Joy valve gear

Valve gear for steam engines

Joy valve gear is a type of steam locomotive valve gear, designed by David Joy, Locomotive and Marine engineer, and patented on 8 March 1879. The British patent has not been found but the US patent has. Joy's gear is similar to Hackworth valve gear but has a compensating mechanism which corrects for "the slight inequality in the motion of the valve arising from the arc of the lever".

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