This is a Flash Animation of a desmodromics system. I have problem with cams and will be fixed soon. You can get much more info about desmodromics sytem at DESMODROMOLOGY
In general mechanical terms, the word desmodromic is used to refer to mechanisms that have different controls for their actuation in different directions.
A desmodromic valve is a reciprocating engine valve that is positively closed by a cam and leverage system, rather than by a more conventional spring. The term desmodromic derives from two Greek roots, desmos (controlled, linked) and dromos (course, track).
Desmodromic poppet valves are used in Ducati Motorcycle engines.