MIL-S-62549 Semitrailer, Low Bed, 40 Ton Nominal Payload For Transportation Of Heavy Engineer Construction Equipment, M870A2This specification covers a level frame, low bed semitrailer equipped with a folding gooseneck for front loading and movement of heavy engineer construction equipment.

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MIL-S-62549(AT)

3.4.11.1 Upper fifth wheel plate. The upper fifth wheel plate shall be adequate for coupling to a fully oscillating fifth wheel and be of sufficient size to cover a fifth wheel of 36 inches in diameter. The forward edge of the plate shall have a turned up lip for ease of coupling with a truck-tractor.

3.4.12 Suspension. The suspension system shall be of a rated capacity or equal to the load imposed at the ground when semitrailer is loaded with its specified payload. The suspension system shall consist of a combination of spring and walking beam suspension. Means shall be provided for axle and suspension alignment in accordance with SAE J875.

3.4.12.1 Axles. The semitrailer shall have a minimum of 3 axles capable of performing under conditions as depicted in requirements for suspension. The axle loads, with the semitrailer loaded with rated payload, shall be at least equal to 25,000 lb for each axle measured at the ground.

3.4.12.2 Suspension and axle clearances. Clearances shall preclude interference between suspension, axles, wheels or tires, and any portion of the vehicle under the conditions specified herein. Difference in height for specified set of dual wheels shall be measured at the center of the tread on the outer tire.

3.4.13 Wheel, rims, tires and tubes. Wheels, rims, tires and tubes shall be in accordance with the Tire and Rim Association recommendations and FMVSS 119 and FMVSS 120. Tire, rim

size, wheel size and ply rating shall be the same for all wheels on each vehicle.

3.4.13.l Tires. Tires shall be radial tube type with highway tread. The cold inflation pressure shall be matched to the payloads specified in accordance with the Tire and Rim Association. The tire shall be a minimum size and rating of 10.00 by 15, load range G.

3.4.13.2 Inner tubes. For tube-type tires, inner tubes shall be of the heavy duty type, and shall be of proper size for tires furnished. Tire flaps shall be provided for tube-type tires in accordance with Tire and Rim Association recommendations.

3.4.13.3 Tire carrier. Mounting provisions shall be provided on the beavertail for at least one spare tire and wheel, readily accessible for removal and replacement by one operator.

3.4.13.4 Spare wheel assembly. Spare wheel(s) or rim(s) with inflated tire(s) shall be mounted on the tire carrier specified in 3.4.12.3. The spare tire(s) shall be the same type, size tread design, and ply rating as the tires furnished on the semitrailer.