Peterbilt Medium Duty Trucks Operator's Manual after 1-07
Peterbilt Medium Duty Trucks Operator's Manual after 1-07
Peterbilt Medium Duty Trucks Operator's Manual after 1-07
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Using the Brake System<br />
WARNING! If the air pressure falls below 60 psi<br />
(414 kPa) the spring brakes may stop the vehicle<br />
abruptly, which could result in an accident<br />
and/or injuries. Observe the red warning lamps<br />
on the gauges. If one comes on, do not continue<br />
to drive the vehicle until it has been properly<br />
repaired or serviced.<br />
WARNING! Do not use the trailer hand brake or<br />
service brakes to park and hold an unattended<br />
vehicle—use the parking brakes. Because service<br />
brakes work with air pressure, these<br />
brakes could slowly release. Your vehicle could<br />
roll, causing a serious accident. Someone<br />
could be hurt or killed. Never rely on the service<br />
brakes to hold a parked vehicle.<br />
Tractor and Trailer Air Supply Valve<br />
Initial Charge<br />
The red octagon knob controls the air supply to the trailer.<br />
With the system completely discharged, both the Red (trailer<br />
air supply) and the Yellow (parking brake) knobs are OUT;<br />
thus, tractor and the trailer parking (spring) brakes are<br />
applied.<br />
Operating Instructions<br />
To supply air to the trailer system and release the trailer parking<br />
brakes:<br />
1. Allow the tractor air system pressure to build up to operating<br />
level.<br />
2. When system pressure reaches 50 psi (345 kPa) the<br />
Red knob may be pushed IN.<br />
3. Hold the Red knob IN by hand until the trailer air pressure<br />
builds to a pre-set level, about 45 psi. At this point it<br />
will remain in, charging the trailer system and releasing<br />
only the trailer brakes.<br />
4. The Yellow knob will remain OUT (tractor brakes ON).<br />
Normal Run Position<br />
• The Yellow knob (system park) may now be pushed IN,<br />
which will supply air to the tractor spring brakes, releasing<br />
them.<br />
• With both knobs pushed IN, air is now being supplied to<br />
both the trailer and the tractor spring brakes; all brakes<br />
are released.<br />
– 76 – Y53-6008 <strong>Medium</strong> <strong>Duty</strong> (R10/06)