A twin unit or twinset is a set of two

railroad Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a pre ...

cars A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, people in ...

or locomotives which are permanently coupled and treated as if they were a single unit. A twinset of cars or coaches can also be called a twin car. In US passenger railroad parlance, twin units are also known as married pairs. On passenger railroads, light rail, and

monorail A monorail (from "mono", meaning "one", and " rail") is a railway in which the track consists of a single rail or a beam. Colloquially, the term "monorail" is often used to describe any form of elevated rail or people mover. More accurat ...

services, married pairs may have machinery necessary for full operation of the cars split between them. Items that are typically shared include

transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...

motor controller A motor controller is a device or group of devices that can coordinate in a predetermined manner the performance of an electric motor. A motor controller might include a manual or automatic means for starting and stopping the motor, selecting forw ...

s, dynamic braking grids, cabs,

current collector Electric current collectors are used by trolleybuses, trams, electric locomotives or EMUs to carry electrical power from overhead lines, electrical third rails, or ground-level power supplies to the electrical equipment of the vehicles. Those for ...

s, batteries, and

air compressor An air compressor is a pneumatic device that converts power (using an electric motor, diesel or gasoline engine, etc.) into potential energy stored in pressurized air (i.e., compressed air). By one of several methods, an air compressor forces m ...

s. This provides significant savings in both cost of equipment and weight, which increases performance and decreases energy consumption. The cost of operating such a pair may be slightly higher when the extra car in such a pair is not needed to meet level-of-service demands at a particular time.

References

Rolling stock {{rail-transport-stub

See also

References