Slack Adjusters. The slack adjusters (1, fig. 4-23) are levers mounted on
the brake camshafts (2). Push rods (3) of the air brake chambers (4) operate the
slack adjusters (1) which in turn rotate the camshafts (2) causing the cams to
press the brake shoes against the brake drums.
f. Spring Brake Chambers. The spring brake chambers (4, fig. 4-23) are mounted
adjacent to the internal wheel brakes. The spring brake chambers convert air
pressure into mechanical motion to operate the slack adjusters when applying brakes.
The spring in the spring brake chamber may be caged in case of air loss or brake
failure to move the semitrailer.
Slack Adjuster and Spring Brake Chamber