Desmodromic Valve Operation
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DESMODROIVIIC operation of valves implies cam-actuated closing as well as opening, rather than relying entirely on springs for the former function. It has hitherto been expensive, so that its use has been confined to special-purpose vehicles such as racing ears, An improved
scheme which is claimed to be ;nexpensive is shown in patent No. 885,151. (F. Porsche, Porschestrasse, Stuttgart, Zuffenhausen, Germany.) The drawing shows an overhead camshaft and valve mechanism according to the invention. A conventional cam (1) is used to open the valve via the medium of a "finger" type of rocker (2). For the closing stroke, a second cam (3) is provided. A follower (4) on this works a forked member (5) which lifts it into the closed position. A means of adjustment to give positiv closing, not illustrated, is provided. A advantage of the scheme is that standard eng;ne can be fitted with eithe the conventional springs or the positiv actuating mechanism with the minimur of disturbance.