The Front Suspension

Chapter
Part of the SpringerBriefs in Applied Sciences and Technology book series (BRIEFSAPPLSCIENCES)

Abstract

In this chapter, the authors introduce the telehydraulic fork, which has become, across the years, the most common kind of front suspension for motorbikes. In chronological order, some noteworthy patents are presented, which help the reader following the main steps of the technical evolution which gave front motorbike suspensions their current shape. Then, the behaviour of some key structural elements of the fork is examined, under the assumption that the fork is subject to a bending moment acting on the front wheel mid-plane. Such a noteworthy loading condition is frequently encountered during the life cycle of a motorbike: consider, for instance, an emergency braking manoeuvre. Tests which simulate the effect of a hard braking on the fork are also part of the product validation programmes of the main motorbike producers. It is illustrated an analytical model useful for calculating the stress state of the fork legs under said loading condition. Such a model takes into account some architectural configurations as well as some characteristic geometrical parameters of the fork and of the motorbike. The model was validated referring to some production forks, both by finite element analyses and by experimental tests on the road. In the case of forks equipped with a single brake disc, the load unevenness between the legs during braking is analysed, and some strategies aimed at reducing such loading unbalance are suggested. The model presented herein could be helpful for designers who are developing new fork models, because it allows foreseeing critical issues due to legs dimensioning since the early phase of product development, when FEA techniques may be difficult to implement.

Keywords

Fatigue Depression Torque Rubber Asphalt 

References

  1. 1.
    Koch E (1901) Bicycle, U.S. Patent 680,048Google Scholar
  2. 2.
    Thompson ED (1898) Bicycle, U.S. Patent 598,186Google Scholar
  3. 3.
    Scott AA (1909) Improvements in or connected with the Front Forks of Motor-cycles, G.B. Patent 7,845Google Scholar
  4. 4.
    Feilbach AO (1914) Improvements in Forks for Velocipedes, motor cycles and the like, mG.B. Patent, 11,301Google Scholar
  5. 5.
    Harley WS (1925) Shock Absorber, U.S. Patent, 1,527,133Google Scholar
  6. 6.
    Nielsen AF, Fisker PA (1934) Improvements in and relating to handles and front fork for cycles, particularly for motor cycles, G.B. Patent, 416,594Google Scholar
  7. 7.
    Schleicher R Flüssigkeitsstoßdämpfer für. Kraftradgabeln, DE Patentschrift 675, 926, 1939Google Scholar
  8. 8.
    Burke PW, Morris RPW, AAJ Willitt (1948) Dowty Equipment Limited, An improved telescopic strut or shock absorber, G.B. Patent, 597,036Google Scholar
  9. 9.
    Torre PL (1956) Spring suspension system for motorbike front wheels, U.S. Patent, 2,756,070Google Scholar
  10. 10.
    Roder A (1958) Schwinghebel Federgabellagerung, insbesondere für das Vorderrad von Motorrädern oder Motorrollern, DE Patentschrift, 1,043,844Google Scholar
  11. 11.
    Turner E (1960) Motorcycle front wheel suspension, U.S. Patent, 2,953,395Google Scholar
  12. 12.
    Roberts JP (1968) Telescoping, spring-loaded, hydraulically damped shock absorber, U.S. Patent, 3,447,797Google Scholar
  13. 13.
    Arces SRL (1979) Perfezionamento nelle sospensioni per motoveicoli, ITA Brevetto per invenzione industriale, 1,039,678Google Scholar
  14. 14.
    Kashima M (1981) Front end shock absorbing apparatus for wheeled vehicle, U.S. Patent, 4,295,658Google Scholar
  15. 15.
    Neupert G, Sydekum H (1986) Valvola di trafilamento per ammortizzatori idraulici pneumatici o idropneumatici, ITA Brevetto per invenzione industriale, 1,145,747Google Scholar
  16. 16.
    Verkuylen AHI (1988) Hydraulic shock damper assembly for use in vehicles, U.S. Patent, 4,732,244Google Scholar
  17. 17.
    Öhlin K, Larsson M (1992) Device associated with a spring suspension system, PCT Patent application, WO 92/16770Google Scholar
  18. 18.
    Shelton H, Obie Sullivan J, Gall K (2004) Analysis of the fatigue failure of a mountain bike front shock. Eng. Fail Anal 11(3):375–386CrossRefGoogle Scholar
  19. 19.
    Croccolo D, Cuppini R, Vincenzi N (2007) The design and optimization of fork-pin compression coupling in front motorbike suspensions. Finite Elem Anal Des 43(13):977–988CrossRefGoogle Scholar
  20. 20.
    Croccolo D, Cuppini R, Vincenzi N (2008) Friction Coefficient Definition in Compression-fit Couplings Applying the DOE Method. Strain 44(2):170–179CrossRefGoogle Scholar
  21. 21.
    Croccolo D, Vincenzi N (2009) A generalized theory for shaft-hub couplings. Proc Inst Mech Eng Part C J Mech Eng Sci 223(10):2231–2239CrossRefGoogle Scholar
  22. 22.
    Croccolo D, Cuppini R, Vincenzi N (2009) Design improvement of clamped joints in front motorbike suspension based on FEM analysis. Finite Elem Anal Des 45(6–7):406–414CrossRefGoogle Scholar
  23. 23.
    Croccolo D, De Agostinis M, Vincenzi N (2010) Recent improvements and design formulae applied to front motorbike suspensions. Eng Fail Anal 17(5):1173–1187CrossRefGoogle Scholar
  24. 24.
    Croccolo D, De Agostinis M, Vincenzi N (2011) Failure analysis of bolted joints: Effect of friction coefficients in torque-preloading relationship. Eng Fail Anal 18(1):364–373CrossRefGoogle Scholar
  25. 25.
    Doyle JF (2004) Modern experimental stress analysis. Wiley, ChichesterGoogle Scholar
  26. 26.
    Pacejka HB (2002) Tire and vehicle dynamics. Butterworth-Heinemann, OxfordGoogle Scholar
  27. 27.
    Croccolo D, De Agostinis M, Vincenzi N (2012) An analytical approach to the structural design and optimization of motorbike forks. Proc Inst Mech Eng Part D J Automobile Eng 226(2):158–168CrossRefGoogle Scholar
  28. 28.
    Belluzzi O, Zanichelli, Bologna, IT, Scienza delle costruzioni 1994Google Scholar
  29. 29.
    Cossalter V (2006) Lulu.com, Motorcycle, dynamicsGoogle Scholar
  30. 30.
    Corno M, Savaresi SM, Tanelli M, Fabbri L (2008) On optimal motorcycle braking. Control Eng Pract 16(6):644–657Google Scholar
  31. 31.
    Cossalter V, Lot R, Maggio F (2004) On the stability of motorcycle during braking. In: Proceedings of the small engine technology conference and exhibition, GrazGoogle Scholar
  32. 32.
    Timoshenko S, Goodier JN (1951) Theory of elasticity. McGraw-Hill, New YorkGoogle Scholar

Copyright information

© The Author(s) 2013

Authors and Affiliations

  1. 1.DIEMUniversita Di BolognaBolognaItaly

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