TRUCK SERVICE MANUAL
When the air pressure is released from brake chamber,
the brake shoe return spring and brake chamber release
spring return the shoes, cam, slack adjuster and brake
chamber back to the released position.
The brake chamber consists of two dished metal
sections, namely, the pressure plate assembly and the
non-pressure plate, separated by a rubber diaphragm, all
of which are held together by a metal two-segment
clamp. In front of the diaphragm are the push rod, push
rod spring and retainer, Fig. 18.
Fig. 19 Typical "Spring Brake" Air Chamber
Position brake chamber on mounting bracket and install
nuts on mounting studs. Install lock nut and yoke on
push rod. Connect air line. Adjust yoke to slack adjuster
(see "Adjustment"). Be sure end of push rod does not
bind with the slack adjuster when brakes are applied.
To disassemble the brake chamber:
1. Mark the non-pressure plate (8), pressure plate (4)
Fig. 18 Brake Chamber (cross-sectional View
and clamp (17). This will make it easier to reassemble
Legend for Fig. 18
air chamber in its original position and avoid installation
2. Remove the yoke (14) and lock nut (10) from the
push rod (1).
3. Remove the nuts and bolts from the clamp ring.
CAUTION: Separate the plates carefully. The return
spring inside the brake chamber is under tension.
With the two sections of the brake chamber
separated, remove the push rod, spring retainer (5) and
spring (6) from the non-pressure plate.
Several types of auxiliary "spring brakes" are used in
conjunction with or are attached to the brake chambers
Cleaning and Inspection
while others replace the entire brake chamber, Fig. 19.
After the brake chamber has been disassembled,
proceed as follows:
The purpose of auxiliary spring brakes is to provide an
1. Using a suitable cleaning solvent, clean all metal
emergency brake which will stop the vehicle in the event
air pressure drops.
These spring brake systems are covered in the "Parking
Disconnect air line and push rod yoke. Remove nuts
from mounting studs and remove chamber.