Stepped torque braking device

A braking device of at least one rotary shaft (S;

• S1, S2) extending along a longitudinal axis X, the braking device comprising at least:
• an actuation unit (I) comprising at least one winding (B;
• B1, B2;
• B1′, B2′) and first and second series of springs (R1, R2) mounted in a fixed housing (C),
• two friction discs (D1, D2) mounted axially slidable on said at least one rotary shaft (S;
• S1, S2),
• a rotationally fixed end flange (F1),
• an intermediate flange (F2) that is rotationally fixed but mounted axially slidable between the two friction discs (D1, D2),
• two magnetic armatures (A1, A2) that are rotationally fixed, but mounted axially slidable and biased respectively, when idle, by the first and second series of springs (R1, R2), in such a way that one (A2) of the two magnetic armatures (A1, A2) is pushed against one (D1) of the two friction discs (D1, D2), which then engages the intermediate flange (F2), which in turn engages the other friction disc (D2), which engages the end flange (F1), and when the winding (B;
• B1, B2;
• B1′, B2′) is supplied with current, the magnetic armatures (A1, A2) are magnetically biased towards the winding (B;
• B1, B2;
• B1′, B2′),
• characterized in that the magnetic armatures (A1, A2) are arranged in series along the longitudinal axis X, with each of the first and second series of springs (R1, R2) respectively biasing a magnetic armature (A1, A2), the second series of springs (R2) passing through the thickness of one of the two magnetic armatures (A1) in order to bias the other magnetic armature (A2),
• wherein the intermediate flange (F2) is elastically biased by a spring (R3) towards the friction disc (D1) adjacent to one of the two magnetic armatures (A2), to be separated when idle from the friction disc (D2) adjacent to the end flange (F1)
• wherein the intermediate flange (F2) engages a fixed stop (G13) under the action of the elastic biasing (R3), so as to be separated when idle from both friction discs (D1, D2) at the same time
• further comprising assembly screws (V) that connect the end flange (F1) to the actuation unit (I), at least some of said assembly screws (V) being provided with guide sleeves (G) that together form the fixed stop (G13) for the intermediate flange (F2), which is biased, advantageously by the spring (R3) mounted around a section (G12) of the guide sleeve (G) and which is supported on the end flange (F1).