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

Operating Instructions
ders which actuate the brake pad mechanisms. Actuation of
these mechanisms force the brake pads against the rotors to
stop the wheels.
A reserve electric motor pump provides a redundant power
source for the hydraulic booster in the event normal flow from
the power steering pump is interrupted. Manual braking is
also available in the event both the power and reserve systems
are inoperative.
WARNING! Never drive your vehicle with the
parking brakes applied. Always release the parking
brakes prior to moving the vehicle. Failure to
disengage the parking brakes prior to moving
your vehicle could result in excessive heat buildup
of the brakes and start a fire.
NOTE: Today’s diesel electronic engines have significant
torque and startability power at low RPM.
Combinations of engine speed and available torque
may over-power the vehicle’s parking brakes.
Using the Brake System
WARNING! The brake system is a critical vehicle
safety system. For the safety of you and others
around you, have the vehicle submitted for periodic
preventive maintenance checks as well as
having any suspected problems immediately
checked by an Authorized Service Center. Failure
to properly maintain your brake system can
lead to serious injury accidents.
Brake Components
The following is a brief description of the hydraulic brake system.
It is intended to supply you with general information on
how the system works. For complete information see the
Peterbilt Medium Duty Maintenance Manual.
Anti-Lock Brake System (ABS) Modulator Valve Body:
adjusts brake fluid flow between the master cylinder and the
wheel calipers to avoid wheel lockup.
ABS Warning Lamp: lights when the ABS controller detects
wheel lock-up while driving and activates the ABS. Lights
also when a fault in the ABS is detected.
Brake Fluid Reservoir: stores brake fluid and offers a place
to replenish when needed.
Medium Duty (R10/06) Y53-6008 – 89 –