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19 Mar 1943 China Air Task Force [Flying Tigers] disbanded as Fourteenth Air Force established by special order of the President with General Claire Lee Chennault as commander.
19 Mar 1944 Operation Margarethe launched by Germany to occupy Hungary.
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M870A3 Medium Heavy Equipment Transporter (MHET)

M870A3 Medium Heavy Equipment Transporter (MHET).  Photo:  Heil Trailer International
M870A3 Medium Heavy Equipment Transporter (MHET). Photo: Heil Trailer International.

The M870A3 Medium Heavy Equipment Transporter (MHET) 40-ton Semi-Trailer provides a state-of-the-art hydraulic detachable gooseneck trailer to replace the older variants of the M870 semi-trailer. The M870A3 trailer is designed to transport engineer equipment, tracked vehicles, wheeled vehicles, containerized cargo on highways, unimproved roads (graded level), and cross-country. Two kingpins are provided for use with different prime movers (3.5 in (8.89 cm) and 2 in (5.08 cm)). The prime mover supplies brake air pressure for control of brakes, hydraulic power for operation of gooseneck, and electric power for trailer lighting.

The M870A3 includes the following features/benefits:

  • Four beam design, machine welded with high strength flanges
  • Main beams continuously welded at interfaces to eliminate rust bleed through
  • Self locking, positive, visible latch
  • Three ride height adjustments, hydraulic gooseneck and deck lift
  • Shot blast prior to paint
  • All tie downs meet MIL-STD 209J
  • 4S/2M ABS
  • Lockable BII storage box on top of neck
  • Davit for raising/lowering spare tire/wheel between rear deck and ground
  • Molded electrical harness
  • Electrical, air and hydraulic lines installed after paint
  • LED lights
  • 102 in. (8 ft 6 in.) overall width
  • Conspicuity reflective tape
  • Fully equalizing mechanical suspension system
  • Spare tire mounting location on the rear deck of the trailer (as with earlier variants)

The M870A3 will allow Engineer units the capability to transport heavy engineer construction equipment to project sites under adverse conditions in a timely manner. With its ease of loading and unloading, by a single operator, the M870A3 provides a productive, safe environment, in significantly less time over earlier M870 models.

M870A3 Semi-trailer Characteristics

Length 45 ft 5.3 in (1,385.1cm)
Width 8 ft 6 in (259.2cm)
Height Overall 105 in (266.7cm)
Ground Clearance at Axle 1 ft 2-3/4 in (37.5cm)
Fording Depth 20 in (50.8cm)
Weight GCVW 131,800 lb (59,837kg)
Payload 80,000 lb (36,320kg)
Weight Empty 23,950 lb (10,863kg)
Tires 13 275/70 R22.5 16 ply commercial, On/Off road tread
Brakes Air actuated S-cam, two-shoe, expanding, self-centering with ABS
Suspension Chalmers walking beam
Max Speed, Highway, 40-ton Load 55 mph (88.5 km/h)
Max Speed, Secondary/Gravel Roads, 40-ton Load 30 mph (48.3 km/h)

Table data from TM 5-2330-325-14&P

The full nomenclature for this trailer is TRAILER, MEDIUM HEAVY EQUIPMENT TRANSPORTER (MHET), 40 Ton M870A3. The M870A3 was assigned NSN 2330-01-458-2061.

The Operator's, maintenance and parts manuals for the M870A2 include:

  • TM 5-2330-325-14&P Trailer, Medium Heavy Equipment Transporter (MHET), 40 Ton, M870A3

The M870A3 was manufactured by Kalyn Siebert, Inc.

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