PART 8: MAINTENANCE AND SERVICE
PB1319 (CAT. NO. 5296 ) —128— 22-01691 (R02/02)
All vehicle operators should check their brakes regularly. Always
adjust your brakes when they are cool. Perform the following checks
and adjustments every 15,000 miles (24,000 km):
• Have brake linings inspected by a qualified mechanic for wear at
least every 15,000 miles. In severe service or off-highway applica-
tions inspect the linings more frequently.
• Check the air system for leaks:
1. Build up air pressure in the system to the governor cut-out point.
2. Stop the engine.
3. Release the parking brakes (push in the yellow knob).
4. Watch the rate of air pressure drop. The rate of drop should not be
more than 2 psi (14 kPa) per minute.
5. Now start the engine and build up the air pressure again.
6. Stop the engine. Ensure that the parking brakes are still released.
Fully apply the service brakes.
7. Watch the rate of air pressure drop registered by the air gauge.
The rate of drop should not be more than 3 psi (21 kPa) per
minute.
8. If you find excessive leakage, a leakage test should be made at
the air line connections and at all air brake control units. To per-
form a leakage test, refer to the detailed instructions in the Peter-
bilt Maintenance Manual, or take your vehicle to an authorized
Peterbilt dealer.
Readjust brakes if pushrod travel reaches 1 3/4 inches (44.4 mm) for
steer axle brakes or 2 inches (51 mm) for rear axle brakes [2 1/4
inches (57 mm) for Type 36 chambers] at 80 - 90 psi (550 - 620 kPa)
application pressure.
WARNING! A nonconforming part in your brake system
could cause an accident. Sizes and types are so related
to one another that a seemingly unimportant change in
one may result in a change in how well your brakes work
for you on the road. If parts don’t work together prop-
erly, you could lose control of your vehicle. Be sure any
replacement parts in your brake system conform exactly
to original specifications.
WARNING! Brake linings with a thickness below the speci-
fied minimum will have lining rivets exposed. Use of such
linings can damage the brake drum and also reduce brake
efficiency, which could cause an accident or system failure.
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