Turntable (rail)
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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.[1]
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[edit] Overview
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:
- the roundhouse that serves as the basis for the Baltimore and Ohio Railroad Museum in Baltimore, MD
- The Roundhouse in London, England, now an arts centre.
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: -
- Aberdeen
- Aviemore
- Barrow Hill
- Carnforth
- Churston
- Didcot
- Fort William
- Hornsey
- Kidderminster
- Keighley
- Neville Hill
- NRM York
- Old Oak Common
- Perth
- Pickering
- Scarborough
- St Blazey
- Swanage
- Tyseley
- Wansford
- Yeovil Junction
[edit] Unusual turntables
- 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.
[edit] Multiple turntables
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)
During the time, when Indian Railways was mostly private owned or state owned like South Indian Railway, Mysore State Railway etc. the Madras & Southern Maratha Railway (M&SMR) existed with Madras as HQ (now called Chennai). On this railway, there was a unique steam loco depot at Bitragunta, homing about 20 to 30 locos. The whole depot had one loco turntable with radial tracks to save space. Each line was meant for a different operation, like watering the tenders, loading coal, fire cleaning, dropping the fire etc. The shed is now defunct and the beautiful structure, like a large stadium, has been demolished.
[edit] See also
- 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.
[edit] References
- ^ The Elements of Railroad Engineering, 5th Edition, 1937, William G. Raymond. Published by John Wiley and Sons, New York
