Timing disc for timer clock - has adjustable switch riders prevented from being removed by integral locking teeth

摘要

The timing disc (1) has guides allowing the switch riders (3) to be moved into positions around the disc (1) corresp. to the required switching programme, the switch riders (3) being permanently attached to the disc (1). The cooperating guide surfaces (8) between the disc (1) and the switch riders (3) incorporate axially effective locking teeth (10, 11) preventing removal of the switch riders once they have been fitted to the disc. Pref. each of the switch riders (3) has a U-shaped cross-section, so that it fits over an annular upstanding shoulder (2) around the periphery of the disc (1). The arms (6, 7) of the U enclose a U shaped guide element (8) in contact with the guide surfaces of the annular shoulder (2). Each arm of the guide element has an inwardly projecting locking tooth (10, 11) at its end. These allow the switch rider (3) to be lifted away from the top of the shoulder (2) when the position of the switch rider (3) is being adjusted, but lock into respective notches in the sides of the shoulder, to prevent the full removal of the switch rider (3). The disc (1) and the switch riders (3) can both be made from injection moulded plastics.