Semi-trailer truck

Combination of a tractor unit and one or more semi-trailers to carry freight

A semi-trailer truck (also known by a wide variety of other terms – see below) 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 type of hitch called a fifth wheel. Semi-trailer trucks replaced traction engines in commercial and heavy haulage roles.

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