locomotive

A locomotive is a rail vehicle that provides the motive power for a train. It converts energy into traction to move assembled cars, usually pulling them, though it can perform pushing duties in some service. Locomotives do not typically carry the train’s passengers or cargo themselves; those are carried by the rest of the train.

There are several propulsion types: steam locomotives burn fuel to boil water and drive a piston or turbine; diesel locomotives use a diesel engine to drive a generator or hydraulic torque; electric locomotives draw power from overhead lines or a third rail and use traction motors. Hybrid designs exist but are rare.

History: The first practical locomotives appeared in the early 19th century. Richard Trevithick built the earliest steam locomotive; George Stephenson’s Rocket (1829) helped establish standard railways. Diesel-electric locomotives became dominant in the mid-20th century; electric locomotives expanded where infrastructure allowed, especially for high-volume routes.

Key components include the prime mover (steam engine, diesel engine, or electric traction motors), transmission, wheelsets and bogies, brakes, fuel or energy storage, control cab, and couplers. Electric locomotives typically use pantographs to collect power from overhead lines.

Locomotives are rated by power and tractive effort; wheel arrangements and gauge vary by region and design. They remain central to rail freight and long-distance travel, though many passenger and some freight operations now use multiple-unit or distributed propulsion systems.