ARRANGEMENT FOR CONNECTING A BRAKE DISC ON A DRIVER

Abstract: Arrangement for releasable fastening of an annular brake disc (2) to a rotatable brake disc carrier (4), such as a wheel hub, which supports a brake disc, whereby the brake disc's internal periphery is provided with driving protrusions (6) which are separated in the circumferential direction, face radially inwards towards the centre (C) of the disc and engage in a corresponding number of external axial grooves (8) between ridges (10) which run axially on the outside of the carrier (4). The extent of the driving protrusions (6) is smaller than the width of the grooves (8) in the circumferential direction of the carrier so that between adjacent sets of mutually engaging driving protrusions and grooves a spacing gap (12) may be formed to accommodate a spacing device (14) fastened removably therein which fits into and fills the spacing gap and hence fixes the brake disc (2) relative to the carrier (4). The spacing device (14) is provided at its axially opposite ends with shoulder portions (18, 20) which prevent mutual axial movement between the brake disc and the carrier.

Description: Arrangement for connecting a brake disc on a driver The present invention relates to an arrangement of the kind indicated in the preamble to patent claim 1. The invention thus concerns an arrangement for releasable fastening of an annular vehicle brake disc to a rotatable carrier which supports the brake disc. The carrier may be a wheel hub or a sleeve-shaped extension which is fastened to and protrudes axially from a wheel hub. The internal periphery of the brake disc is provided with driving protrusions which are separated in the circumferential direction, face radially inwards towards the centre of the disc and engage in a corresponding number of external axial grooves between ridges which run axially on the outside of the carrier. In other words, the brake disc is fitted to the carrier by means of a splined connection. State of the art Vehicle brake discs which are fitted to and rotate jointly with a wheel hub provided with external splines, or some other kind of brake disc carrier, have a definite tendency to gradually rust fast to the wheel hub or carrier after certain time in operation on a vehicle. This may often result in it being very difficult or totally impossible to detach brake discs from the hub or carrier. There has hitherto been no easy and reliable way of solving this well-known problem of rusted-on brake discs. An example of known technology which may be cited with regard to brake disc fastening is international patent publication WO 97/20151 (PCT/EP96/04948) which describes a brake disc hub connection whereby a brake disc is releasably connected to a wheel hub, particularly in the case of disc brakes of commercial vehicles. The internal periphery region of the brake disc is provided with supporting elements, and the wheel hub has chambers on its outer periphery. At the same time, special intermediate elements are arranged for torque and force transmission from the hub's chambers to the brake disc's supporting elements. The intermediate elements are so designed that the wheel hub's chambers engage in them. The intermediate elements engage in turn in the supporting elements and their shape results in their bearing, in the circumferential direction, on the supporting elements. The chambers are also connected by shape and/or force to the intermediate elements. However, this relatively complicated type of connection arrangement between brake disc and hub does not solve the rusting-on problem in an entirely reliable manner, nor does it afford the manufacturing advantages of a splined connection. Object of the invention The object of the invention is to solve the aforesaid problem, which arises when trying to remove brake discs, by providing a new type of brake disc fastening which effectively eliminates the risk of brake discs rusting fast such that it becomes impossible or extraordinarily difficult to detach them from the carrier or hub. For, among others, service and maintenance reasons, it is extraordinarily important to be able to carry out necessary brake disc changing quickly and easily and without needing special tools. Description of the invention The aforesaid object is achieved according to the invention by an arrangement of the kind indicated in the introduction which exhibits the constructional features indicated in the characterising part of patent claim 1. A primary distinguishing feature of the fastening arrangement according to the invention is that the brake disc's driving protrusions are of smaller extent in the circumferential direction of the carrier than the width of the grooves in their circumferential direction, so that it is possible for there to be between adjacent sets of mutually engaging driving protrusions and grooves a spacing gap to accommodate a spacing device removably fastened therein. This spacing device is so designed as to fit into and fill the spacing gap and hence fix the brake disc relative to the carrier. At its axially opposite ends the spacing device is also provided with shoulder portions to prevent mutual axial movement between the brake disc and the carrier (the hub). When the time comes to replace the brake disc fitted to the carrier with a new brake disc and rusting-on ("chemical rust connection") is found to have occurred between the brake disc and the spacing devices inserted in the gaps between the driving protrusions and the carrier grooves, the first step is to remove the shoulder portions at one end of the spacing devices. Thereafter the spacing devices can be removed without difficulty from the spacing gaps between the brake disc driving protrusions and the carrier ridges. The fastening arrangement according to the invention may further afford various functional and manufacturing advantages by exhibiting the features indicated in dependent patent claims 2-7. For both fitting and removal of the spacing devices to be easy to carry out, it may be advantageous to adopt a version whereby each spacing device incorporates not only a preferably substantially T-shaped spacing element with a stem and a transverse head which constitutes one of the two shoulder portions and is intended to abut against a first side of the brake disc and the carrier, but also a shoulder element which is fastenable in the stem of the spacing element, comprises the second shoulder portion and is intended to abut against an opposite second side of the brake disc and the carrier. Removing a spacing device, i.e. extracting the device from the spacing gap in which it is inserted, involves first detaching the shoulder element from the stem of the spacing element, followed by removing the spacing element from the spacing gap. A particularly simple version is distinguished by the T-shaped spacing element having a hollow stem which is substantially prismatic or cylindrical on the outside and by the fastenable shoulder element consisting of a locking screw which is screwable into the hollow stem of the spacing element and which has a screw head which constitutes the second shoulder portion. In this case the two shoulder portions of the spacing device are thus respectively the transverse T-head of the spacing element and the head of the locking screw. To optimise the possibility of detaching the spacing device from the spacing gap even when the spacing device has rusted fast to the brake disc, it may be particularly advantageous for the hollow stem of the spacing element to be split axially into two parallel stem halves which may then be pressed together when the locking screw has been removed (unscrewed) from the hollow stem of the spacing element. Pressing the stem halves together has the effect of somewhat reducing the transverse dimension of the stem, thus greatly facilitating the removal of the spacing element from the spacing gap. To reduce the risk of the locking screw rusting fast in the hollow shaft of the spacing element, it may be advantageous for the locking screw to have a stem with external thread on only the outermost portion of the length of the stem, and for the spacing element to be provided with a corresponding internal thread on only its transverse T- head. As an alternative to a spacing element with a hollow stem and a locking screw screwable into it, a version is also conceivable whereby the fastenable shoulder element takes the form of a cylindrical pin which is screwable into the hollow stem of the spacing element and which is provided, in its outer end situated outside the outside of the brake disc/carrier, with a positionally fixed locking device which then constitutes the second shoulder portion. This locking device may for example be a split-pin running through the pin, or a locking ring or lock washer inserted in a circumferential recess on the outside of the end of the cylindrical pin. To minimise any risk of the spacing devices rusting fast to the brake disc, it is of course best of all if both the spacing element and the shoulder element fastenable in it are made of a material which tends not to rust, e.g. stainless steel. Brief description of the drawings The arrangement for brake disc fastening according to the invention will now be explained in more detail and exemplified with reference to an embodiment depicted in the attached drawings, which are as follows: Fig. 1 depicts in side view and partial cross-section a brake disc placed on a carrier; Fig. 2 depicts the brake disc according to Fig.l viewed in perspective on a smaller scale; Fig. 3 depicts in axial longitudinal section parts of a carrier with a brake disc fastened to it; Fig. 4 depicts on a larger scale and in expanded peripheral section part of the engagement region between brake disc and carrier; Fig. 5 depicts in perspective a T-shaped spacing element belonging to a spacing device according to the invention; Figs. 6a-6b depict in side and end views respectively the spacing element according to Fig. 5; Fig. 7 depicts on a larger scale than Fig. 6a an axial longitudinal section through the spacing element; and Fig. 8 depicts in perspective a locking screw which belongs to a spacing device according to the invention and is intended to be screwed into a spacing element according to Figs. 5-7. Description of an embodiment of a fastening arrangement and relating parts Reference will first be made to Figs. 1-4 which depict parts of an embodiment of a fastening arrangement according to the invention. The arrangement is intended for releasable fastening of an annular brake disc 2 to a rotatable brake disc carrier 4 which supports the brake disc. On its internal periphery the brake disc 2 is provided with ten driving protrusions 6 which are separated in the circumferential direction, face radially inwards towards the centre C of the disc and engage in a corresponding number of external axial grooves 8 between ridges 10 which run axially on the outside of the carrier 4. The extent of the driving protrusions 6 in the circumferential direction of the carrier 4 being smaller than the width of the grooves 8 in the same circumferential direction means that there is between adjacent sets of mutual engaging drive protrusions 6 and grooves 8 a spacing gap 12 intended to accommodate a spacing device 14 fastened removably therein (see Figs. 3-4). The spacing device 14 is so dimensioned that its stem 16 fits into and fills the spacing gap 12, thereby fixing the brake disc 2 to the carrier 4. The two axially opposite ends of the spacing device 14 are provided with shoulder portions 18, 20 which prevent mutual axial movement between the brake disc 2 and the carrier 4. Each such spacing device 14 partly comprises a spacing element 22 which incorporates a stem 16 and has a transverse head 24 at one end of the stem 16. The spacing device 14 also includes a shoulder element 26 which is fastenable in the stem 16 of the spacing element 22 and which in the case depicted takes the form of a locking screw which is screwable into a hollow stem 16 of the spacing element 22 and which has a screw head 28 which constitutes the second shoulder portion 20. The transverse head 24 of the spacing element 22 constitutes on its side the first shoulder portion 18. The head 24 of the spacing element 22 is designed to abut against a first side of the brake disc 2 and the carrier 4, while the head 28 of the locking screw is designed to abut against the opposite side of the brake disc 2 and the carrier 4. As may best be seen in Fig. 5, the T-shaped spacing element 22 has a hollow stem 16 which is substantially prismatic on the outside. As further indicated in Figs. 5-7, the hollow stem 16 of the spacing element 22 is split axially into two parallel stem halves 30' and 30". This stem version makes possible a certain pressing together of the two stem halves after the locking screw 26 has been unscrewed from the hollow stem 16 of the spacing element 22. As indicated by Fig. 8, the locking screw 26 has a stem 32 with an external thread 34 on at least the outermost third of the length of the stem. In a corresponding manner, the spacing element 22 has a corresponding internal thread 36 in its transverse head 24 only. The spacing element 22 depicted in Figs. 5-7 has a hollow stem 16 which is prismatic on the outside so that the stem exhibits two parallel contact surfaces 38, 40 intended to abut against the respective cooperating planar surfaces of adjacent driving protrusions 6 and carrier ridges 10. The shoulder element fastenable in the T-shaped spacing element 22 may, as described above, consist of the locking screw 26 depicted in Fig. 8. As an alternative to this locking screw it is possible, for example, to use a cylindrical pin (not depicted) which is screwable into the hollow stem 16 of the spacing element 22. In that case the cylindrical pin is provided, in its outer end situated outside the respective outsides of the brake disc 2 and the carrier 4, with a positionally fixed locking device which forms the head 28 of the locking screw 26 corresponding to the second shoulder portion 20. This positionally fixed locking device may for example be a split-pin running diametrically through the pin, or a locking ring or lock washer inserted in a circumferential groove on the outside of the cylindrical pin. Both the spacing element 22 and the shoulder element fastenable in it, e.g. the locking screw 26, are preferably made of stainless steel or some other material not tending to rust. Finally it may be mentioned that the spacing element 22 may be provided with parallel recesses 42 in the transitional angle regions between the T-head 24 and the mutually parallel contact surfaces 38, 40 on the stem 16. This improves the flexibility of the parallel stem halves 30' 30", which is important for making possible the necessary pressing together of the stem halves to make it easier to remove the T-shaped spacing element 22 from the spacing gap 12 in cases where rusting fast has taken place.

Claims: Patent claims 1. Arrangement for releasable fastening of an annular brake disc (2) to a rotatable brake disc carrier (4), such as a wheel hub, which supports a brake disc, whereby the brake disc' s internal periphery is provided with driving protrusions (6) which are separated in the circumferential direction, face radially inwards towards the centre (C) of the disc and engage in a corresponding number of external axial grooves (8) between ridges (10) which run axially on the outside of the carrier (4), characterised in that the extent of the driving protrusions (6) is smaller than the width of the grooves (8) in the circumferential direction of the carrier so that between adjacent sets of mutually engaging driving protrusions and grooves a spacing gap (12) may be formed to accommodate a spacing device (14) fastened removably therein which fits into and fills the spacing gap and hence fixes the brake disc (2) relative to the carrier (4), and that the spacing device (14) is provided at its axially opposite ends with shoulder portions (18, 20) which prevent mutual axial movement between the brake disc and the carrier. 2. Arrangement according to claim 1, characterised in that each spacing device (14) includes not only a preferably substantially T-shaped spacing element (22) with a stem (16) and a transverse head (24) which constitutes one of the two shoulder portions (18, 20) and is intended to abut against the first side of the brake disc (2) and the carrier (4), but also a shoulder element (26) which is fastenable in the stem (16) of the spacing element, includes the second shoulder portion (20) and is intended to abut against an opposite second side of the brake disc and the carrier. 3. Arrangement according to claim 2, characterised in that the T-shaped spacing element (22) has a hollow stem (16) which is substantially prismatic or cylindrical on the outside, and that the shoulder element fastenable therein consists of a locking screw (26) which is screwable into the hollow stem (16) of the spacing element and which has a screw head (28) which constitutes the second shoulder portion (20). 4. Arrangement according to claim 3, characterised in that the hollow stem (16) of the spacing element is made axially split into two parallel stem halves (30', 30"), thereby allowing a certain pressing together of the stem halves after removing the locking screw (26), so that the transverse dimension of the stem (16) can be reduced somewhat to make it easier to remove the spacing element (22) from the spacing gap (12). 5. Arrangement according to claim 3 or 4, characterised in that the locking screw (26) has a stem (32) with external thread (34) at least on the outermost third of the length of the stem, and the spacing element (22) is provided with a corresponding internal thread (36) at least in its transverse head (24). 6. Arrangement according to claim 2, characterised in that the T-shaped spacing element (22) has a hollow stem which is substantially prismatic or cylindrical on the outside, and that the shoulder element (26) fastenable therein consists of a cylindrical pin which is screwable into the hollow shaft (16) of the spacing element and which is provided, in its outer end situated outside the outside of the brake disc/carrier (2/4), with a positionally fixed locking device, such as a split-pin or locking ring/lock washer, which constitutes the second shoulder portion (20). 7. Arrangement according to any one of claims 2-6, characterised in that both the spacing element (22) and the shoulder element (26) fastenable therein are made of a material which does not tend to rust, e.g. stainless steel.

Inventors: WIRTANEN ANDERS, WIRTANEN, ANDERS
Applicants: SCANIA CV ABP, WIRTANEN ANDERS, SCANIA CV AB (PUBL), WIRTANEN, ANDERS
Application year: 2001
Main classification: F16D65
IPC codes: F16D65