(4) Adjust the top adjusting stud in a
cloth. Attach a tube to the bleeder valve and
similar manner.
place other end of tube in a suitable container.
(c) Fill the master cylinder with brake
(5) Adjust remaining wheel in a similar
fluid. Refer to the current lubrication chart.
manner.
(d) Pump brake pedal on towing vehicle
b. Bleeding.
until pressure is applied. Hold pedal pressure
(1) General. It is necessary to bleed air
and open bleeder valve (fig. 3-15) until pres-
from hydraulic portion of service brakes if
sure is released on pedal, then close valve.
the system is opened or a component of the
(e) Repeat action until fluid has re-
system has been replaced.
placed air in system, then close valve; remove
(2) Manual Bleeding.
hose.
(a) Connect trailer service brake hoses
(f) Refill master cylinder with brake
fluid and install filler cap.
to a towing vehicle for manual bleeding as the
brake pedal must be pressed and released to
(g) Repeat the above operation on the
other wheel cylinders.
actuate the system. The master cylinder must
be kept full of brake fluid or air will enter the
Caution: Maintain a high level of
system.
fluid in the master cylinder while bleeding
(b) Clean the bleeder valve with a clean
each wheel cylinder.
3-24
