MOTOR TRUCK SERVICE MANUAL BRAKES-PARKING
extend the push rod.
the head end towards you when charged with air
pressure.
With the spring brake chamber charged, check and
observe the following:
Push rod should travel into parking spring brake
chamber. If push rod does not travel into chamber, this
can indicate a damaged head, spring or piston.
CAUTION: With a damaged piston, the heavy spring in
the parking brake unit is no longer restricted and could
be forcefully expelled when snap ring retaining head to
cylinder case is removed. When the above condition
exists or when in doubt as to the spring being restricted,
use a tool similar to SE17151 (crankshaft gear puller)
under press during disassembly of the cylinder, Fig. 11.
Release air pressure from parking spring brake
chamber.
Fig. 9 Removing Clamp Ring.
7. Prior to disassembly, back off and remove
release bolt and special small air seal washer.
5. Remove pressure plate from push rod, Fig. 10.
Fig. 10 Removing Pressure Plate.
Fig. 11 Removing Snap Ring.
6. At this point the spring brake section must be
8. With assembly under tool (SE17151 or similar
checked to determine the condition of the
tool) and press, remove snap ring, Fig. 11.
internal
parts
before
continuing
with
NOTE: Snap ring removal may be somewhat
disassembly. With parking brake unit on work
difficult due to a sealer applied over the snap
bench, apply 60 psi of air to the spring brake
ring and snap ring groove.
chamber air inlet.
9. With snap ring removed, relieve press slowly.
CAUTION : When applying air pressure to spring
As the press is relieved and while the press will
brake chamber, always keep brake chamber head
still act as a restric
(release bolt end) pointed away from you. Never point
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