Link 1, designed as a push button, slides in fixed guides b and has crossbar a to which links 2 are hinged. Links 2 are held in the position shown in the drawing by flat spring 3. Button 1 is held in its upper position by spring 6. Three-armed lever 5 turns about fixed axis A and has pins d which are engaged by notches c of links 2. Lever 4 is connected by turning pair E to lever 5. Link 7, ending in head f, slides along the axis of lever 4 and is actuated by spring 8. When button 1 is pressed, three-armed lever 5 is turned by means of links 2 about pin A. Pin h of lever 5 depresses head f of link 7 and shifts lever 4 from one extreme position to the other. The mechanism passes by inertia through the middle neutral position and, as a result, lever 4 is shifted.
$356$SL,SE$