Medium Duty Operator's Manual - Peterbilt Motors Company

USING THE BRAKE SYSTEM
Hydraulic Booster: The hydraulic booster applies additional
hydraulic force from the power steering gear to the
master cylinder piston when the brake pedal is applied.
Parking Brake Lamp: illuminates when the parking brake
is engaged (the lever is in the up position.)
Parking Brake Lever: the hand lever located in the cab
which engages or disengages the driveline drum brake.
Power Steering Flow Switch: senses flow of power
steering fluid.
Power Steering Fluid Reservoir: stores power steering
fluid and offers a place to replenish when needed.
Power Steering Gear: assists the steering operation and
sends pressurized power steering fluid to the brake
booster.
Power Steering Pump: draws power steering fluid from
the reservoir and sends it to the power steering gear.
Warning Buzzer: sounds when either power steering
fluid flow is interrupted or when a pressure differential is
present between the primary and secondary brake fluid
pressure. Either case adversely affects braking operation.
STARTING AND OPERATING THE VEHICLE
Brake Warning Lamp
When the brake warning lamp comes on, it indicates a
malfunction in the brake system. Possible malfunctions
include loss of hydraulic pressure from the power steering
circuit or a pressure differential between the primary and
secondary brake circuits.
WARNING! Do not operate the vehicle if the
brake light or buzzer comes on. The light or
buzzer indicates a failure in one of the brake
components/system. Drive your vehicle to the
side of the road immediately. Failure to do this
may lead to an accident and severe injury.
!
BRAKE
If the buzzer sounds while driving, or if the BRAKE light
comes on, do the following:
1. Slow down carefully.
SERVICE BRAKE WARNING INDICATOR
Here are some things you can do to assist in slowing
the vehicle:
– 120 – Y53-6008A Medium Duty (R05/09)