Twin unit
Two railcars operating together as one
A twin unit, twinset, or double unit is a set of two railroad cars 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 services, married pairs may have machinery necessary for full operation of the cars split between them. Items that are typically shared include transformers, motor controllers, dynamic braking grids, cabs, current collectors, batteries, and air compressors. 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.
Sources and credits
This article is adapted from the Wikipedia article “Twin unit”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Trams at Cabin, Blackpool - geograph.org.uk - 1632323.jpg by Dr Neil Clifton, CC BY-SA 2.0
- Hugh llewelyn 3168 (5707290830).jpg by Hugh Llewelyn, CC BY-SA 2.0
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