The desmodromic valve engine, widely used by Ducati, uses cams and levers to close its valves in place of what conventional mechanism?
Desmodromic valve 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.
Nutating disc engine A nutating disc engine (also sometimes called a disc engine) is an internal combustion engine comprising fundamentally of one moving part and a direct drive onto the crankshaft. Initially patented in 1993, it differs from earlier internal combustion engines in a number of ways and utilizes a circular rocking or wobbling "nutating motion", drawing heavily from similar steam-powered engines developed in the 19th century, and similar to the motion of the non-rotating portion of a swash plate on a swash plate engine.