TRACTOR/SEMITRAILER COUPLING/UNCOUPLING (CONT)
The adjusting nut needs to be backed off only one full turn minimum when
connecting the semitrailer from one tractor to another of the same type (example:
M911 to M911 or MK48/16 to MK48/16).
The adjusting nut needs to be backed off three full turns minimum when
connecting the semitrailer from one type of tractor to another (example: M911 to
(10) Using a 3/4-inch ratchet, a 3/4-inch extension, and 1-7/8-inch socket, turn adjusting nut (10) appropriate
number of full turns counterclockwise. This will ensure steering wedge (2) is properly fitted and can be
tightened after kingpin (1) is locked into tractor fifth wheel (4).
Two personnel are required for coupling. During hookup, the operator of the
tractor must know the position of the spotter at all times or injury to personnel may
(11) With a spotter positioned on streetside of semitrailer and using hand signals, aline tractor with semitrailer. A
spotter must visually check tractor fifth wheel (4), vee entry ramps (3), semitrailer kingpin (1), and steering
wedge (2) for alinement.
(12) Have operator continue backing so that fifth wheel is approximately 2 inches (5.0 cm) from front of gooseneck
pickup plate (11) and then stop.
(13) Adjust gooseneck height (para. 2-18) so that gooseneck pickup plate (11) is approximately 1 to 2 inches (2.5
to 5.0 cm) lower than tractor fifth wheel (4).
Do not allow the kingpin to miss and/or overrun the fifth wheel or severe damage
to the tractor and semitrailer may result.
(14) With a spotter positioned at semitrailer hydraulic control panel, have spotter make final adjustments to
steering wedge alinement by operating steering valve (9).
(15) Have tractor operator back up until kingpin (1) is firmly in place in fifth wheel (4). Have spotter confirm that
semitrailer kingpin (1) is seated and both fifth wheel locks (5) are properly engaged.
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