| A | B |
|---|
| pigtail | cable used to transmit electrical power from the tractor to the trailer |
| pounds per square inch | in trucking, unit of measurement for tire air pressure, air brake system pressure and turbocharger boost |
| retarder / jake brake | device used to assist brakes in slowing the vehicle. |
| revolutions per minute | Measure of the speed at which a shaft spins; most often used to describe engine crankshaft speed; indicated by a tachometer |
| runaway truck ramp / escape ramp | emergency area adjacent to a steep downgrade that a heavy truck can steer into after losing braking power |
| semitrailer | truck trailer supported at the rear by its own wheels and at the front by a fifth wheel mounted to a tractor or dolly |
| sleeper | sleeping compartment mounted behind a truck cab, sometimes attached to the cab or even designed to be an integral part of it |
| sliding fifth wheel | fifth wheel mounted to a mechanism that allows it to be moved back and forth to adjust the distribution of weight on the tractor’s axles; and to vary vehicle combination lengths |
| tractor / truck tractor / highway tractor | truck designed primarily to pull a semitrailer by means of a fifth wheel mounted over the rear axle(s). |
| tractor trailer | tractor and semitrailer combination |
| truck / straight truck | vehicle which carries cargo in a body mounted to its chassis, rather than a trailer towed by the vehicle |
| Vehicle Identification Number | assigned by the manufacturer, this number is unique to each vehicle and appears on the vehicle’s registration and title |
| weigh-in-motion | technology for determining a vehicle’s weight without requiring it to come to a complete stop |
