A yard mule, also called a yard jockey or terminal tractor, is a specialized truck used to move trailers around warehouse yards. Unlike road tractors, a yard mule has a short wheelbase, a single-person cab, and a sliding rear door for quick access to trailer hoses. It is built for speed and maneuverability in tight spaces, allowing operators to spot trailers at loading docks in a fraction of the time.
The most important feature of a yard mule is its hydraulic fifth wheel. The operator can lift the trailer front end without getting out of the cab to crank the landing gear up and down. This saves time and physical effort. Because they are not driven on public highways, yard mules do not need to meet standard highway emission or licensing laws and are kept strictly on terminal property.