railcar

Railcar is a self-propelled railway vehicle designed to transport passengers or freight, and it is distinct from a locomotive that pulls unpowered cars. The term covers lightweight passenger cars with their own propulsion—such as diesel- or electric-powered motor cars—as well as certain light freight and service vehicles used on railways. Railcars may operate singly or as part of a multiple-unit train.

In passenger service, railcars include diesel multiple units (DMUs), electric multiple units (EMUs), and stand-alone motor cars sometimes referred to as railcars or autocars. Railbuses are lightweight, economical units designed for low-demand, rural lines. Historically, steam-powered railcars appeared in the 19th century and were later displaced by diesel and electric propulsion.

In freight operations, railcars are less common; most freight is moved by locomotives pulling unpowered wagons. However, self-propelled service and maintenance vehicles—maintenance-of-way cars, hi-rail inspection vehicles, and other motorized workcars—are widely used for track inspection, repair, and yard operations. Modern railcars typically use diesel-electric or pure electric propulsion, with powertrain mounted in the car body and controlled from a cab.

Design and performance features vary, but common elements include a steel or aluminum body, integrated or adjacent driving cabs, standardized couplers, and braking systems that combine air brakes with dynamic or electric braking on powered units. Railcars are favored on short lines and dense urban routes where a full locomotive-hauled train is unnecessary or impractical due to lower speed, capacity, or infrastructure constraints.