Difference between revisions of "Desmodromic valve"

The common valve spring system is satisfactory for traditional mass-produced engines that do not rev highly and are of a design that requires low maintenance.<ref>Rivola, A., et al.: "Modelling the Elastodynamic Behaviour of a Desmodromic Valve Train", ''Proceedings of SMA2002 International Conference on Noise & Vibration Engineering'',16–18 September 2002 - Leuven, Belgium</ref> At the period of initial desmo development, valve springs were a major limitation on engine performance because they would break from metal fatigue. [[Vacuum Induction Melting|Vacuum melt]] processes developed in the 1950s helped remove impurities in the steel used to make valve springs, although after sustained operation above 8000 RPM often springs would still fail. The desmodromic system was devised to remedy this problem.<ref name="herald">{{cite web|url=http://www.mrs.org/s_mrs/bin.asp?CID=2984&DID=94886&DOC=FILE.PDF|format=PDF|title=MRS.org ''The Art and Materials Science of 190&nbsp;mph Superbikes''|accessdate=2006-11-02}}</ref> Furthermore, as maximum RPM increases, higher spring pressure is required to return the valve, leading to increased cam drag and higher wear on the parts at all speeds, problems addressed by the desmodromic mechanism.