Abstract: An actuating mechanism of a three-position switch, the switch comprising a main shaft supporting or actuating contacts and able to be moved selectively to three stable positions and a center crank which is pivotally mounted and can be actuated so as to take the three positions of the main shaft, the mechanism in addition having a mechanical system which produces a kinetic ratio between the angular movement of the center crank and that of the main shaft which increases when the center crank moves from the open position to the closed position, which results in the force transmitted to the electrical contacts increasing continuously as movement takes place from the open position to the closed position.

Abstract: An operating mechanism of a three-position switch having a contact-bearing main shaft comprises a switch closing and opening operation device, and an earthing device closing and opening operating device. The two devices comprise driving flange plates connected by a common spring capable of being loaded by rotation of either of the operating shafts and transmitting, after the deadpoint has been reached, a drive movement of these flange plates transmitted by articulated levers to a crank handle wedged onto the main shaft. All the operations are high-speed and the torque transmitted to the main shaft increases in the course of the operating movement. A locking device maintains the main shaft in the open position during the loading phase of the spring.