Disc brake for an aircraft wheel

1. A disk brake for an aircraft wheel, comprising:

a plurality of friction discs ( 20 , 30 ; 120 , 130 ), including rotor discs and stator discs;

a plurality of braking actuators ( 14 , 15 , 16 ; 114 );

a structure comprising a torsion tube ( 11 ; 111 ) on which the plurality of friction discs are fitted, a rear plate ( 12 ; 112 ) which is located at one end of the tube, and a support ( 13 ; 113 ) for the plurality of braking actuators at another end of the tube, each actuator in the plurality of actuators being activate able in order to selectively apply a pressing force to the plurality of discs;

wherein the plurality of discs comprise two separate groups, including a first group of friction disks ( 20 , 120 ) which is pressed alone by said actuators for braking operations below a specific braking torque threshold, and a second group ( 30 , 130 ) of friction disks which is pressed alone or in conjunction with the first group of disks by said actuators for braking operations above said torque threshold.

2. The disk brake according to claim 1 , in which the two groups of discs ( 20 , 30 ) extend at one side and the other of the torsion tube ( 11 ).

3. The disk brake according to claim 2 , in which the plurality of braking actuators comprise two groups of actuators, the support ( 13 ) carries said two groups of actuators ( 14 , 15 ), each of the groups of actuators acting on one of the groups of discs.

4. The disk brake according to claim 2 , in which the support ( 13 ) carries at least two actuators which are associated with a distribution member which, as long as the braking force developed by one of the at least two actuators does not exceed a specific threshold, applies the force of the one actuator to the first group of discs ( 20 ) and, when the force required exceeds the threshold, applies the force of the another of the at least two actuators to the two groups of discs.

5. The disk brake according to claim 1 , in which the two groups of discs ( 120 , 130 ) are arranged one behind the other around the torsion tube ( 111 ).

6. The disk brake according to claim 5 , which is provided with a distribution member which, up to a specific force threshold applied by the actuators ( 114 ), generates a braking torque by the first group of discs and, beyond the threshold, generates a braking torque by the two groups of discs.

7. The disk brake according to claim 5 , in which the distribution member comprises an abutment plate ( 145 ) which is arranged behind the second group of discs and which is repelled towards a stop ( 147 ) by springs ( 146 ) which define a force threshold, and in which the rim is provided with bars ( 148 ) for rotatably driving the rotor discs which have a discontinuity in the region of the second group of discs so that, when the actuators apply a force which presses the two groups of discs below the threshold, only the rotor discs of the first group of discs are rotatably driven whilst, when the force of the actuators exceeds the threshold, the assembly of the two groups of discs recoils so that the rotor discs of the second group are rotatably driven by means of engagement on the bars.

8. The disk brake according to claim 5 , in which the distribution member comprises a sheath ( 150 ) which is mounted so as to slide without any rotation on the torsion tube ( 111 ) and which carries the first group of discs ( 120 ), the sheath ( 150 ) being repelled by springs ( 151 ) towards a stop ( 152 ) and carrying an abutment plate ( 153 ) on which the first group of discs rests so that, as long as the force applied by the actuators ( 114 ) does not exceed a threshold determined by the springs, the sheath does not move and only the first group of discs is urged in order to generate a braking torque, and, when the force applied by the actuators exceeds this threshold, the sheath moves and is pushed against the second group of discs which, urged in this manner, also generates a braking torque.

9. The disk brake according to claim 5 , in which the distribution member comprises an abutment plate ( 160 ) which is interposed between the groups of discs ( 120 , 130 ) and is anchored in a frangible manner on the torsion tube, so that the force applied by the actuators ( 114 ) is lower than a threshold, the abutment plate ( 160 ) does not touch the second group of discs ( 130 ) and only the first group of discs ( 120 ) is urged and generates a braking torque, whilst, when the force applied exceeds the threshold, the anchoring gives way and the abutment plate ( 160 ) is released in order to move into contact with the second group of discs which is consequently urged and also generates a braking torque.

10. The disk brake according to claim 5 , in which the distribution member comprises a flexible abutment plate ( 160 ) which is interposed between the groups of discs ( 120 , 130 ) and is anchored on the torsion tube so that the force applied by the actuators ( 114 ) is lower than a threshold, the abutment plate ( 160 ) bends under the force but does not touch the second group of discs ( 130 ) and only the first group of discs ( 120 ) is urged and generates a braking torque, whilst, when the force applied exceeds the threshold, the abutment plate ( 160 ) bends sufficiently to move into contact with the second group of discs, which is consequently urged and also generates a braking torque.