TM9-2330-207-14
4-38. DESCRIPTION OF BRAKES (Cont)
h. Slack Adjusters (M127). The slack adjusters
shafts. Push rods of the air chambers operate the
slack adjusters which in turn rotate the camshafts
causing the cams to press the brake shoes against
the brake drums. Provision is made to adjust the
angle of the slack adjuster on the camshaft to afford
the most efficient brake operation. This is obtained
when the travel of the arm of the slack adjuster is
held to a minimum and full leverage is used. Such
adjustment is termed the "minor" adjustment of
the brakes. Gearing in the housing of the slack
adjuster permits positioning it at precise angles on
the camshaft. A round opening through the body
of the slack adjuster exposes the splined hub of a
worm wheel. The splines in the worm wheel engage
the splines on the brake camshaft. A worm gear in
the housing engages the worm wheel. The worm
gear is mounted on a worm shaft, one end of which
protrudes through the slack adjuster. When the
worm shaft is turned with a wrench, the worm
gear causes the housing to rotate around the
worm wheel. The worm shaft is locked against
undesirable turning by a lock spring.
and 4-35) on the semitrailer extends from the air hose
coupling (tagged SERVICE), on the right side of the
front crossmember, along the right chassis longitudinal
frame rail to an elbow in the top of the emergency
transmit changes in air pressure originated in the
towing vehicle, which causes the emergency relay
valve to function.
air reservoir and lines (All models except M127)
j. Emergencv Air Line. The emergency air line
its air hose coupling (tagged EMERGENCY), on the
left side of the front crossmember, along the left
longitudinal frame rail to a threaded opening near
and 4-41). This air Iine transmits compressed air to
fill the semitrailer reservoir and to maintain the
proper air pressure, under control of the emergency
relay valve, to apply the brakes on the semitrailer.
lines (M127)