Push-button 1 slides in fixed guide B and has cam shoe a at its upper end. When push-button 1 is pressed, cam shoe a alternately engages pawls 2 and 3 which are connected together by links 6 and 5, and by spring 4. At this, lever 7 is switched to the corresponding position, alternately to the left and right of the vertical centre line, about fixed axis A, on successive strokes of push-button 1.
$3268$CmL,SE$