Multiple-unit train control
Overview
 
Multiple-unit train control, sometimes abbreviated to multiple-unit or MU, is a method of simultaneously controlling all the traction equipment in a train
Train
A train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...

 from a single location, whether it is a Multiple unit
Multiple unit
The term multiple unit or MU is used to describe a self-propelled carriages capable of coupling with other units of the same or similar type and still being controlled from one driving cab. The term is commonly used to denote passenger trainsets consisting of more than one carriage...

 comprising a number of self-powered passenger cars or a set of locomotives.

A set of vehicles under multiple unit control is referred to as a consist
Consist
A consist , in North American railway terminology, is used as a noun to describe the group of rail vehicles that make up a train. A near-equivalent UK term is rake but this excludes the locomotive....

 in the United States.
Multiple-unit train control was first used in Electric Multiple Unit
Electric multiple unit
An electric multiple unit or EMU is a multiple unit train consisting of self-propelled carriages, using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages...

s in the 1890s.
The multiple unit traction control system was pioneered by Frank Sprague
Frank J. Sprague
Frank Julian Sprague was an American naval officer and inventor who contributed to the development of the electric motor, electric railways, and electric elevators...

 and first applied and tested on the South Side Elevated Railroad
South Side Elevated Railroad
The South Side Elevated Railroad was the first elevated rapid transit line in Chicago, Illinois. The line ran from downtown Chicago to Jackson Park, with branches to Englewood, Normal Park, Kenwood, and the Union Stock Yards...

 (now part of the Chicago 'L'
Chicago 'L'
The L is the rapid transit system serving the city of Chicago and some of its surrounding suburbs. It is operated by the Chicago Transit Authority...

) in 1897.

In 1895, derived from his company's invention and production of direct current elevator control systems, Frank Sprague invented a multiple unit controller for electric train operation.
 
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