Brake Component Inspection
1. Park the vehicle on a level surface, set the park-
ing brake, and chock the tires. Once the tires are
chocked, release the parking brake.
WARNING
Manually adjusting an automatic slack adjuster to
bring the pushrod stroke within legal limits is
likely masking a mechanical problem. Adjustment
is not repairing. Before adjusting an automatic
slack adjuster, troubleshoot the foundation brake
system and inspect it for worn or damaged com-
ponents. Improperly maintaining the vehicle brak-
ing system may lead to brake failure, resulting in
property damage, personal injury, or death.
2. With the engine off, and 100 psi (689 kPa) of air
tank pressure, have an assistant apply and hold
an 80 to 90 psi (550 to 620 kPa) brake applica-
tion.
3. Check to see if the colored over-stroke band on
each brake chamber pushrod is exposed.
If a band shows, the stroke is too long. Check
the foundation brake components for wear or
damage, and repair as needed. See Group 42 of
the Century Class Trucks Workshop Manual for
inspection, troubleshooting, and repair proce-
dures.
4. Measure the applied chamber stroke. See
Table 1 for the proper stroke for the type of
chamber being used. If the stroke is too short,
the brakes may drag or will not fully apply. Check
for improper operation or adjustment of the auto-
matic slack adjuster. See Group 42 of the
Century Class Trucks Workshop Manual for in-
spection and troubleshooting procedures.
5. Start the engine and build air pressure to at least
100 psi (689 kPa). Shut down the engine.
6. Check all of the foundation brake components for
damage, wear, and loose or missing parts. Re-
pair as needed. See Group 42 of the Century
Class Trucks Workshop Manual for repair proce-
dures.
Brake Chamber Stroke Specifications
Chamber
Max Applied Stroke: inch (mm)
Manufacturer Type
*
Size
†
Gunite
Standard Stroke
9
1-3/8 (35)
12
16
1-3/4 (44)20
24
30 2 (51)
36
‡
2-1/4 (57)
Long Stroke
16
2 (51)
20
24 (2-1/2 inch rated
stroke)
24 (3 inch rated
stroke)
2-1/2 (64)
30
Brakes42
Century Class Trucks Maintenance Manual, January 201642/10
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