What’s the Difference Between a Semi-Truck and a Semi-Trailer?

A lot of names are used interchangeably to refer to a cargo carrying truck. Semi-truck, semi-trailer, tractor-trailer, 18-wheeler, the list goes on. Though everyone understands that you’re referring to a truck when you use any one of these terms, they actually don’t all mean the same thing.

A semi-truck refers to the actual truck, which contains the engine. A semi-truck can run on its own without a trailer, in fact you’ve probably seen semi-trucks on the highway occasionally without a trailer in tow. This brings us to our next term, semi-trailer.

A semi-trailer is hauled by the semi-truck. It has wheels but no front axle and no engine, so it can’t move on its own. The trailer contains the cargo which is being hauled. The semi-truck also supports a lot of the weight of a trailer when the two are attached.

Tractor-trailer and 18-wheeler both refer to the combination of a semi-truck and semi-trailer. Together, they form a tractor-trailer unit, also referred to as an 18-wheeler, owing to the number of wheels present on the unit as a whole.


trucking lingo


Evan Transportation was founded in 1992 by Jerry Wolfarth, who at the time had over 25 years of experience in the trucking and transportation industry. The initial operation consisted of a few trucks and drivers who were dedicated and professional. The goal of the company was to provide excellent, dependable service.

If you need materials and products moved in the Mid-Atlantic region, contact Evan Transportation. We hire professional drivers with excellent driving records, and maintain a fleet of trailers and vehicles that are reliable and ready to roll.

Contact us today for all of your freight shipment needs or call us at 443-673-3365

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