Electromechanical calendar drive - includes differential gear to cover different number of days in month

摘要

An electro-mechanical calendar includes a facility for the variation in the length of the month. The input shaft is driven by an electric motor to perform 1/2 revolution per day. The shaft providing transmission to the main display functions, is coupled to the input shaft over a planetary differential gear. A parallel shaft provides the month display function. Two notched discs respectively provide for 1/12 and 13/12 revolutions per month.