Bobtail Truck Definition

by Will Charpentier

Two kinds of trucks carry the moniker "bobtail." Both are short, like the tail on a bobcat. One is a semi tractor without a trailer. The other is a straight truck, in which all of the truck's axles are attached to the same chassis. Straight trucks that transport propane gas are also known as bobtails.


In trucker's slang, a bobtail is the tractor part of a semi. Usually truckers "run bobtail" when they have no trailer to pull. For example, when they leave a loaded trailer at its destination and must drive to a new location to pick up a different trailer, the tractor alone, because it's shorter than a tractor and trailer, is called a bobtail.

Short and Straight

The U.S. Department of Energy calls a straight truck that's used to carry propane a bobtail. Such trucks, DoE says are powered by propane and have a tank that's significantly shorter than other petroleum transport trucks.

About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.

Photo Credits

  • photo_camera Tim Boyle/Getty Images News/Getty Images