Armature rotors of electromagnetic brakes

Claim 1

Armature rotor for an electromagnetic brake that includes a stator, the rotor comprising at least one disc axially mountable spaced from the stator and connected to an inner fastening ring by a ring of arms, said arms being inclined to the corresponding radii so as to form ventilation fins, the disc having a first surface adjacent the stator and a substantially flat, second surface furthest therefrom, the portions of largest diameter of these arms projecting axially on the disc and their crests being joined together by an annular web, this web, the disc and those portions of the fins which connect the web and disc defining channels for ventilation air, characterized in that said second disc surface is striated or undulated by annular and concentric ribs extending in a direction inclined to the direction of flow of the air in these channels, the angle formed between side of a rib and the portion of the contiguous surface being at the most equal to 90°, and the ratio between the spacing (D) of successive ribs and the height (H) of these ribs being comprised between 5 and 15.