Engaging The Clutch - Navistar ProStar+ Operation And Maintenance Manual

Operation
7. Double-clutch between all upshifts and downshifts.
8. After your shifting ability improves, you may want to
skip some of the ratios. This may be done only when
operating conditions permit, depending on the load,
grade, and road speed. Transmissions with a greater
number of speeds are optionally available. They may
include the use of a splitter selector switch in addition
to the range selector switch.

Engaging the Clutch

• Always start in the proper gear: An empty vehicle
can be started in a higher gear than a fully loaded one.
But starting in a gear too high for the load can cause
too much clutch slippage, generating excessive heat
and unnecessary wear. A gear that will start the vehicle
moving with the engine at idle speed is usually correct.
If the engine must be revved up to prevent stalling, the
gear selection is too high. As the clutch pedal is released
and the clutch begins to engage, the engine speed will
drop slightly. When this happens, fully engage the clutch
and increase the engine speed. Increasing the engine
speed before fully engaging the clutch can damage the
clutch and drivetrain.
• Do not upshift until the engine has reached proper
speed. Upshifting before the vehicle has reached the
right speed will lug the engine.
• When approaching a hill, depress accelerator smoothly
to start the upgrade at full power, then downshift as
needed to maintain vehicle speed.
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• Never hold a vehicle on a hill with the clutch. To
hold on a hill with the clutch requires that the clutch be
purposely slipped. By doing this enough heat can be
generated to burn up the clutch.
• Never coast with the clutch disengaged. This can
cause clutch failure by the very high RPM encountered
when coasting in gear with the clutch released. In this
situation, the rear wheels are driving the disc through
the multiplication of the rear axle and transmission ratios.
This can result in over 10,000 RPM, which is beyond the
burst strength of the facing material. Something as simple
as coasting down an unloading ramp can burst a driven
disc.
Reengaging a clutch after coasting causes tremendous
shock to the clutch and the whole drivetrain. It can result in
internal engine damage and / or clutch and flywheel failure.
Always report unusual clutch operation promptly. Proper
maintenance, performed on time, will greatly extend the life
of the clutch. The driver should report any change in free
pedal (free travel) slippage or any strange feel to the clutch
operation.
Helpful Hints to Operate Vehicles with Ceramic Clutch
Facings
1. Driver must start vehicle in first (low) gear.
2. While operating a ceramic clutch the driver has to
engage the clutch before giving the engine any fuel (at
idle).
3. The driver should not try to slip the ceramic clutch
by raising engine RPMs and riding or feathering