Brake bell of a brake disk and brake disk

Abstract

The object of this invention is a brake bell (100) for connecting a brake band (1) of a brake disc (2) to a hub (101) of a vehicle (102); wherein said brake bell (100) comprises at least a first bell part (103); said brake bell (100) comprises at least a second bell part (104); wherein said first bell part (103) and said second bell part (104) are connected to each other in a separable manner by means of disconnectable bell connecting devices (105); and wherein said first bell part (103) comprises a first bell toothing (106) suitable for connecting to a brake band (1); and wherein said second bell part (103) comprises a second bell toothing (109) distinct from said first bell toothing (106) and suitable for connecting to said brake band (1).

Description

Brake bell of a brake disk and brake disk1DESCRIPTION

[0001] , Field of the invention

[0002] , The present invention relates to braking devices comprising brake discs suitable for vehicles.

[0003] , In particular, the present invention relates to a brake disk comprising a brake bell and a braking band coupled to each other with teeth.

[0004] , Prior art

[0005] , In a disc brake, the brake caliper is generally arranged astride the outer peripheral edge of a brake disk, suitable for rotating about an axis of rotation (X-X) defining an axial direction (A-A). In a disc brake, a radial direction (RR) is also defined, substantially orthogonal to said axial direction (XX), and a tangential direction (CC) or circumferential direction (CC), in all its points orthogonal both to said axial direction (XX) and to said radial direction (RR).

[0006] , The brake calipers are constrained to a support structure that remains stationary with respect to the wheel of the vehicle, such as a spindle of a suspension of a vehicle or a hub of a wheel of a vehicle or a fork. The brake caliper usually comprises a caliper body having two elongated portions arranged so as to face opposite braking surfaces of a brake disk, and at least one bridge that connects said two elongated portions to each other. The calipers, when properly operated, press the pads against the braking band, and the braking action is produced by the friction between the pads and the braking band of the brake disk.

[0007] , Brake discs are known in which the bell is made of a material different from that of the braking band, for example, braking bands made of carbon-containing material, and bells made of aluminum or steel, or in deformed and cup-shaped steel sheet and provided with a circumferential toothing for coupling to the braking band.

[0008] , Such brake discs, which we can call composites, allow, for example, a lower weight and thus contribute to reducing the weight of the unsprung masses of the relative vehicle.

[0009] , The known state of the art relating to the dragging of brake bands made of carbon-containing material, or carbon-carbon, can be traced back to three macro-families: dragging with bushings, dragging with teeth, dragging with extended teeth.

[0010] , In the drag with bushings, the drag occurs through "bobbin" elements that interface between the "brake band" and the "bell" which, in turn, is connected to the wheel hub. Its main problem lies in the fact that in the area of the bushings adequate ventilation of the band cannot be achieved, due to the need to leave sufficient material which has the task of providing the necessary structural strength to the components. For high torques / powers and the consequent increase in the number / size of the bushings, the component suitable for cooling the braking band is further penalized. This constructive solution provides for having areas dedicated to ventilation alternating with areas dedicated to dragging, effectively limiting one over the other.

[0011] , A brake disk of this type is known, for example, from WO2020128963A1.

[0012] , Furthermore, document WO2020128963A1 discloses a disc brake whose braking band has internal radial protrusions for the connection, by means of guide elements, to a side-by-side dragging bell.

[0013] , In toothed dragging, the dragging occurs through a form fit (the toothing) which occupies portion of the thickness of the braking band. This solution involves using portion of the thickness of the band to drag the braking band and portion of the thickness of the braking band to ventilate the disk.

[0014] , The form-fitting coupling that causes the dragging is made directly between the bell element and the braking band without the need for additional elements.

[0015] , This solution overcomes the concept of dragging with bushings, so that it is possible to have separation between the dragging area and the area dedicated to the ventilation / cooling of the disk.

[0016] , The limit of this embodiment lies in the fact that for materials of the band that are not sufficiently robust, the dragging portion must in any case be of generous dimensions, taking up portion of the space for ventilation or being very bulky, which is incompatible with the limited space present inside a wheel rim of a vehicle.

[0017] , Furthermore, by dragging only one side of the ventilated braking band, during braking, bending stresses are triggered on the braking band itself, stresses that should be avoided.

[0018] , A brake disk of this type is known, for example, from EP3147529A1.

[0019] , The drag with extended toothing occurs through a form fit (the toothing) which occupies the entire thickness of the brake band.

[0020] , In this embodiment, similarly to that with bushes, there is an alternation between areas of the band intended for the dragging function with areas intended for the passage of air and the cooling of the disk itself. The direct coupling of the bell / band makes it possible to reduce, but not eliminate, the areas in which it is not possible to achieve the ventilation of the disk as occurs in the drag with bushings.

[0021] , A brake disk of this type is known, for example, from BR102018073672A2.

[0022] , In particular, document BR102018073672A2 discloses a brake disk comprising a ventilated braking band or friction ring, in which the inner edge facing the axis of rotation is closed by a toothed ring portion.

[0023] , Other solutions are known from EP1801448A1, W02018050821A1.

[0024] , However, these known solutions are not very suitable for applications where the braking band is made of a resistant but at the same time fragile material, such as, for example, braking bands made of carbon (also known as carbon-carbon) or in carboceramic. In fact, in this case, connecting and guiding elements that are anchored to the braking band are to be avoided, creating localized areas of great stress and high risk of breakage.

[0025] , Furthermore, one of the most significant drawbacks in the dragging of the prior art braking bands made of fragile material by means of dragging elements, typically dragging bells or brake bells, is the impossibility of simultaneously dragging both sides of the ventilated braking band, leaving free the central portion of the inner edge of the braking band which is usually the area of the braking band most dedicated to ventilation.

[0026] , Solution

[0027] , Aim, therefore, of the present invention is to provide a brake band for a brake disk which provides a toothed connection to a brake bell and which allows the dragging of both sides of the brake band, but, at the same time, avoids occluding the ventilation passages of the brake band.

[0028] , This and other objects and advantages are achieved with a brake bell according to claim 1 and a brake disk according to claim 13.

[0029] , Some advantageous embodiments are the subject of the dependent claims.

[0030] , From the analysis of this embodiment, it has emerged that the proposed embodiment makes it possible to obtain a braking band and a brake disk in which the support between the band and the bell is axially distributed.

[0031] , Thanks to the proposed solutions, it is also possible to minimize the non-ideal mass distribution to resist and minimize the thermal distortions generated by the heating of the braking band and, at the same time, the ventilation and above all a heat exchange between the braking band and the cooling air is not compromised.

[0032] , The coupling between the portions of the bell, made with toothed couplings, guarantees the structural integrity and correct rigidity of the braking band and guarantees the best possible coupling between the disk and the bell.

[0033] , Furthermore, thanks to proposed solutions, and in particular a bell that can be separated into two or more portions, it is possible to mount and replace the braking band once the pre-established wear limits have been reached.

[0034] , Thanks to the proposed solutions it is possible to divide the "brake bell" element, which has the task of connecting the braking band to the wheel hub, into two or more distinct components that can be assembled together, hereinafter referred to as the first portion of the bell, or simply "bell", and the second portion of the bell, or simply "external driver".

[0035] , The dragging of the braking band takes place on the outer bands of the latter, not affecting the central area which is completely dedicated to the ventilation / cooling of the disk. In this way, the dragging area is separated from the ventilation area, being able to develop / modify them according to the needs without mutual interference.

[0036] , Compared to a toothed dragging of the prior art which generally has a monolithic bell that drags only one portion of the band, this embodiment is able to drag both folders or portions of the braking band, in fact being more robust and allowing the transmission of higher torques, but at the same time not going to the detriment of ventilation. It goes without saying that this aspect leads to a different constructive form deriving from the need to have the bell split, or in several portions, to be reassembled, once the braking band has been positioned on the bell.

[0037] , Some of the elements constituting this embodiment can be made by mechanical machining by removal of shavings, in particular the bell.

[0038] , The driver could be made with the aid of laser cutting, water cutting or other technology suitable for maintaining the shape and the appropriate tolerances provided for the piece.

[0039] , Another advantage of the proposed embodiment with respect to traditional toothed driving mechanisms is that of having the driving compartment closed axially (that is, in the axial direction A-A) and not passing on both sides of the braking band. In this way the dragging structure is more robust than a traditional one which has an axially "open" tooth, and allows to have greater resistance with less thickness at the same size.

[0040] , The axially closed compartment structure provides a further advantage in terms of ventilation because it allows to exploit the volume contained between the two faces on which the braking band is dragged to increase the available exchange surface with respect to a traditional drive.

[0041] , A variant of the basic configuration of the embodiment provides for the integration of an axial sealing ring and an external driver in a single element.

[0042] , Compared to the solution in separate portions, the elimination of a physical component facilitates the management of the components.

[0043] , This variant enables weight savings at the expense of greater manufacturing complexity which requires machining by removal of material also for the construction of the integrated driver.

[0044] , Figures

[0045] , Further characteristics and advantages of the device will become apparent from the following description of its preferred embodiment examples, given by way of non-limiting example, with reference to the accompanying figures in which:

[0046] , - Figure 1 shows an axonometric view of a disc brake from the vehicle side, according to a first embodiment;

[0047] , - Figure 2 represents the disk of Figure 1 in axonometric view from the wheel side;

[0048] , - Figure 3 shows a side view of the disk of Figure 1;

[0049] , - Figure 4 shows a section according to a plane containing a circumferential and radial direction in the centre of the disc of Figure 1;

[0050] , - Figure 5 illustrates an axonometric view in separate portions of the braking band and the bell of the disk of Figure 1 from the wheel side;

[0051] , - Figure 6 shows a detail of the brake band and brake bell coupling of the disk of Figure 1 in a section according to a plane containing an axial direction and a radial direction and passing through depressions of teeth of the brake bell and in which the ventilation ducts are highlighted which from the inside of the brake bell allow a flow of ventilation air towards the second bell teeth, as well as the large bell ventilation windows that allow the flow of air to the ventilation opening of the brake band, here made as a plurality of holes arranged in quincunx;

[0052] , - Figure 7 illustrates a detail of the coupling of the braking band and brake bell of the disk of Figure 1 in a section according to a plane containing an axial direction and a radial direction and passing through the centreline of teeth of the brake bell and in which the large bell ventilation windows are highlighted which allow the flow of air to the ventilation opening of the braking band, here made as a plurality of holes arranged in a quincunx;

[0053] , - Figure 8 illustrates a detail of the coupling of the braking band and brake bell of the disk of Figure 1 in a section according to a plane containing an axial direction and a radial direction and passing through the centreline of removable connecting devices between the second portion of the bell and the wall of the second bell teeth, here a bell stud, where a spacer element of said second bell teeth wall is in the foreground;

[0054] , - Figure 9 shows a detail of the separate portions of the brake band coupling and brake bell of the disc of Figure 1 in a section according to a plane containing an axial direction and a radial direction;

[0055] , - Figure 10 shows, according to a different point of view more shifted towards the vehicle side, a detail in separate portions of the coupling of the braking band and brake bell of the disc of Figure 1 in a section according to a plane containing an axial direction and a radial direction;

[0056] , - Figure 11 shows, according to a different point of view more shifted towards the wheel side, a detail in separate portions of the brake band coupling and brake bell of the disc of Figure 1 in a section according to a plane containing an axial direction and a radial direction;

[0057] , - Figure 12 illustrates a disc brake in axonometric view from the vehicle side, according to a second embodiment;

[0058] , - Figure 13 shows the disc of Figure 12 in an axonometric projection from the wheel side;

[0059] , - Figure 14 illustrates a side view of the disk of Figure 12;

[0060] , - Figure 15 shows a section according to a plane containing a circumferential and radial direction in the centre of the disc of Figure 12;

[0061] , - Figure 16 illustrates in axonometric view in separate portions the braking band and the bell of the disc of Figure 12 from the wheel side;

[0062] , - Figure 17 shows a detail of the coupling of the braking band and brake bell of the disk of Figure 12 where the braking band is sectioned in a section according to a plane containing an axial direction and a radial direction and passing through depressions of teeth of the brake bell;

[0063] , - Figure 18 shows an axonometric view of a disc brake from the vehicle side to which a brake caliper is associated, placed astride the braking band and in which a wheel hub of a car is associated with the brake bell.

[0064] . Description of some preferred embodiments

[0065] , According to a general embodiment, a brake disk 2, comprising a brake bell 100 and a braking band 1.

[0066] , According to a general embodiment, a brake bell 100 for connecting a braking band 1 of a brake disk 2 to a hub 101 of a vehicle 102, comprises the following characteristics.

[0067] , Said brake bell 100 is suitable for rotating about an axis of rotation XX, an axis of rotation which defines an axial direction AA, a radial direction RR orthogonal to said axial direction AA and intersecting said axis of rotation XX, a circumferential direction CC, concentric to said axis of rotation XX and, at a point of intersection between said axial direction AA and said radial direction RR, orthogonal to both said axial direction AA and said radial direction RR.

[0068] , Said brake bell 100 comprises at least a first bell portion 103.

[0069] , Said brake bell 100 comprises at least a second bell portion 104.

[0070] , Said first portion of the bell 103 and said second portion of the bell 104 are connected to each other in a separable manner by means of detachable bell connecting devices 105.

[0071] , Advantageously, said first portion of the bell 103 comprises a first bell teeth 106 suitable for connecting to a braking band 1.

[0072] , Said second portion of bell 103 comprises a second bell teeth 109 distinct from said first bell teeth 106 and adapted to connect to said braking band 1.

[0073] , According to one embodiment, said first bell teeth 106 comprise first bell teeth protrusions 107 interspersed with first bell teeth recesses 108.

[0074] , According to one embodiment, said first bell teeth protrusions 107 and said first bell teeth recesses 108 are distributed along a circumferential extension CC so as to interface with said braking band 1.

[0075] , According to one embodiment, said second bell teeth 109 comprise second bell tooth protrusions 110 interspersed with second bell teeth recesses 111. Said second bell teeth protrusions 110 and said secondbell teeth recesses 111 are distributed along a circumferential extension CC so as to interface with said braking band 1.

[0076] , According to one embodiment, said first bell teeth 106 comprise first bell teeth protrusions 107 interspersed with first bell teeth recesses 108. Said first bell teeth protrusions 107 and said first bell teeth recesses 108 are regularly distributed alternating with each other without interruption along a circumferential extension CC, so as to interface with said braking band 1.

[0077] , According to one embodiment, said second bell teeth 109 comprise second bell teeth protrusions 110 interspersed with second bell teeth recesses 111. Said second bell teeth protrusions 110 and said second bell teeth recesses 111 are regularly distributed and alternating with each other without interruption along a circumferential extension C-C so as to interface with said braking band 1;

[0078] , According to one embodiment, said first bell teeth 106 comprise a first bell teeth wall 112 which at least partially covers and closes said first bell teeth 106 in the axial direction A-A on the opposite side with respect to the direction of engagement of said first bell teeth 106 with said braking band 1.

[0079] , According to one embodiment, said first bell teeth 106 comprise a first bell teeth wall 112 which at least partially covers and closes in axial direction A-A said first bell teeth 106 on the opposite side with respect to the direction of engagement of said first bell teeth 106 with said braking band 1; and wherein said first bell teeth wall 112 is a ring with an annular body.

[0080] , According to one embodiment, said first bell teeth 106 comprise a first bell teeth wall 112 which at least partially covers and closes in axial direction A-A said first bell teeth 106 on the opposite side with respect to the direction of engagement of said first bell teeth (106) with said braking band (1); and wherein said first bell teeth wall (112) is a ring with an annular body and said ring is integral, that is, in a single piece with said first bell portion (103).

[0081] , According to one embodiment, said second bell teeth 109 comprises a second bell teeth wall 113 which at least partially covers and closes in the axial direction A-A said second bell teeth 109 on the opposite side with respect to the direction of engagement of said second bell teeth (109) with said braking band (1).

[0082] , According to one embodiment, said second bell teeth 109 comprise a second bell teeth wall 113 which at least partially covers and closes said second bell teeth 109 in axial direction A-A from the side opposite to the direction of engagement of said second bell teeth 109 with said braking band 1.

[0083] , Said second bell teeth wall 113 comprises spacer elements 120 which keep said second bell teeth wall 113 spaced at least in some of its portions from said second bell toothing 109 so as to create a bell cavity 121 between said second bell teeth wall 113 and said second bell toothing 109.

[0084] , According to one embodiment, said brake bell 100 comprises an inner side of bell 122 facing said axis of rotation XX.

[0085] , Said second bell teeth 109 comprise a second bell teeth wall 113 which at least partially covers and closes said second bell teeth 109 in the axial direction A-A on the opposite side with respect to the direction of engagement of said second bell teeth 109 with said braking band 1.

[0086] , Said second bell teeth wall 113 comprises spacer elements 120 which keep said second bell teeth wall 113 spaced at least in some of its portions from said second bell toothing 109 so as to create a bell cavity 121 between said second bell teeth wall 113 and said second bell toothing 109.

[0087] , Said first bell portion 103 comprises openings or pass-through ducts which connect said bell cavity 121 with said bell interior 122.

[0088] , According to one embodiment, said second bell teeth 109 comprise a second bell teeth wall 113 which at least partially covers and closes in axial direction A-A said second bell teeth 109 on the side opposite with respect to the direction of engagement of said second bell teeth (109) with said braking band (1); and wherein said second bell teeth wall (113) is a ring with an annular body.

[0089] , According to one embodiment, said second bell teeth 109 comprise a second bell teeth wall 113 which at least partially covers and closes said second bell teeth 109 in axial direction A-A on the opposite side with respect to the direction of engagement of said second bell teeth 109 with said braking band 1; and wherein said second bell teeth wall 113 is integral with said second bell portion 104.

[0090] , According to one embodiment, said second bell teeth 109 comprise a second bell teeth wall 113 which at least partially covers and closes said second bell teeth 109 in the axial direction A-A on the opposite side with respect to the direction of engagement of said second bell teeth 109 with said braking band 1; and wherein said second bell teeth wall 113 is a ring with an annular body; and wherein said second bell teeth wall 113 is of a separate piece, that is, a piece removably connected by means of removable connection devices 114, with said second bell portion 104.

[0091] , According to one embodiment, said first bell portion 103 and said second bell portion 104 respectively have a first bell portion teeth 115 and a second bell portion teeth 116 which are engaged with each other and releasably join said first bell portion 103 and said second bell portion 104.

[0092] , According to one embodiment, said first bell portion 103 comprises at least one threaded connection seat 117.

[0093] , Said second bell portion 104 comprises at least one through connection seat 118.

[0094] , at least one bell stud screw 119 is received in said through connection seat 118 and is screwed into said threaded connection seat 117, joining said first bell portion 103 to said second bell portion 104.

[0095] , In accordance with one embodiment, said second bell teeth 109 comprise a second bell teeth wall 113 which at least partially covers and closes in axial direction A-A said second bell teeth 109 on the opposite side with respect to the direction of engagement of said second bell teeth (109) with said braking band (1).

[0096] , Said second bell teeth wall 113 is a ring with an annular body; and wherein said second bell teeth wall 113 is a separate piece, that is, a piece removably connected by means of removable connection devices 114, with said second bell portion 104.

[0097] , Said first bell portion 103 comprises a plurality of threaded connection seats 117.

[0098] , Said removable connection devices 114 are set screws housed in said threaded connection seats 117, arranging said second portion of the bell 104 between said first portion of the bell 103 and said second bell teeth wall 113.

[0099] , According to one embodiment, said first bell teeth 105 and said second bell teeth 109 are connected to each other by bell bridges 123 suited to form bell ventilation windows 124 suited to allow the passage of an air flow through the brake bell 100 to reach at least one braking band ventilation duct 8.

[0100] , According to one embodiment, said first bell teeth 106 and / or said second bell teeth 109 comprise a first and / or second bell teeth engagement surface 125, 126 shaped with a "spline" shape in its circumferential development C-C.

[0101] , According to one embodiment, said first bell teeth 106 and / or said second bell teeth 109 comprise a first and / or second bell teeth engagement surface 125, 126 shaped with a "spline" shape in itscircumferential development CC and with the ends of the teeth of said first bell teeth 106 and / or said second bell teeth 109 lying on a single cylindrical surface concentric to the axis of rotation XX.

[0102] , According to one embodiment, said first bell teeth 106 and / or said second bell teeth 109 comprise protrusion openings 127 which form through openings in said teeth 106 and / or 109.

[0103] , According to one embodiment, said first bell teeth 106 comprise first bell teeth protrusions 107 interspersed with first bell teeth recesses 108.

[0104] , Said second bell teeth 109 comprise second bell tooth protrusions 110 interspersed with second bell teeth recesses 111.

[0105] , At least some of said first bell teeth protrusions 107 and said second bell teeth protrusions 110 comprise protrusion openings 127 which form through openings.

[0106] , According to one embodiment, said first bell teeth 106 comprise first bell teeth protrusions 107 interspersed with first bell teeth recesses 108.

[0107] , Said second bell teeth 109 comprise second bell tooth protrusions 110 interspersed with second bell teeth recesses 111.

[0108] , All said protrusions of the first bell teeth 107 and said protrusions of the second bell teeth 110 comprise protrusion openings 127 which form through openings.

[0109] , In accordance with one embodiment, said first bell portion 103 and said second bell portion 104 respectively have a first bell portion teeth 115 and a second bell portion teeth 116 which are engaged with each other and releasably join said first bell portion 103 and said second bell portion 104.

[0110] , Some teeth of said first bell portion teeth 115 and / or said second bell portion teeth 116 comprise bell protrusion openings for connecting bell 128 which form through openings in said teeth.

[0111] , According to one embodiment, said second bell toothing 109 is a ring forming a ring gear.

[0112] , said brake bell 100 comprises a ring with an annular body which forms a wall of second bell teeth 113.

[0113] , Said second bell teeth wall 113 is a separate piece with respect to said first bell portion 103 and with respect to said second bell toothing 109 with a ring gear.

[0114] , Said second bell teeth wall 113 is connected by means of removable connection devices 114 to said first bell portion 103 by interposing between said second bell teeth wall 113 and said first bell portion 103 said second bell toothing 109 with a ring gear, avoiding being directly constrained to said second bell toothing 109 with a ring gear.

[0115] , According to one embodiment, said second bell teeth 109 is a ring forming a ring gear.

[0116] , Said brake bell 100 comprises a ring with an annular body which forms a wall of second bell teeth 113.

[0117] , Said second bell teeth wall 113 is a separate piece with respect to said first bell portion 103.

[0118] , Said second bell teeth wall 113 is in one piece, that is, of one piece, with said second bell toothing 109 with toothed crown.

[0119] , Said second bell teeth wall 113 is connected by means of removable connection devices 114 to said first bell portion 103 by interposing between said second bell teeth wall 113 and said first bell portion 103 said second bell toothing 109 with a ring gear.

[0120] , The present invention also relates to a brake disk 2 comprising a brake bell 100 as defined in any one of the previously described embodiments, as well as comprising a braking band 1 engaged with said first bell teeth 106 and second bell teeth 109.

[0121] , In accordance with one embodiment, said braking band 1 comprises the following features.

[0122] , A braking band body 3. Said braking band body 3 being suitable to rotate about an axis of rotation X-X, axis of rotation which defines an axial direction A-A, a radial direction R-R orthogonal to said axial direction A-A and intersecting said axis of rotation X-X, a circumferential direction C-C, concentric to said axis of rotation X-X and, at a point of intersection between said axial direction A-A and said radial direction R- R, said circumferential direction C-C being orthogonal to both said axial direction A-A and said radial direction R-R.

[0123] , Said braking band body 3 comprises an inner radial band edge 4 and an outer radial band edge 5 which delimit internally and externally said braking band body 3, wherein internally and externally means with respect to a radial direction travelled away from said axis of rotation XX.

[0124] , Said braking band body 3 comprises a first vehicle-side braking surface 6 and a second opposing braking surface 7; said surfaces 6, 7 being arranged parallel to each other and in respective planes, each plane comprising said radial R-R and circumferential C-C directions; said opposing braking surfaces 6, 7 being adapted to cooperate with brake pads housed in a brake caliper adapted to be placed astride the outer edge of said braking band 1, so as to bring said brake pads facing said opposing braking surfaces 6, 7.

[0125] , Said braking band body 3 comprises at least one braking band ventilation duct 8 which comprises at least one ventilation opening 9 which connects the inner radial band edge 4 with the outer radial band edge 5.

[0126] , said inner radial band edge 4 and said first braking surface 6, or their extensions, meet in a first vehicle side inner edge 10.

[0127] , Said inner radial band edge 4 and said second braking surface 7, or their extensions, meet in a second inner edge opposite the vehicle side 11.

[0128] , Said first vehicle side inner edge 10 comprises a first band teeth 12 which meshes with said first bell teeth 106.

[0129] , Said second inner edge on the side opposite the vehicle 11 comprises a second band toothing 16 distinct from said first band teeth 12, and which meshes with said second bell toothing 109.

[0130] , According to one embodiment, between said first band teeth 12 and said first bell teeth 106, when engaged with each other, a ventilation window 129 is present for each tooth between the free end of each tooth and the depression in which it engages.

[0131] , In accordance with a general embodiment of the invention, a braking band 1 of a brake disk 2 comprises a braking band body 3.

[0132] , braking band body 3 is suited to rotate about an axis of rotation X-X, an axis of rotation which defines an axial direction A-A, a radial direction R-R orthogonal to said axial direction A-A and intersecting said axis of rotation X-X, a circumferential direction C-C, concentric to said axis of rotation X-X and, at a point of intersection between said axial direction A-A and said radial direction R-R, said circumferential direction C- C being orthogonal to both said axial direction A-A and said radial direction R-R.

[0133] , Said braking band body 3 comprises an inner radial band edge 4 and an outer radial band edge 5 which delimit internally and externally said braking band body 3.

[0134] , The terms "internally" and "externally" refer to the position with respect to a radial direction travelled away from said axis of rotation XX.

[0135] , Said braking band body 3 comprises a first braking surface on the vehicle side 6 and a second opposing braking surface 7.

[0136] , Said surfaces 6, 7 are arranged parallel to each other and in respective planes. Each of these planes comprises said radial R-R and circumferential C-C directions.

[0137] , Said opposing braking surfaces 6, 7 are suitable for cooperating with brake pads housed in a brake caliper 129 suitable for being placed astride the outer edge of said braking band 1, so as to bring said brake pads facing said opposing braking surfaces 6, 7.

[0138] , braking band body 3 comprises at least one braking band ventilation duct 8 which delimits at least one ventilation opening 9 which connects the inner radial band edge 4 with the outer radial band edge 5.

[0139] , For example, in accordance with one embodiment, said ventilation opening is a plurality of through holes that pass through said brake band body in a radial-circumferential plane from its inner edge to its outer edge.

[0140] , Always in accordance with said general embodiment, said inner radial band edge 4 and said first braking surface 6, or their extensions, meet in a first vehicle side inner edge 10.

[0141] , The term "edge" refers to a region of the band body which is arranged in proximity to the intersection between the plane containing the braking surface and the inner radial band edge, so as to face both in the radial direction (towards the axis of rotation) and in the axial direction (away from the band body).

[0142] , Said inner radial band edge 4 and said second braking surface 7, or their extensions, meet in a second inner edge on the side opposite the vehicle 11.

[0143] , Advantageously, said first vehicle side inner edge 10 comprises a first band teeth 12.

[0144] , With further advantage, said second inner edge on the side opposite the vehicle 11 comprises a second band toothing 16 distinct from said first band teeth 12.

[0145] , In accordance with one embodiment, said first band teeth 12 comprise first teeth protrusions 13 interspersed with first teeth recesses 14.

[0146] , Said first teeth protrusions 13 and said first teeth recesses 14 are distributed along the circumferential extension CC of said first vehicle side inner edge 10.

[0147] , According to one embodiment, said first teeth recesses 14 face in the axial direction A-A outwardly, that is, on the opposite side of said braking band body 3.

[0148] , According to one embodiment, said first teeth recesses 14 are delimited internally by a first teeth recess edge 15.

[0149] , According to one embodiment, each of said first teeth 15 recess edges delimits in axial direction A-A the respective first teeth recesses 14 recess.

[0150] , According to one embodiment, said second band toothing 16 comprises second teeth protrusions 17 interspersed with second toothing recesses 18.

[0151] , According to one embodiment, said second teeth protrusions 17 and said second teeth recesses 18 are distributed along the circumferential extension CC of said second inner edge on the side opposite the vehicle 11.

[0152] , According to one embodiment, said second teeth recesses 18 face in the axial direction A-A outwardly, that is, on the opposite side of said braking band body 3.

[0153] , According to one embodiment, said second teeth recesses 14 are delimited internally by a second teeth recess edge 19.

[0154] , According to one embodiment, each of said second teeth recess edges 19 delimits in axial direction A-A the respective second teeth recess 14.

[0155] , According to one embodiment, said first teeth recesses 14 and said second toothing recesses 18 do not communicate with each other in the axial direction A-A.

[0156] , In accordance with an embodiment, said first teeth protrusions 13 and said first teeth recesses 14 are distributed along the circumferential extension C-C of said first vehicle side inner edge 10 with regular alternation avoiding interruptions.

[0157] , According to one embodiment, said second teeth protrusions 17 and said second teeth recesses 18 are distributed along the circumferential extension C-C of said second inner edge opposite the vehicle side 11 with regular alternation avoiding interruptions.

[0158] , According to one embodiment, braking band body 3 is in a single piece.

[0159] , With the term "single piece", it is understood that the brake band body is not made up of several portions assembled together by means of removable connection means, such as screws or bolts or snap connections, but is produced directly as a single piece.

[0160] , In accordance with an embodiment, said first band teeth 12 comprise a first band teeth engagement surface 20 which has the direction orthogonal thereto contained in a plane comprising the radial direction R-R and the circumferential direction C-C.

[0161] , According to one embodiment, said second band toothing 16 comprises a second band teeth engagement surface 21 which has the direction orthogonal thereto contained in a plane comprising the radial direction R-R and the circumferential direction C-C.

[0162] , According to one embodiment, all said first teeth recesses edges 15 lie in the same plane comprising the same radial direction R-R and the same circumferential direction C-C.

[0163] , According to one embodiment, all said second toothing recess edges 19 lie on the same plane comprising the same radial direction R-R and the same circumferential direction C-C.

[0164] , According to one embodiment, said first band teeth 12 and / or said second band toothing 16 comprises a first and / or second band teeth engagement surface 20 or 21 shaped with a "spline" shape in its circumferential development CC.

[0165] , The term "spline" means a surface that contains a line which, in mathematics, is a function, consisting of a set of polynomials connected together, the purpose of which is to interpolate a set of points (called spline nodes) in an interval, so that the function is continuous at least up to a given order of derivatives at each point of the interval.

[0166] , In accordance with one embodiment, said spline surface shape is intended to be applied to the sides of the teeth and to the recesses.

[0167] , According to one embodiment, said first band teeth 12 and / or said second band toothing 16 comprises a first and / or second band teeth engagement surface 20 or 21 shaped with a "spline" shape in its circumferential development CC and with the ends of all the protrusions 13 lying on a single cylindrical surface concentric to the axis of rotation XX.

[0168] , According to one embodiment, said at least one braking band ventilation duct 8 are a plurality of ventilation ducts comprising a plurality of through ventilation holes 22.

[0169] , In accordance with one embodiment, said at least one ventilation duct of the brake band 8 are a plurality of ventilation ducts comprising a plurality of through ventilation holes 22 and said plurality of through holes 22 are a plurality of series of through holes and each series of through holes is distributed in a plane containing a radial direction R-R and circumferential direction C-C.

[0170] , According to one embodiment, said at least one braking band ventilation duct 8 are a plurality of ventilation ducts comprising a plurality of through ventilation holes 22. Said plurality of through holes 22 are a plurality of series of through holes in which the series are arranged parallel to each other.

[0171] , According to one embodiment, said at least one braking band ventilation duct 8 are a plurality of ventilation ducts comprising a plurality of ventilation through holes 22. Said plurality of through holes 22 are a plurality of series of through holes in which the series are arranged parallel to each other and through holes 22 of adjacent and adjacent series are arranged in quincunx.

[0172] , According to one embodiment, said at least one braking band ventilation duct 8 is a plurality of ventilation ducts comprising a plurality of ventilation through holes 22. Said plurality of through holes 22 are a plurality of series of through holes. Said plurality of through holes 22 of each set avoids intersecting with through holes of an adjacent set.

[0173] , According to one embodiment, braking band body 3 comprises composite material.

[0174] , According to one embodiment, braking band body 3 comprises carbon-containing material.

[0175] , According to one embodiment, braking band body 3 comprises material containing carboceramic.

[0176] , According to one embodiment, braking band body 3 comprises material containing reinforcing fibres, for example, fibres containing carbon and / or glass fibres.

[0177] , According to one embodiment, said first band teeth 12 and second band toothing 16 are contained within planes lying on said parallel braking surfaces 6, 7.

[0178] , According to one embodiment, said first vehicle side inner edge 10 and said second inner edge on the opposite side to the vehicle 11 are connected to said braking surfaces 6, 7 each interposing a circumferential band channel 23, 24.

[0179] , According to one embodiment, said inner radial band edge 4 in its portion affected by said at least one braking band ventilation duct 8 has a toroidal channel shape 25, that is, a channel whose envelope surface resembles the outer portion of the toroidal surface.

[0180] , The present invention also relates to a brake disk 2 comprising a braking band according to any one of the previously described embodiments.

[0181] , In accordance with one embodiment, said brake disk further comprises a brake bell 100.

[0182] , Said brake bell 100 comprises a first bell teeth 106 which meshes with said first band teeth

[0183] , Said brake bell 100 comprises a second bell toothing 109 which meshes with said second band toothing 16.

[0184] , According to one embodiment, said brake bell 100 is a brake bell 100 for connecting a braking band 1 of a brake disk 2 to a hub 101 of a vehicle 102.

[0185] , According to one embodiment, said brake bell 100 is suitable for rotating about an axis of rotation XX, an axis of rotation which defines an axial direction AA, a radial direction RR orthogonal to said axial direction AA and intersecting said axis of rotation XX, a circumferential direction CC, concentric with said axis of rotation XX and, at a point of intersection between said axial direction AA and said radial direction RR, orthogonal to both said axial direction AA and said radial direction RR.

[0186] , According to one embodiment, said brake bell 100 comprises at least a first bell portion 103.

[0187] , According to one embodiment, said brake bell 100 comprises at least a second bell portion104.

[0188] , According to one embodiment, said first bell portion 103 and said second bell portion 104 are connected to each other in a separable manner by means of detachable bell connecting devices 105.

[0189] , According to one embodiment, said first portion of the bell 103 comprises said first bell teeth 106.

[0190] , According to one embodiment, said first bell teeth 106 comprise first bell teeth protrusions 107 interspersed with first bell teeth recesses 108.

[0191] , According to one embodiment, said first bell teeth protrusions 107 and said first bell teeth recesses 108 are distributed along a circumferential extension CC so as to interface with said braking band 1.

[0192] , According to one embodiment, said second portion of bell 103 comprises said second bell teeth 109 distinct from said first bell teeth 106.

[0193] , In accordance with one embodiment, said second bell teeth 109 comprise second bell teeth protrusions 110 interspersed with second bell teeth recesses 111.

[0194] , In accordance with an embodiment, said second bell teeth protrusions 110 and said second bell teeth recesses 111 are distributed along a circumferential extension CC so as to interface with said braking band 1.

[0195] , To the embodiments described above, a person skilled in the art, in order to meet contingent and specific requirements, may make numerous modifications, adaptations and replacement of elements with others functionally equivalent, without however departing from the scope of the following claims.REFERENCE LIST braking band brake disc brake band body inner radial band edge outer radial band edge vehicle-side braking surface opposite side braking surface or wheel side brake band ventilation duct ventilation opening first inner edge on the vehicle side second inner edge opposite the vehicle side first band toothing protrusions of first toothing first teeth recesses edge of the first teeth recess second band toothing second gear teeth protrusions second teeth recesses second teeth recesses edge engagement surface of first band toothing second band toothing engagement surface through-holes for ventilation circumferential band channel circumferential band channel toroidal channel brake bell hub vehicle first portion of the bell104 second portion of the bell105 detachable bell connecting devices106 first bell teeth107 protrusions of first bell teeth108 recesses of first bell teeth109 second bell teeth110 second bell teeth protrusions111 recesses of second bell teeth112 wall of first bell teeth113 wall of second bell teeth114 removable connection devices between the second portion of the bell and the wall of the second bell toothing115 first bell portion teeth116 second row of teeth of the bell portion117 threaded connection seat118 through connection seat119 bell stud screw120 spacer elements121 bell cavity122 bell interior123 bell bridges124 bell ventilation windows125 engagement surface of first bell teeth126 second bell toothing engagement surface127 protrusion openings128 bell protrusion openings of bell connecting bell129 brake caliperX-X axis of rotationA-A axial directionR-R radial directionCC circumferential direction

Claims

CLAIMS1. A brake bell (100) for connecting a braking band (1) of a brake disc (2) to a hub (101) of a vehicle (102) ; wherein said brake bell (100) being adapted to rotate about a rotation axis (X-X) , said rotation axis defining an axial direction (A-A) , a radial direction (R-R) orthogonal to said axial direction (A-A) and intersecting said rotation axis (X-X) , a circumferential direction (C-C) , concentric with said rotation axis (X-X) and, at a point of intersection between said axial direction (A-A) and said radial direction (R-R) , orthogonal to both said axial direction (A-A) and said radial direction (R-R) ; said brake bell (100) comprises at least a first bell portion (103) ; said brake bell (100) comprises at least a second bell portion (104) ; wherein said first bell portion (103) and said second bell portion (104) are separably connected to each other through disconnectable bell connecting means (105) ; and wherein said first bell portion (103) comprises a first bell toothing (106) adapted to connect to a braking band (1) ; and wherein said second bell portion (103) comprises a second bell toothing (109) distinct from said first bell toothing (106) and adapted to connect to said braking band (1) .

2. A brake bell (100) according to claim 1, whereinsaid first bell toothing (106) comprises first bell teeth protrusions (107) interspersed with first bell toothing recesses (108) ; wherein said first bell teeth protrusions (107) and said first bell toothing recesses (108) are distributed along a circumferential extension (C-C) so as to interface with said braking band (1) ; and / or wherein said second bell toothing (109) comprises second bell teeth protrusions (110) interspersed with second bell toothing recesses (111) ; wherein said second bell teeth protrusions (110) and said second bell toothing recesses (111) are distributed along a circumferential extension (C-C) so as to interface with said braking band (1) ; or wherein said first bell toothing (106) comprises first bell teeth protrusions (107) interspersed with first bell toothing recesses (108) ; wherein said first bell teeth protrusions (107) and said first bell toothing recesses (108) are regularly distributed, alternating to each other without interruption along a circumferential extension (C-C) , so as to interface with said braking band (1) ; and / or wherein said second bell toothing (109) comprises second bell teeth protrusions (110) interspersed with second bell toothing recesses (111) ; wherein said second bell teeth protrusions (110) and said second bell toothing recesses (111) are regularly distributed, alternating to each other withoutinterruption along a circumferential extension (C-C) , so as to interface with said braking band (1) ;3. A brake bell (100) according to claim 1 or 2, wherein said first bell toothing (106) comprises a first bell teeth wall (112) at least partially covering and closing in the axial direction (A-A) said first bell toothing (106) on the opposite side with respect to the direction of engagement of said first bell toothing (106) with said braking band (1) ; or wherein said first bell toothing (106) comprises a first bell teeth wall (112) at least partially covering and closing in the axial direction (A-A) said first bell toothing (106) on the opposite side with respect to the direction of engagement of said first bell toothing (106) with said braking band (1) ; and wherein said first bell teeth wall (112) is a ring with an annular body; or wherein said first bell toothing (106) comprises a first bell teeth wall (112) at least partially covering and closing in the axial direction (A-A) said first bell toothing (106) on the opposite side with respect to the direction of engagement of said first bell toothing (106) with said braking band (1) ; and wherein said first bell teeth wall (112) is a ring with an annular body and said ring is in one piece, i.e. , in a single piece with said first bell portion (103) ; and / or whereinsaid second bell toothing (109) comprises a second bell teeth wall (113) at least partially covering and closing in the axial direction (A-A) said second bell toothing (109) on the opposite side with respect to the direction of engagement of said second bell toothing (109) with said braking band (1) ; or wherein said second bell toothing (109) comprises a second bell teeth wall (113) at least partially covering and closing in the axial direction (A-A) said second bell toothing (109) on the opposite side with respect to the direction of engagement of said second bell toothing (109) with said braking band (1) ; and wherein said second bell teeth wall (113) comprises spacer elements (120) which keep said second bell teeth wall (113) separated, at least in some of its portions, from said second bell toothing (109) so as to create a bell gap (121) between said second bell teeth wall (113) and said second bell toothing (109) ; or wherein said brake bell (100) comprises an inner bell side (122) facing said rotation axis (X-X) ; and wherein said second bell toothing (109) comprises a second bell teeth wall (113) at least partially covering and closing in the axial direction (A-A) said second bell toothing (109) on the opposite side with respect to the direction of engagement of said second bell toothing (109) with said braking band (1) ; and whereinsaid second bell teeth wall (113) comprises spacer elements (120) which keep said second bell teeth wall (113) separated, at least in some of its portions, from said second bell toothing (109) so as to create a bell gap (121) between said second bell teeth wall (113) and said second bell toothing (109) ; and wherein said first bell portion (103) comprises pass-through openings or ducts putting said bell gap (121) in communication with said bell interior (122) ; or wherein said second bell toothing (109) comprises a second bell teeth wall (113) at least partially covering and closing in the axial direction (A-A) said second bell toothing (109) on the opposite side with respect to the direction of engagement of said second bell toothing (109) with said braking band (1) ; and wherein said second bell teeth wall (113) is a ring with an annular body; or wherein said second bell toothing (109) comprises a second bell teeth wall (113) at least partially covering and closing in the axial direction (A-A) said second bell toothing (109) on the opposite side with respect to the direction of engagement of said second bell toothing (109) with said braking band (1) ; and wherein said second bell teeth wall (113) is in one piece, i.e., in a single piece with said second bell portion (104) ; or wherein said second bell toothing (109) comprises a second bell teeth wall (113) at least partially covering and closing in the axial direction (A-A) said second bell toothing (109) on the opposite side with respect to thedirection of engagement of said second bell toothing (109) with said braking band (1) ; and wherein said second bell teeth wall (113) is a ring with an annular body; and wherein said second bell teeth wall (113) is of a separate piece, i.e. , a piece removably connected by means of removable connection devices (114) to said second bell portion (104) .

4. A brake bell (100) according to any one of the preceding claims, wherein said first bell portion (103) and said second bell portion (104) have a first bell portion toothing (115) and a second bell portion toothing (116) , respectively, which are engaged with each other and releasably join said first bell portion (103) and said second bell portion (104) .

5. A brake bell (100) according to any one of the preceding claims, wherein said first bell portion (103) comprises at least one threaded connection seat ( 117 ) ; said second bell portion (104) comprises at least one pass-through connection seat (118) ; at least one bell stud (119) is accommodated in said pass-through connection seat (118) and is screwed into said threaded connection seat (117) , joining said first bell portion (103) to said second bell portion (104) .

6. A brake bell (100) according to any one of the preceding claims, whereinsaid second bell toothing (109) comprises a second bell teeth wall (113) at least partially covering and closing in the axial direction (A-A) said second bell toothing (109) on the opposite side with respect to the direction of engagement of said second bell toothing (109) with said braking band (1) ; and wherein said second bell teeth wall (113) is a ring with an annular body; and wherein said second bell teeth wall (113) is of a separate piece, i.e., a piece removably connected, by means of removable connection devices (114) , to said second bell portion (104) ; and wherein said first bell portion (103) comprises a plurality of threaded connection seats ( 117 ) ; said removable connection devices (114) are studs accommodated in said threaded connection seats (117) , arranging said second bell portion (104) between said first bell portion (103) and said second bell teeth wall(113) .

7. A brake bell (100) according to any one of the preceding claims, wherein said first bell toothing (105) and said second bell toothing (109) are connected to each other by bell bridges (123) adapted to form bell ventilation windows (124) therebetween, adapted to allow an airflow to pass through the brake bell (100) to reach at least one braking band ventilation duct (8) .

8. A brake bell (100) according to any one of the preceding claims, whereinsaid first bell toothing (106) and / or said second bell toothing (109) comprises a first and / or second bell toothing engagement surface (125, 126) having a spline-shaped circumferential extension (C-C) ; or wherein said first bell toothing (106) and / or said second bell toothing (109) comprises a first and / or second bell toothing engagement surface (125, 126) having a spline-shaped circumferential extension (C-C) and with the tooth ends of said first bell toothing (106) and / or said second bell toothing (109) lying on a single cylindrical surface concentric with the rotation axis (X-X) .

9. A brake bell (100) according to any one of the preceding claims, wherein said first bell toothing (106) and / or said second bell toothing (109) comprises protrusion openings (127) forming pass-through openings in said toothing (106 and / or 109) ; or wherein said first bell toothing (106) comprises first bell teeth protrusions (107) interspersed with first bell toothing recesses (108) ; wherein said second bell toothing (109) comprises second bell teeth protrusions (110) interspersed with second bell toothing recesses (111) ; wherein at least some of said first bell teeth protrusions (107) and said second bell teeth protrusions (110) comprise protrusion openings (127) forming pass-through openings; or whereinsaid first bell toothing (106) comprises first bell teeth protrusions (107) interspersed with first bell toothing recesses (108) ; wherein said second bell toothing (109) comprises second bell teeth protrusions (110) interspersed with second bell toothing recesses (111) ; wherein all said first bell teeth protrusions (107) and said second bell teeth protrusions (110) comprise protrusion openings (127) forming pass-through openings .

10. A brake bell (100) according to any one of the preceding claims, wherein said first bell portion (103) and said second bell portion (104) have a first bell portion toothing (115) and a second bell portion toothing (116) , respectively, which are engaged with each other and releasably join said first bell portion (103) and said second bell portion (104) ; and wherein some of the teeth of said first bell portion toothing (115) and / or said second bell portion toothing (116) comprise bell protrusion openings (128) for the bell connection, which form pass-through openings in said toothing.

11. A brake bell (100) according to any one of the preceding claims, wherein the second bell toothing (109) is a ring forming a ring gear; said brake bell (100) comprises a ring having an annular body forming a second bell teeth wall (113) ;said second bell teeth wall (113) is a separate piece with respect to said first bell portion (103) and with respect to said second bell toothing (109) in the shape of a ring gear; said second bell teeth wall (113) is connected by means of removable connection devices (114) to said first bell portion (103) interposing said second bell toothing (109) in the shape of a ring gear between said second bell teeth wall (113) and said first bell portion (103) , thus avoiding being directly constrained to said second bell toothing (109) in the shape of a ring gear; or wherein the second bell toothing (109) is a ring forming a ring gear; said brake bell (100) comprises a ring having an annular body forming a second bell teeth wall (113) ; said second bell teeth wall (113) is a separate piece with respect to said first bell portion (103) ; said second bell teeth wall (113) is in a single piece, i.e. , in one piece, with said second bell toothing (109) in the shape of a ring gear; said second bell teeth wall (113) is connected by means of removable connection devices (114) to said first bell portion (103) interposing said second bell toothing (109) in the shape of a ring gear between said second bell teeth wall (113) and said first bell portion (103) .

12. A brake disc (2) comprising a brake bell (100) according to any one of the preceding claims and a braking band (1) engaged with said first bell toothing (106) and second bell toothing (109) .

13. A brake disc (2) according to claim 12, wherein said braking band (1) comprises a braking band body (3) ; said braking band body (3) being adapted to rotate about a rotation axis (X-X) , which rotation axis defines an axial direction (A-A) , a radial direction (R-R) orthogonal to said axial direction (A-A) and intersecting said rotation axis (X-X) , a circumferential direction (C-C) , concentric with said rotation axis (X-X) and, at a point of intersection between said axial direction (A-A) and said radial direction (R-R) , said circumferential direction (C-C) being orthogonal to both said axial direction (A-A) and said radial direction (R-R) ; said braking band body (3) comprises an inner radial band edge (4) and an opposite outer radial band edge (5) , which internally and externally delimit, respectively, said braking band body (3) , wherein internally and externally mean with respect to a radial direction traveled away from said rotation axis (X-X) ; said braking band body (3) comprises a first vehicle-side braking surface (6) and a second opposite braking surface (7) ; said surfaces (6, 7) being arranged parallel to each other and on respective planes, each plane comprising said radial (R-R) and circumferential (C-C) directions; said opposite braking surfaces (6, 7) being adapted to cooperate with brakepads housed in a brake caliper adapted to be placed straddling the outer edge of said braking band (1) , so as to bring said brake pads to face said opposite braking surfaces (6, 7) ; wherein said braking band body (3) comprises at least one braking band ventilation duct (8) comprises at least one ventilation opening (9) which puts the inner radial band edge (4) in communication with the outer radial band edge ( 5 ) ; said inner radial band edge (4) and said first braking surface (6) , or the extensions thereof, meet in a first vehicle-side inner corner (10) ; said inner radial band edge (4) and said second braking surface (7) , or the extensions thereof, meet in a second opposite vehicle-side inner corner (ID ; and wherein said first vehicle-side inner corner (10) comprises a first band toothing (12) which engages said first bell toothing (106) ; and wherein said second opposite vehicle-side inner corner (11) comprises a second band toothing (16) , distinct from said first band toothing (12) , and which engages said second bell toothing (109) .

14. A brake disc (2) according to claim 12 or 13 wherein between said first band gearing (12) and said first bell toothing (106) , when engaged with each other, a ventilation window (129) is present forT1each tooth between the free end of each tooth and the depression in which the latter is engaged .

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