Section XIV. MAINTENANCE OF BRAKES
(3) Apply brakes and hold pedal down for at
least 10 seconds. Repeat this three times, allowing
Drycleaning solvent, P-D-680, used to
30 seconds between applications.
clean parts is potentially dangerous to
(4) Release the brakes and open all four bleeder
personnel and property. Do not use near
valves. Bleed fluid from the brakes until flow stops
open flame or excessive heat. Flash point
and then close the bleeder valve.
of solvent is 138°F.
(5) Repeat (3) and (4) above until no air can be
detected escaping from the fluid.
This section contains information for organizational
(6) Repeat the entire bleeding procedure if the
brakes show any evidence of dragging or
maintenance of the brakes.
overheating during the first few hours of operation.
4-59. Service Brakes
Brake lines should be checked for air after
a. General. The service brakes are expander tube
the first shift of operation. If brakes do
type, hydraulically operated. Pressure is supplied
not release properly after application,
by an engine driven hydraulic pump and application
replace hydraulic tank filter. A clogged or
is controlled by an applicator valve located under
restricted filter will prevent the oil from
the operator's floor plate. The brake adjustment is
returning to the tank and therefore will
accomplished automatically by slack adjusters (fig.
not allow the brakes to release.
4-37) located in the hydraulic lines between the
applicator valve and the wheel brake assemblies.
4-60. Emergency Brake Cable and Lever
There is no manual adjustment. If a malfunction
a. Removal. Refer to figure 4-36 and remove the
occurs which cannot be corrected by the bleeding
emergency brake cable and lever.
process, report to direct support maintenance. Do
b. Cleaning and Inspection.
not attempt to repair a slack adjuster, replace it.
Lining wear can be detected by observing the arc of
(1) Clean the emergency brake cable and lever
with drycleaning solvent (item 1, App F), and dry
the brake lining retract springs. Retract springs are
visible on the inboard side of the brake assembly,
(2) Inspect the cable for broken wires and kinks.
just below the outer circumference of the backing
Inspect emergency brake lever and mounting
plate. Flattened springs (with the brakes off) in-
brackets for cracks, breaks, and damaged parts.
dicate need for lining replacement. When the lining
Replace all defective parts.
is in good condition, the springs will form a shallow
arc. Check brake fluid for air after the first shift of
c. Installation. Refer to figure 4-36 and install
emergency brake cable and lever.
b. Straight Hydraulic Brake System Bleeding
(1) Release emergency brake.
(1) Fill the reservoir with hydraulic oil (OE 10).
(2) Refer to figure 4-36 and remove yoke pin
and cotter pin.
Reservoir must be free of dirt. A screen
(3) Turn yoke clockwise to tighten brake and
should be provided in the reservoir to
counterclockwise to loosen brake.
keep out foreign particles.
(4) Replace yoke pin and cotter pin.
(2) While engine is idling, open each bleeder
(5) Minor adjustment is accomplished by
valve (located on top of automatic slack adj uster fig.
turning the knurled adjusting knob which is located
4-37) and depress brake pedal until oil flows free of
at the top of the brake lever. Turn clockwise to
air. Close the bleed valves.
tighten; counterclockwise to loosen.