TM9-2320-361-1O 2-29. OPERATION OF TRACTOR AND FIFTH WHEEL a. General. A fifth wheel (semitrailer coupler) is mounted on the rear of M275A2 tractor trucks. When connected to a semitrailer, the fifth wheel pivots up, down, and sideways to allow for changes in road conditions. Fifth wheel maximum load ratings are 36,000 lb (16,304 kg) highway, and 17,000 lb (7,718 kg) cross-country. b. Wedge Adjustment. (1) Position fifth wheel wedges (2) fully below walking beam (1) for on- highway operations. (2) Position wedges (2) back and away from walking beam (1) for cross- country operations. (3) To position wedges: (a) Remove screws (3) from center of each wedge (2). (b) Remove wedge (2) and reverse position. (c) Using same holes as in step (a), install screws (3) and tighten. c. Coupling Semitrailer. NOTE Two crewmembers are required to complete the following procedures. (1) Back up tractor so fifth wheel coupler jaws (9) aline with semitrailer kingpin (5). (2) Stop tractor in front of semitrailer, place transmission gearshift lever (11) in “N” (neutral) position, and apply parking brake lever (10). (3) Adjust trailer landing gear (6) to raise or lower semitrailer skid plate (4). Skid plate (4) should be slightly lower than fifth wheel (8). 2-136