Multiple-unit train control: Difference between revisions

Revision as of 12:25, 17 November 2017

Revision as of 04:12, 8 February 2018

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'''Multiple-unit train control''', sometimes abbreviated to '''''multiple-unit''''' or '''''MU''''', is a method of simultaneously controlling all the traction equipment in a [[train]] from a single ___location, whether it is a [[Multiple unit]] comprising a number of [[Self-powered car|self-powered]] passenger cars or a set of locomotives.

A set of vehicles under multiple unit control is referred to as a [[consist]] in the United States.<ref>[http://www.railway-technical.com/newglos.shtml#C Railway Technical Web Pages:Modern Railway Terminology] {{webarchive|url=https://web.archive.org/web/20141007220720/http://www.railway-technical.com/newglos.shtml |date=2014-10-07 }} ''railway-technical.com''</ref><!-- a better reference is needed-->

==Origins==

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Terms used in North America are A unit and B unit where the B or "slave" unit does not have a control cab; [[slug (railroad)|slug]] where the B unit has traction motors powered by the "mother" unit via extra connections; and [[Cow-calf]] for [[switcher]] units. A [[Control Car Remote Control Locomotive]] has remote control but not traction equipment.

Most modern [[diesel locomotive]]s are now delivered equipped for MU operation, allowing a consist (set) of locomotives to be operated from one cab. Not all MU connections are standardized between manufacturers, thus limiting the types of locomotives that can be used together. However, in North America there is a high level of standardization between all railroads and manufacturers using the [[Association of American Railroads]] (AAR) system which allows any modern locomotive in North America to be connected to any other modern North American locomotive.<ref>[http://www.railway-technical.com/us-musp.shtml US Loco MU Control<!-- Bot generated title -->] {{webarchive|url=https://web.archive.org/web/20080201090339/http://www.railway-technical.com/us-musp.shtml |date=2008-02-01 }}</ref> In the [[United Kingdom]] several different incompatible [[Multiple working|MU systems]] are in use (and some locomotive classes were never fitted for MU working), but more modern diesel locomotives used on British railways use the standard [[Association of American Railroads]] system.

Modern locomotive MU systems can be easily spotted due to the large MU cables to the right and left of the [[Railway coupling|coupler]]. The connections typically consist of several air hoses for controlling the [[air brake (rail)|air brake]] system, and an electrical cable for the control of the traction equipment. The largest hose, located next to the coupler, is the main air brake line or "train line". Additional hoses link the air compressors on the locomotives and control the brakes on the locomotives independently of the rest of the train. There are sometimes additional hoses that control the application of sand to the rails.