Driving - Peterbilt 348 2017 Operator's Manual

Clutch Brake and Travel (9–, 10–,
and 11–Speed Transmissions only)
These transmissions utilize a clutch
brake, rather than synchronizers. The
clutch brake works by stopping all of
the gears in the transmission, allowing
you to easily shift into first gear or
reverse without grinding gears. The
total stroke of the clutch pedal is about
10 inches. The first part is the release
stroke: the part that fully releases
the clutch. The last inch engages the
clutch brake.
During hard-shifting with vehicle
not moving
•
To apply the clutch brake (while
the vehicle is stopped) fully
depress the clutch pedal to the
floorboard to stop the gears. With
the throttle at idle, select first gear
then release the clutch pedal to
let the vehicle start forward, until
the clutch is fully engaged. See
(03/17)
the transmission manufacturer's
manual that is included with your
vehicle for further details.
During Normal Driving
If you want to shift directly into any gear
other than first or reverse, depress the
clutch pedal only far enough to release
the clutch. Pushing the clutch to the
floor applies the clutch brake and could
cause gear hang-up.
CAUTION
Be careful not to apply the clutch
brake while the vehicle is moving.
The purpose of the clutch brake is
to stop the transmission so that you
can shift into a starting gear without
grinding gears. Applying the clutch
brake when the vehicle is moving
causes a braking effect on the drive-
train and shortens the service life of
the clutch brake.
Double Clutching
Y53-6060-1C1
OPERATING THE TRANSMISSION
Whether you are upshifting or down
shifting, it is best to double clutch.
Double clutching is easier on the
transmission and on the engine,
helping your vehicle match engine
speed with driveline speed and
achieving clash-free shifts. To double
clutch:
1. Push the clutch pedal down to
disengage the clutch.
2. Move the gear shift lever to
Neutral.
3. Release the pedal to engage
the clutch. This lets you control
the rpm of the mainshaft gears,
allowing you to match the rpm of
the mainshaft gears to those of the
output shaft.
°
Upshifts: let the engine and
gears slow down to the rpm
required for the next gear.
4
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