Closure apparatus for openings for access to industrial machines

A closure apparatus for openings accesses to industrial machines, the closure apparatus comprising:

• a movable door and an actuator adapted to move the movable door between an active closure position for closing an opening, and an inactive position for noninterference with said opening, at which said movable door substantially clear said opening, wherein said actuator comprises a motorized shaft which supports, at its ends, at least two mutually opposite pulleys driven by said motorized shaft and adapted to wind respectively first and second flexible elements connected to respective substantially upper and external portions of said movable door, said actuator further comprising, substantially at an intermediate section of said motorized shaft, at least one third idle pulley idly mounted on said motorized shaft for winding at least one third flexible element connected to a substantially upper and central portion of said movable door, said at least one third idle pulley being provided with at least one position sensor for detecting an unrolling of said at least one third flexible element, which corresponds to the active closure position of said opening.