Abstract: Each stage of the transmission includes a composite ring gear for operatively connecting spaced coplanar drive and idler gears on engine and idler shafts, respectively. The ring gear comprises a plurality of rotationally offset element assemblies, each of which includes first and second ring gear sectors, each mounted on a different end of a rotatable element. In this manner, as one gear sector engages the drive gear, the other sector engages the idler gear. Means operably connected to each element assembly of the composite ring gear are provided for varying the position of the axis of rotation of each of the assemblies relative to the drive and idler gears so as to change the ratio of the distances between the axes of rotation of the element assemblies and that of the drive and idler gears, respectively, and thus the speed transfer ratio of the stage.

Abstract: A flexible member in a harmonic gear reduction unit is operatively connected at its other end also to an output member of the gear reduction unit through a second coupling arranged symmetrically with respect to the first coupling about an axis of engagement between the teeth of the flexible and rigid members, elements imparting radially directed deformations to the flexible member being also arranged in the unit symmetrically about the axis of engagement between the teeth of the flexible and rigid members.

Abstract: A harmonic drive in which the teeth on either or both of the flexspline and internal spline have a modified involute profile with a small contact angle when fully meshed, and considerable tip relief. The former preferably comprises three discs in line on an input shaft which is cranked to a small eccentricity, the center disc eccentricity being diametrically opposite that of the outside pair. Pressure lubricated plain bearings are advantageously used.

Abstract: A gear mechanism for transmission of small forces, such as in a hand mechanism gear for clocks or watches which has a driving shaft, a driven shaft coaxial thereto, two gearwheels developed as crown wheels, mounted coaxially engaging each other over a small portion of their circumferences and having each a different number of teeth, one of these gearwheels being stationary and the other rotary. A coupling means such as a clutch is fastened to the driving shaft for rotation therewith. The clutch and the two gearwheels are mounted in relation to each other in such a manner that when the clutch rotates with the driving shaft, the rotary gearwheel resting on the driven shaft, while itself rotating, rolls off on the stationary gearwheel.

Abstract: A Z-axis drive assembly for a turret machining center incorporates a variable speed DC motor mounted on a vertically adjustable carriage and connected through a harmonic drive unit to rotate a pinion. The pinion forms part of a rack and pinion mechanism, for controlling the vertical elevation of the rack relative to the carriage.