WARNING
Do not use the trailer air supply for parking trail-
ers not equipped with spring parking brakes.
This applies the trailer service brakes only. As air
bleeds from the trailer brake system, brake appli-
cation is lost. This could allow the unattended
vehicle to roll away, possibly resulting in serious
personal injury or death.
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.
NOTE: The fifth wheel may have to be moved
slightly to enable the locking plungers to enter
the fully locked position.
8.
Lock the sliding member into position using one
of the following methods:
WARNING
Check to be sure that the slide plungers are in
the locked position. Failure to achieve complete
lockup may allow disengagement of the tractor
from the trailer, possibly resulting in serious per-
sonal injury or death.
8.1
For air-operated models, set the cab-
operated control switch to LOCK. Visually
check the slide plungers to make sure
they are engaged in the fully locked posi-
tion. See
Fig. 10.7
.
8.2
For manual release models, trip the re-
lease lever (
Fig. 10.3
) using a release
hook or other suitable tool. Make sure that
both plungers have locked (retracted into
their pockets), and are fully engaged in
the rack teeth. See
Fig. 10.7
. It may be
necessary to move the tractor slightly
while keeping the trailer brakes locked.
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.
1
1
A
B
01/24/96
f310439
A. Locked (engaged)
B. Unlocked (released)
1.
Plunger
Fig. 10.7, Plunger Positions
Fifth Wheels and Trailer Couplings
10.5
