power units

Noun

power unit (plural power units)

1. A truck (large road vehicle) capable of moving under its own power.
   • The combination unit was traversing a straight section of roadway, on an approximate 4 percent upgrade, when the tractor began to jackknife. As the power unit rotated clockwise, it left the roadway to the right and traveled several feet before the driver corrected the jackknife. The unit was...1988 October 12, National Transportation Safety Board, “CASE NO. 9”, in Safety Study: Case Summaries of 189 Heavy Truck Accident Investigations, archived from the original on 17 Feb 2017
2. Any other unit capable of providing power.
   • For many years the horse provided a cheap and effective power unit for town cartage, but in recent years it has been replaced largely by mechanical power.1944 November and December, T. F. Cameron, “Motor and Cartage Working”, in Railway Magazine, page 335