elastic devices abruptly actuate a contact carrier in the upward direction when a push - member reaches a tensioning position from a position of rest . in the event of any blockage preventing such abrupt movement a lever constrainedly produces the movement when the push - member continues its movement as far as a constrained actuation position . the push - member carries colored zones . the contact carrier carries a colored zone . from the relative position of these zones viewed through a window in the casing , the user can adjust the positioning of the limit switch with respect to a movable member intended to actuate it so that the two phases of the actuation take place at the required points . the user can also check whether the contact carrier moves in response to the elastic devices or in response to the lever .