US Military HEMTT

The Truck, Cargo: 10-Ton, 8x8 Heavy Expanded Mobility Tactical Truck (HEMTT) went into service with the U.S. Army in 1982, a replacement for the M-520 GOER. The HEMTT mission is to provide heavy transport capabilities for supply and re-supply of combat vehicles and weapons systems, for the Army and Marine Corps. Having proved itself as a key workhorse of the heavy tactical wheeled vehicle fleet, about 13,000 HEMTT vehicles were in service over 20 years later. HEMTT operated successfully both on-road and off-road for the U.S. Army and Marine Corps.

Kansas Army National Guard 778th Transportation Company, M977 Truck, Cargo: 10-Ton, 8x8 Heavy Expanded Mobility Tactical Truck (HEMTT) in convoy toward Alexandria, LA, after a rest stop in Shreveport, 29 September 2005
Kansas Army National Guard 778th Transportation Company, M977 Truck, Cargo: 10-Ton, 8x8 Heavy Expanded Mobility Tactical Truck (HEMTT) in convoy toward Alexandria, LA, after a rest stop in Shreveport, 29 September 2005.

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Heavy Expanded Mobility Tactical Truck (HEMTT)

All of the vehicles in the HEMTT family are manufactured by Oshkosh Truck Corporation of Oshkosh, WI. There are five basic configurations of the HEMTT series trucks plus the M1120 HEMTT Load Handling System and M1977 HEMTT Common Bridge Transporter:

The M1120 HEMTT LHS consists of a standard HEMTT M977, M978 or M985 chassis equipped with an integral load-handing system. Additional information and photos of the specific models are found on the linked pages. The M1977 Common Bridge Transporter (CBT) is a modification of the HEMTT M1120 for the purpose of supporting the Engineer Corps in transporting all bridging assets.

M977 Truck, Cargo: 10-Ton, 8x8 Heavy Expanded Mobility Tactical Truck (HEMTT)
M977 Truck, Cargo: 10-Ton, 8x8 Heavy Expanded Mobility Tactical Truck (HEMTT)

Another HEMTT-based vehicle system is the M1142 Tactical Firefighting Truck and its associated water tender. The M1142 Tactical Firefighting Truck (TFFT) is a standard M977A2 HEMTT chassis carrying an add-on commercial firefighting package. The XM1158 HEMTT-based Water Tender (HEWATT) supports Army requirement for a water tender capability for Army Engineer Firefighting detachments and Ordnance Ammunition Companies. HEWATT carries a 2,500 gallon polypropylene water tank, a Darley 500 gpm pump (hydraulic drive), a booster reel with capacity for 200 feet of 1.0 inch booster hose (electric rewind), 400 feet of 3.0 inch inlet and fill valving identical to the TFFT. HEWATT procurement is planned for FY2008-2009, replacing the M916 LET tractor combined with a water tank semitrailer.

In addition to these HEMTT variants, M985 HEMTT is used as a prime mover for the Patriot missile system, Pershing II missile system, M7 forward repair system (FRS) and tactical water purification system (TWPS). The HEMTT is augmented by the M989A1 Heavy Expanded Munitions Ammunition Trailer (HEMAT) in the transport of Multiple-Launch Rocket System (MLRS) family of munitions.

Manuals for the HEMTT series of trucks are numbered TM 9-2320-279-xx where the xx represents the maintenance level. All together there are dozens of multi-volume manuals for the series of trucks.

Find additional photos and hi-res versions of the Heavy Expanded Mobility Tactical Truck (HEMTT) at the Olive-Drab Military Mashup.

HEMTT Recapitalization, Repair & Return Program (R3)

HEMTT vehicles performed well and had high readiness until the Operation Desert Storm in 1991. After that severe test, the HEMTT fleet had difficulty meeting the Army readiness goal of 90 percent. By the early 2000s, although remaining a critical resource, the HEMTT vehicles were two decades old and required an update.

The HEMTT Recapitalization Program was established in October 2001. The priority units to receive new and recap vehicles were Stryker brigades, Patriot battalions, counterattack corps, and other high priority units including the Army National Guard and Reserve. In FY2003, 621 trucks were contracted for the Recap program. However, trucks to feed the Recap program were hard to find since the Post-9/11 demands on active and reserve component units left few HEMTT vehicles uncommitted.

In December 2002, the Army and Oshkosh developed an innovative rapid rebuild program called Recap, Repair and Return (R3) to provide turnaround of vehicles fast enough to break the bottleneck. With R3 the turnaround was reduced to 100 days, including shipping time. That is, a unit could turn in a well-worn HEMTT and in 100 days receive a zero miles/zero hours, like-new replacement vehicle.

R3 began with III Corps who "picked their worst dogs from across the corps to send in." A HEMTT vehicle carcass was accepted for R3 even if not operational, so long as it had a complete power train (engine, transmission, and transfer case), axles, frame rails, and crane. R3 was successful for III Corps and became a model for reconstitution programs for the repair of battle-damaged equipment returning from Operation Iraqi Freedom.

Vehicles that have been process through the R3 program are designated by suffix R1 on their model number. For example, M1120A2 becomes M1120A2R1.

HEMTT Specifications

Standard HEMTT features include front and rear tow eyes, blackout lights, 24-volt electrical system, and rear pintle hook for towing trailers and artillery. All models are C130, C141 and C17 air transportable, a requirement for the highly mobile brigade combat teams. All HEMTT models are capable of fording water crossings up to 48 inches deep. A self-recovery winch is available on all models.

  M977 M978 M985 M983 M984
Length 401 in 401 in 401 in 351 in 392 in
Height (all) Operational 112 in, Transport 102 in
Width (all) 96 in
Wheelbase 210 in 210 in 210 in 181 in 191 in
Turning circle 100 in 100 in 100 in 91 in 95 in
Ground clearance (all) 24 in
Vehicle curb weight 38,800 lbs; w/o winch - 37,900 lbs 38,200 lbs; w/o winch - 37,300 lbs 39,600 lbs; w/o winch - 38,700 lbs 39,200 lbs; w/o crane - 32,200 lbs 50,900 lbs
Max speed (all) 57 mph
Cruising range (all) 300 mi
Maximum grade (all) 60% with payload of 22,000 lbs
Engine (all) 450 hp @ 2100 rpm Detroit Diesel Allison Model 8V92TA. 8 cylinder, 2-stroke, V-type Diesel. An electronic controller for the engine went into production in April 2002.
Transmission (all) 4-speed automatic & 2-speed Oshkosh transfer case w/ air-operated front tandem axle disconnect. A new electronic transmission went into production in April 2002.
Crew(all) Two

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