TM 9-2330-271-14&P
b.
Master Cylinder Service.
(3) No leakage is permissible.
(4) Check non-pressure side of the air chamber
(1) Master cylinder service includes only
by applying soap and water solution to holes min
flushing and refilling hydraulic system as follows:
chamber body.
(2) Remove vent tube assembly and filler plug
(5) If leaks exist, replace chamber.
and spacer from top of master cylinder.
c. Brake Air Chamber Push Rod Travel Test.
(2), and (4) at each wheel cylinder.
vehicle.
(4) Keep master cylinder reservoir filled with
(2) With brakes released, insert a small rod
denatured alcohol while brake pedal is slowly pumped
through one of two inspection holes in left side of brake
until clean fluid passage is observed.
penetration when contacting push rod.
clean brake fluid specified on lubrication order (figs. 3-1
and 3-2) to
force all flushing agent from system.
(6) Add hydraulic fluid to master cylinder
reservoir until fluid level is one-half inch to three-eights of
an inch below top of reservoir.
(7) Perform steps (6), (8), and (10) of
c. Removal.
(1) Release air pressure from system by
opening drain cock on air reservoir.
(2) Disconnect master cylinder-to-tee flexible
hose from rear of cylinder.
(3) Remove three nuts and lock washers which
attach cylinder to bracket.
(4) Move cylinder to one side sufficiently to
detach rubber bellows.
(5) Remove master cylinder.
d. Installation.
(1) Position master cylinder over the three
studs and against bracket. Make sure that brake air
chamber push rod is properly seated in master cylinder
piston.
(2) Install rubber bellows over lip on master
Figure 4-31. Testing brake air chamber push rod travel.
cylinder.
(3) Secure cylinder in place with three nuts and
(3) Apply brakes and again mark rod at surface
lock washers.
of mounting bracket with rod in contact with push rod.
(4) Connect master cylinder-to-tee hose to rear
(4) Withdraw rod and measure distance
of cylinder.
between marks. This indicates amount of piston travel.
(5) Close drain cock on air reservoir.
necessary, to permit a minimum of one-half inch to a
4-39.
Brake Air Chamber
maximum of seven-eighths of an inch travel.
d. Removal.
a. General. The brake air chamber is mounted to
the front of master cylinder. It converts air pressure into
WARNING
mechanical motion to operate the master cylinder.
Release air pressure from system by
Excessive brake air chamber push rod travel will result in
opening drain cock on air reservoir.
damage to rubber cup in master cylinder. Insufficient
(1) Disconnect air chamber-to-relay valve tube.
travel will result in ineffective brakes.
(2) Remove two nuts and lock washers
b. Air Chamber Leakage Test.
attaching air chamber to bracket.
(1) With brakes applied, coat air chamber
(3) Remove air chamber. Be careful not to
flange with soap and water solution and inspect for
damage rubber bellows.
leaks.
(2) If a leak is detected, tighten flange nuts
evenly and sufficiently to stop leak.
4-46