Wheel brake disc for rail vehicles

Abstract

Wheel brake disc (2) comprising at least two friction discs (2a, 2b) arranged on both sides of a web (10) of a wheel body (1) of a rail wheel and fastened by means of through bolts (3), wherein the at least two friction discs (2a, 2b) have cooling fins (14, 14'; 16, 17, 17') and domes (9), wherein the through bolts (3) extend through the domes (9) of both friction discs (2a, 2b) and the web (10), wherein bearing surfaces (9a) of the domes (9) and bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a, 17b) of the cooling fins (14, 14'; 16, 16';17, 17') from a respective rear side (R) of the at least two friction discs (2a, 2b) project in a first length and are in contact with bearing surfaces (11) of the web (10) of the wheel body (1), wherein end faces (14b, 14'b) of the cooling fins (14, 14'), which are arranged radially above and below the dome (9) with a dome (9) in screwing sectors (20) of the at least two friction discs (2a, 2b), project from the respective rear side (R) of the at least two friction discs (2a, 2b) in a second length, the dimension of which is less than the dimension of the first length, in which the bearing surfaces (9a) of the domes (9) and bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a, 17b) of the cooling fins (14, 14'; 16, 16';17, 17') protrude, and wherein the end faces (14b, 14'b) of the cooling fins (14, 14') are arranged at a distance from the web (10), wherein the screwing sectors (20) are first circular sectors around each dome (9) with the cooling fins (14, 14') arranged radially above and below the dome (9), and wherein a respective width of the screwing sectors (20) is determined by the respective dome (9), which is arranged on a mean diameter (22) approximately in the middle third of the respective friction disc (2a, 2b), and wherein the bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a) of the cooling fins (14, 14'; 16, 16';17, 17') outside the screw sectors (20) are arranged both on an outer diameter (23) in an outer third of the at least two friction discs (2a, 2b) and on an inner diameter (21) in an inner third of the at least two friction discs (2a, 2b), characterized in that only the cooling fins (14, 14') in the screw sectors (20) do not have a bearing surface to the web (10).

Description

[0001] The invention relates to a wheel brake disc for rail vehicles according to the preamble of claim 1.

[0002] Such a wheel brake disc of rail vehicles is usually attached to the wheel body of a rail wheel. This is in Fig. 1 shown in a schematic partial section of a schematic radial section view of a wheel body 1 with a wheel axle 1a and with a wheel brake disc 2 according to the prior art.

[0003] The wheel brake disc 2 has two friction discs 2a, 2b, each with a friction surface 15. The two friction discs 2a, 2b are clamped together against a wheel disc or against a web 10 of the wheel body 1 by means of through bolts 3. On the rear sides R of the friction discs 2a, 2b, mounting bosses 9, each with a bearing surface 9a, project to a specific length parallel to the direction of the wheel axis 1a and are evenly spaced around a diameter. These bearing surfaces 9a are in contact with a respective bearing surface 11 of the web 10.

[0004] Rotation of the friction discs 2a, 2b on the wheel disc or on the web 10 is typically prevented by radially arranged sliding blocks (not shown). These also absorb all forces on the wheel disc in the tangential direction, such as the frictional force between the brake pad (not shown, but easily imagined) and the friction discs 2a, 2b, and transmit them to the wheel body 1 of the corresponding wheel.

[0005] The purpose of screwing the friction discs 2a, 2b together during operation is to - to hold the friction discs 2a, 2b in their position on the web 10 of the wheel body 1 against the accelerations occurring from vibrations and shocks, - to allow the thermal expansion of the friction discs 2a, 2b through temperature changes in the radial direction, - to largely prevent uneven deformation of the friction discs 2a,2b due to uneven heating or cooling during and after braking.

[0006] The temperature gradient across the thickness of each friction disc 2a, 2b causes, for example, a disc deformation of the friction disc 2a, 2b if the friction disc 2a, 2b is not held firmly in place (see Fig. 1, friction disc 2b) and a curvature of a friction surface 16 of a respective friction disc 2a, 2b (see Fig. 1. Friction disc 2a) in radial direction upon heating during braking: Both effects lead to a deformation of the respective friction surface 2a, 2b, resulting in uneven wear of the brake pad, while simultaneously altering or reducing the contact surfaces between friction discs 2a, 2b and web 10. This is in Fig. 1 schematically represented.

[0007] In particular, thermally induced deformation leads to high dynamic stresses on the screws in tension and bending. Since the screws are generally only designed for a limited lifespan, the number of load cycles they can withstand is correspondingly limited.

[0008] Document EP 2 715 180 B1 describes wheel brake discs and their bolting. It shows... Fig. 2 a schematic partial section of a schematic radial section view of a wheel body 1 with a wheel brake disc 2 according to the prior art. In Fig. Figure 3 is a schematic top view of a section of a rear side R of a friction disc 2a, 2b of the wheel brake disc according to Fig. 2 shown from the state of the art.

[0009] The friction discs 2a, 2b of the wheel brake disc 2 are arranged coaxially to the wheel body 1 and its wheel axle 1a.

[0010] The through bolts 3 each have a bolt head 4 with a sleeve 4a arranged underneath, extend through through bores 12 in the respective flanges 9b of the domes 9 of both friction discs 2a, 2b and the web 10 in a direction parallel to the wheel axis 1a, and are each secured with a nut 5. The bolt heads 4 with the sleeves 4a and the nuts 5 are each arranged in an undercut 8 of a countersink 6 of a respective dome 9. The countersink 6 has a cylindrical section 7 on its inlet side, which transitions into the undercut 8, with a rounded transition 13 from the undercut 8 to the flange 9b being formed. The sleeve 4a lies on the inside of the flange 9b of the Fig. 2 shown left friction disc 2a, with the nut 5 on the inside of the flange 9b of the in Fig. The contact surfaces 9a of the flanges 9 of the friction discs 2a, 2b are each in contact with the contact surface 11 of the web 10.

[0011] The special design of the recesses in the friction discs 2a, 2b and the comparatively small flange thickness of the respective flange 9b under the bolt head or nut bearing surface result in a relatively elastic flange 9b, which experiences correspondingly low thermal expansion during braking. This reduces the load on the through bolts 12 caused by the thickness change of a heating flange 9b.

[0012] The screw force of the through bolts 12 is chosen to be just large enough to allow radial expansion of the friction discs 2a, 2b against the frictional force in the respective flange surface of the flanges 9b when heated.

[0013] It should be noted that the contact surfaces 9a of the flanges 9b of the friction discs 2a, 2b extend radially and circumferentially over the entire surface of each friction disc 2a, 2b on the web 10 of the wheel body 1. Furthermore, the friction discs 2a, 2b have cooling fins 14, 14'; 16, 16'; 17, 17', which also extend substantially radially on the rear surface R of the friction discs 2a, 2b and have respective contact surfaces 14a, 14'a; 16a, 16'a; 17a, 17'a, which are in contact with the contact surfaces 11 of the web 10. The cooling fins 14, 14'; 16, 16'; 17, 17' are in contact with the respective contact surfaces 14a, 14'a; 16a, 16'a; 17a, 17'a protrude with a specific first length parallel to the direction of the wheel axis 1a. This first length corresponds to the length of the domes 9. Thus, all bearing surfaces 9a; 14a, 14'a; 16a, 16'a; 17a, 17'a lie in one plane.

[0014] The cooling fins 14, 16, 17 with their contact surfaces 14a, 16a, 17a are arranged on an inner diameter 21, and the cooling fins 14', 16', 17' with their contact surfaces 14'a, 16'a, 17'a are arranged on an outer diameter 23. On a central diameter 22, approximately in the middle third of the friction disc 2a, 2b, the domes 9 with their contact surfaces 9b are arranged, with each dome 9 located radially between two cooling fins 14, 14'.

[0015] Fig. Figure 3 shows the distribution of the aforementioned contact surfaces 9b; 14a, 14'a; 16a, 16'a; 17a, 17'a for better clarity in cross-hatching on the reverse side R of a friction disc 2a, 2b. The diameters 21, 22, 23 approximately indicate a mean diameter of each imaginary third in the radial direction of the friction disc 2a.

[0016] Due to the comparatively large radial extent of the bearing surfaces 9b; 14a, 14'a; 16a, 16'a; 17a, 17'a, the thermal deformation of the friction discs 2a, 2b can be largely kept flat by the screw force of the through bolts 12.

[0017] In the circular sectors between the screw connections, the friction discs 2a, 2b are located in the middle third, i.e. in the area of ​​the middle diameter 23 - if a sprue for a sliding block with a radial groove 18 is present - but especially near the inner and outer diameters 22, 21 on the web 10 of the wheel body 1.

[0018] GB 2 519 896 A also discloses a wheel brake disc in which contact surfaces of cooling fins, which are formed radially inside and outside a dome accommodating a through bolt on the rear sides of the friction discs, rest against the web of the wheel body.

[0019] Further wheel brake discs are known from publications DE 66 09 470 U and DE 10 2012 015 378 A1.

[0020] In other designs on the market, the contact surface of the friction discs 2a, 2b on the web 10 of the wheel body 1 is only realized in areas below the screw head or nut bearing surface, i.e., in the area of ​​the mean diameter 22: The areas towards the inner and outer diameters 22, 21 can deform freely. As a result, the disc flattening of the friction discs 2a, 2b by the through bolts 12 is only supported radially by the comparatively short extent of the bearing surface 9b. This leads to the disc flattening of the respective friction disc 2a, 2b forming almost unhindered, and the through bolts 12 are subjected to a higher bending moment.

[0021] Therefore, the object of the invention is to reduce the screw load of the screws with which the two friction discs are clamped against the wheel disc or against the web of the wheel body and thereby increase the fatigue strength, i.e. to increase the number of load cycles that can be tolerated.

[0022] The problem is solved by the subject matter of claim 1 and claim 2.

[0023] One aspect of the invention is that the contact or bearing surface of the friction disc of the wheel brake disc is designed such that, in circular sectors where the screw connections are located, the friction discs only contact the web of the wheel body in an area directly below the screw head or nut bearing surface. The radially inner and outer areas are spaced from the web of the wheel body such that no contact or bearing occurs between the friction disc and the web of the wheel body.

[0024] A wheel brake disc according to the invention comprises at least two friction discs arranged on either side of a web of a wheel body of a rail wheel and fastened by means of through bolts, wherein the at least two friction discs have cooling fins and domes, wherein the through bolts extend through the domes of both friction discs and the web, wherein bearing surfaces of the domes and bearing surfaces of the cooling fins project from a respective rear side of the at least two friction discs in a first length and are in contact with bearing surfaces of the web of the wheel body. End faces of the cooling fins, which are arranged radially above and below the dome in screw sectors of the at least two friction discs with a dome, project from the respective rear side of the at least two friction discs in a second length, the dimension of which is less than the dimension of the first length.in which the bearing surfaces of the domes and bearing surfaces of the cooling fins protrude, and wherein the end faces of the cooling fins are arranged at a distance from the web, wherein the screwing sectors are first circular sectors around each dome with the cooling fins arranged radially above and below the dome, and wherein a respective width of the screwing sectors is determined by the respective dome, which is arranged on a mean diameter approximately in the middle third of the respective friction disc, and wherein the bearing surfaces of the cooling fins outside the screwing sectors are arranged both on an outer diameter in an outer third of the at least two friction discs and on an inner diameter in an inner third of the at least two friction discs, wherein only the cooling fins in the screwing sectors do not have a bearing surface to the web.

[0025] This has the advantage that, on the one hand, the disc shape of the friction disc(s) is counteracted by the screw force, even if the friction disc(s) does not contact the inner and outer diameter over its entire circumference.

[0026] Secondly, the friction discs in the area of ​​the screw connection, i.e., in the screw sectors, are connected with significantly more elasticity. Any warping of each disc only results in a reduced increase in stress within the through bolt. This advantageously increases the number of load cycles the bolt can withstand.

[0027] A wheel brake disc according to the invention comprises at least two friction discs arranged on either side of a web of a wheel body of a rail wheel and fastened by means of through bolts, wherein the at least two friction discs have cooling fins and domes, wherein the through bolts extend through the domes of both friction discs and the web, wherein the contact surfaces of the domes and the contact surfaces of the cooling fins project from a respective rear side of the at least two friction discs in a first length and are in contact with contact surfaces of the web of the wheel body. The contact surfaces of the cooling fins project from the respective rear side of the at least two friction discs in a first length and are in contact with contact surfaces of the web of the wheel body in second and third circular sectors around cooling fins without domes, and end faces of the cooling fins.which are arranged radially above and below the dome in the screwing sectors of the at least two friction discs, project from a respective rear side of the at least two friction discs in a second length, the dimension of which is less than the dimension of the first length in which the bearing surfaces of the domes and bearing surfaces of the cooling fins project, and wherein the end faces of the cooling fins in the screwing sectors are arranged at a distance from the web, wherein the screwing sectors are first circular sectors around each dome with the cooling fins arranged radially above and below the dome, and wherein a respective width of the screwing sectors is determined by the respective dome, which is arranged on a mean diameter approximately in the middle third of the respective friction disc,and wherein the contact surfaces of the cooling fins outside the screw sectors are arranged both on an outer diameter in an outer third of the at least two friction discs and on an inner diameter in an inner third of the at least two friction discs, wherein only the cooling fins in the screw sectors have no contact surface to the web.

[0028] In the bolted sectors, the friction discs only contact the wheel body web in an area directly below the screw head or nut bearing surface. The radially inner and outer areas are spaced from the wheel body web such that no contact occurs between the friction disc and the wheel body web. In the circular sectors between the bolted sectors, the friction discs contact the web in a central area, primarily near an inner and an outer diameter.

[0029] In one embodiment, the contact surfaces of the cooling fins in the second circular sectors, outside the screw sectors, are arranged both in an inner third with an inner diameter of the friction disc and in an outer third with an outer diameter of the friction disc, and are in contact with the web. This is advantageous because the cooling fins thus have both a cooling and a support function.

[0030] It is further advantageous if the contact surfaces of the cooling fins (17, 17') are arranged in third circular sectors outside the screw sectors in an inner third with an inner diameter of the friction disc, the contact surfaces of the cooling fins in a middle third with a middle diameter of the friction disc and the contact surfaces of the cooling fins in an outer third with an outer diameter of the friction disc and are in contact with the web.

[0031] In another embodiment, a radial groove for sliding blocks is formed in the middle third of the third circular sector (20b), with the mean diameter of the friction disc, between the bearing surfaces. This is an advantageously compact design.

[0032] Another embodiment provides that the contact surfaces in the inner third have a T-shaped cross-section corresponding to the inner diameter of the friction disc, the contact surfaces in the middle third have essentially semicircular cross-sections corresponding to the middle diameter of the friction disc, and the contact surfaces in the outer third have a rectangular cross-section corresponding to the outer diameter of the friction disc, with one rounded side. This arrangement provides advantageous support and facilitates heat transfer by conduction to the cooling fins.

[0033] One embodiment, wherein the screw head of each through bolt is seated in a recess of a dome on one friction disc and a nut screwed onto the through bolt is seated in a recess of a dome on the other friction disc, each bearing directly or indirectly against an inner surface of a flange of the dome, wherein each recess has an inlet side with a cylindrical section that transitions into an undercut extending to the inner surface of a base of the dome, is characterized in that the ratio of the length of the cylindrical section in the direction of the central axis of the dome to the length of the undercut in the direction of the dome is in the range of 0.75 to 1.5. This advantageously allows high stability to be achieved. Alternatively, it is also possible that the...The ratio of the length of the cylindrical section in the direction of the dome's central axis to the length of the undercut in the direction of the dome has a value in the range of 1.2 to 1.3. In a further alternative embodiment, the length of the cylindrical section in the direction of the dome's central axis corresponds to the length of the undercut in the direction of the dome.

[0034] Another embodiment involves a ratio of the inner diameter of the undercut to the inner diameter of the cylindrical section that is between 1.1 and 1.4. This achieves a further advantageous increase in stability.

[0035] In another embodiment, the ratio of the dome's outer diameter to the undercut's inner diameter can be in the range of 1.3 to 1.5. This is advantageous because it increases the dome's strength.

[0036] An embodiment of the invention is described below with reference to the accompanying drawings.

[0037] They show: Fig. 1-2 schematic partial sections of a schematic radial section view of a wheel body with a wheel brake disc according to the state of the art; Fig. 3 a schematic top view of a section of the back of a friction disc of the wheel brake disc according to Fig. 2 according to the state of the art;; Fig. 4 a schematic top view of the rear side of a friction disc of a wheel brake disc according to the invention; Fig. 5 a schematic partial section of a schematic radial section view of a wheel body with a wheel brake disc according to the invention in a section plane V from Fig. 4; and Fig. 6 a schematic partial section of a schematic radial section view of a wheel body with a wheel brake disc according to the invention in a section plane VI from Fig. 4.

[0038] Fig. Items 1-3 have already been described above.

[0039] Fig. Figure 4 shows a schematic top view of a rear side R of a friction disc 2a, 2b of a wheel brake disc 2 according to the invention. Fig. Figure 5 is a schematic partial section of a schematic radial section view of a wheel body 1 with a wheel brake disc 2 according to the invention in a section plane V. Fig. 4 shown. Fig. Figure 6 shows a schematic partial section of a schematic radial section view of a wheel body 1 with a wheel brake disc 2 according to the invention in a section plane VI. Fig. 4.

[0040] The friction disc 2a, 2b in Fig. For clarity, the 4 is divided radially into three thirds. The inner third is indicated by the inner diameter 21. This is followed by the middle third with the middle diameter 22 and the outer third with the outer diameter 23.

[0041] Circular sectors 20, 20a, 20b are arranged distributed across the friction disc 2a, 2b, of which only three are described here as examples. Domes 9 for the screw connections and cooling fins 14, 14' are arranged in the circular sectors 20. The circular sectors 20 are therefore referred to as screw connections 20 in the following. The circular sectors 20a have cooling fins 16, 16'. A radial groove 18 for the aforementioned sliding block (not shown) and cooling fins 17, 17' are each arranged in the circular sectors 20b.

[0042] In the circular sectors 20a, 20b between the screwing sectors 20, the friction discs 2a, 2b are located in the middle area - if a sprue for a sliding block is present - but especially near the inner and outer diameters 21, 23 on the web 10.

[0043] In contrast to the friction disc 2a, 2b-from the prior art, which in Fig. As described in 2-3 above, the friction disc 2a, 2b according to the invention demonstrates Fig. 4-6 in the screw sectors 20 each only one bearing surface 9a of a flange 9b of a respective dome 9. This bearing surface 9a of the flange 9b projects from the rear side R of the friction disc 2a, 2b in a first length parallel to the wheel axle 1a. The cooling fin 14, 14', arranged radially above and below the dome 9, projects from the rear side R of the friction disc 2a, 2b in a second length parallel to the wheel axis 1a and parallel to the dome 9, this second length being shorter than the first length of the dome 9. In this way, free end faces 14b, 14'b of the cooling fin 14, 14' are arranged at a distance from a clearance surface 11a of the web 10, so that contact between the cooling fin 14, 14', i.e., the free end faces 14b, 14'b, and the web 10 of the wheel body 1 is not present in either the outer third with outer diameter 23 or the inner third with inner diameter 21.

[0044] This is shown in a radial section in Fig. 5 along a section plane V through a dome 9 in Fig. 4 in the screw connection sector 20 is shown in detail and is described further below.

[0045] Another radial section along a sectioning plane VI in Fig. 4 through cooling fins 14, 14' shows the arrangement, in Fig. 6 in detail.

[0046] In Fig. Figure 5 shows the wheel brake disc 2 according to the invention with the two friction discs 2a, 2b with a wheel body 1 of a rail wheel in a radial section through a screw connection.

[0047] In contrast to the wheel brake disc 2 from the state of the art according to Fig. 2. The friction discs 2a, 2b are located only under the bolted bearing surface, i.e., the respective inner side of the flanges 9b (viewed radially in the middle third of the friction disc) rests against the bearing surface 11 of the web 10 of the wheel body 1 via the respective bearing surface 9a of the outer side of the flange 9b. The cooling fins 14, 14' in the bolted sectors 20 have no bearing surface against the web 10; neither in the outer nor in the inner third of the friction disc 2a, 2b. Instead of a bearing surface, these cooling fins 14, 14' each have end faces 14b, 14'b. Between these end faces 14b, 14'b and a free surface 11a of the web 10, a distinct gap is realized between the free end faces 14b, 14'b of the cooling fins 14, 14' and the free surfaces 11a of the web 10. This gap is also referred to as the gap 19, 19'.

[0048] In other words, the end faces 14b, 14'b of the cooling fins 14, 14' in the screw sectors 20 protrude from the rear faces R of the friction discs 2a, 2b by a second length which is smaller than the first length of the domes 9.

[0049] The cross-hatching indicates the bearing surfaces 9a; 14a, 14'a; 16a, 16'a, 17a, 17'a in Fig. Figure 4 highlights the contact surface 11 on the wheel web or web 10 of the wheel body 1. It can be seen that in the screw sector 20, the friction disc 2a, 2b only has contact surface 9a with the web 10 of the wheel body 1 in the middle third (mean diameter 22; viewed in the radial direction).

[0050] Outside of a screw sector 20, for example in the circular sectors 20a, contact surfaces 16a, 16'a of the cooling fins 16, 16' are provided in both the outer and inner thirds of the friction disc 2a, 2b.

[0051] In the circular sectors 20b, both the contact surfaces 17a, 17'a of the cooling fins 17, 17' and the contact surfaces 17b in the middle third of the friction disc 2a, 2b bear loads. The radial groove 18 for the sliding blocks is formed between the contact surfaces 17b.

[0052] In contrast to the friction discs 2a, 2b from the prior art, the contact surfaces 14a, 16a, 17a of the cooling fins 14, 16, 17 are larger in the friction discs 2a, 2b according to the invention.

[0053] In Fig. 5 can also be clearly seen that the domes 9 of the friction discs 2a, 2b according to the invention differ from the domes 9 of the friction discs 2a, 2b from the prior art ( Fig. 2) are trained.

[0054] In the example shown, the ratio of the inner diameter of the undercut 8 to the inner diameter of the cylindrical section 7 is approximately 1.3, whereas in the prior art it is approximately 1.5. The inner diameter of the undercut 8 is reduced in this case.

[0055] Furthermore, the ratio of the outer diameter of the dome 9 to the inner diameter of the undercut 8 is approximately 1.44 and is therefore larger than the ratio of these diameters in the prior art of approximately 1.14.

[0056] Furthermore, the length of the cylindrical section 7 in the direction of the central axis of the dome 9 is increased compared to the prior art: The ratio of the length of the cylindrical section 7 to the length of the undercut 8 can, for example, be in the range of 0.75 to 1.5. In the example shown, this ratio is approximately 1.25 and is therefore greater than in the prior art, where this ratio is approximately 0.3.

[0057] This results in greater stability and strength of the Dome 9.

[0058] Fig. Figure 6 shows a schematic partial section of a schematic radial section view of a wheel body 1 with a wheel brake disc 2 according to the invention with the friction discs 2a, 2b in a section plane VI. Fig. 4 by a cooling fin outside the screw sectors 20, such as in the circular sectors 20a and in the circular sectors 20b (but without the central contact surface 17b).

[0059] The cooling fins 14, 14' each have a contact surface 14a, 14'a which is in contact with the contact surface 11 of the web 10 of the wheel body 1. Thus, the contact surfaces 14a are arranged in the inner third of the friction discs 2a, 2b and the contact surfaces 14'a in the outer third of the friction discs 2a, 2b (see also Fig. 4).

[0060] The invention is not limited by the embodiment given above, but can be modified within the scope of the claims. Reference symbol list 1 wheel body 1a Wheel axle 2 wheel brake discs 2a, 2b friction disc 3 through bolts 4 screw heads 4a Sleeve 5 Mother 6 reduction 7 Cylindrical area 8 Undercut 9 Mounting dome 9a Support surface 9b flange 10 Bridge 11 Contact surface 11a Open space 12 through holes 13 Transition 14, 14' cooling fin 14a, 14'a Support surface 14b, 14'b Front surface 15 friction surface 16, 16'; 17, 17' Cooling fin 16a, 16'a; 17a, 17'a, 17b Support surface 18 Radial groove 19.19' gap 20, 20a, 20b circular sector 21, 22, 23 diameter R Back

Claims

[1] Wheel brake disc (2) comprising at least two friction discs (2a, 2b) arranged on both sides of a web (10) of a wheel body (1) of a rail wheel and fastened by means of through bolts (3), wherein the at least two friction discs (2a, 2b) have cooling fins (14, 14'; 16, 17, 17') and domes (9), wherein the through bolts (3) extend through the domes (9) of both friction discs (2a, 2b) and the web (10), wherein bearing surfaces (9a) of the domes (9) and bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a, 17b) of the cooling fins (14, 14'; 16, 16';17, 17') project from a respective rear side (R) of the at least two friction discs (2a, 2b) in a first length and are in contact with bearing surfaces (11) of the web (10) of the wheel body (1), wherein end faces (14b, 14'b) of the cooling fins (14, 14'), which are arranged radially above and below the dome (9) with a dome (9) in screw sectors (20) of the at least two friction discs (2a, 2b), project from the respective rear side (R) of the at least two friction discs (2a, 2b) in a second length, the dimension of which is less than the dimension of the first length, in which the bearing surfaces (9a) of the domes (9) and bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a, 17b) of the cooling fins (14, 14'; 16, 16';17, 17') protrude, and wherein the end faces (14b, 14'b) of the cooling fins (14, 14') are arranged at a distance from the web (10), wherein the screwing sectors (20) are first circular sectors around a dome (9) with the cooling fins (14, 14') arranged radially above and below the dome (9), and wherein a respective width of the screwing sectors (20) is determined by the respective dome (9), which is arranged on a mean diameter (22) approximately in the middle third of the respective friction disc (2a, 2b), and wherein the bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a) of the cooling fins (14, 14'; 16, 16'; 17, 17') outside the screwing sectors (20) are located on an outer diameter (23) are arranged in an outer third of the at least two friction discs (2a, 2b) as well as on an inner diameter (21) in an inner third of the at least two friction discs (2a, 2b), ; characterized by, that only the cooling fins (14, 14') in the screw sectors (20) have no contact surface to the web (10). [2] Wheel brake disc (2) comprising at least two friction discs (2a, 2b) arranged on either side of a web (10) of a wheel body (1) of a rail wheel and fastened by means of through bolts (3), wherein the at least two friction discs (2a, 2b) have cooling fins (14, 14'; 16, 16', 17, 17') and domes (9), wherein the through bolts (3) extend through the domes (9) of both friction discs (2a, 2b) and the web (10), wherein bearing surfaces (9a) of the domes (9) and bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a, 17b) of the cooling fins (14, 14'; 16, 16'; 17, 17') are faced from a respective rear side (R) of the at least two friction discs (2a, 2b) protrude in a first length and are in contact with bearing surfaces (11) of the web (10) of the wheel body (1), wherein the bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a, 17b) of the cooling fins (14, 14'; 16, 16';17, 17') protrude from the respective rear side (R) of the at least two friction discs (2a, 2b) in the first length and are in contact with bearing surfaces (11) of the web, (10) of the wheel body (1) in second circular sectors (20a) and third circular sectors (20b) around cooling fins (14, 14'; 16, 16'; 17, 17') without dome (9) and end faces (14b, 14'b) of the cooling fins (14, 14'), which are arranged radially above and below the dome (9) with a dome (9) in screwing sectors (20) of the at least two friction discs (2a, 2b), protrude from the respective rear side (R) of the at least two friction discs (2a, 2b) in a second length, the dimension of which is less than the dimension of the first length, in which the bearing surfaces (9a) of the domes (9) and bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a, 17b) of the cooling fins (14, 14'; 16, 16';17, 17') protrude, and wherein the end faces (14b, 14'b) of the cooling fins (14, 14') in the screwing sectors (20) are arranged at a distance from the web (10), wherein the screwing sectors (20) are first circular sectors around a dome (9) with the cooling fins (14, 14') arranged radially above and below the dome (9), and wherein a respective width of the screwing sectors (20) is determined by the respective dome (9), which is arranged on a mean diameter (22) approximately in the middle third of the respective friction disc (2a, 2b), and wherein the bearing surfaces (14a, 14'a; 16a, 16'a; 17a, 17'a) of the cooling fins (14, 14'; 16, 16'; 17, 17') are located outside the screwing sectors (20) are arranged both on an outer diameter (23) in an outer third of the at least two friction discs (2a, 2b) and on an inner diameter (21) in an inner third of the at least two friction discs (2a, 2b), ; characterized by, that only the cooling fins (14, 14') in the screw sectors (20) have no contact surface to the web (10). [3] Wheel brake disc (2) according to one of the preceding claims, characterized by , that the contact surfaces (14a, 14'a; 16a, 16'a) of the cooling fins (14, 14'; 16, 16') in the second circular sectors (20a) outside the screwing sectors (20) are arranged both in an inner third with an inner diameter (21) of the friction disc (2a, 2b) and in an outer third with an outer diameter (23) of the friction disc (2a, 2b) and are in contact with the web (10). [4] Wheel brake disc (2) according to one of the preceding claims, characterized by, that the contact surfaces (17a) of the cooling fins (17, 17') are arranged in third circular sectors (20b) outside the screwing sectors (20) in an inner third with an inner diameter (21) of the friction disc (2a, 2b), the contact surfaces (17b) of the cooling fins (17, 17') are arranged in a middle third with a middle diameter (22) of the friction disc (2a, 2b) and the contact surfaces (17'a) of the cooling fins (17, 17') are arranged in an outer third with an outer diameter (23) of the friction disc (2a, 2b) and are in contact with the web (10). [5] Wheel brake disc (2) according to claim 4, characterized by , that in the third circular sectors (20b) in the middle third with the middle diameter (22) of the friction disc (2a, 2b) between the bearing surfaces (17b) a radial groove (18) for sliding stones is formed. [6] Wheel brake disc (2) according to one of claims 3 to 5, characterized by, that the bearing surfaces (14a, 16a, 17a) in the inner third with an inner diameter (21) of the friction disc (2a, 2b) have a T-shaped cross-section, the bearing surfaces (17b) in the middle third with the middle diameter (22) of the friction disc (2a, 2b) have essentially semicircular cross-sections, and the bearing surfaces (14'a, 16'a, 17'a) in the outer third with the outer diameter (23) of the friction disc (2a, 2b) have a rectangular cross-section with a rounded side. [7] Wheel brake disc (2) according to one of the preceding claims, wherein a screw head (4) of each through screw (3) is located in a recess (6) of a dome (9) of one friction disc (2a) and a nut (5) screwed onto the through screw (3) is located in a recess (6) of a dome (9) of the other friction disc (2b), each directly or indirectly bearing against an inner side of a flange (9b) of the dome (9), wherein each recess (6) has on its inlet side a cylindrical area (7) which transitions into an undercut (8) which extends to the inner side of a base of the dome (9), characterized by , that the ratio of the length of the cylindrical area (7) in the direction of the central axis of the dome (9) to the length of the undercut (8) in the direction of the dome (9) is in a range of 0.75 to 1.

5. [8] Wheel brake disc (2) according to claim 7, characterized by, that the ratio of the length of the cylindrical area (7) in the direction of the central axis of the dome (9) to the length of the undercut (8) in the direction of the dome (9) has a value in the range of 1.2 to 1.

3. [9] Wheel brake disc (2) according to claim 7, characterized by , that the length of the cylindrical area (7) in the direction of the central axis of the dome (9) corresponds to the length of the undercut (8) in the direction of the dome (9). [10] Wheel brake disc (2) according to one of claims 7 to 9, characterized by , that the ratio of an inner diameter of the undercut (8) to an inner diameter of the cylindrical area (7) has a value in the range of 1.1 to 1.

4. [11] Wheel brake disc (2) according to one of claims 7 to 10, characterized by , that the ratio of the outer diameter of the dome (9) to the inner diameter of the undercut (8) has a value in the range of 1.3 to 1.5.

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