Operating mechanism with snap action component

A spring and an intermediate lever are linked by their ends as well as connected to the end of the contact lever. This leaves a freedom for displacement at right angle to the contact lever. A constant contact pressure is ensured during the displacement of the drive lever to the operating position, and therefore, provides a reliable performance in conditions of vibration and shock during slow and reversible drive. In the starting position, the compressed spring (11) provides a force (P) acting on the end (14) of the intermediate lever (12). The contact lever (6) is subject to moments of force due to vertical (P1) and horizontal components of force of the spring (1). The application of the external force to the drive element (19) shifts the lever (4) and causes a change in the position of lever (12) w.r.t. the spring (11). When connection of the lever (6) with the lever (4) is aligned with the line drawn through the ends of the spring (11) it ensures switching of the contact (9).