Three-position switch actuating mechanism

An actuating mechanism of a three-position switch, comprising:

• a main shaft for actuating electrical contacts and adapted to be selectively rotated between three stable positions, an open position and, on each side of the open position, respectively a switch closed position and a grounded closed position;
• a center crank which is pivotally mounted on the main shaft, said center crank being rotatable between three angular pivoting positions corresponding respectively to said three stable positions;
• and
• a mechanical movement transformation system connected to said center crank, said mechanical movement transformation system producing a kinetic ratio between the rotational movement of the center crank and the rotational movement of the main shaft which increases when the center crank rotates from the open position to the switch closed position, whereby a force transmitted to the electrical contacts increases continuously as movement takes place from the open position to the switch closed position.