MIL-T-62491 Trucks, Wrecker: 4540 To 40 820 Kilograms 5-Ton To 45-Ton Lifting Capacity, Modified CommercialThis specification covers all commercial, non-tactical wreckers procured for military use. Vehicles procured under this specification are commercial items which are warranted by the manufacturer as specified in acquisition documents.

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MIL-T-62491C

TABLE XI.  Body thickness.

3.5.3  Front push bumper.  Unless a front mounted winch is specified, a front push bumper shall be provided.  The bumper shall be constructed of not less than 4.76 mm (0.187 inch)

steel plate for sizes 5T and 7T, and not less than 6.35 mm (0.25 inch) steel plate for all other sizes, all flanged to a depth of 75 mm (three inches) top and bottom, or flanged to a depth of

50 mm (two inches) top, bottom and ends; all shall be not less than 368 mm (14.50 inches) between top and bottom flanges; all shall extend across the full width of the vehicle cab, plus or minus 75 mm (three inches); all shall have rubberized push pads or padding; and all shall be reinforced and mounted to the chassis frame to withstand a push of not less than 22.25 kN

(5,000 pounds) on any portion without permanent distortion.  When the front bumper is mounted on the front spring hanger brackets, the brackets shall be reinforced to reduce the shear forces on the bracket-to-frame mounting bolts or rivets.

3.5.4  Backplate.  A backplate shall be provided.  The backplate shall be constructed of not less than 4.76 mm (0.187 inch) steel plate for sizes 5T and 7T.  The backplate shall be not less than 6.4 mm (0.25 inch) steel plate for all other sizes, flanged at the bottom, reinforced and mounted to transfer the loads imposed on the backplate and towing devices directly to the chassis frame.  The backplate shall be the full width of the vehicle.  The backplate on sizes 20T through

45T shall be not less than 530 mm (21 inches) from the bottom flange to the top edge of the plate. The backplate shall curve forward or shall be offset forward at each end to provide the maximum cornering clearance when towing a vehicle.  Taillights, stoplights, and directional signal lights

shall be inset in the backplate or shall be in a protected location.  Slots for scotch block chains shall be furnished.

3.5.5  Load line winches.  Not less than one winch on size 5T and two independent winches on sizes 7T through 45T shall be provided.  The winch(s) shall be of the variable speed, hydraulic type.  Each winch shall have a drum pull rated capacity with a single line on the bare drum of not less than that specified in line "m" of table X, with a safety factor of not less than 2.0.  Each winch shall be provided with a pressure relief valve set at 110 percent of the maximum winch rating. Winches shall conform to or exceed the requirements of SAE J706.  Means shall be provided for free unreeling of the load line.  Means shall be provided to prevent overtravel of the drum when free unreeling.  Load lines shall be equipped with hooks of sufficient capacity for rated loads.

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