Pennie & Edmonds
Timepiece calendar indexing apparatus
 An indexing apparatus for changing automatically and rapidly calendar information of a clock includes an indexing assembly having both day and date means, each engageable with for driving respective day and date discs provided with calendar indicia. A cam driven by the drive train of the clock mechanism rotates through a full revolution each 12-hour period. A member including a plurality of gear teeth arranged in a sector is mounted for pivota movement against the bias of a spring which positions the member in the path of movement of the cam. The indexing assembly, further, includes an element formed by a disc and a sector gear which is driven in opposite directions by the member whose gear teeth are in driving engagement therewith. The disc of the element includes a pair of substantially diametrically oppositely disposed notches having oppositely inclined ramps between the upper and lower surfaces of the clutch disc. The components of the indexing assembly are mounted in a stack with the day means between the date means and the element. The day means includes a pair of follower projections which normally are disposed within the notches, the day means being movable with the element in one direction to index the day disc through a partial revolution yet will idle upon movement of the element in the other direction whereby the teeth ride out of the notches along the ramps. Means are provided to prevent movement of the day and date means during idling. The day disc includes a plurality of projections which sequentially engage the date means so that upon each second index of the day means the date disc undergoes an indexing movement in the one direction. The calendar information, also, may be changed selectively by a clutch arrangement activated by a setting stem. 
General Time Corporation
G
G04B
inventional
David Donald J.
Morrison Rogers