(under the class definition) Subject matter and also including means to alter the temperature of an element thereof during operation. [figure] [caption] In a variable friction gearing, comprising two revoluble members adapted for direct-drive engagement in coaxial position and for indirect drive engagement in relatively eccentric position, one of said members having an air inlet opening adjacent to its axis, a plurality of air discharge openings adjacent to its periphery, and its interior open for passage of air from said inlet to said discharge openings, said inlet opening being freely accessible in the eccentric position of said members.
