3.15 Dolly. The dolly shall be furnished by the contractor.
3.15.1 Contractor-furnished dolly.
22.214.171.124 Fifth wheel. A fixed lower fifth wheel shall be furnished. The height of the fifth
wheel with the semitrailer loaded shall be 61 inches plus or minus 2 inches.
3.15.2 Drawbar coupler. A ring drawbar coupler in accordance with MS51337 shall be
installed in a housing integral with the towbar. The housing shall support the coupler the entire
length of the shank. The clearance between the shank and support shall be not greater than
0.035 inch. When the dolly is in towing position, the height range of the lunette shall provide
compatibility with pintles in SAE J849, ranging between 31 through 37 inches from level
ground. The center of the lunette and the center line of the towbar shall be located within
1/8 inch of the longitudinal center line of the dolly. The towbar shall be hinged. When the dolly
is loaded and the towbar is not locked rigid, the hinge shall permit the lunette to lower without
additional load. The towbar shall be rigid when the dolly is being stored or towed without load.
When coupled to the semitrailer, the dolly shall turn 110 degrees both to the right and to the left
of the longitudinal centerline of the semitrailer. The coupler shall be compatible for towing with
a military, M917 20-ton dump truck or with a military 20-ton, 6 x 6, M9l6 truck-tractor and shall
permit the centerline of the truck to be at an angle of not less than 60 degrees to the right or to
the left of the centerline of the dolly when in towing position. There shall be no interference
between either the truck or the dolly-semitrailer combination.
3.15.3 Landing leg. The towbar of the dolly shall be provided with an adjustable landing leg
to permit one man to couple and uncouple the lunette and the pintle on the towing vehicle.
Ground clearance shall be not less than 18 inches when the towbar and landing leg are in travel
3.15.4 Dolly suspension. The dolly suspension shall include two single wide base tire axles
as specified in 3.14.2 and 3.14.3 in a single point mount, tandem axle configuration. A complete
air brake system shall be furnished as specified in 3.14.5. The dolly brakes shall be correctly
balanced in application pressure and timing to reduce the possibility of jackknifing the crusher
during stops. The dolly brakes shall have less effectiveness than the rear crusher brakes through
use of smaller chambers or by installation of a pressure holding or reducing valve in the dolly
3.15.5 Dolly electrical system. The electrical system of the dolly shall conform to 3.14.6.
Service and blackout rear combination lights only shall be required and installed.
3.15.6 Dolly intervehicular connections. The dolly shall be provided with electrical and
airbrake lines to connect the truck systems to the semitrailer systems. All forward intervehicular
connections between the dolly and the truck shall extend 36 to 42 inches toward the truck and