Moving the fifth wheel control lever inside the cab to the UNLOCK position operates
an air cylinder under the fifth wheel which allows it to travel on the slide track rack
a total of 12 inches forward or backward. This feature allows for adjustment of amount
of cargo load carried by the rear tandem axles, within rated capacity.
With a trailer coupled to the fifth wheel and the control in the UNLOCK position, ad-
justment is made by driving forward or backward slowly with the trailer brake hand
control applied. After sliding adjustment is made, move the fifth wheel control lever
to the LOCK position and release the trailer brake hand control.
Use of the sliding fifth wheel for axle weight distribution requires scales to determine
the weight being placed on each axle of the tractor and trailer. The normal position
of the sliding fifth wheel is mid-way between the two rear tandem axles of the tractor
with an unloaded or loaded trailer. From this starting position, weight on the front ax-
le of the tractor can be increased by moving the sliding fifth wheel forward, and
decreased by moving the sliding fifth wheel backward. See NORMAL LOCATION decals
on both sides of the fifth wheel assembly for correct positioning when towing the M-872
2-16. Coupling and Uncoupling.