Historically, steam propulsion predominated until dieselisation occurred between the 1940s and 1970s. The most common types of modern locomotive are diesel and electric, the latter supplied by overhead wires or additional rails. Locomotives operating on mainlines are placed at the front, sometimes within the train (typically mid-train), and occasionally at the end. The term ' engine' is often used as an alternative to locomotive, although more specifically it applies to the machinery that conveys movement from the cylinders to the wheels in a steam locomotive, or the internal combustion propulsion machinery in a diesel locomotive. Ī train's motive power is provided by one or more separate locomotives or, in a self-propelled multiple unit, by under-floor motors. The word train comes from the Old French trahiner, derived from the Latin trahere meaning 'to pull, to draw'. A train is a form of rail transport consisting of a series of connected vehicles that generally run along a railroad (or railway) track to transport passengers or cargo (also known as 'freight' or 'goods').
