Operating The Brake System; Introduction - Peterbilt 348 2017 Operator's Manual

OPERATING THE BRAKE SYSTEM

OPERATING THE
BRAKE SYSTEM

Introduction

This vehicle's brake system functions
with the use of compressed air
generated from the engine's air
compressor. The compressed air is
stored in various air tanks to ensure
that air pressure is available whenever
the driver needs it.
4
Compressed air is delivered to the
brake system through the valve at
the brake pedal and is controlled
with various valves and braking
circuits. The brake system is designed
with separate front, rear and (when
applicable) trailer circuits so that if one
circuit is compromised and loses air,
the other circuits will not be affected.
Safety valves in each circuit will protect
the other circuits in the event that a
circuit loses air.
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The air compressor on the engine will
typically provide 100-130 psi (690-896
kPa) to the air tanks. The vehicle
is also designed with an air dryer,
which removes moisture from the
compressed air in order to protect all
components in the air system.
The brake system may be further
enhanced by additional devices
such as brake proportioning valves,
Anti-lock braking systems or sensors
designed to let you know if your brake
pads need to be serviced.
Certain conditions may result in the
brake surfaces getting wet. Brake
surfaces that are wet do not perform
as well as when they are dry. There
may be situations where wet brake
surfaces cannot be avoided. In such
situations, apply the brakes while in
motion, to dry the brake surfaces.
Y53-6060-1C1
Certain conditions may result in your
brake surfaces becoming overheated
(above 800° F or 427° C). Overheated
brakes will damage linings and
drum surfaces, ultimately decreasing
braking performance. Refer to
Retarders and Descending a grade to
avoid overheating the brakes.
This vehicle may be equipped with
an anti-lock braking system (ABS).
This ABS reduces the possibility of
wheel lock-up. If a wheel is about
to lock during braking, the ABS will
automatically adjust air pressure to the
brake chambers on the appropriate
wheel(s) to prevent wheel lock-up. The
ABS is automatically turned on when
the ignition switch is turned on.
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