Tram with suspended articulation
{{Short description|Type of tram}}
A tram with a suspended articulation is a type of tram or streetcar architecture with one or more articulations being suspended. Here, articulations (i.e. permanent coupling) work like a hinge joint and are not supported by a bogie. This is unlike the more common solution with an articulation resting on a special connecting bogie, called jacobs bogie. Seen from the side at ground level, the suspended joint seems to be 'floating' because the lack of wheels directly under the joint.
The shortest examples consist of two sections. One section on two axles or two bogies; the other section rests both on one bogie and the other section, similar to a semi-trailer.{{cite book |url=https://books.google.com/books?id=yJJKFV0uwHQC&q=permit+eventually&pg=PA9 | last1 = De Leuw, Cather & Company | title=Light Rail Transit: A State of the Art Review | date = 1976 | access-date =3 November 2024}}{{Rp|page=119}} In the diagram to the right, the short centre section supports the two end sections. Each of the end sections rests on one bogie and also on the centre section.{{cite book |last1=Urban Rail Transit |title=Technical Comparison of Commercially Available Trams and Review of Standardization Frame and Design Principles |date=2022 |url=https://link.springer.com/article/10.1007/s40864-021-00163-6 |access-date=1 February 2024 |pages=18, 19 }} It is a popular tram/light rail architecture for vehicles in North America.{{cite web |title=Low-floor light rail vehicles |url=https://www.mobility.siemens.com/us/en/portfolio/rolling-stock/trams-and-light-rail/light-rail-vehicles.html |website=Siemens Mobility Global |access-date=1 February 2024 |language=en}}
History
File:Strab Brem 1963 918 4 Arsterdamm.jpg
File:106R32200783 Schwedenplatz, Blick Richtung Urania, Strassenbahn Linie N, Typ F 717.jpg
In 1928 an experimental tram was constructed in Görlitz and then put into service in Dresden until the mid-1960s. This car was numbered 2501 and had three sections: the center section had four fixed wheels, both end sections had each only one adjustable axle.{{cite web |last1=Kenning |title=Damals in Dresden: Der Traum von der Schnellstraßenbahn (m22B) |url=https://www.drehscheibe-online.de/foren/read.php?17,3875696 |website=Drehscheibe Online |access-date=1 February 2024}}
Genoa was the first city to have a series of trams of this type. From 1940 onwards 31 trams were built by combining older tramcars. The lay out was very simple: the front section had one four wheeled truck, the end sections followed like a semi-trailer and had one fixed axle at the rear. The ride comfort was rather poor.{{cite book |last1=Gragt |first1=F. van der |title=Moderne Trams: De ontwikkeling van de moderne tram in Europa van 1927 tot heden |date=1972 |publisher=Wyt |location=Rotterdam |isbn=9060075188 |page=129 |language=Dutch}}
The first newly build series appeared in Bremen in 1956. The only difference with the type in Genoa was that the end car hand a one-axle bogie and therefore slight improved ride qualities.{{cite web |title=Museumstriebwagen 917 |url=http://www.ingo-teschke.privat.t-online.de/bahn-hb/fz/technik/rfzt_917.html |access-date=1 February 2024}} Vienna had an improved version of this type, with a two axle bogie at the end. This so-called Type F was longer than the version in Bremen and had a more streamlined design.{{cite web |title=Type F (1963-1996) – Straßenbahnjournal |url=https://www.strassenbahnjournal.at/wiki/index.php/Type_F_(1963-1996) |website=www.strassenbahnjournal.at |access-date=1 February 2024}}
= Second generation =
The second generation of trams all have a pivoting bogie both at the front and the end side. This way the ride is much smoother when entering curves. The first to use this concept was the Mirage type in Zürich in 1966. The center rests on a set of four fixed wheels.{{cite news |title=Adieu Mirage - Eine Ära geht zu Ende - Stadt Zürich |url=https://www.stadt-zuerich.ch/vbz/de/index/die_vbz/medien/medienmitteilungen/adieu_mirage.html |access-date=1 February 2024 |work=www.stadt-zuerich.ch |date=29 June 2010 |language=de}}
= Low floor designs =
The first modern low floor tram design also had floating articulations. Both Vevey and Duewag joined forces to create this tram type for the network in Geneva.{{cite journal |last1=Hondius |first1=Harry |title=The development of low‐floor trams |journal=Journal of Advanced Transportation |date=March 1993 |volume=27 |issue=1 |page=80 |doi=10.1002/atr.5670270108 |url=https://onlinelibrary.wiley.com/doi/epdf/10.1002/atr.5670270108 |language=en |issn=0197-6729|url-access=subscription }} Though the design didn't have an entirely low floor, as it was still 48 cm above the rail. The second type (being named TFS-2) has a similar setup as the Mirage trams for Zürich. Using floating articulations, Alstom was able to create a low floor (less than 35 cm high) over 60% of the tramcar length.{{cite book |last1=Cambursano |first1=Roberto |last2=Gut |first2=Martin |title=Tram-Enzyklopädie: Geschichte und Technik der Strassenbahn |date=2022 |publisher=EK-Verlag |location=Freiburg im Breisgau |isbn=9783844668667 |pages=76, 77}} Since the start of the Sheffield Supertram, it uses only vehicles with floating joints.{{cite web |title=Vehicle information - Siemens Supertram |url=https://www.stagecoachbus.com/supertram/vehicle-information# |access-date=1 February 2024}} This setup is used for the majority of LRVs in North America.
Gallery
Type 9 on Reservoir yard leads, March 2022.JPG|Coupled Green line LRVs in Boston
2-car Central Link train in Tukwila.jpg|Coupled LRVs in Seattle
Green Line train at Southwest 5th & Oak, June 2020 (cropped).jpg|Coupled Green line LRVs in Portland
SDT4046 (cropped).jpg|San Diego Trolley LRV
MM tram at Wolverhampton.jpg|LRV in Birmingham (UK)
20200729 Sheffield Supertram 203.jpg|Tram train in Sheffield
2021 at Torino ATM 5000 5020 side.jpg|Tram in Turin
Saint Petersburg tram 8111 2005-07 1122657423 Kronshtadtskaya street LVS-97.jpg|Tram in Saint Petersburg
Melbourne Tram E-Class 6007.jpg|Tram in Melbourne