STARTING AND OPERATING THE VEHICLE BRAKE SAFETY AND EMERGENCY
Regional Haul
(R05/10) Y53-6033 – 107 –
WARNING! Do not use the trailer hand brake
or service brakes to park and hold an unat-
tended vehicle—use the parking brakes.
Because service brakes work with air pres-
sure, these brakes could slowly release. Your
vehicle could roll, causing a serious accident.
Someone could be hurt or killed. Never rely on
the service brakes to hold a parked vehicle.
Parking Tractor and Trailer
• With both knobs pushed in for normal operating
modes, the parking brakes of both the tractor and the
trailer may be applied by pulling the
Yellow knob
OUT. This will exhaust the air from the tractor spring
brakes, and simultaneously cause the
Red knob to
pop OUT, which will apply the trailer brakes. This
complies with the FMVSS 121 requirement that one
control should apply all the parking brakes on the
vehicle.
Trailer Charge
• If both knobs are OUT (combination vehicle is
parked), and it is desired to recharge the trailer, the
Red knob may be pushed IN to repressurize the trailer
supply line. The tractor will remain parked. For more
information on air supply pressure requirements, see
page 105
.
Brake Safety and Emergency
WARNING! Do not operate the vehicle in the
event of a malfunction in any air circuit. The
vehicle should not be operated until the sys-
tem is repaired and both braking circuits,
including all pneumatic and mechanical com-
ponents, are working properly. Loss of sys-
tem air can cause the service brakes to not
function resulting in the sudden application of
the spring brakes causing wheel lock-up, loss
of control, or over-take by following vehicles.
You could be in an accident and killed or
severely injured.
