Turntables are circular platforms used to turn locomotives and rolling stock. They were developed because early steam locomotives were difficult to operate in reverse. Most modern locomotives have a reverse gear, but turntables are still used where steam locomotives are used or space to maneuver is limited. Laneways are triangular tracks that allow trains to change direction. Turntables can also be used for cable cars and trams. A famous cable car turnaround can be found in San Francisco.
A turntable is a large circular platform that is used to turn locomotives and other rolling stock for railroads. A well-designed turntable is designed in such a way that the efforts of only two or three people are needed to operate the turntable, even when dealing with very large and heavy locomotives. A related railway term is “wye,” a term used to describe a special configuration of track that essentially allows trains to make really big three-point turns so they can turn in the direction they came from.
The reason the turntable was developed was because early steam locomotives were somewhat difficult to operate in reverse. In some cases, the locomotives lacked a reverse gear altogether, and in other cases, the reverse speed was very slow and awkward, which could be a hindrance in a busy switching station or hub. As a result, railroad companies began building turntables so they could turn their locomotives around quickly.
To use a turntable, a locomotive or railroad car is driven or pushed onto the platform and locked into place before the platform is rotated to face in a new direction. As well as being used to turn rolling stock 180 degrees, turntables can also be used to shunt locomotives onto sections of track positioned at a variety of angles to the turntable. Once the platform has been turned and locked in place, the locomotive can be unlocked and moved.
Most modern locomotives either have a reverse gear, or are capable of running in both directions, making them very easy to move. However, turntables are still in use at railway companies where steam locomotives are used and on sites where room to maneuver is limited, encouraging the use of a space-efficient turntable to move locomotives.
Laneways, on the other hand, are made by creating a series of roughly triangular tracks, allowing trains to move back and forth along the star’s arms to change direction. In addition to being used to turn a train, a star can also allow a train to move to give way to another train on the same track.
As well as being used for locomotives, a turntable can also be used for cable cars and trams, in which case the car’s catch mechanism must be detached before being rolled onto the turntable. For people who want to see a turntable in action, a well-known cable car turnaround can be found in active use at Market and Powell Streets in San Francisco, California; turntables can also be seen in railway museums.
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