In rail terminology, a turntable is a device used to turn railroad rolling stock. When steam locomotives were still in wide use, many railroads needed a way to turn the locomotives around for return trips as their controls were often not configured for extended periods of running in reverse and in many locomotives the top speed was lower in reverse motion. Turntables were also used to turn observation cars so that their windowed lounge ends faced toward the rear of the train.
The turntable bridge (the part of the turntable that included the tracks and that swiveled to turn the equipment) could span anywhere from 6 to 120 feet, depending on the railroad's needs. Larger turntables were installed in the locomotive maintenance facilities for longer locomotives, while short line and narrow gauge
railroads typically used smaller turntables as their equipment was smaller. Turntables as small as 6 feet in diameter have been installed in some industrial facilities where the equipment is small enough to be pushed one at a time by human or horse power.
In engine maintenance facilities, a turntable was usually surrounded, in part or in whole, by a roundhouse. It was more common for the roundhouse to only cover a portion of the land around a turntable but fully circular roundhouses exist, such as these preserved roundhouses:
Turntables still in use are more common in North America than in Europe, where locomotive design favors configurations with a controller cabin on both ends or in the middle.
In Britain, where steam hauled trains generally have vacuum operated brakes, it was quite common for turntables to be operated by vacuum powered motors worked from the locomotive's vacuum ejector or pump via a flexible hose or pipe although a few manually and electrically operated examples exist. Several working examples remain; many on Heritage railways in Great Britain. Examples include: -
Chicago B. & Q.R. Co. v. Krayenbuhl
- Near the turn of the century, a four year old child was playing on an unlocked, unguarded railroad turntable. Other children set the turntable in motion, and it severed the ankle of the young child. The child's family sued the railroad company on a theory of negligence and won at trial. The Nebraska Supreme Court held that the Railroad company may have been liable for negligence after considering the "character and location of the premises, the purpose for which they are used, the probability of injury therefrom, the precautions necessary to prevent such injury, and the relations such precautions bear to the beneficial use of the premises." However, the Supreme Court reversed the trial court's decision based on an improper jury instruction as to the evidence.
- In one location in France, lack of space forced the installation of an asymmetric turntable, where the pivot point was about one-third along its length. Such a turntable cannot rotate 360 degrees.
- At Ventnor railway station, due to lack of space a small turntable was provided to allow steam engines to run around their trains. Similarly Bembridge railway station.
Stations housing large numbers of engines may have more than one turntable:
- - Royal Oak near Paddington - 4
- Enfield - 2
- Broadmeadow - 2
- Linwood - Formerly 2 (second removed during 1980/1990's)
- Wye - a way of turning whole trains.
- Transfer table (UK: 'traverser') - provides access to two or more parallel tracks in a space saving manner like a turntable, but without the ability to turn.