The Heavy Expanded Mobility Tactical Truck (HEMTT) is an eight-wheel drive, diesel-powered, tactical truck used by the US military and others. In evolving configurations it has been in continuous production since 1982.
There are seven main configurations of the HEMTT series trucks: M977 cargo truck (three variants), M978 9,500 liter tanker, M983 tractor, M984 wrecker, M985 cargo truck (two variants), M1120 LHS and M1977 CBT. A tactical fire-fighting truck (M1142 TFFT) and support tanker (M1158 HEWATT) are also available, as is a Terminal (formerly Theatre) High Altitude Area Defense (THAAD) missile launcher.
By early 2015 more than 27,000 HEMTTs in various configurations had been produced by Oshkosh Defense through either new-build or re-manufactured. Current variants have the A4 suffix.