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semi truck, or semi tractor trailer, and 18 wheeler.
Semi or Tractor Trailer-semi.
3-6 mpg
Four to eight miles per gallon, all factors dependent.
The word semi means half, or part.The tractor and trailer are two parts, hence semi truck and or trailer.
You call it a semi because it pulls a semi trailer.A semi is a type of trailer. A semi-trailer, as opposed to a full trailer, means it only has axles at the rear of the trailer and a full trailer has axles at the front and rear of the trailer. We call these in the UK "drags", as in wagon and drag, where the wagon that pulls the drag can carry a load on its own, whereas the semi-trailer truck, or tractor unit cannot carry anything without a trailer.
The semi truck is also known as a tractor trailer
semi cab
The "tractor" is the vehicle which actually powers the combination. A semi-trailer is any trailer in which the weight of the trailer (and the payload) is shared between the trailer's axles and the axles of either a dolly or the towing unit (in contrast, a full trailer supports all of its own weight).
The prefix "semi-" means "half", and the standard tractor-trailer articulated vehicle is called a "semi" because of the trailers they pull. A "full" trailer has wheels in the front and back, like a railway car, and connects to the tractor from the front. A "semi-trailer" (or, essentially, "half-trailer") only has wheels in the back, and the front sits over the back wheels of the tractor pulling it.
An articulated lorry is a truck and trailer - a combination involving a tractor unit and a semi-trailer, known in the United States as a semi-trailer truck.
It's used to refer to the power unit of a semi-articulated tractor-trailer. In reality, any truck pulling a trailer could be considered a truck tractor.