These are the general terms for the trucking industry.
This truck is used to pull semi-trailers. The units are used for distances of less than 100 miles radius from the home terminal. These units are usually used for P&D (pickup & drop) and city work. Sometimes these shorter units are used to pull longer trailers (60'), which allows the unit to say within the overall legal length of 75' or 23 metres.
Driving empty to another location to pick up a load, or returning home.
It is an axle with a 5th wheel assembly and a hitch. The hitch is usually a pintle hitch. The dolly converter is used to hook two semi-trailers together.
Is anything that aids in securing the load to the truck or trailer. Material such as pieces of wood, matting, shrink wrap, or similar material used to keep a cargo in position while being transported.