Multi-Unit Car

A multi-unit car is a railcar made up of two or more units permanently connected together and operated as a single car. The units are joined by drawbars or by articulation rather than by ordinary couplers, so the connected units stay together in normal service and move as one piece of equipment.

Drawbar-Connected and Articulated Units

There are two common ways to build a multi-unit car. In a drawbar-connected car, each unit has its own complete set of trucks, and the units are joined by a rigid drawbar in place of a coupler. In an articulated car, adjacent units share a single truck between them. Either way, the result is treated as one car for operating and record-keeping purposes.

How It Is Identified and Handled

Even though it is made of several units, a multi-unit car carries a single car ID and is registered and billed as one car. The individual units are designated by letters (for example, A and B at the ends) so that components, axles, and trucks can be located precisely for inspection and for Car Repair Billing. Building cars as multi-unit sets allows long or heavy loads to be carried on equipment that is lighter and handles better than a series of separately coupled cars would.