A prime mover is the motorized front section of an articulated truck, housing the engine, cab, and the fifth wheel coupling used to attach a trailer. It carries no freight itself, serving entirely to pull unpowered trailing units. The term is widely used in fleet management and vehicle registration to distinguish the power unit from the cargo-carrying trailers.
Heard on the job
Disconnect the prime mover from the flatbed and take it to bay four for an oil change.
Insider tip
While tractor is the common term in North America, prime mover is the standard regulatory and industry term in Australia, New Zealand, and parts of Asia.
Also heard as
- tractor
- cab
- tractor unit