Peterbilt Medium Duty Truck Owner's Manual - Peterbilt Motors

Brake System
• Do not use moly-disulfide loaded grease or oil (they may
shorten the service life of the slack adjuster).
• Do not use pressure-release grease fittings when lubricating
the slack adjuster.
Checks and Adjustments
All vehicle operators should check the brakes regularly.
Always adjust the brakes when they are cool.
• Park the vehicle on a level surface and block the wheels
before attempting any brake checks or adjustments.
Brake Linings
WARNING! Do not use brake linings with a thickness
below the specified minimum. Such linings
will have lining rivets exposed that can damage
the brake drum and reduce brake efficiency,
which could cause death , personal injury or
system failure.
• Brake linings should be inspected for wear by a qualified
mechanic at an Authorized Service Center. See Table 2,
“Maintenance Schedule,” Page 157. In severe service
applications inspect the linings more frequently.
Automatic Slack Adjusters
Preventive Maintenance
Your Medium Duty vehicle is equipped with automatic brake
(slack) adjusters.
Periodically, brake adjustment should be checked using
the following procedure:
1. Check brakes when the temperature of the service brake
linings are cool and the system air pressure is at 100 psi
(690 kPa) minimum.
2. Release the parking brakes to allow the slack adjusters
to retract.
3. Measure the retracted pushrod length from the face of
the brake chamber to the center of the pushrod pin.
4. Apply 80 to 90 psi brake application and measure the
same distance.
5. The difference is the pushrod travel distance (applied
stroke).
Verify that the result is within the correct range (see Table 4,
”Brake Adjuster Stroke”). Correctly installed and functioning
brakes (auto slack) will produce the strokes listed for each
chamber type.
– 186 – Y53-6027 Medium Duty (R05/09)