Pulley comprising: - a securing head, - a first flange fixed to the securing head, - a first shaft extending from the first flange, - a second flange mounted rotatable between an open position and a closed position around the first shaft with respect to the first flange, the second flange having an inner surface and an outer surface, - a sheave mounted movable in rotation around the first shaft between the first flange and the second flange, the sheave being facing the inner surface of the second flange, - a rod fixed to the first flange and mounted movable between a first position and a second position with a first movement, the rod having an apex being salient from the outer surface of the second flange, pulley wherein, in the first position, the rod engages with the second flange in the closed position to keep the second flange in the closed position and wherein, in the second position, the rod allows rotation of the second flange, pulley characterised in that it comprises: - a blanking plate fixed on the second flange and mounted movable between a first position and a second position with a second movement, the first position of the blanking plate being arranged so that a blanking area at least partially covers the apex of the rod in the first position so as to prevent movement of the rod from the first position to the second position, covering being observed in a direction of observation parallel to the axis of rotation of the second flange with respect to the first flange. - a securing head, - a first flange fixed to the securing head, - a first shaft extending from the first flange, - a second flange mounted rotatable between an open position and a closed position around the first shaft with respect to the first flange, the second flange having an inner surface and an outer surface, - a sheave mounted movable in rotation around the first shaft between the first flange and the second flange, the sheave being facing the inner surface of the second flange, - a rod fixed to the first flange and mounted movable between a first position and a second position with a first movement, the rod having an apex being salient from the outer surface of the second flange, pulley wherein, in the first position, the rod engages with the second flange in the closed position to keep the second flange in the closed position and wherein, in the second position, the rod allows rotation of the second flange, pulley characterised in that it comprises: - a blanking plate fixed on the second flange and mounted movable between a first position and a second position with a second movement, the first position of the blanking plate being arranged so that a blanking area at least partially covers the apex of the rod in the first position so as to prevent movement of the rod from the first position to the second position, covering being observed in a direction of observation parallel to the axis of rotation of the second flange with respect to the first flange. - a blanking plate fixed on the second flange and mounted movable between a first position and a second position with a second movement, the first position of the blanking plate being arranged so that a blanking area at least partially covers the apex of the rod in the first position so as to prevent movement of the rod from the first position to the second position, covering being observed in a direction of observation parallel to the axis of rotation of the second flange with respect to the first flange.