1.
Verify that both the yellow parking-brake and red
trailer-air supply knobs are out, the tractor and
trailer parking brakes are set, and that the trailer
is prepared for uncoupling.
2.
Push and hold the kingpin release switch, shown
in Fig. 17.22, for a minimum of 3 seconds. The
system will apply air for 20 to 30 seconds to
ensure the kingpin unlocks. When the kingpin is
unlocked, a notification is displayed as shown in
Fig. 17.25.
3.
Release the tractor parking brake.
4.
Drive out from under the trailer.
Fifth Wheel Slide
WARNING
Adjust the fifth wheel slide correctly. Do not
overload any tractor axle by incorrectly loading
the trailer.
Incorrect slide adjustment or improper axle
loading could cause erratic steering and loss of
vehicle control, possibly resulting in serious
personal injury or death.
On sliding fifth wheel assemblies, the fifth-wheel
plate is attached to rails that allow forward and
rearward movement of the fifth wheel to optimally
distribute the load across the axles. Slots are evenly
spaced along the slide rails, and retractable wedges
are positioned through the slots to hold the fifth
wheel in the desired position.
The amount of load distribution on the front steering
axle and rear drive axle(s) will have a direct effect on
the steering control of the vehicle. Determine the
front and rear axle weights by weighing the vehicle
on scales designed for this purpose.
The maximum axle weight ratings are shown on the
Federal Motor Vehicle Safety Standard (FMVSS)
label or Canadian Motor Vehicle Safety Standard
(CMVSS) label; see the ’Vehicle Identification’
chapter for the location of these labels on your
vehicle. The desired load on the axle is no less than
80 percent of the maximum axle weight rating, but in
no instances should the axle load exceed the
maximum axle weight rating given on the FMVSS or
CMVSS label.
Fifth Wheel Slide Control Switch
NOTICE
Do not activate the fifth wheel slide control valve
while the vehicle is in motion. To do so could
cause damage to the fifth wheel member, the
kingpin, the cab or trailer, and ultimately to the
drivetrain.
The fifth wheel air slide switch operates an air
cylinder that locks and unlocks the slide. See
Fig. 17.26.
f61198711/24/2021
Fig. 17.24, Kingpin Release Not Activated Popup, ICUC
f61142606/14/2016
Fig. 17.25, Kingpin Release Alert Screen, ICUC
f61183705/19/2020
5TH
WHL
Fig. 17.26, Fifth Wheel Slide Control Switch
Fifth Wheels and Trailer Couplings
17.10
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