(57) A safety electric switch, comprising a casing (2,3,4) with at least two slots (18,
19) for the insertion of a key actuator (20) of pre-defined shape, at least one pair
of electric contacts (5,5', 6,6',7,7',8,8') disposed in the casing (3) and displaceable
between a closed and an open position, a cam (15) mounted inside the casing (4) and
operatively connected to the contacts to promote their movement and commutation, the
cam being rotatable around a first axis (H) by insertion of the actuator in the casing,
blocking means (22) adapted to prevent rotation of the cam (15) and the consequent
displacement of the contacts, elastic means (23) acting on the blocking means (22)
to maintain them in a cam blocking position when the actuator is disinserted from
the casing. The blocking means (22) comprise at least one lever element (24,24') pivoted
about a second axis (K) distal from the first axis (H) and positioned so as to act
on one side face of the cam (15). The second pivot axis (K) is substantially parallel
to the cam pivot axis (H).
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