US Air Force Airmen assigned to the 110th Civil Engineering Squadron, 110th Fighter Wing, upload a John Deere 444H Wheeled Excavator onto an M172 25-ton, Two-Axle, Low-bed, HET semi-trailer, being towed by an M818 5-ton (6x6) Tractor Truck, at Battle Creek Air National Guard Base, MI, 17 July 2005.
The M172 and M172A1 low-boy trailers are four-wheel, front goosenecked semi-trailers used for general transportation requirements. The two rear axles were equipped with four dual-tired wheels.
The 15-ton M172 low-bed semitrailer is used to transport outsized and heavy equipment over all types of roads, trails, and open cross-country terrain. Semitrailer, Low-Bed, M172A1 25-ton is identical in characteristics to the M172 except in its carrying capacity. The M172A1 can be towed over prepared roads with up to a 50,000-pound load.
Overall dimensions of the M172A1 are:
Length: 414 in. (10.52 m)
Width: 115 in. (2.92 m)
Height: 68 in. (1.72 m)
The M172 trailer is slightly shorter, at 406 inches, while the width is identical. These semitrailers have open wheel wells and a usable bed length of 192 inches. M172A1 has 19 lashing rings (D-rings); 5 on each side, 3 on the rear, and 6 on the gooseneck./p>
A stowage box with a pull handle is located on the top forward portion of the gooseneck. A kingpin extends below a fifth wheel upper plate and fits into the tractor fifth wheel when semitrailer is coupled.
When towed by the Truck, Tractor, M123 the semitrailers are designed to be towed over prepared roads at up to 50 miles per hour (mph) and over unimproved roads and open rolling terrain at up to 30 mph.
The manual covering operations and maintenance for the M172 and M172A1 low bed semirailers is TM 9-2330-211-14 dated October 1969. Based on that TM, the FSN for the M172 trailer is 2330-735-9326 and for the M172A1 is 2330-317-6448. Later versions of the manual are numbered TM 9-2330-211-14&P and use NSN format numbers.
An earlier version of the manual was TM 9-8222, dated November 1954.