluid off type which
operates the parking brake. It is connected, through a
slack adjuster to the power screw shaft, screwed into a
piston in the brake calliper head assembly.
A push control on the dash panel, in the operators
compartment, activates the solenoid on the brake
manifold valve, controlling oil pressure from the rear
brake circuit accumulator to the actuator. Application of
the push control releases oil from the actuator allowing
internal springs in the actuator to apply the parking
brake. Pulling out the push control directs oil pressure
from the front brake circuit accumulator to the actuator,
compressing internal springs, to release the parking
brake.
REMOVAL
Numbers in parentheses refer to Fig. 1.
WARNINGS
To prevent personal injury and property
damage, be sure wheel blocks, blocking
materials and lifting equipment are properly
secured and of adequate capacity to do the job
safely.
Hydraulic fluid pressure will remain
within the braking system after engine shut
down. Operate the treadle pedal continuously
until the pressure has dissipated before
carrying out any work on the braking system or
serious injury could result.
1. Position the vehicle on a level surface, raise the
body and install safety prop to secure body in the
partially raised position.
2. Block all road wheels and place the steering lock bar
in the 'Locked' position.
3. Pull out push control to release the parking brake.
Fig. 1 - Actuator Mounting
SM - 2648
9
1110
7,86
2
12
15
1
3
4
14
13
5
1 - Bracket Assembly
2 - Calliper Head Assembly
3 - Slack Adjuster
4 - Bolt
5 - Washer
6 - Nut
7 - Clevis Pin
8 - Cotter Pin
9 - Actuator
10 - Nut
11 - Washer
12 - Control strap
13 - Cap assembly
14 - Slack adjuster screw
15 - Bolt