A strain wave gearing includes a wave generator that creates a state in which a flexible externally toothed gear is flexed into a non-circular shape and partially meshes with a rigid internally toothed gear, and that includes a wave plug having a non-circular outer peripheral surface and a wave bearing attached to the non-circular outer peripheral surface of the wave plug. The wave bearing includes an outer ring having an inner peripheral surface and an outer-ring-side raceway surface formed on the inner peripheral surface, an inner ring having an outer peripheral surface and an inner-ring-side raceway surface formed on the outer peripheral surface, and a plurality of rolling elements rotatably inserted between the outer-ring-side raceway surface and the inner-ring-side raceway surface,

A power conversion device has a buckled wave disk that has an axis and is radially compressed between a hub and a wave ring. The buckled wave disk is buckled in the radial direction to form circumferential waves which are displaced in the axial direction and extending around the buckled wave disk with lines formed of inflection points of the circumferential waves extending between the hub and wave ring. The wave ring is outwardly radially displaced at nodes corresponding to lines formed of inflection points of the circumferential waves. A wave propagation actuator cooperates with the buckled wave disk for driving a wave and the lines formed of inflection points of the circumferential waves around the buckled wave disk. An outer ring surrounds the wave ring, the outer ring being driven by or driving the wave ring at the nodes. A method of making a wave disk is provided.

A circular wave drive system, and a method for use of a circular wave drive, are provided. In one embodiment, a circular wave drive is provided, the circular wave drive comprising: a substantially enclosed housing having a chamber therein, a ring-shaped wheel residing in the chamber, a wave generator having a wheel-driving portion that is oriented within the hollow central portion of the ring-shaped wheel; and an output element having a wheel-driven portion that is oriented within the hollow central portion of the ring-shaped wheel opposite the wheel-driving portion of the wave generator.

A harmonic drive apparatus (also known as a strain wave gear) is constructed with a circular, flexible spline disc having a generally flat configuration or a slightly conical configuration.