Lesson 3/Learning Event 1
FIGURE 20. SLACK ADJUSTER.
The pushrod of the brake chamber is connected to a slack adjuster.
The slack adjuster serves two purposes: to change the back and forth
motion of the pushrod to rotary motion and to make minor adjustments
to the brake shoes and linings.
The slack adjuster is splined to one end of a shaft that goes through
the backing plate of the wheel brake. The other end of the shaft
contains a cam. When the brake chamber pushrod moves the end of the
slack adjuster, it causes the shaft to rotate. As the cam on the
brake end of the shaft rotates, it causes the brake shoes with
linings to move against the drum.
Minor adjustment of the brakes is made by rotating the worm shaft on
the slack adjuster.
The wheel brake assemblies are much the same as those for hydraulic
or airhydraulic systems. The main difference is the wheel cylinder
is replaced with an operating cam.
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