Navistar WorkStar Series, Operator'S Manual

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Operation
Connecting/Disconnecting a Trailer to a Vehicle with Air
Suspension
The Air Suspension has a dump valve system option (Code
14899) that permits exhausting air from the suspension system,
thus lowering the frame when connecting, disconnecting, or
loading the trailer. The vehicle speed must be below 5 mph
before the switch will operate the valve.
When connecting to a trailer, switch the SUSP/DUMP switch,
located on the instrument panel gauge cluster, to the DUMP
position and air will exhaust from the suspension system
lowering the tractor. This will permit backing under the trailer
without undue loading of suspension system. After making the
connection to the trailer, return the switch to the SUSP position,
then raise landing gear.
When disconnecting the trailer, lower the landing gear,
disconnect the brake hoses and rear light connectors from
the trailer, and pull the release lever on the fifth wheel. Slowly
pull the tractor forward just far enough to release the king pin
from the fifth wheel and stop. Switch the SUSP/DUMP switch to
the DUMP position and pull the tractor away from the trailer.
The SUSP/DUMP switch must be returned to the down SUSP
position before operating with a trailer or operating in the bobtail
mode.
Fifth Wheel Operation
WARNING
Always follow the fifth wheel manufacturer’s
instructions for hooking and unhooking as well
as sliding the fifth wheel.
Failure to follow
this warning could result in property damage,
personal injury, or death.
The hand control valve should never be used
to apply the trailer brakes when the tractor and
trailer are parked. Air pressure may leak from the
system, and the vehicle could roll away, resulting
in property damage, personal injury, or death.
WARNING
When using an assistant to reposition a sliding
fifth wheel, the driver must be ready to stop as
soon as the fifth wheel moves to the desired
position. The assistant must keep feet, hands
and body clear of the vehicle’s tires and other
moving parts to prevent personal injury or death.
The driver must not begin to move the vehicle
until the assistant is clear and signals the driver
to move the vehicle.
Fifth Wheel Slide Switch (Optional)
An optional Fifth Wheel Slide switch may be present. This switch
allows the operator to electronically unlock the fifth wheel to
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