Stepper drive for 3-position electric switch

摘要

The stepper drive uses a spiral wound flexure spring (6) with radial end sections (7,8) acted on by a manually operated tensioning lever (10). The stored spring energy is transferred to a drive lever (11) mounted on a stepping shaft (2), with a cooperating ratchet defining the switch positions. The tensioning lever is blocked during the spring tensioning by an automatic latch mechanism (40,41) when the fully tensioned spring position is reached. Respective latches and counter-bearings (54,55) are provided for tensioning the spring for each rotation direction of the stepping shaft. The latches are spring-biased into a rest position, and one or the other is released via the manual operating lever (35) for the tensioning lever.