Long arm swing arm

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Long arm swing arm pushed
Long arm swing arm pulled

The long arm swing arm describes a swing arm type of front wheel guidance on motorcycles . The long -swing fork is synonymous ; many more modern designs are based on the patent for the Earles fork . Chassis with long arm swing arms on the front and rear wheels were often referred to as full swing chassis . Another, simpler type of swing arm on the front wheel is the short swing arm . Rocker arm fork is a generic term that was created in the 1950s and generally refers to the rocker arm guide on the front wheel of motorcycles. From a technical point of view, motorcycle rear swing arms are also (drawn) long arm swing arms.

history

The first long-arm swing arms are known from Peugeot (1904) and Allright (1905); the models used were Truffault forks . Jules Truffault developed this type of front wheel control on a bicycle as early as 1898 and was granted a patent in 1902. The British Ernest Richard George Earles (1903–1972) received a patent on December 5, 1951 for the pushed long arm swingarm . This design was initially developed for motorcycle racing . The first users of the Earles fork were MV Agusta on the 4-cylinder racing machine in 1952 , and BSA , also on a racing machine. In 1953, BMW brought the RS 54 , a vertical shaft-controlled racing motorcycle with Earles fork, to the race track - series production later benefited from this in the same year as Mondial. The first production motorcycle with an Earles fork was the Tornax S250 from 1953. Numerous other manufacturers then brought an Earles fork onto the market under the name swing arm or full swing arm. At BMW , the long swing fork completely replaced the telescopic fork from series production from 1955 to 1969 (see full swing arm BMW ), and MZ only produced motorcycles with long swing arms from 1963–1968.

technology

With the long arm swing arm, the pivot point is outside the tire circumference, with the short swing arm or short arm swing arm within the tire circumference. The long-swing fork in Earles design is a pushed swing arm, it guides the front wheel in a swing arm that is guided around the rear of the wheel and is supported by two spring struts under the lower fork bridge . With the pushed long arm swing arm, the pivot point is behind the wheel axle when viewed in the direction of travel, with the pulled long arm swing arm in front of the wheel axis. Most motorcycles with a long arm swing arm are externally recognizable by the massive swing arm support and the swing arm. However, there were also designs in which the components were integrated into the fender and partially covered, an example of which is the Simson Schwalbe .

  • Pushed long arm swing arm (BMW)

  • Pulled long arm swing arm (FN)

Use on the front wheel

Pushed long arm swing arm (selection)

Pulled long arm swing arm

gallery

  • MV Agusta (1952)

  • MV Agusta 175 Bialbero (1954)

  • BMW RS 54 (1954)

  • Douglas Dragonfly (1955)

  • BMW R50 (1955)

  • Long swing fork (BMW) with second pivot axis

  • BMW racing team with full swing chassis

  • DKW RT 175 VS with front and rear swing arm

  • MZ ES 250 (1956)

  • Kreidler Foil (1957)

  • MZ ES 125 (1962)

  • Simson Swallow (1964)

Advantages and disadvantages

The decisive advantage of the pushed long-arm swing arm compared to the telescopic fork is that the vehicle does not “dip” during braking, and the pitching movements are less. Especially compared to telescopic forks from the 1950s, the long arm swing arm offered significantly better suspension comfort and at the same time greater rigidity thanks to its finer response to uneven road surfaces . Overall, a better division of management and suspension functions is achieved. Small, negligible changes to the wheelbase are typical of swing chassis during compression and rebound . The caster also changes due to the circular arc movements of the wheel axles, the shorter the front link, the stronger.

The main disadvantage is the greater weight. The moment of inertia around the steering axis is therefore 74% greater than that of the telescopic fork. The righting braking torque of pushed long arm swing can even lead to a relief of the front wheel during braking in some constructions, which in this case worsens the driving stability when braking. Furthermore, on some vehicles with a long arm swing arm, there is a tendency for the handlebars to swing in certain driving conditions, for example when driving hands-free in push mode or when the luggage rack is heavily loaded.

Today's application

The long-arm swing arm for front wheel control is currently no longer offered on any production motorcycle. Since the advantages of the front link predominate in trailer operation and the higher weight of the wheel guidance is of less importance due to the higher gross vehicle weight, the long link fork is still used in trailer combinations . In order to convert a current solo machine for sidecar operation, a small overrun is necessary anyway, as otherwise very high steering forces arise when cornering. With the long swing arms produced by BMW, this was achieved with a pair of second axle mounts (in front of the “solo” position), which reduced caster. This can be seen in the photo directly behind the wheel: the silver-colored aluminum cap shows the quick-release axle in the solo position. About 50 mm in front of it there are the second holes for the carriage operation, here correctly covered with a black rubber mushroom plug.

For use as a rear swing arm, on the other hand, the one or two-armed drawn long arm swing arm has established itself on motorcycles.

literature

  • Stefan Knittel: Motorcycle Lexicon, History, Brands, Technology from A - Z , BLV Verlag , Munich / Vienna / Zurich 1981, ISBN 3-405-12226-0 .

Web links

References and comments

  1. ^ Helmut Werner Bönsch: Introduction to motorcycle technology . 3rd edition, Motorbuch Verlag Stuttgart, 1981, ISBN 3-87943-571-5 , p. 88.
  2. ^ Wolfgang Matschinsky: Wheel guides of road vehicles. 2nd edition, Springer Verlag 1998, ISBN 978-35406-4155-1 , p. 333
  3. ↑ J. Kleine Vennekate: German motorcycles of the 50s. Verlag Kleine Vennekate, 2002, ISBN 978-39355-1707-2 , p. 9.
  4. ↑ The MOTORCYCLE Issue 25/1956
  5. ↑ S. Ewald: Encyclopedia of the motorcycle . Bechtermünz Verlag, Augsburg 1996, ISBN 3-86047-142-2 , p. 379.
  6. ^ LJK Setright: The Guinness Book of Motorcycling. Facts and Feats. 1982, ISBN 0-85112-255-8 , p. 152.
  7. ^ Horst Nordmann / Fritz, Mika Hahn: Kölsche Zweiradgeschichten . Pioneers, racing drivers, fates, Cologne 2003, ISBN 3-00-011139-5 , p. 34.
  8. ↑ U.S. Patent 695508
  9. ↑ bmwdean.com Earles Fork Patent (accessed September 26, 2013)
  10. ^ Stefan Knittel: Motorcycle Lexicon . BLV, Munich a. a. 1981, ISBN 3-405-12226-0 , p. 52
  11. ^ Mario Colombo / Roberto Patrignani: MV Agusta . Motorbuch, Stuttgart 2000, ISBN 3-613-01416-5 . P. 224.
  12. ^ Roy Poynting: The Sammy Miller Museum Collection. 2009, ISBN 978-0-9555278-0-7 , p. 22
  13. ^ Norbert Adolph: chassis - link to the road. In: Christian Bartsch (Ed.): A century of motorcycle technology . VDI Verlag , Düsseldorf 1987, ISBN 3-18-400757-X , p. 199.
  14. ^ Stefan Knittel: Motorcycle Lexicon. BLV Verlag, Zurich u. a. 1981, ISBN 3-405-12226-0 , p. 52.
  15. ^ Wolfgang Matschinsky: Wheel guides of road vehicles. 2nd edition, Springer Verlag 1998, ISBN 978-35406-4155-1 , p. 332
  16. ^ Helmut Werner Bönsch: Introduction to motorcycle technology . 3rd edition, Motorbuch Verlag Stuttgart, 1981, ISBN 3-87943-571-5 , p. 79.
  17. ↑ Tony Foale, Vic Willoughby: Motorcycle Chassis Today. Motorbuch Verlag, Stuttgart 1988, ISBN 3-613-01226-X , p. 21
  18. ↑ Institute for Motorcycle Safety : practice books Motorcycle Safety 5. Heinrich Vogel Verlag, Munich 1990, ISBN 3-574-27318-5 , page 14
  19. ↑ On the rear wheel, the long arm swing arm is always referred to as a swing arm.