In 1993 the U.S. Army started fielding the M1070 Truck Tractor and the M1000 Heavy Equipment Transporter Semi-trailer. The tractor is produced by Oshkosh Truck, and the trailer is manufactured by Systems & Electronics, Inc. in St. Louis. The HETS transports payloads up to 70 tons – primarily Abrams tanks, but is also used for other large military equipment such as forklifts and various tracked vehicles. It is capable of operating on highways (with permits), secondary roads, and cross-country. This version of HETS has a number of features that significantly improve the mobility and overall performance of the system in a tactical environment. The M1070 tractor has front- and rear-axle steering, a central tire-inflation system, and cab space for six personnel to accommodate the two HETS operators and four tank crewmen. The M1000 semi-trailer has automatically steerable axles and a load-leveling hydraulic suspension. It is air-transportable by both C-5 Galaxy and C-17 Globemaster III aircraft.