Clutch Operation - freightliner cascadia Driver Manual

it generates considerable heat. An improperly ad-
justed or slipping clutch will rapidly generate suffi-
cient heat to destroy itself.
To ensure long service life of the clutch; start in the
right gear, be alert to clutch malfunctions, and know
when to adjust the clutch.

Clutch Operation

Clutch Break-In
With a new or newly installed clutch, the clutch may
slip for a short time while the friction surfaces break-
in. However, allowing the clutch to slip for more than
two seconds can severely damage the clutch disc,
pressure plate, and the flywheel.
During initial operation of a new vehicle or a vehicle
with a new clutch, check for clutch slippage during
acceleration. If the clutch slips, decelerate until the
clutch does not slip. Allow the clutch to cool 15 to 30
seconds, and then gradually accelerate again. If the
clutch continues to slip, repeat the procedure. If nec-
essary, repeat the procedure up to five times. If the
clutch slips after five attempts, stop the vehicle. Allow
the clutch to cool for at least one hour. Notify your
Freightliner dealer of the problem.
CAUTION
Do not allow sustained slippage of the clutch;
this could severely damage the clutch disc, pres-
sure plate, or flywheel. Damage caused by clutch
slippage due to improper break-in is not warrant-
able.
Moving the Vehicle in the Proper Gear
An empty truck can be started in a higher transmis-
sion gear than can a partially or fully loaded truck. A
good rule of thumb for the driver to follow is to select
the gear combination that allows the vehicle to start
moving with an idling engine, or, if necessary, just
enough throttle to prevent stalling the engine. After
the clutch is fully engaged, the engine can be accel-
erated to the correct rpm for the upshift into the next
higher gear.
Gear Shifting Techniques
Shift into the next higher gear when the vehicle
speed allows the transmission input shaft speed to
match the flywheel speed when engaging the clutch.
This technique results in the smallest speed differ-
Manual Transmissions and Hydraulic Clutch
ence between the clutch disc and the flywheel and
causes the least heat and wear on the clutch assem-
bly. When downshifting, the input shaft speed must
be increased by slightly revving the engine to match
the flywheel speed for smooth clutch engagement.
For transmission operating instructions, refer to the
transmission headings in this manual.
Vehicle Loading
Clutches are designed for specific vehicle applica-
tions and loads. These weight limitations should not
be exceeded.
CAUTION
Exceeding vehicle load limits can not only result
in damage to the clutch, but can also damage the
entire powertrain.
Using the Clutch
The clutch pedal must be used only to start the ve-
hicle moving or while shifting. To start the vehicle
moving, depress the clutch pedal all the way to the
floor plate (see "Using the Clutch Brake") and shift
from neutral to a low gear. Slowly raise your foot until
the clutch starts to engage. In this position the clutch
is starting to connect the transmission input shaft to
the flywheel and is causing the most heat and wear.
Slightly increase the engine speed and smoothly
allow the clutch pedal to return to its at rest position.
Do not allow the clutch to remain in the partially en-
gaged position any longer than necessary to obtain a
smooth start.
To shift gears while the vehicle is moving, push the
clutch pedal most of the way (but not all of the way)
to the floor plate. Shift the transmission into neutral
and fully release the clutch pedal. If upshifting, wait
long enough for the engine speed to decrease to the
road speed. If downshifting, increase the engine
speed to match the road speed. Again, push down
the clutch pedal part way and then move the shift
lever to the next gear position. Fully release the
clutch pedal after completing the shift.
Slightly depressing the clutch pedal while driving is
damaging to the clutch, because partial clutch en-
gagement causes slippage and heat. Resting your
foot on the clutch pedal will also put a constant thrust
load on the release bearing, thinning the bearing lu-
bricant and increasing the wear on the bearing.
14.6