Navistar ProStar+, Operation And Maintenance Manual

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Operation
Parking Brake Indicator
WARNING
To prevent property damage, personal injury, and
/ or death, avoid driving with the parking brakes
applied, which can lead to excessive heat buildup
and possible fire.
The Parking Brake indicator is operated in conjunction with the
parking brake. With the ignition switch on and the parking brake
set, the PARK indicator will illuminate.
If the indicator does
not illuminate with the parking brake set, the indicator may be
inoperative.
Bobtail Proportioning System
Bobtail proportioning is available with tractor air brake systems
(for export only with code 04092) with or without ABS or ABS
/ Traction Control Systems.
The proportioning valve senses
when trailer brakes are not connected to the vehicle air brake
system, and automatically adjusts rear braking power when
operating in the bobtail mode, then returns full braking power
when a trailer is attached.
When operating in the bobtail
mode, bobtail proportioning provides more braking control and
shorter stopping distances, particularly on wet and slippery road
surfaces.
It should be noted that there is a noticeably different brake pedal
feel on tractors with this feature while operating in the bobtail
mode. Higher brake pedal efforts will be experienced by the
driver than when in a brake system without bobtail proportioning.
Antilock Brake System (ABS)
General Information
WARNING
To prevent property damage, personal injury,
and / or death, Antilock Brake System(s) (ABS)
are designed to enhance overall vehicle safety
when a vehicle is driven within its safe operating
limits.
ABS cannot compensate for a vehicle
that is being driven beyond the physical limits
of control. Drivers operating an ABS equipped
vehicle should employ safe driving practices and
assume no additional driving risks.
WARNING
To prevent property damage, personal injury, and
/ or death, do not rely on the ABS to interrupt
vehicle engine brake on slippery road surfaces.
Turn these devices off during hazardous driving
conditions. Failure to follow this warning may
cause wheel slippage and / or loss of vehicle
control.
The ABS is a mandated feature added to the standard air brake
system. It electronically monitors vehicle wheel speed at all
times, and engages only when wheel lock is imminent. The
standard air brake system controls normal braking when the ABS
is not engaged.
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