Navistar WorkStar Series, Operator'S Manual

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Operation
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.
Never engage the clutch while coasting. 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 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 clutch pedal, since the
vehicle will experience erratic engagement.
Erratic engagement can cause engine stalling and potential
serious damage to your vehicle’s drivetrain components (i.e.,
clutch, transmission, driveshaft(s), rear axle).
Clutch Brake (Vehicles with Nonsynchronized Transmission) –
Vehicle Not Moving
A clutch brake is used to stop transmission input shaft rotation so
that the initial first or reverse gear selection can be accomplished
when the vehicle is at a standstill and the engine running at idle
speed. Clutch brake application occurs in the last 1 inch (25mm)
of pedal travel.
When using the clutch brake, fully depress the clutch pedal and
shift the transmission into either first or reverse gear.
If the
transmission does not go into first gear or reverse, toothbutting
may be occurring. Slowly release the clutch pedal while applying
light pressure on the shift lever until the transmission goes into
gear. This will provide for a smooth shift into either a forward or
reverse gear.
NOTE: After engagement of first gear, DO NOT use the clutch
brake for upshifting and downshifting. To do so will shorten the
service life of the clutch brake, and gear selection shift efforts
may be increased. Clutch brake application occurs in the last 1
inch (25mm) of pedal travel.
Double Clutch Procedures, Nonsynchronized
In order to properly upshift or downshift be sure to do the
following:
• Depress the clutch pedal to disengage the clutch.
• Shift the transmission into neutral.
• Release the clutch pedal.
• If upshifting, wait until the engine speed matches the
transmission speed of the gear you desire to shift into.
• If downshifting, accelerate the engine until the engine speed
matches the input speed of the gear you desire to shift into.
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