Regional Haul Model Operator's Manual - Peterbilt Motors Company

BRAKE SYSTEM
PREVENTIVE MAINTENANCE
SLACK
ADJUSTER
BRAKE
CHAMBER
PUSHROD
WARNING! Manual adjustment of automatic
slack adjusters is a dangerous practice that
could result in an accident involving death or
injury. It gives the operator a false sense of
security about the effectiveness of the brakes.
Contact the Service Department at your dealership
if the stroke exceeds the above specifications.
A stroke exceeding these values may
indicate a problem with the slack adjuster or
the brake foundation.
Measuring Pushrod Travel
Table 4
Brake Adjuster Stroke
80–90 PSI (552 – 621 KPA) BRAKE APPLICATION
AIR CHAMBER
TYPE (Size)
BRAKE
“APPLIED STROKE”
01830
PUSHROD TRAVEL
(Applied Stroke)
20 Front 1 to 1–3/4 in. (25–44mm)
30 Rear 1–1/4 to 2 in. (32–51mm)
• If the pushrod travel reaches the above specifications,
check the slack adjuster installation. Inspect brake
adjuster and anchor bracket for damage. The anchor
bracket should be tight.
• With the air system at 100 psi (690 kPa) or more,
apply the brake.
If adjustment is necessary and the slack adjuster is working,
the adjusting hex nut will rotate during the chamber
return stroke. Installing a wrench on the hex nut will make
this easier to see. On each stroke after the first, the
amount of adjustment and chamber travel will be less.
– 184 – Y53-6033 Regional Haul (R05/10)