Theory of the Combination of Observations Least Subject to Errors

The carriage for the friction driving disc of a friction disc planetary transmission is shiftable axially on a pivot shaft by a manually operated cam to change the contact path of a pair of driven friction wheels connected to input gears of a planetary unit to effect infinitely variable forward and reverse speeds and neutral. The pivot shaft is transverse to and spaced from the axis of the driving disc. The driving disc is driven by a belt which, when placed under driving tension urges the carriage to pivot about its pivot shaft in a direction urging the friction driving disc against the driven friction wheels. Additionally, the carriage is urged by a pair of springs in the same direction to insure proper frictional engagement of the driving disc with the driven wheels. In order to insure proper proportioning of pressure exerted by the driving disc against the driven wheels, the driving disc support is pivoted to the carriage on an axis lying in the plane of the friction face of the driving disc and intersecting the axis of the driving disc. The biasing springs are connected to the driving disc support and are oriented in relation thereto in such a way as to insure normal driving pressure between the driving disc and the driven wheels throughout the range of axial shifting of the carriage on its pivot shaft. The carriage pivot shaft is connected at its opposite ends to spaced walls of the transmission housings in a manner permitting vertical adjustment of either or both ends. These adjustments permit proper alignment of the driving disc with the driven wheels. A clutching device is provided to disengage the driving disc from the driven wheels to provide free wheeling. The planetary unit is carried on a shaft mounted on the spaced walls of the transmission housing in a manner permitting removal of the planetary unit and shaft as an assembly.