Rail motor

Railmotor is a term which was used by several British railway companies for a lightweight railcar, that is, a railway carriage with a small steam traction unit or diesel or petrol engine integrated into it.

In the earliest days of railways, designers wished to produce a vehicle for passenger carrying that was economical to build and operate on routes where passenger numbers were light. A single coach with its own prime mover was a solution adopted in some cases; this may be thought of as the predecessor to the railcar, a term more associated with the use of internal combustion engines.

William Bridges Adams started building railmotors in small numbers as early as 1848. The Bristol and Exeter Railway used a steam carriage.

In most cases the early designs were unsuccessful technically, but in the early years of the twentieth century, street-running passenger tramways started to use small steam engines to draw tramcars, replacing the customary horse traction. In many cases the tramways soon adopted electric traction instead, and the attractiveness of the cheap and frequent conveyance abstracted business from the railways in urban areas.

The railways responded by opening new stopping places (to serve more closely the new suburban housing) and sought to reduce their operating cost by reintroducing railmotors, which were cheaper to construct.

The London and North Western Railway, Lancashire and Yorkshire Railway, London Brighton and South Coast Railway and Great Western Railway introduced them.

Nonetheless the railmotors had a number of disadvantages: their frequency, and the closeness of their stopping places, could not match that of the tramcars. The intrinsic compromises in fitting a steam engine inside the limited space available made them mechanically inefficient, and their power was (in most designs) insufficient to handle attached vehicles for parcels or additional coaches at times of exceptional demand such as public holidays; and in nearly all cases they still required a three-man crew (driver, fireman and guard), a significant expense compared with the single crew member of a tramcar.

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