Disc brake disc with parking brake cylindrical surface

1. A disc brake disc with a parking brake cylindrical surface suitable for cooperating with shoes of a parking brake, wherein said disc brake disc comprises:

a braking band comprising opposite braking surfaces and a geometric connection portion of the band connecting the braking band to a bell;

said bell comprising a connection plate with a wheel hub and an annular geometric connection portion of the bell connecting the bell to the geometric connection portion of the band;

said braking band and said bell being separate pieces from each other and geometrically coupled to each other by said geometric connection portion of the band and said geometric connection portion of the bell so as to transfer a braking action exerted by a brake caliper on said opposite braking surfaces from said braking band to said bell and thus to said wheel hub;

said bell comprising a bell connection surface opposite to said braking band;

and wherein

said disc brake disc further comprises a parking ring wherein an inner portion of said parking ring is delimited in a radial direction by the parking brake cylindrical surface and wherein the parking brake ring is delimited in an external radial direction by a ring connection portion;

wherein a radially outer surface of said parking ring only touches a radially inner surface of said bell, and a radially outer surface of said bell only touches a radially inner surface of said braking band so that said parking ring does not touch the braking band,

said ring connection portion being coupled to said bell connection surface to transfer a parking braking action exerted by the shoes on the parking brake cylindrical surface to said bell and thus to the wheel hub.

2. The disc brake disc of claim 1 , wherein

said geometric bell connection surface is opposite to said braking band;

said geometric ring connection portion is coupled geometrically to said geometric bell connection surface to transfer the parking braking action exerted by the shoes on the parking brake cylindrical surface to said bell and thus to the hub; and/or wherein

said parking ring has a transverse section, or cross-section in a plane comprising a radial direction and an axial direction, I shaped, so that said geometric ring connection portion is connected to said inner portion of ring by a neck portion of ring extending in the axial direction less than both the extension in the axial direction of said geometric ring connection portion and the extension in the axial direction of said inner portion of ring; and/or wherein

said bell comprises a geometric bell connection surface opposite to said braking band which circumferentially forms a substantially uniformly distributed coupling;

said parking ring comprises radially externally a geometric ring connection portion which circumferentially forms a substantially uniformly distributed coupling;

said geometric ring connection portion is coupled geometrically to said geometric bell connection surface to transfer the parking braking action exerted by the shoes on the parking brake cylindrical surface to said bell and thus to the hub.

3. The disc brake disc of claim 1 , wherein

said geometric connection portion of band and said geometric connection portion of bell form a shape geometric coupling which constrains said braking band to said bell at least in radial and tangential directions to the brake disc;

said geometric ring connection portion and said geometric bell connection surface form a shape geometric coupling which constrains said braking band to said bell at least in the radial and tangential directions to the brake disc;

said geometric connection portion of band and said geometric connection portion of bell form a pair of radial toothings meshed with each other; and

said geometric ring connection portion and geometric bell connection surface form a pair of radial toothings meshed with each other.

4. The disc brake disc of claim 1 , wherein

said bell is made of metal sheet of constant thickness and shaped at least to form said connection portion of bell and said bell connection surface;

said parking ring is made from any of the materials selected from the group consisting of: steel, cast iron, aluminium, plastic and zamak; and/or wherein

said parking ring is obtained by sintering, casting, forging, stamping or additive manufacturing.

5. The disc brake disc of claim 1 , wherein

said parking ring is blocked to said bell by a weld or separate welding points or riveting points of the ring connection portion to the bell connection surface or by interference by radially deforming said ring connection portion against said bell connection surface or by gluing.

6. The disc brake disc of claim 1 , wherein

said bell is obtained by deep drawing a metal sheet and, at least its annular bell connection portion is made by radial deformation; and/or wherein

said braking band is obtained by casting; and/or wherein

said parking ring is made by moulding, sintering or forging and said parking brake cylindrical surface is made by chip removal to form a surface substantially coaxial with the axis of rotation of the disc brake disc.

7. A method for assembling a disc brake disc, comprising the following steps:

providing a braking band, a bell and a parking ring according to claim 1 ;

coupling said bell to said braking band by coupling to each other said geometric connection portion of band and said geometric connection portion of bell; and

coupling said parking ring to said bell by coupling said ring connection portion to said bell connection surface.

8. The method of claim 7 , wherein said coupling step of the parking ring to the bell takes place before said coupling step of the braking band to the bell.

9. The method of claim 7 , wherein said coupling step of the braking band to the bell takes place by radially deforming said bell against said braking band so that said geometric connection portion of bell matches said geometric connection portion of band.

10. A service and parking brake comprising a disc brake disc according to claim 1 .

11. A disc brake disc with a parking brake cylindrical surface suitable for cooperating with shoes of a parking brake, wherein said disc brake disc comprises:

a braking band comprising opposite braking surfaces and a geometric connection portion of the band connecting the braking band to a bell;

said bell comprising a connection plate with a wheel hub and an annular geometric connection portion of the bell connecting the bell to the geometric connection portion of the band;

said braking band and said bell being separate pieces from each other and geometrically coupled to each other by said geometric connection portion of the band and said geometric connection portion of the bell so as to transfer a braking action exerted by a brake caliper on said opposite braking surfaces from said braking band to said bell and thus to said wheel hub;

said bell comprising a bell connection surface opposite to said braking band;

and wherein said disc brake disc further comprises a parking ring wherein an inner portion of said parking ring is delimited in a radial direction by the parking brake cylindrical surface and wherein the parking brake ring is delimited in an external radial direction by a ring connection portion;

wherein the bell separates the parking ring from the braking band so that the parking ring does not touch the braking band,

said ring connection portion being coupled to said bell connection surface to transfer a parking braking action exerted by the shoes on the parking brake cylindrical surface to said bell and thus to the wheel hub.