Wooden Diagram Model of Joy's Patent radio valve gear

Wooden Diagram Model (scale 1: ) of Joy's Patent 1879-80 radial valve gear on board

This combined reversing and variable expansion valve gear was patented in 1879-80 by Mr. Joy who had been at work upon the problem since 1868. The model is one of several early ones constructed by the inventor, and shows the application to a horizontal engine. No eccentrics are used as the motion of the valve is derived from the oval path described by a point in the engine connecting rod. A valuable feature of the gear is that it brings the valve chest readily into a position at right angles to that usually occupied.