3.
After positive lockup of the fifth wheel lock
mechanism has been accomplished, release the
slide using one of the following methods:
3.1
For air-operated models, set the cab-
operated control switch (Fig. 10.6)toUN-
LOCK.
3.2
For manually-operated models, raise the
safety latch and pull the slide operating
rod (Fig. 10.9) outward until the shoulder
is outside of the operating rod support,
then lower the operating rod as far as it
will go.
4.
Lower the trailer landing gear just enough to re-
move the weight from the tractor.
5.
Pull the trailer air supply valve to cut off the air
supply to the trailer.
NOTICE
After moving the fifth wheel to the desired posi-
tion, be sure the trailer landing gear will not, at
any time, come in contact with the tractor frame
or other components. Make sure that the front of
the trailer will not come in contact with the rear
of the cab or with other components if they ex-
tend beyond the rear of the cab.
6.
Slowly move the tractor forward or backward
until the fifth wheel is in the desired location.
7.
Apply the tractor parking brakes.
WARNING
Check to be sure that the lockpins are seated in
the holes and that the operating rod is in the
locked position with the safety latch securing the
operating rod. Failure to achieve complete lockup
may cause the trailer to detach from the tractor,
possibly resulting in serious personal injury or
death.
NOTE: The fifth wheel may have to be moved
slightly to enable the locking pins to enter the
fully locked position.
8.
Lock the sliding member into position using one
of the following methods:
For air-operated models:
Set the cab-operated
control switch to LOCK. Visually inspect the lock-
pins to make sure they have seated in the base-
plate rail holes.
For manually-operated models:
Raise the operat-
ing rod so that it is free to move inward. Make
sure that the lockpins have seated in the base-
plate rail holes and the operating rod moves into
the locked position. Also, the safety latch must
drop downward so that it holds the operating rod
in the locked position.
9.
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 attached to the left rear
door post of the tractor. 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 rat-
ing given on the FMVSS or CMVSS label.
WARNING
Adjust the fifth wheel slide correctly, and 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 seri-
ous personal injury or death.
Fifth Wheel Lubrication
WARNING
Keep the fifth wheel plate lubricated to prevent
binding between the tractor and trailer. A binding
fifth wheel could cause erratic steering and loss
of vehicle control, possibly resulting in personal
injury or death.
The fifth wheel plate must be kept well lubricated
with chassis grease to prevent friction and binding
between the tractor fifth wheel plate and the trailer.
For lubrication instructions, see Group 31 of the
Century Class Trucks Maintenance Manual
.
Fifth Wheels and Trailer Couplings
10.10
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