JP4023129B2 - Rotating member for braking and rolling bearing unit with wheel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a wheel constituting a wheel of an automobile, a braking rotary member for supporting a braking rotary member such as a rotor or a drum, and a rolling bearing unit with a wheel .
[0002]
[Prior art]
A wheel 1 constituting a wheel of an automobile and a rotor 2 constituting a disc brake as a braking device and a braking device are rotatable to a knuckle 3 constituting a suspension device, for example, by a structure as shown in FIG. Is supported. That is, an outer ring 6 that is a stationary ring and that constitutes the rolling bearing unit 5 is fixed to a circular support hole 4 portion formed in the knuckle 3 by a plurality of bolts 7. On the other hand, the wheel 1 and the rotor 2 are coupled and fixed to a hub 8 constituting the rolling bearing unit 5 by a plurality of studs 9 and nuts 10. Further, double row outer ring raceways 11a and 11b, each of which is a stationary side raceway surface, are formed on the inner peripheral surface of the outer ring 6, and a coupling flange 12 is formed on the outer peripheral surface. Such an outer ring 6 is fixed to the knuckle 3 by connecting the connecting flange 12 to the knuckle 3 with the bolts 7.
[0003]
On the other hand, in a part of the outer peripheral surface of the hub 8, the outer end opening of the outer ring 6 (outside with respect to the axial direction refers to a portion that is outside in the width direction when assembled to the automobile, and excludes FIG. On the other hand, the left side of each figure is the center side in the width direction when assembled to a car, and the right side of each figure except for FIG. A flange 13 is formed. The wheel 1 and the rotor 2 are coupled and fixed to the outer surface of the mounting flange 13 by the studs 9 and the nuts 10.
[0004]
Further, an inner ring raceway 14a is formed on the outer peripheral surface of the intermediate portion of the hub 8 at a portion of the double row outer ring raceways 11a and 11b formed on the inner peripheral surface of the outer ring 6 that faces the outer outer raceway 11a. is doing. Further, an inner ring 16 that constitutes a rotating wheel together with the hub 8 is externally fitted and fixed to a small diameter step portion 15 formed at the inner end portion of the hub 8. The inner ring raceway 14b formed on the outer peripheral surface of the inner ring 16 is opposed to the inner outer ring raceway 11b of the double row outer ring raceways 11a and 11b. Between each of the outer ring raceways 11a and 11b and each of the inner ring raceways 14a and 14b, a plurality of balls 17 and 17 each serving as a rolling element can be rolled while being held by cages 18 and 18, respectively. Provided. With this configuration, a double-row angular type ball bearing that is a rear combination is configured, and the hub 8 and the inner ring 16 are supported inside the outer ring 6 so as to be rotatable and support a radial load and a thrust load. ing.
[0005]
Seal rings 19a and 19b are provided between the inner peripheral surface of both ends of the outer ring 6, the outer peripheral surface of the intermediate part of the hub 8 and the outer peripheral surface of the inner end of the inner ring 16, respectively. , 17 and the external space are shut off. Furthermore, since the illustrated example is a rolling bearing unit 5 for driving wheels (the rear wheels of FR and RR vehicles, the front wheels of FF vehicles, and all wheels of 4WD vehicles), a spline hole is formed at the center of the hub 8. 20 is formed. The spline shaft 22 of the constant velocity joint 21 is inserted into the spline hole 20.
[0006]
When using the rolling bearing unit 5 as described above, as shown in FIG. 5, the outer ring 6 is fixed to the knuckle 3, and the wheel 1 and the rotor 2 combined with tires (not shown) are fixed to the mounting flange 13 of the hub 8. To do. A brake disc brake is configured by combining the rotor 2 and the support and caliper (not shown) fixed to the knuckle 3. During braking, a pair of pads provided across the rotor 2 are pressed against both side surfaces of the rotor 2.
[0007]
The wheel 1 and the rotor 2 are coupled and fixed to the outer surface of the mounting flange 13 by the stud 9 and the nut 10 as described above. That is, a plurality of the studs 9 whose base end portions (right end portions) are supported by the mounting flange 13 are inserted into through holes 24 and 25 formed in the rotor 2 and the mounting plate portion 23 of the wheel 1, respectively. In this state, the wheel 10 and the rotor 2 are coupled and fixed to the outer surface of the mounting flange 13 by screwing the nut 10 into the stud 9. Here, when the rotor 2 is assembled to the rolling bearing unit 5, the runout width (displacement amount in the rotation axis direction) of the {rotation of the side surface of the rotor 2 in the rotation axis direction (left and right direction in FIG. 5)}. ) Adjustment (to 0 as much as possible). If the side surface of the rotor 2 is not perpendicular to the rotation center of the rotor 2 when the rotor 2 is fixed to the mounting flange 13, the surface runout occurs when the rotor 2 rotates. When such a runout width is large, vibration accompanied by unpleasant noise called judder is generated during braking of the automobile. For this reason, it is preferable to perform adjustment so that the runout width of the surface runout is reduced by turning the side face of the rotor 2 while the rotor 2 is assembled to the rolling bearing unit 5.
[0008]
However, it is not realistic to adjust the surface runout of the braking rotating member such as the rotor as described above at the automobile assembly factory. That is, conventionally, the rolling bearing unit and the brake rotating member are separately delivered to the automobile assembly factory, and these assembling operations have been performed at the automobile assembly factory. It is unrealistic to adjust the surface runout of the rotating member for braking accompanying the turning process during the assembling work, because the work setup is greatly deteriorated. In an automobile assembly factory that performs final assembly of an automobile, it is possible to improve the productivity of the automobile and reduce the manufacturing cost of the automobile by reducing as much as possible the adjustment process of the automobile parts such as adjustment of the runout of the rotor. In view of such circumstances, Japanese Patent Application Laid-Open No. 2000-227132 preliminarily adjusts the surface runout of a braking rotary member such as a rotor, and the brake rotary member that has been subjected to the surface runout adjustment is a rolling bearing. A structure that can be delivered to an automobile assembly plant while being connected to a unit has been proposed. In the structure described in the above publication, the braking rotary member adjusted for surface runout is coupled to the mounting flange of the rolling bearing unit with a screw different from the stud, so that the braking rotary member is attached to the mounting flange. It can be delivered to an automobile assembly plant while being connected to the flange.
[0009]
As described above, by supplying the braking rotating member with adjusted surface runout to the automobile assembly factory while being coupled to the mounting flange, vibrations during braking of the braking rotating member and the wheeled rolling bearing unit are reduced. The performance which suppresses the accompanying noise can be improved. That is, since the adjustment of the surface runout is performed in a state where it is coupled to the mounting flange, if the braking rotary member is removed after the adjustment, the surface runout is likely to occur even if it is coupled to the mounting flange in the same manner. Since the surface runout adjustment is performed so that the runout width becomes extremely small, a slight assembling error when removing and re-joining once greatly affects the runout width. When the combination of the mounting flange and the brake rotating member is changed or the phase of the combination is changed, the above-described deflection width is considerably increased. Therefore, it is necessary to deliver the brake rotating member and the wheeled rolling bearing unit from the standpoint of preventing judder from the standpoint of preventing judder. Performance will be improved.
[0010]
[Problems to be solved by the invention]
In the case of the conventional structure described in Japanese Patent Application Laid-Open No. 2000-227132 as described above, a coupling screw is used to couple the rotor to the rolling bearing unit. Machining work is required. That is, an operation of machining the screw hole for the screw separately from the mounting hole for the stud in the mounting flange constituting the rolling bearing unit, and the screw through hole for the rotor separately from the through hole for the stud, respectively. Is required. Thus, an increase in the work for coupling the rotor to the rolling bearing unit is not preferable because the manufacturing cost of the braking rotary member and the wheeled rolling bearing unit increases.
[0011]
On the other hand, in order to connect the rotor to the mounting flange, only the rotor is supported on the mounting flange, and the nut is screwed onto the stud without supporting the wheel, so that only the rotor is mounted on the mounting flange. It can be fixed and transported from the parts factory to the car assembly factory. In this way, it is not necessary to use a screw for coupling the rotor and the mounting flange as in the structure of the above-mentioned Japanese Patent Laid-Open No. 2000-227132. Disappears. However, in this way, when assembling the wheel at the automobile assembly factory, it is necessary to first remove the nut and then install the wheel, and then screw the nut into the stud again. It becomes troublesome.
In view of the circumstances as described above, the present invention is a braking rotating member that does not bother the work in an automobile assembly plant, has a low manufacturing cost, and has high performance for preventing vibration and noise during braking. And a rolling bearing unit with wheels .
[0012]
[Means for Solving the Problems]
The braking rotary member and the rolling bearing unit with wheels of the present invention have a stationary raceway surface on the stationary peripheral surface, and are supported and fixed to the suspension device in use, A rotating wheel having a rotating raceway surface on a peripheral surface and rotating together with the wheel while supporting the wheel; a plurality of rolling elements provided between the rotating raceway surface and the stationary raceway surface; A mounting flange provided on the outer peripheral surface of the rotating wheel and having mounting holes formed at a plurality of locations in the circumferential direction; a plurality of studs each having a proximal end supported by the mounting flange; and at a plurality of locations in the circumferential direction. while inserting the respective stud through holes formed respectively, and a wheel constituting supported fixed to the side surface of the mounting flange, a braking rotary member and the wheel.
[0013]
In particular, at the braking rotary member and the rolling bearing unit with wheels of the present invention, the side surface of the mounting flange of the braking rotating member By loosely inserted through the respective studs to each through hole of the brake rotating body In such a state, an elastic member having a distal end smaller in diameter than the proximal end is externally fitted to at least one of the studs, and the distal end of the elastic member is attached to the at least one stud. with locking of the intermediate portion of the stud, resiliently against the peripheral portion of the portion in the through hole of the opposite side with the mounting flange of the side surface of the elastic member rotating member for the braking proximal portion of By contacting the brake rotating member, the brake rotating member is connected to the mounting flange without separation. Further, a bulging portion that bulges in the opposite direction to the mounting flange is formed in a portion where each through hole of the wheel exists, or each of the braking rotary members on the side surface opposite to the mounting flange. By providing a recess around the through hole, the elastic member is prevented from interfering with the wheel in a state where the wheel is assembled on the side opposite to the mounting flange of the braking rotary member.
[0014]
[Action]
The rolling member for braking and the rolling bearing unit with wheels of the present invention are the same as the conventional structure described in Japanese Patent Laid-Open No. 2000-227132 described above. It can be delivered to an automobile assembly plant with the rotating members connected. As a result, it is possible to provide a braking rotary member and a rolling bearing unit with wheels that have high performance to prevent vibration and noise during braking, and reduce the number of steps for assembling the vehicle and improve the productivity of the vehicle. I can do things.
[0015]
In particular, in the case of the present invention, in order to couple the brake rotating member to the mounting flange, screw holes and through holes other than those originally required for stud insertion are processed in the brake rotating member and the mounting flange. Thus, the manufacturing cost of the braking rotating member and the wheeled rolling bearing unit can be reduced. In addition, since the elastic member is prevented from interfering with the wheel in a state where the wheel is assembled on the side opposite to the mounting flange of the braking rotating member , the wheel is held with the elastic member being locked to the stud. It can be assembled, and the work at the automobile assembly plant is not troublesome.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a first example of an embodiment of the present invention. The feature of the present invention lies in the structure in which the rolling bearing unit 5 and the rotor 2 as a braking rotating member are coupled. In the case of braking the rotary member and the rolling bearing unit with wheels of this embodiment, the crimped portion 26 formed on the inner end portion of the hub 8 By suppressing the inner end face of the inner ring 16, there is ensured the captive of the inner ring 16 The balls 17 and 17 are preloaded. Since the configuration and operation of the other parts are the same as those of the conventional structure shown in FIG. 5 described above, the explanation for the equivalent parts will be omitted or simplified, and the following will focus on the characteristic parts of the present invention.
[0017]
In the case of the braking rotating member and the wheeled rolling bearing unit of this example, the rotor 2 is coupled to the mounting flange 13 by the stud 9 and the coil spring 28 which is an elastic member described in the claims. For this purpose, a plurality of studs 9 supported by press-fitting and fixing serration portions provided at the base end portions (right end portions) to the mounting holes 27 formed at a plurality of locations in the circumferential direction of the mounting flange 13 are provided. The rotor 2 is loosely inserted into through holes 24 formed at a plurality of locations in the circumferential direction. In the state where the rotor 2 is supported on the outer surface of the mounting flange 13 in this manner, the diameter of the distal end portion is larger than the diameter of the proximal end portion at the intermediate portion of at least one of the studs 9. The coil spring 28 having a small length is externally fitted. Then, the distal end portion (left end portion) of the coil spring 28 is locked to the intermediate base end side of the male screw portion 29, and the proximal end portion (right end portion) of the coil spring 28 is connected to the outer surface of the rotor 2. Is partly elastically in contact with the peripheral portion of the through hole 24. With this structure, the stud 9 is prevented from coming out of the through hole 24 , so that the rotor 2 is coupled to the mounting flange 13 without separation.
[0018]
The coil spring 28 is formed by winding a wire such as spring steel (SUP) or a spring oil temper wire (SWO) in a spiral shape so that the diameter increases from the distal end toward the proximal end. And the diameter of the front-end | tip part of the coil spring 28 in a free state is made smaller than the outer diameter of the said external thread part 29. FIG. Further, the diameter of the wire constituting the coil spring 28 is made small enough to fit a part of the wire in the groove of the male screw portion 29. For this reason, the tip end portion of the coil spring 28 is locked in the thread groove of the male screw portion 29, and the stud spring 9 does not move in the axial direction with the force applied during transportation. Since the thread groove of the male thread portion 29 is spiral, the tip of the coil spring 28 is locked along the spiral thread groove. In order to externally fit such a coil spring 28 to the male screw portion 29, the distal end portion of the coil spring 28 is elastically expanded from the outer diameter of the male screw portion 29, and the axial direction of the male screw portion 29 is illustrated in FIG. From the left side to the right side, the coil spring 28 is pushed in until it comes into contact with the outer surface of the rotor 2. Further, the distal end portion of the coil spring 28 is locked to a part of the male screw portion 29 in a state where the outer surface of the rotor 2 is pressed by the elastic force of the coil spring 28.
[0019]
The rotor 2 can be coupled to the mounting flange 13 even if only one stud 9 is fitted around the coil spring 28. Preferably, the coil spring 28 is attached to a plurality of studs 9 (2 to 3). Fit outside. For example, in the case of a rolling bearing unit in which four studs are supported, the coil springs 28 may be externally fitted in two places so that the positions of the studs 9 for externally fitting the coil springs 28 are on the opposite side in the radial direction. preferable. Since the coupling of the rotor 2 to the mounting flange 13 by the coil spring of this example only serves as a temporary stop until delivery to the automobile assembly factory, it is necessary to externally fit the coil spring 28 to all the studs 9. However, it does not matter if it is externally fitted to all the studs 9.
[0020]
The brake rotating member and the rolling bearing unit with wheels of this example are configured as described above, and are configured to be delivered to the automobile assembly plant with the mounting flange 13 and the rotor 2 adjusted for surface runout being coupled. That is, the adjustment of the surface run-out is performed by fixing the mounting flange 13 and the rotor 2 with a jig or the like while the rotor 2 is coupled to the outer surface of the mounting flange 13 by the stud 9 and the coil spring 28 as described above. Then, by turning the surface where the pad lining of the rotor 2 is in sliding contact, the runout width of this surface is made extremely small. Therefore, even after the adjustment of the surface runout is completed, even if the mounting flange 13 and the rotor 2 are removed from the jig, the mounting flange 13 and the rotor 2 remain coupled by the stud 9 and the coil spring 28. It can be delivered to the automobile assembly plant in this state. For this reason, it is possible to provide a rotating member for braking and a rolling bearing unit with a wheel that can prevent vibration and noise from being generated during braking, and reduce the assembly work process at the automobile assembly plant, thereby improving the productivity of the automobile. Can be improved.
[0021]
In particular, in the case of this example, the rotor 2 is coupled to the mounting flange 13 by the stud 9 and the coil spring 28 as described above. For this reason, in order to couple the rotor 2 to the mounting flange 13, it is necessary to work on screw holes and through holes other than those originally necessary for inserting the stud 9 into the rotor 2 and the mounting flange 13. Thus, the manufacturing cost of the rolling bearing unit with a braking rotating member can be reduced. Further, the operation of fitting the coil spring 28 to the male screw portion 29 can be performed more easily than the operation of tightening the fixing screw because it is only necessary to push the coil spring 28 into the male screw portion 29.
[0022]
Also, FIG. 2 shows a state assembled with the wheel 1 in the rolling bearing unit 5 combines the rotor 2 as described above. As shown in FIG. 5, the wheel 1 is formed by pressing a steel plate. Through holes 25 are provided at a plurality of locations in the circumferential direction of the mounting plate portion 23, and the through holes 25 are present. A substantially truncated cone-shaped bulged portion 30 is formed in a portion that bulges on the opposite side of the mounting flange 13 (left side in FIG. 2) . In addition, the inner peripheral surface of the through hole 25 is a conical concave surface inclined in a direction in which the diameter decreases from the outer side toward the inner side in the axial direction, and is engaged with a conical convex surface provided on the nut 10 side that is screwed into the stud 9. The alignment surface is matched. Such a wheel 1 is supported on the outer surface of the rotor 2 with the stud 9 inserted through the through hole 25. Then, the nut 10 is screwed into the male thread portion 29 of the stud 9 and further tightened, whereby the wheel 1 is coupled and fixed to the rolling bearing unit 5.
[0023]
In the case of this example, when the wheel 1 is assembled to the rolling bearing unit 5, it is not necessary to remove the coil spring 28 fitted on the stud 9. That is, the coil spring 28 bulges between the inner surface of the mounting plate portion 23 of the wheel 1 and the outer surface of the rotor 2 as shown in the figure in a state where the wheel 1 is assembled to the rolling bearing unit 5. It will be located in the space 31 enclosed by the part 30. FIG. For this reason, the coil spring 28 does not interfere with a part of the wheel 1, and the coil spring 28 does not interfere with the assembly of the wheel 1 to the rolling bearing unit 5 . Therefore , the wheel 1 can be assembled to the rolling bearing unit 5 to which the rotor 2 is fixed while the coil spring 28 is externally fitted to the stud 9, so that the work at the automobile assembly plant is not troublesome. .
[0024]
Next, FIGS. 3 to 4 show a second example of the embodiment of the present invention. In this example, a disc spring 32 is used as the elastic member in place of the coil spring 28 of the first example described above. The disc spring 32 is formed by punching a steel plate such as SK5 into a fan shape and bending it into a conical shape. That is, the disc spring 32 has a partial cone whose diameter increases from the distal end (left end in FIG. 3, upper end in FIG. 4) to the base end (right end in FIG. 3, lower end in FIG. 4). It is in the shape. Further, a discontinuous portion 33 exists in a part of the side surface of the disc leaf spring 32. That is, in a state where the fan-shaped plate material is processed into a conical shape, the gaps exist between the end portions without joining the end portions of the plate materials by welding or the like. Due to the discontinuous portion 33, the plate spring 32 can be elastically deformed in the radial direction. Further, the inner diameter in the free state of the tip portion of the disc spring 32 is made smaller than the outer diameter of the male thread portion 29 of the stud 9. In this example, circular recesses 34 are provided on the outer surface of the rotor 2 around the plurality of through holes 24 so as to be concentric with the through holes 24.
[0025]
Also in the case of this example, as in the first example described above, the distal end portion of the disc spring 32 is locked to the proximal end side of the middle threaded portion 29 of the stud 9, and the proximal end portion is attached to the outside of the rotor 2. It is elastically brought into contact with the concave portion 34 formed on the side surface. That is, the disc spring 32 is illustrated in the axial direction of the male screw portion 29 while elastically expanding the inner diameter of the tip portion of the disc plate spring 32 to be larger than the outer diameter of the male screw portion 29. Then, the base edge of the disc spring 32 is elastically brought into contact with the inner part of the recess 34. In this state, the tip of the disc spring 32 is locked to a part of the male screw portion 29 at the intermediate portion of the stud 9. In order to securely lock the disc spring 32 to the male screw portion 29, it is preferable that the inner peripheral edge of the tip portion of the disc spring 32 is along a spiral thread groove. Since the discontinuous portion 33 is provided on the side surface of the disc spring 32, the inner peripheral edge of the tip portion of the disc spring 32 can be along the screw groove.
[0026]
Further, in this example, by providing the recess 34, the wheel 1 and the disc spring 32 are connected to each other with the wheel 1 (see FIGS. 2 and 5) assembled to the rolling bearing unit 5 to which the rotor 2 is fixed. I try not to interfere. In other words, the concave plate 34 is provided so that the plate spring 32 does not interfere with the assembly of the wheel even when an aluminum wheel or the like that does not have the bulging portion 30 (FIG. 2) is assembled. Therefore, regardless of the structure of the wheel, the wheel can be assembled to the rolling bearing unit 5 to which the rotor 2 is fixed while the disc spring 32 is locked to the stud 9. Such a structure in which the concave portion 34 is provided can be combined with the structure using the coil spring 28 shown in FIGS. Other structures and operations are the same as those in the first example described above.
[0027]
In the first and second examples of the embodiment of the present invention described above, an example in which a rotor is used as a brake rotating member is shown. However, in the present invention, a drum is used as a brake rotating member. It can also be applied to. In the first and second examples described above, the braking rotating member for driving wheels and the rolling bearing unit with wheels have been described. However, the present invention relates to driven wheels (front wheels of FR and RR vehicles, rear wheels of FF vehicles). The present invention can also be applied to a braking rotary member for a wheel and a rolling bearing unit with a wheel .
[0028]
【The invention's effect】
Since the braking rotating member and the wheeled rolling bearing unit of the present invention are configured and act as described above, the braking rotating member and the wheeled rolling bearing unit excellent in performance of suppressing vibration and noise generated during braking, In addition, the manufacturing cost of an automobile incorporating the same can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a state where a wheel is similarly attached.
FIG. 3 is a sectional view showing a second example of the embodiment of the present invention.
FIG. 4 is a perspective view showing only a disc spring.
FIG. 5 is a cross-sectional view showing an example of an assembled state of a conventional braking rotating member and a rolling bearing unit with wheels .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Wheel 2 Rotor 3 Knuckle 4 Support hole 5 Rolling bearing unit 6 Outer ring 7 Bolt 8 Hub 9 Stud 10 Nut 11a, 11b Outer ring track 12 Coupling flange 13 Mounting flange 14a, 14b Inner ring track 15 Small diameter step 16 Inner ring 17 Ball 18 Cage 19a, 19b Seal ring 20 Spline hole 21 Constant velocity joint 22 Spline shaft 23 Mounting plate part 24, 25 Through hole 26 Caulking part 27 Mounting hole 28 Coil spring 29 Male thread part 30 Swelling part 31 Space 32 Disc spring 33 Discontinuous part 34 recess

Claims (1)

A stationary wheel has a stationary raceway on the stationary peripheral surface, and a stationary wheel that is supported and fixed to the suspension device in use, and a rotating raceway on the rotating peripheral surface, and rotates with this wheel while supporting the wheel. A rotating wheel, a plurality of rolling elements provided between the rotation-side raceway surface and the stationary-side raceway surface, and attachment holes are formed at a plurality of locations in the circumferential direction provided on the outer peripheral surface of the rotation wheel. a mounting flange, and the stud of the mounting flange to the plurality of which are supported each at the proximal end, while inserting the respective stud through holes formed respectively in the circumferential direction a plurality of locations, on the side surface of the mounting flange supported fixed, in the braking rotary member and the rolling bearing unit with wheels and a wheel constituting a braking rotary member and the wheel, loosely inserting the respective stud on each through hole of the rotary member for said braking this by In a state where the rotating member for movement is supported on the side surface of the mounting flange, an elastic member having a distal end smaller in diameter than the proximal end is fitted on at least one of the studs. the distal portion of the member while engaging an intermediate portion of said at least one stud, the through the proximal end of the elastic member at a portion of the surface opposite to the said mounting flange of the side surface of the rotary member for the braking By elastically contacting the peripheral portion of the hole, the braking rotating member is connected to the mounting flange in a non-separable manner, and the portion where the through holes of the wheel are present is opposite to the mounting flange. Forming a bulging portion that bulges to the side, or providing a recess around each through-hole on the opposite side of the mounting flange of the braking rotating member, thereby making the wheel the braking rotating member This mounting franc And in a state assembled to the opposite side, the braking rotary member and the rolling bearing unit with wheels the elastic member is characterized in that to prevent it from interfering with the wheel.

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