TM 9-2330-297-14&P
Section III. PRINCIPLES OF OPERATION
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Airbrake System.................................................
Electrical System ..................................
AIRBRAKE SYSTEM
Service and emergency air pressure from the towing vehicle is supplied to the chassis brake system through the
gladhand couplings at the front of the chassis. The couplings are marked to ensure correct hookup and must not be
crossed when coupling. Tubing extends the length of the chassis to supply service and emergency air to the relay valve
and reservoir. Both lines tee into 10 quick disconnects located along the chassis frame This provides an air source for the
bogie in any of Its five positions. The airbrake system consists of two bogie-to-chassis airhoses with quick disconnects
tubing, a relay valve, an air reservoir, two brake chambers, two slack adjusters, two camshafts, and four brakeshoes.
When the towing vehicle service brakes are applied, air is sent through the service air line to the relay valve. The relay
valve action then releases reservoir air to the air chamber. The air chamber movement, through the slack adjuster,
rotates the camshaft which forces the brakeshoes against the brakedrum. Brakeshoe and drum friction slows, stops, and
holds the semitrailer until the brake pedal is released, venting pressurized air from the brake chamber.
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