turntable
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A turntable is a device for the horizontal turning of rail vehicles , less often of road vehicles. This process was mainly carried out on steam locomotives with tender , which can only travel in the forward direction at their maximum speed. In addition, turntables are used to move a vehicle to adjacent tracks in a space-saving manner, for example to accommodate them in locomotive sheds or as a replacement for shooting curves in railway guns . A rotating part in the form of a bridge is sometimes called a revolving platform .
construction
The turntables developed from simple systems that were arranged in the track area in early train stations to turn locomotives in the opposite direction of travel. They were covered to protect people from falling into the pit and therefore looked like windows.
The turntable is a mechanical system with which a vehicle (mostly rail vehicle) can be turned, or with which a route can optionally be created between two or more tracks. The turntable is often used to connect radially arranged tracks in a narrow space (often referred to as fan-shaped tracks ). With the turning function, locomotives or other vehicles can be brought into a desired position. A distinction is made between cross-type turntables (in simple conditions, e.g. in mining and on field railways), segment turntables (in confined spaces, e.g. in connecting railways) and bridge turntables with and without towing frames. It is always a steel structure with bridges carrying the running rails to accommodate the vehicles. The turntable pits are circular or designed as a segment of a circle and can have different diameters.
The size of the turntables grew with the length of the locomotives. In Prussia, eight to twelve meters were initially sufficient, in 1889 14 meters were required, in 1892 16 meters. Standard turntables of the Deutsche Reichsbahn had a diameter of 20 meters in 1920, from 1928 then 23 and later 26 meters, in Switzerland 13 or 16 meters, but other dimensions are also possible.
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The turntable bridge is supported in the central pivot point on the so-called king's chair and at both ends with running wheels that are usually without flange and roll on the turntable running ring installed in the turntable pit. In the case of larger turntables, several turntable races are often found. Smaller turntables were and are moved by muscle power, in the 20th century electric motors were used, and in rare cases also diesel engines and compressed air. The compressed air drive is usually the emergency drive, it is supplied by the compressed air system of a motor vehicle to be turned. With motor-driven turntables, two of the four wheels are usually driven. Early turntable bridges consisted of a one-piece girder, in which the support on the king's chair and the running wheels is not clearly determined and is dependent on the accuracy of the running ring design. With a one-sided drive, the vehicle to be turned must be parked on the bridge in such a way that the driven wheels are sufficiently loaded. As the length of the turntable bridges increased, this indefinite requirement became more problematic. As a result, articulated turntables were developed. The bridge girder is provided with a joint in the middle above the king's chair. Both parts rest evenly and stably on three points each, the wheels are always loaded. In addition, the span is reduced to about half, the girders can be made lower. This also reduces the necessary depth of the turntable pit.
A secure connection by means of a locking device must be able to be established between the turntable bridge and the attached fixed track. This locking device is often coupled with maneuvering signals and the turntable control.
Another way of turning rail vehicles around is with track triangles , track pentagons or turning loops . With the appropriate connection lengths, railcar units or longer trains can also be turned as a whole. In North and South America in particular, this was and is still the norm, especially for train units that are designed for only one main direction of travel.
use
Rail vehicles
Since most steam locomotives with a tender are only allowed to travel at full speed when moving forward, it is necessary to turn such a locomotive if the journey is to be started in the opposite direction. Turntables were therefore mainly located at terminal stations , for example the first train station in Altona or the Berlin train station in Hamburg . In railway depots they were located directly in front of the locomotive shed, which were designed as roundhouse sheds in large depots . There they also enabled access to the individual stands, which otherwise would only have been possible with an elaborate route. In addition, the turntable enables the locomotives to be parked in one direction, usually with the smoke chamber facing the turntable. This means that each shed only needs one chimney, and it is also possible to pull the boiler tubes while the locomotive is in the shed. In the 1950s in particular, the great decline of steam locomotives took place, and with it that of the turntables, too.
Nowadays, transfer platforms are mainly installed in railway depots , as they make it possible to operate several parallel tracks with the smallest space requirement. You only need a parallel access track and you can then use storage facilities on both sides of the stage (Neustrelitz, Dresden Altstadt).
Many locomotives operated by European railway administrations are usually bidirectional vehicles that do not require a turntable. As a result, turntables have become rare in regular rail operations, but can still be seen frequently in railroad museums. A new building that has been considered for practical reasons, such as the Vitznau-Rigi Railway in 1988 , is a rarity. It is more likely that, as with the Minehead Railway Station, a revolving platform removed in 1968 is rebuilt in 2008 for primarily nostalgic reasons. This is different in North America, Australia and New Zealand, where many locomotives only have a driver's cab on one side, especially large, diesel-electric ones. This means that even more turntables are in constant use there and are even sometimes built from scratch (for example by the Canadian Pacific Railway in East Binghamton (New York) shortly before 2000).
Large turntables were the ones used by the Union Pacific Railroad in 1941 for their class 4000 steam locomotives, called the "Big Boy" (overall length: 132 ft 9¼ in (40.47 meters), overall axle base: 117 ft 7 in (35.83 meters) ), built 135-foot turntables (41 meters) in Ogden, Utah , Green River, Wyoming, and Laramie, Wyoming . At least in Northern California, there was a 150-foot turntable in place until a fire in 1962.
A track triangle was specially built for the even longer PRR class S1 steam locomotive . In comparison, the largest diesel-electric locomotive, the EMD DDA40X , was almost 30 meters long, and these types often run in multiple traction, which was not common with steam locomotives.
Another area of application for turntables is turning snow plows . Therefore, in snowy regions, the turntables were preserved beyond the era of steam locomotives.
particularities
A curiosity was the turntable of the Corkscrew Gulch of the Silverton Railway in Colorado ( USA ). Since the route led into a canyon , there were large inclines and small radii . Since the slope at Corkscrew Gulch was a turning bow too steep and should continue the route in the opposite direction, was a there hairpin built where the train had to change direction, and to go to the respective Streckengleis. A turntable was installed there, which was accessible from both the mountain and the valley side via a gradient . When passing, the cars were separated from the locomotive and the locomotive was turned. After the locomotive had cleared the track, the rest of the train was led over the incline onto the turntable. If the total length of the wagon train exceeded the platform length of the turntable, the wagons had to be fed to the turntable individually. The extreme gradients of the route allowed only very short trains anyway. The locomotive then reversed and the wagons were hitched up again to continue.
In the Vienna U-Bahn , one-sided wheel flange wear occurs on the U2 line due to a part of a circle that has been driven over several stations. In order to counteract this, the relevant sets are rotated at certain time intervals. Since the type U double multiple units used at the time can only be separated with great effort and cannot be driven separately on their own, the turntable that went into operation at the Wasserleitungswiese depot ( 48 ° 14 ′ 29.3 ″ N , 16 ° 21 ′ 47 .5 ″ O ) has a diameter of 40 meters, making it the largest in Europe.
Road vehicles
Turntables are rarely used in road-bound vehicles, a well-known example is the Unterburg turntable , a turntable for trolleybuses in the Burg an der Wupper district of Solingen . Two other trolleybus hubs previously existed in Great Britain , these were the Christchurch hub and the Longwood hub . A fourth existed from 1976 to 1985 in the Guadalajara trolleybus tunnel in Mexico . The limited space in the underground did not permit any other solution. A fifth system served as a turning point on the first trolleybus line in Shanghai from 1914.
In addition, there are or were some hubs for buses
- in Japan
- at the Dogo Onsen depot in Matsuyama City ,
- at Mukōgaoka-Yūen station on the Odawara line of the Odakyū Dentetsu railway company and
- in Hakone in the Gora district,
- in the UK
- in the Snow Hill district of Saint Helier parish on the Channel Island of Jersey , in operation between 1932 and 1964, and
- at Hexham bus station (defunct), as well
- in the Spanish town of Elantxobe in the Basque Country .
In the public area, from 1949 to 2006, at the end of the Birsig car park in Basel there was a turntable with a diameter of 5.5 meters and a load capacity of three tons, connected via contact strips .
In Switzerland, some larger artillery fortresses , for example the Furggels fortress or the Magletsch fortress , have underground turntables with which trucks driven into the entrance tunnel can be turned. Otherwise, small turntables are used for private cars in the private sector where space is limited, especially when converting older apartment buildings, where the requirements could not be taken into account from the outset.
Trolleybus turntable in Solingen-Burg
Omnibus hub in Matsuyama
Car turntable at the Birsig car park in Basel
Auto hub in Louisville, Colorado
Ship turntable
The structure of the ship lift at the Krasnoyarsk Reservoir can also be described as a rack railway. As there are strong fluctuations in the upstream and downstream waterways, in contrast to canals with constant water retention, no lock chamber sealed with gates can be used. Rather, the ships are led into a horizontally stored trough with seals, which is then driven up or down the sloping bank slopes on rails. An intermediate turntable is used, which rotates the trough with the ship by 140 ° in the required direction; This means that the same gradient can be maintained on the entire route from the underwater via the turntable to the upper water and the trough always remains horizontal. The turntable has a diameter of 105 meters. ( 55 ° 56 ′ 20.4 ″ N , 92 ° 17 ′ 7.8 ″ E )
Airships
In 1929 the concept of a turntable was developed to place an airship in one of several radially arranged airship halls by means of a rail-guided carriage.
Special designs
Segment turntable
The segment turntable is a special design. With her, the bridge girder only sweeps over a segment of the circle. As a result, it cannot turn completely, so it is only suitable for turning a vehicle if it can be turned at least 180 degrees. Such a segment turntable is for example in front of the roundhouse in Neuenmarkt-Wirsberg .
It is primarily used to move vehicles onto adjacent tracks in a space-saving manner, sometimes requiring less space than switches . The elaborate construction and maintenance, however, also rarely allowed this type of construction to be implemented. A recently built segment turntable can be found in the Bezau train station of the Bregenzerwaldbahn .
Other segment turntables that are no longer in use are located at Bayreuth Central Station or at Bebra Station . In the Klütz train station at the end of the Grevesmühlen – Klütz railway line , a segment turntable was converted from normal to narrow gauge .
There are also turntables that can be pushed back and forth between two pivot points and are therefore better suited for distributing locomotives on different tracks.
89 6024 the German Steam Locomotive Museum on the segment hub in New Market Wirsberg
Locomotives can turn around on the segment turntable in Neuenmarkt-Wirsberg
Discontinued segment turntable in Bolzano
Bezau train station, transfer to the segment turntable
Double turntable
Another special design is the double turntable. It was installed in places where a large number of locomotives should be parked to save space.
With this design, the radius of action of two turntables is designed to overlap. The two pits are thus connected to one another and the turntable rims cross in the outer pit area due to the overlap.
The railway depot in Altona station and Cologne depot , for example, had double hubs . They were created from two adjacent turntables of the standard design when the turntable bridges had to be lengthened. The turntable operators had to coordinate because of the overlapping running treads
Others
Automatic high-bay car parking systems require a turntable inside if they want to turn over vehicles to the building side of the entrance. In order to avoid this necessity, however, if possible, the entrance and exit via the loading platform are arranged as a drive-through situation. This passage can take place through a building or just inside a building parallel to the building front.
A design of mast-guided construction hoist with a rotatable square-U-shaped platform offers a turntable function: At street level, one or two wheelbarrows are set up parallel to the front of the building to save space, after the lift has been raised slightly, the platform is rotated by 90 ° and locked so that its straight opening side is higher Floors can dock to a scaffolding or doorway of a building, where the wheelbarrows can be pulled out in a straight line.
In articulated wagons , especially trams that travel on curved tracks with small curve radii, the joints of which bend at relatively large angles, the floors inside the wagon can be rotated along a joint in the form of a semicircle, a full circle or two slightly drawn apart semicircles. At the arcs of a circle, floor surfaces butt against each other without overlapping. The full circle and double semicircle form a kind of disc, the movement of which relative to the adjacent sections of the car can be experienced especially when you stand on it as an observer and the car slowly turns into a narrow curve or - twice as far - changes from one to a counter-curve as is often the case on reverse loops. It can be observed that at first only the leading carriage part moves relative to the pane and only later does the following section start moving in the opposite direction. This movement of a joint can be felt if one stands exactly on a joint with a leg that is not under stress, for example with the ball of a toe (with shoes on).
Crossing a slowly rotating, flat, flush turntable between railings on foot is the task of the public in a fairground ride that plays with the steadfastness of visitors. On the other hand, you should sit or lie on the much larger and slightly convexly curved devil's wheel and try to resist the centrifugal force . When you subjectively walk away radially , the Coriolis force sweeps your legs away.
literature
- Markus Tiedtke: Bahnbetriebswerke Part 3. Turntables and engine sheds . In: EK special. 34, EK Verlag, Freiburg 1994.
Web links
Individual evidence
- ↑ Dominik Stroner: Turning and turning: The turntable in the Bw . in BAH >> N Extra Bahnbetriebswerke in Germany, Munich 2003 ISBN 3-89724-163-3 pp. 40–66
- ^ Turntable turnaround for West Somerset Railway , May 5, 2008, bbc.co.uk
- ^ Railway gazette international, Volume 79, Reed Business Pub., 1943, p. 192
- ↑ The Signalman's Journal, Vol. 43-44, Brotherhood of Railroad Signalmen of America, 1962, p. 64
- ^ The Trolleybuses of Latin America in 2010 - Guadalajara. on www.tramz.com
- ↑ Shanghai: 100 years of operation with a new fleet of vehicles, report on www.trolleymotion.eu from December 1, 2014 ( Memento of the original from March 5, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ disused-stations.org.uk
- ↑ Project day at the GIBM, Plant Engineering Department, from December 18, 2003. ( Memento of the original from June 5, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 0.8 MB)
- ^ Heidi Siefert: Underground river in Basel.
- ↑ р. Енисей: Красноярский судоподъемник , lhp.rushydro.ru
- ↑ Dennison Burney: Mooring and Docking Raft advancements , In: The World The Air The Future, 1929. Documented in: www.airshipsonline.com, Airship Heritage Trust, accessed November 30, 2014
- ↑ Photo of the U 25 locomotive on the segment turntable in Bezau
- ↑ Jakob Bobleter / Thomas Hammerer: From 2003 , blog of the Museum Railway Association on waelerbaehnle.at.
- ↑ Double turntable BW Cologne on Drehscheibe-Online.de
- ↑ Between the individual wagons, the transitions are narrower and - here differently - implemented by slightly convex upwardly arched transition bridges that overlap between the wagons. This overlap tolerates both the horizontal and vertical shear between the ends of the wagon and the deflection of the buffers on both sides when coupling and when shunting.
