2-27. OPERATION OF TRACTOR AND TRACTOR WRECKER
a. General. A fifth wheel (semitrailer coupler) is mounted on the rear of M818 tractor
trucks and M819 tractor wrecker trucks. The base of the fifth wheel pivots on a walking
beam which in turn pivots on the subbase. This construction permits fifth wheel to move
in all planes determined by road conditions. For fifth wheel maximum load ratings, refer
to table 1-3.
A newer model fifth wheel is provisioned as a replacement item on
the M818 tractor. Operating instructions for this fifth wheel will
apply to M818 vehicles only.
b. Coupling the Semitrailer.
Two crewmembers are required to complete the following procedures.
(1) Start engine (refer to paragraphs 2-12 and 2-13).
(2) Move tractor truck and aline fifth wheel coupling jaws (4) with semitrailer
(3) Place gearshift lever (1) in N (neutral) position.
(4) Apply parking brake (2).
(5) Adjust trailer landing gear (7) to raise or lower semitrailer skid plate (8). Skid
plate (8) should be slightly lower than tractor fifth wheel (5).
(6) Position semitrailer wheel chocks (6) in place.