PREPARATION FOR USE (Con't)
1. Ensure that proper size kingpin (7) is installed to match the tractor (para 2-2). Install kingpin for either a 2 or 3
in. (6.4 or 8.9 cm) coupling.
2. To change the kingpin (7), open hinged access door (9) on top of the gooseneck. Open access door by
unlocking a bolt-type latch located in and operated through the stowage box door (10).
3. Place kingpin (7) into socket (8). Screw on clamp retainer (6) and lock into position with locking pin (5). Insert
locking pin through holes in clamp retainer and socket.
4. Close access door (9) and secure latch.
All persons not involved in coupling operation must stand clear of tractor and
semitrailer to prevent possible injury.
The 5 ton tractor is compatible with the M172A1 and is suitable for towing semitrailers
with loads up to 15 tons. It is not suitable for loads exceeding 15 tons due to its limited
towing and braking abilities. The 10 ton tractor is also compatible with the M172A1 and
is capable of towing this vehicle with loads up to 25 tons.
1. Aline tractor (11) with semitrailer (12).
2. Review and perform tractor operating procedures to prepare tractor for coupling. Refer to applicable tractor