4-40. Brake Drum Replacement
(2) Inspect brake drum for cracks, scoring or
a. Remove hub and brake drum as per paragraph
4-38 d. (1) (2) (3) and (4).
b. Adjustment. The trailer is equipped with a
b. On inside of brake drum loosen and remove 6
straight-air system of the cam type brake. Each cam
bolts securing brake drum to wheel and hub. (fig. 4-4).
brake is actuated by a brake chamber which forces a
c. Replace brake drum and assemble in reverse
slack adjust er lever to rotate the cam shaft. The cam at
the outer end of the cam shaft acting on a cam follower
pushes the brake lining out against the brake drum.
4-41. Brake Shoe and Assembly Inspection, Brake
Wheel bearings should be properly adjusted before
making brake adjustment.
a. Inspection. Periodic adjustment, cleaning and
(1) Have the wheel raised off the ground.
lubrication of brake equipment should be established
by the organizational maintenance on the basis of past
(2) With the wheel turning slightly (by hand)
experience and severity of operation. Linings and
rotate the adjusting screw (worm shaft) on the slack
drums are parts particularly subject to wear.
adjuster (note worm shaft lock must be depressed) until
compensate for this wear brakes should be adjusted as
the wheel is locked by the brakes. (fig. 4-10).
frequently as required to maintain satisfactory operation
(3) Back off the adjusting screw until the
and maximum safety. Brakes should be cleaned,
wheel turns freely with no evidence of brake drag.
inspected, lubricated and adjusted each time the hubs
Usually two clicks of the slack adjuster screw is
sufficient to provide the proper clearance.
(4) After adjusting brakes, if the brake will not
release (cam returns to closed position) the linings
saturation, wear and loose bolts. Lining should not be
should be replaced.
allowed to wear to the point where bolts may contact
c. Chamber Stroke. When travel increases from
liner wear to 2 inches, readjust. (fig. 4-11).