with concave friction surface, e.g. a hollow toroid surface

Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members > without members having orbital motion > Gearings providing a continuous range of gear ratios > in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B > in which the member B has a curved friction surface formed as a surface of a body of revolution generated by a curve which is neither a circular arc centered on its axis of revolution nor a straight line > with concave friction surface, e.g. a hollow toroid surface

Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members (control of change-speed or reversing-gearings conveying rotary motion F16H59/00 - F16H63/00) > without members having orbital motion > Gearings providing a continuous range of gear ratios > in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B > in which the member B has a curved friction surface formed as a surface of a body of revolution generated by a curve which is neither a circular arc centered on its axis of revolution nor a straight line > with concave friction surface, e.g. a hollow toroid surface