| A | B |
|---|
| gross axle weight rating | maximum weight an axle is rated to carry by the manufacturer; includes both weight of axle and portion of vehicle’s weight carried by the axle |
| gross combination weight | total weight of a loaded combination vehicle, such as a tractor-semitrailer or truck and full trailer(s) |
| gross vehicle weight | total weight of a vehicle and everything aboard, including its load |
| gross vehicle weight rating | total weight a vehicle is rated to carry by the manufacturer, including its own weight and the weight of its load |
| hazardous materials | dangerous substances, as classified by the U.S. Environmental Protection Agency (EPA); transport of hazmat is strictly regulated by U.S. Department of Transportation |
| headache rack | heavy protective barrier mounted behind the tractor’s cab; prevents “headaches” caused by load shifting forward from the trailer and crushing the cab |
| jackknife | to place the trailer at a very sharp angle to the tractor |
| kingpin (axle) | pin around which a steer axle’s wheels pivot |
| kingpin (trailer) | anchor pin at the center of a semitrailer’s upper coupler which is captured by the locking jaws of a tractor’s fifth wheel to attach the tractor to the semitrailer |
| landing gear | retracting legs which support the front of a semitrailer when it is no coupled to a tractor |
| load range (tires) | letter code system for the weight-carrying capacity of tire |
| lowboy | open flat-bed trailer with a deck height very low to the ground, used to haul construction equipment or bulky or heavy loads |
| overdrive | gearing in which less than one revolution of a transmission’s input shaft causes one turn of the output shaft |
| payload | weight of the cargo being hauled |
