freightliner C SB FS65, Maintenance Manual

Page: 75 / 91

measurements given previously. If the chamber
stroke is too short, the linings can drag, which
could damage the brake.
4.5 If removed, install the pawl, pawl spring,
gasket, and pressure-relief capscrew.
Tighten the capscrew 15 to 20 lbf·ft (20 to
27 N·m). Or, remove the screwdriver from
the pull-pawl assembly (if so equipped).
5. Check for correct brake chamber stroke.
5.1 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.
5.2 Build air pressure to 100 psi (690 kPa).
Shut down the engine. Fully apply the
brakes, then 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 mea-
surements is the brake chamber stroke.
5.3 The brake chamber stroke must be less
than the measurements shown in
Table 1 . If the brake chamber stroke is
incorrect, remove the pressure-relief cap-
screw, gasket, pawl spring, and pawl from
the slack adjuster housing. See
Fig. 1 ,
Ref. 5. If equipped with a pull-pawl as-
sembly, carefully insert a screwdriver and
raise the relief cap about 1/8 inch (3.2
mm). See
Fig. 3 .
Chamber Size
Effective Area:
square inches
Maximum
Allowable Stroke * :
inches (mm)
(B minus A)
12 Less than 1-3/8 (35)
16 Less than 1-3/4 (44)
20 Less than 1-3/4 (44)
24 Less than 1-3/4 (44)
24 Long Stroke Less than 2 (51)
30 Less than 2 (51)
*
Adjust the brakes whenever the applied stroke exceeds the maximum.
Table 1, Maximum Allowable Brake Chamber Stroke,
with Meritor Automatic Slack Adjusters
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.
5.4 Turn the adjusting nut one-eighth turn, as
shown in
Fig. 4 . Measure the stroke
again, and adjust until correct.
If the stroke varies or remains greater
than the specified range, check the brake
components, including the camshafts,
camshaft bushings, anchor pins, rollers,
chamber brackets, clevis, and clevis pins.
f420693a
09/27/94
A
A. Insert screwdriver here.
Fig. 3, Pull-Pawl Assembly (sectional view)
A
B
f420181a 07/05/95
A. Shorten stroke.
B. Lengthen stroke.
Fig. 4, Brake Stroke Adjusting
Brakes
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School Bus Chassis Maintenance Manual, March 2003
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