TM 9-2330-371-14&P
AIRBRAKE SYSTEM - CONTINUED
Wheel Brake Mechanism The brakes are air-over-hydraulic type. Two brake hydraulic master
cylinders, with air chambers attached, provide the means for converting the energy of compressed air
into hydraulic pressure necessary to operate the hydraulic semitrailer wheel brakes. The wheel brake
mechanism, located within the brake drums, is of the self-centering type. This type brake assembly
has two identical brakeshoes and one wheel cylinder assembly. When the brakes are applied, the
wheel cylinder pistons apply equal force against the tow of each shoe. As the shoe linings come into
contact with the drum, self-energization develops. The rotation of the drum pulls the shoes against
the drum surface to add to the hydraulic force acting on the shoes and to produce additional braking
action.
TA224180
1-10