SECTION V
PREVENTlVE MAINTENANCE
will release the lock spring and apply the brake with the
brake cylinder.
2. With no load on the hook, place the pawl switch in the
"ON" position and be sure the pawl engages into the drum
ratchet teeth. Release the foot brake pedal.
3. Check the piston extension of the lock cylinder with the
drum brake switch "ON". This dimension should be 1/2
inch. To adjust the piston extension to the correct setting,
proceed as follows:
A. Move the drum brake switch to the "OFF" position
(spring brake released).
B. Tighten the brake band adjusting bolt a small incre-
ment.
C. Move the drum brake switch to the "ON" position
(spring brake set) and check the piston extension.
D. Repeat steps A through C until piston extension is cor-
rect.
4. Check the lock spring length with the drum brake switch
"ON" (pressure to lock cylinder released and lock spring
Figure 5B-7. Propel Gear Case Level Plug
set). Tighten the adjusting nuts "B" to set the lock spring at
7-3/4 inches.
5. Check the hanger springs for proper support of the brake
CHECK LEFT AND RIGHT DRUM BRAKES
bands.
6. Check the brake adjustment by lifting a capacity load an
The left and right drum brakes control the rotation of the left
inch or two off the ground, and apply the foot brake. Place
and right drums.
the drum brake switch in the "ON" position. Release the
Both the left and right drum brake bands are connected to
foot brake pedal. The load must now be held, without drift-
two hydraulic cylinders with opposing springs (see Figure
ing, by the lock spring.
7. If the load drifts during this test, lower the load to the
ground.
When there is no pressure in the hydraulic system (drum
brake switch is "ON"), each brake is set by the lock spring
which opposes the lock cylinder. When system pressure is
available (drum brake switch "OFF"), the lock cylinder com-
presses the lock spring, releasing the brake so that it maybe
Reapply the foot brake before moving the
operated by the brake cylinder. When the operator depes-
drum brake switch to the "OFF" position, and
ses the brake pedal, the brake is applied by the brake cylin-
lower the load under the control of the foot
der. When the operator releases the brake pedal, the brake
brake.
is released by the return spring which opposes the brake
cylinder. An additional return spring IS used to retract the
Set the pawl, release the foot brake and tighten the band ad-
piston of the cylinder.
justing bolt as necessary.
NOTE
The following adjustment procedure applies to week
to week checks and adjustments for normal lining
The final criterion for correct adjustment is,
wear. If the bands have to be relined, or the operaring
will the brake hold the load? The brake must
mechanism has been disturbed, see the Shop Manual
hold for safe load handling.
for adjustment instructions.
8. After the brakes have been properly adjusted, check the
following:
To adjust the left and right drum brakes to compensate for
normal lining wear, proceed as follows (see Figure 5B-8):
A. The hanger springs should be adjusted so that the brake
band clears the drum uniformly around its circumfer-
1. With the engine running, place the drum brakeswitch in
ence, with the brakes released.
the "OFF" position and depress the foot brake pedal. This
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