Cycloidal rotary engine piston

Cycloidal rotary engine piston by the British Cycloidal Engine Syndicate, Ltd

This is a rotary steam engine of the form patented by Mr. J. F. Cooley in 1901, 1903, and 1907. It is of a very novel design, intended to offer an alternative to more conventional steam engines. Its construction depends upon the fact that if two elements rotate in the same direction, about fixed centres, with a speed ratio of 32, then three points on the slower element, equidistant from its centre, will describe, relative to the faster element, one and the same two-lobed peritrochoidal curve known as a nephroid. If a piston of this form is made to revolve at the correct speed, in a suitably shaped revolving chamber, having the three describing points on it in contact with the piston, then the chamber will be divided into three expanding and contracting spaces which can be used as working cylinders.