Multiple unit
type of train consisting of self-propelled carriages capable of coupling with others of the same or similar type
A multiple-unit train (or multiple unit (MU)) is a self-propelled train or trainset composed of one or more carriages joined, and where one or more of the carriages have the means of propulsion built in. By contrast, a locomotive-hauled train has all of the carriages unpowered.
An implication of this is that all powered carriages must be controllable by a single engineer or driver, which falls under the broader concept of multiple-unit train control. In other words, all "multiple units" employ some variation of multiple-unit train control. In the broader context, "unit" means any powered rail vehicle, including locomotives (that do not carry cargo) and powered cargo-carrying carriages. In the context of this article, "unit" refers specifically to the latter only (whether the cargo is passengers or some other cargo).
What follows is that if coupled to another multiple unit, all MUs can still be controlled by the single driver, with multiple-unit train control.
Although multiple units consist of several carriages, single self-propelled carriages – also called railcars, rail motor coaches or railbuses – are in fact multiple units when two or more of them are working connected through multiple-unit train control (regardless of whether passengers can walk between the units or not).
History
Multiple-unit train control was first used in electric multiple units in the 1890s.
The Liverpool Overhead Railway opened in 1893 with two-car electric multiple units, controllers in cabs at both ends directly controlling the traction current to motors on both cars.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Aug 18, 2026. The linked authority identifier is Q3959904. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1893.
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