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
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Operating Instructions<br />
(2) Trailer Air Supply<br />
Control (Red)<br />
(1) Parking Brake Control<br />
(Yellow)<br />
To release the trailer brakes ONLY:<br />
Using the Brake System<br />
• Push IN the Red knob on the dash. The truck or tractor<br />
will remain parked.<br />
To release the full combination of brakes:<br />
Combination (Tractor/Trailer) Parking Brake Control Valves<br />
The parking brakes act on the rear wheels only. They are<br />
spring-applied, with air pressure used to release them.<br />
Release air is supplied by both the front and rear circuit reservoirs<br />
through a double check valve.<br />
To release the truck or tractor parking brakes ONLY:<br />
02394<br />
• Push IN the Yellow knob on the dash. Your trailer will<br />
remain parked.<br />
Below 60 psi (414 kPa) the Yellow parking brake valve<br />
remains OUT (ON position). If air pressure is not<br />
restored above 60 psi (414 kPa), the knob will automatically<br />
return to the OUT position if you attempt to push it<br />
in. See page 26 for more information.<br />
• Push IN BOTH knobs on the dash.<br />
• In the event that air pressure is reduced below a safe<br />
level: the low air warning light will come on first; if air<br />
pressure continues to drop, the parking brake valve will<br />
pop OUT, automatically applying the spring brakes.<br />
CAUTION: Do not try to put the vehicle in<br />
motion before pressure in the system reaches<br />
100 psi (689 kPa) because the wheels are<br />
locked by the spring brake action.<br />
• Unnecessary stress and possible brake malfunction<br />
could occur if the vehicle is forced to<br />
move before the air system reaches 100 psi (689<br />
kPa).<br />
• Below 60 psi (414 kPa) the parking brake valve<br />
button remains in the applied (ON) position. If air<br />
pressure is not restored, the button will automatically<br />
return to its initial position.<br />
<strong>Medium</strong> <strong>Duty</strong> (R10/06) Y53-6008 – 75 –