Automatic calendar with year lever, month disc and day disc - has month-end interlock to distinguish between short and long months

摘要

The automatically switching calendar movement comprises a cam disc (1) on shaft (2) which in 31 days rotates 1-1/12 revolutions. This disc has peripheral recesses (b) which are so arranged that, at the end of a 30-day month, a projection (a) of a spring-loaded (11) pivoted (10) lever (9) enters, thereby allowing a disc (3) to be rotated by 1/4 turn. At the February-March transition, the recess (c) is longer to allow 3/4 turns of the disc (3). At the January-February transition, a projection (e) of an annually rotating lever (7) engages a projection (d) on the lever (9), thus preventing the projection (a) from entering the recess (c). The month disc (5) is geared in ratio 12 to 13 relative to the day disc (1).