Abstract: A reduction gear can provide a relatively large reduction gear ratio by changing the number of gear teeth but without increasing the number of gears, thereby simplifying the structure thereof. The power transmission flow in the reduction gear occurs as follows. In one embodiment, power simultaneously flows to both a first sun gear and to a second sun gear. From the first sun gear, power flows through, in succession, a planetary gear, a ring gear, a carrier and finally to an output ring gear and output shaft. From the second sun gear, power successively flows through a first differential gear and a second differential gear to the output ring gear and the output shaft. In another embodiment, power flows, in succession, through an input sun gear, a first differential gear and a second differential gear, to simultaneously both a differential sun gear and to a differential ring gear.

Abstract: A variable transmission includes an input shaft with an input sun gear mounted thereon and a differential gear carrier rotatably mounted thereon to enable independent rotation about input shaft. A transmission shaft is coaxially mounted on input shaft. A differential gear carrier is rotatably mounted on the transmission shaft. A plurality of pins interlink carriers to enable simultaneous rotation. A first differential gear is rotatably mounted on each pin, and each gear is meshed with an input sun gear. A control ring gear is rotatably mounted on the transmission shaft with the controlling gear meshed with each differential gear. A plurality of rods rotatably secures each carrier to enable rotation about its axis and to enable simultaneous rotation of the carriers. An output shaft terminating in an output ring gear is rotatably mounted relative to the input shaft. A second differential gear is rotatably mounted on each rod and is meshed with the gear differential and output ring gear.