Peterbilt Medium Duty Trucks Operator's Manual after 1-07

Using the Brake System
Using the Parking Brake
The yellow diamond-shaped knob on the dash controls the
truck/tractor parking brakes. These are spring brakes that
you activate by releasing air pressure from their chambers.
When they are not in use, air pressure compresses the
springs and releases the brakes. Pulling the knob OUT
applies the parking brake, which exhausts air from the chambers
and allows the springs to extend and apply the brakes.
WARNING! Do not pull out the parking brake
valve while the vehicle is moving. Stopping with
the parking brake controls can cause a sudden
wheel lock-up, loss of control, or over-take by
following vehicles. You could be severely
injured.
WARNING! Do not leave the cab without applying
the parking brake. The truck could roll and
cause an injury accident. Always apply the parking
brake before you leave the cab.
Before you leave the cab:
Operating Instructions
1. Apply all parking brakes. Pull out the Yellow Parking
Brake Control knob located on the dash. The Red (octagon-shaped)
Trailer Air Supply Control knob on tractors
will automatically pop out. (An optional dash warning
light will indicate when the brake is ON.)
2. Shift the transmission into PARK position:
• manual transmission, select First or Reverse gear
• automatic transmission, select Neutral.
3. Turn the key to OFF.
4. Remove the key.
38//
72$33/<
3$5.,1*
%5$.(
386+72
5(/($6(
02394-1
Full Truck Parking Brake Control Knob
– 74 – Y53-6008 Medium Duty (R10/06)