Rotary speed-change transmission

A transmission comprising:

• a housing having a main axis;
• a retaining element fixed in the housing and forming a set having a predetermined number of radially extending and angularly equispaced guides;
• an output element having two parts each rotatable in the housing about the main axis, and formed with an array having a number smaller than the predetermined number of radially inwardly open recesses axially adjacent the guides with the recesses of one of the output-element parts axially aligned with the recesses of the other output-element parts;
• an input element flanked by the output-element parts, formed by a disk or ring generally centered on a center plane perpendicular to the main axis, rotatable in the housing about the main axis, and having a radial outer and generally circular peripheral surface centered on an axis radially offset from the main axis;
• and
• respective transmission elements symmetrical to the plane, radially displaceable in the guides between inner and outer positions, and each having a shaft extending substantially parallel to the axis with a guide section engaged and radially shiftable in the respective guide, a driven section engageable in the recesses, and a drive section radially engageable with the input-element surface, the transmission elements each having two of the driven sections aligned radially with the respective parts of the output element.