Wabash National Dry and Refrigerated Van Trailers, Operator'S Manual

Page: 27 / 42

23
foundation brake System
The foundation brake system consists of brake
chambers, slack adjusters, S-cams, and shoes or
pads.
During a service brake application, the brake
chambers convert air pressure to mechanical force
through the slack adjusters and camshafts to apply
the brakes. All trailer brake chambers perform both
service and parking brake functions. The service
brake stops the trailer from a signal from the tractor.
The parking brake applies when the driver applies
the parking brake. The parking brake also applies
automatically when the air supply is unintentionally
lost. During routine maintenance or in emergency
situations, it may be necessary to move the trailer
before air pressure can be restored. In such cases,
the mechanical spring brake can be manually
backed off and released.
WaRNING:
always chock the wheels securely to prevent
any trailer movement before releasing the
spring parking brakes. See the brake chamber
manufacturer’s service manual for details on
how to manually release the spring brake.
It is standard practice for most brake chamber
suppliers to attach a caging bolt to the exterior
housing for emergency purposes.
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SySTeMS aND feaTUReS