operators_manual

Brakes
Air Brake System
WARNING
DO NOT drive through water deep
enough
to wet brake components, as it
may cause the brakes to work less ef-
ficiently than normal. The vehicle's
stopping distance may be longer than
expected, and the vehicle may pull to
the left or right when brakes are ap-
plied, which could contribute to an ac-
cident involving death or personal in-
jury.
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.
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, antilock
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.
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 brake performance.
Refer to Retarders and Descending a
grade to avoid overheating the brakes.
Parking Brake
1
2
3
1. Normal run position
2.
Trailer park with vehicle released
3. System park or trailer charge with
vehicle parked
Parking brakes work in reverse action of
the regular brakes. When the parking
brakes are engaged, air is exhausted from
the spring chambers, which allows the
spring to engage the brakes. This design
also provides a safety function if a brake
DRIVING - Brakes
114 Y53-6096-1C1 (09/20)
4