resistor shall be selected to reduce the 28-volt dc regulated voltage of the tactical truck to within
the maximum rated voltage of the semitrailer electrical components. The resistor assembly shall
be located in a protective housing, shall be provided with adequate ventilation or a heat sink to
prevent overheating and any damage to resistors, wiring, or adjacent components, and shall not
be located in close proximity to any vent or pump exhaust.
3.12 Landing gear. The semitrailer shall have two vertical lift, telescopic, nonrotating
landing legs with two speed gears and a handcrank on the curb side. Landing legs shall be
equipped with steel wheels or self-leveling skid pads. Both legs shall be capable of being
simultaneously operated by a handcrank from the curbside. Supports for the crank extension
shafts and clips for holding the crank when folded shall be provided. The landing gear shall
withstand, without deformation, the combined static and dynamic forces due to the proportion of
gross weight sustained and the forces resulting from impact during coupling and uncoupling
operations. When placed in travel position, the landing gear legs shall remain positively locked.
The landing gear shall be protected to prevent the entrance of foreign matter which would impair
its functioning or mechanical efficiency.
3.12.1 Landing gear range of adjustment. The landing gear shall have a range of adjustment
sufficient to vary the height of the upper fifth wheel from 47 inches to not less than 52 inches
from the ground. With the semitrailer coupled to a towing tractor and in level position, the
clearance under the fully retracted landing gear shall be not less than 14 inches.
3.13 Rear end protection. Semitrailer rear end protection shall be in accordance with
Federal Motor Carrier Safety Regtuation 393.86, and shall conform to DoT Safety Regulation
* 3.14 Rear wheel splash and stone throw protection. Real wheels shall have fender
extensions or mud flaps at the rear. Splash and stone throw protection shall be in accordance
with SAE J682. The semitrailer shall have skirting or fenders that cover the area above the
wheels. The skirting on the fenders shall be essentially flat on top and capable of supporting a
person weighing 250 pounds. Fenders shall be aluminum or stainless steel. A step and grab
handle for ease of mounting the top of the curbside fender shall be provided. A metal strip not
less than 1/8 inch thick and not less than one inch wide, extending the entire width of the mud
flap, shall be used as a backing to prevent bolt head or bolt nut from rupturing the mud flap
during tightening operation upon installation. As an alternate method of attaching the mud flaps,
tabs or clips with minimum surface contact dimensions of 1 inch high by 1.25 inch wide by
0.094 inch thick shall be furnished at each bolt.
3.15 Lubrication. Lubrication means shall be provided for all part of the equipment
normally requiring lubrication. Where the use of high lubrication pressure will damage grease
seals or other parts, fittings with pressure release shall be used.