Abstract: A brake disc of a rotation axis, comprising a support carrier, a braking band comprising two flanges connected by a plurality of connection elements which define ventilation channels for the braking band, at least one drive element able to connect the support carrier and the braking band to each other. The connection elements have a variable resistant section in an axial direction parallel to the rotation axis, the resistant section being measured in an area substantially parallel to the direction of the air flow inside the ventilation channels. Such resistant section progressively increasing as it moves from a median resistant section towards the respective connection resistant sections of the connection element to the flanges.

Abstract: A device for protecting an electrical system against surge voltages, comprising one or more protection components (10), means (20) for disconnecting the protection component (10) and means (30) for visually indicating the state of the component (10), operationally connected to the disconnection means (20) and comprising at least one control part (40) and at least one means (50) for indicating the state of the protection component (10), combined with the control part (40), whereby the relative arrangement of the control part (40) and the disconnection means (20) is such that, when the disconnection means are opened (20), the disconnection means release the control part (40), thereby allowing the control part to move.