4-18
F-473-0212 Edition
MAINTENANCE AND LUBRICATION
Spring Air Brake Chambers
Check for faulty units. Check the condensation holes on
the underside of the brake chambers to make sure they
are open. The spring brake has two brake chambers, a
service chamber and an emergency chamber or spring
chamber. Service brake chambers should be
disassembled and cleaned per interval described in
The diaphragm and any marginal parts should
be replaced. When replacing the service diaphragm,
replace the corresponding parts for the other chamber on
the same axle (to aid in even brake application and
release). Examine yoke pin for wear and replace as
necessary. The spring chamber should not be serviced.
Replace entire unit (both service and spring chamber) if
spring chamber becomes faulty.
WARNING
Caging the Power Spring
1.
Chock the trailer wheels.
2.
Remove dust cap from spring brake chamber.
3.
Remove the release bolt from its holding brackets
and insert it into the spring brake chamber. DO NOT
USE AN IMPACT WRENCH TO CAGE THE SPRING
BRAKE.
4.
Turn the bolt until the spring brake is caged. This
should be 2-1/4 to 2-1/2 inches of release bolt
extension.
5.
The brakes should now be totally released. Do not
operate loaded trailer with brake manually released.
6.
To reset the spring brake, turn the release bolt until
the spring is released. Remove the release bolt and
store it in its brackets.
7.
Snap the dust cap back in place on the chamber.
Removal
1.
Chock all tractor and trailer wheels and drain the air
system.
2.
Mark the brake chamber for proper air line port
alignment for reassembly.
3.
CAGE THE POWER SPRING following the steps
outlined in
4.
Disconnect the slack adjuster from the connecting
rod by removing the clevis pin
5.
Mark all air service lines for proper reinstallation and
disconnect from the brake chamber.
6.
Remove the brake chamber from the axle brackets.
Installation
1.
CAGE THE POWER SPRING following the steps
outlined in
2.
Position the inlet ports by loosening the service
chamber clamp bands and rotating center housing
such that ports are located according to alignment
marks made during disassembly, then retighten the
clamp bands.
3.
Position the breather hole in the downward facing
position by loosening the clamp bands on the spring
brake chamber and rotating the chamber housing
until the breather hold faces downward. Retighten
the clamp bands.
4.
Remount the brake chamber on the axle brackets
and reconnect the air service hoses and the slack
adjuster connecting rod
IMPORTANT
Be sure the service line on the service chamber port
and the emergency line is on the spring brake port.
5.
Check for leakage by charging the air system to a
minimum of 90 psi and applying soap suds to the
brake chamber and connections. If a growing bubble
is detected or bubbles are blown away, locate the
source of the leak and repair.
6.
Insure that the clamp band is properly seated and
tight
before
uncaging the power spring.
The spring brake chamber employs a spring with
high forces. Service should not be attempted.
Serious injury or death may result.
