Eighteen Wheeler

Description: A semi-trailer truck (more commonly semi truck or simply "semi") is the combination of a tractor unit and one or more semi-trailers to carry freight. A semi-trailer attaches to the tractor with a fifth-wheel coupling (hitch), with much of its weight borne by the tractor. The result is that both the tractor and semi-trailer will have a distinctly different design than a rigid truck and trailer. It is variously known as a transport in Canada; semi or single in Australia and New Zealand; semi, tractor-trailer, big rig, or eighteen-wheeler in the United States; and articulated lorry, abbreviated artic, in the United Kingdom, Ireland and New Zealand.