freightliner cascadia Driver Manual page 134

Brake Systems
Engine Brake
Each engine manufacturer uses a specific engine
brake for their engine. Regardless of the manufac-
turer, the engine brake is operated with the principles
outlined in here. Refer to the engine manufacturer's
operation manual for details of their particular engine
brake product.
WARNING
To avoid injury from loss of vehicle control, do
not activate the engine brake system under the
following conditions:
•
on wet or slippery pavement, unless the
vehicle is equipped with antilock braking
system (ABS) and you have had prior expe-
rience driving under these conditions;
•
when driving without a trailer or pulling an
empty trailer;
•
if the tractor drive wheels begin to lock, or
there is fishtail motion after the engine
brake is activated.
NOTE: When the engine brake is enabled, the
engine brake lamp illuminates in the ICU. See
Fig. 13.3, Item 1.
Whenever vehicle braking is required on good road
conditions, the engine brake may be used in con-
junction with the service brakes. There is no time
limit for operation of the engine brake. However, an
engine brake does not provide the precise control of,
and is not a substitute for, service brakes.
WARNING
Usage of the engine brake as the primary braking
system can cause unpredictable stopping dis-
tances, that could result in personal injury or
property damage. Service brakes are the primary
vehicle braking system.
Since the engine brake is most effective at rated en-
gine speed, gear selection is very important. Gearing
down the vehicle within the limits of the rated engine
speed makes the engine brake more effective. Rec-
ommended engine braking speed is above 1800 rpm
and below the rated speed.
13.5
WARNING
The engine brake must be disengaged when
shifting gears using the clutch pedal. If the en-
gine brake is engaged when the transmission is
in neutral, the braking power of the engine brake
can stall the engine, which could result in loss of
vehicle control, possibly causing personal injury
and property damage.
"Control speed" is the speed at which the engine
brake performs 100 percent of the required downhill
braking, resulting in a constant speed of descent.
The control speed varies, depending on vehicle
weight and the downhill grade.
For faster descent, select a higher gear than that
used for control speed. Service brakes must then be
used intermittently to prevent engine overspeed and
to maintain desired vehicle speed.
For slower descent, select a lower gear, being care-
ful not to overspeed the engine. Occasional deactiva-
tion of the engine brake may be necessary to main-
tain the designated road speed under these
conditions.
If the engine is equipped with both cruise control and
an engine brake, the engine brake can operate auto-
matically while cruise control is activated. The maxi-
mum amount of braking is selected with the engine
brake control. When the vehicle returns to the set
cruise speed, the engine brake will turn off.
The engine brake will only operate when the accel-
erator and clutch pedals are fully released.
Vehicles equipped with ABS have the ability to turn
the engine brake off if wheel slip is detected. The
engine brake will automatically turn back on once
wheel slip is no longer detected.
Engine Brake Operation
NOTICE
Do not allow the engine to exceed its governed
speed, or serious engine damage could result.
NOTE: Depending on the brake type, the engine
brake may be disabled when engine tempera-
ture falls below a set level.