Motive power depot

Motive power depot, usually abbreviated to MPD, or railway depot is a term given to places where usually locomotives are housed when not being used, and also repaired and maintained. They were originally known as "running sheds", "engine sheds", or, for short, just sheds. Facilities are provided for refuelling and replenishing water, lubricating oil and grease and, for steam engines, disposal of the ash. There are often workshops for day to day repairs and maintenance, although locomotive building and major overhauls are usually carried out in the locomotive works.

MPDs in Britain are now often known as traction maintenance depots.

The equivalent of such depots in German-speaking countries is the Bahnbetriebswerk or Bw which has similar functions, with major repairs and overhauls being carried out at Ausbesserungswerke. The number of these reduced drastically on the changeover from steam to diesel and electric traction and most modern Bw in Germany are specialised depots, often responsible for a single rail class.

Engine sheds could be found in many towns and cities as well as in rural locations. They were built by the railway companies to provide accommodation for their locomotives that provided their local train services. Each engine shed would have an allocation of locomotives that would reflect the duties carried out by that depot. Most depots had a mixture of passenger, freight and shunting locomotives but some such as Mexborough had predominantly freight locomotives reflecting the industrial nature of that area in South Yorkshire. Others, such as Kings Cross engine shed in London, predominantly provided locomotives for passenger workings.

Nearly all depots at this time had a number of shunting locomotives. Normally 0-4-0T or 0-6-0T tank engines, these would be allocated to shunt turns and could be found in goods yards, carriage sidings, goods depots and docks.

Many large rail connected industrial sites also had engine sheds primarily using shunting locomotives.

Each railway company had its own architectural design of engine shed but there were three basic designs of shed:

The turntables for straight and dead end sheds were generally outside. Those in roundhouses could be inside (such as those at York in the Uk) or outside such as that at the East Broad Top Railroad & Coal Company Roundhouse, Rockhill, Huntingdon County, Pennsylvania, USA.

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