Medium Duty Operator's Manual - Peterbilt Motors Company
Medium Duty Operator's Manual - Peterbilt Motors Company
Medium Duty Operator's Manual - Peterbilt Motors Company
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Air System<br />
CAUTION: Do not use penetrating oil, brake<br />
fluid, or wax-based oils in the air system. These<br />
fluids may cause severe damage to air system<br />
components.<br />
• Maintain the air compressor to prevent excessive oil bypass.<br />
See the <strong>Medium</strong> <strong>Duty</strong> Maintenance <strong>Manual</strong> for<br />
maintenance details.<br />
• Replace worn seals in valves and air motors as they are<br />
needed. Your <strong>Peterbilt</strong> Dealer carries rebuild kits for most<br />
units.<br />
Dual Air Gauge and Air Leaks<br />
Your <strong>Medium</strong> <strong>Duty</strong> comes with a primary and secondary air<br />
pressure guage. The gauge indicates the amount of air pressure<br />
in pounds per square inch (psi). See “Primary (Secondary)<br />
Air Pressure Gauge (Air Reservoir)” on page 41.<br />
If the pressure in either or both systems is too low for normal<br />
brake operation, i.e., either pointer falls below 60 psi (414<br />
kPa), a warning light on the gauge will glow and the audible<br />
alarm will sound. If the light and alarm do not turn off at startup,<br />
do not try to drive the vehicle until the problem is found<br />
and fixed.<br />
Preventive Maintenance<br />
WARNING! Do not operate the vehicle if leakage<br />
in the air system is detected. Conduct the following<br />
procedure and contact an Authorized Service<br />
Center (or any other properly equipped<br />
service center) if a leak is detected. Failure to<br />
check the brakes or follow these procedures<br />
could cause a system failure, increasing the risk<br />
of an injury accident.<br />
Follow the procedure below to check the compressed air<br />
system for leaks:<br />
1. Periodically, or after maintenance or replacement of air<br />
system components:<br />
2. Build up air pressure in the system to the governor cutout<br />
point or until 120 psi (827 kPa) is reached.<br />
3. Stop the engine and release the service brakes.<br />
4. Without applying the brake pedal, observe the rate of air<br />
pressure drop. This rate should not exceed 2.0 psi (14<br />
kPa) per minute.<br />
5. Start the engine and build up the air pressure again.<br />
6. Stop the engine, and apply the brakes fully. Apply the<br />
brake pedal and hold it down for five minutes. The pressure<br />
drop should not exceed 3.0 psi (21 kPa) per minute.<br />
– 194 – Y53-6008A <strong>Medium</strong> <strong>Duty</strong> (R05/09)
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