TM 5-3805-258-24-1
A I R S Y S T E M A N D B R A K E S
3. Leakage around seals (4) and (5) in the wheel
brake head assembly. This leakage can be
caused by incorrect installation or a cut or
damaged seal.
H E A D A S S E M B L Y O F W H E E L B R A KE
4. Seal. 5. Seal.
Test
Use the tests that follow to find the cause for
brake fluid leakage.
1.
2.
For large amounts of brake fluid leakage, in-
spect all hoses, tubes and fittings in the brake
system for an indication of leakage. If any
leakage is found, it must be corrected before
going to the next step.
Check the brake fluid level in the reservoirs.
Measure the distance from top edge (6) to the
fluid level. The correct distance is 13 mm (.5
in.). If the reservoir is too full, remove fluid
until it is at the correct level. If the fluid level
is too low, add fluid until it is at the correct
level. Install the diaphragm and cover on the
reservoir.
CAUTION
Use only DOT 3 brake fluid.
C H E C K O F B R A K E F L U I D L E V E L I N R E S E R V O IR
6. Top edge of reservoir. 7. Reservoir for rear axle (rear
w h e e l b r a k e s ) . 8 . R e s e r v o i r f o r f r o n t a x l e ( f r o n t w h e e l
b r a k e s ) .
3.
4.
TESTING AND ADJUSTING
Put a clean metal oil pan under the master
cylinders to catch brake fluid drops from the
master cylinders.
Start the engine and let the air pressure and
oil temperature go up to normal pressure and
temperature for operation. Keep the engine in
operation during this procedure to make sure
of correct air pressure. Make 100 complete
brake applications and releases. Stop (pause)
ten seconds between applications.
NOTE: Do not move the machine for this test.
5.
6.
Check the brake fluid level in the reservoirs
again. If a loss of brake fluid can be measured,
check the oil pan for drops of brake fluid. Make
a comparison of the amount of fluid in the
oil pan with the amount of fluid loss from the
reservoir.
If the amounts of fluid are ap-
proximately the same, the problem is in the
master cylinder. If the amounts are different,
go to the next step.
If brake fluid loss from the reservoir is more
than the leakage from the master cylinder, the
probable location of the leakage is at seals (4)
and (5) in the wheel brake head assembly. The
leakage can be from either or both wheel brakes
on the axle. To find the location of the leakage
(if only one brake is leaking), do the procedure
that follows:
NOTE: Reservoir (7) is for the rear axle (rear wheel
brakes). Reservoir (8) is for the front axle (front
wheel brakes).
a. Find which axle has the problem (leakage).
b. On this axle, disconnect tube (9) from the
head assembly on one of the wheel brakes.
c.
R I G H T F R O N T W H E E L B R A K E
9. Tube.
Connect a 9S7692 Inverted Flare Connector
to the fitting on tube (9). Install a 1/8 in.
pipe plug in the connector. One wheel brake
4-62
