freightliner C SB FS65, Maintenance Manual

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4. Check the free-stroke. If the vehicle has new
brakes or brakes with new linings, you must
check the free-stroke. If the vehicle is in for rou-
tine maintenance and the brakes or linings are
not new, go to the next step and check the brake
chamber stroke.
IMPORTANT: Do not use installation tem-
plates to check the slack adjuster angles.
Installation templates are used only when
installing a new slack adjuster or reinstalling
the existing slack adjuster.
4.1 With the brakes fully released, measure
the distance from the bottom of the brake
chamber to the center of the large clevis
pin. See
Fig. 2 , Ref. A.
4.2 Use a pry bar to move the slack adjuster,
applying the brakes. Again, measure the
distance from the bottom of the brake
chamber to the center of the large clevis
pin. See
Fig. 2 , Ref. B.
The difference between the two measure-
ments is the initial free-stroke, and sets
the clearance between the linings and the
drum. The free-stroke must be 5/8 to 3/4
inch (16 to 19 mm).
4.3 If the free-stroke is incorrect, remove the
pressure-relief capscrew, gasket, pawl
spring, and pawl from the slack adjuster
housing. See
Fig. 1 , Ref. 5. If equipped
with a pull-pawl assembly, carefully insert
a screwdriver and raise the relief cap
about 1/8 inch (3.2 mm). See
Fig. 3 .
CAUTION
Before turning the adjusting nut, remove the pres-
sure relief capscrew, spring, and pawl assembly. If
equipped with a pull-pawl assembly, raise the re-
lief cap as instructed. Failure to do so could strip
the teeth on the pawl.
4.4 Turn the adjusting nut 1/8 turn, as shown
in
Fig. 4 . Measure the stroke again, and
adjust until correct.
CAUTION
Do not make the adjusted chamber stroke too
short. The free-stroke must not be less than the
f420012a
10/20/93
1
2
3
4
5
6
7
1. Brake Chamber
2. Clevis
3. Actuator Rod
4. Boot
5. Pressure-Relief Capscrew, Gasket, Pawl Spring,
and Pawl
6. Manual Adjusting Nut
7. Grease Fitting (or Lube Plug)
Fig. 1, Meritor Automatic Slack Adjuster
A
B
09/27/94 f420180a
NOTE: For a drum brake, A minus B must equal 5/8" to
3/4" (16 to 19 mm).
A. With the brakes applied, measure this distance.
B. With the brakes released, measure this distance.
Fig. 2, Measuring Free-Stroke
Brakes
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School Bus Chassis Maintenance Manual, March 2003
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