FR2517002A1 - Safety or parking disc brake - has spring-loaded actuator resisted by hydraulic piston and screw to adjust clearances - Google Patents

Abstract

The brake is fitted to a wheel hub of an earthmoving machine. One or more discs (37) are fitted to the hub (18) with brake discs (38) interposed. A screw (60) is provided to adjust the brake clearances and to release the brake when it has operated. The brake is applied by a spring (36) which is normally restrained by a hydraulically operated piston (53). When oil pressure acting on the piston is released, either deliberately for parking, or due to a fault in the circuit, the brake is automatically applied.

Description

 The present invention relates generally to energy-lacking brakes, of the type usually used in certain wheel hubs, and in particular in the drive wheel hubs of certain industrial vehicles, or of certain agricultural machines. or public works, for the creation, more often than not, of a parking and / or emergency brake.

 Such a lack of energy brake comprises, overall, a rotary member to be braked, which is, in practice, a shaft on which the hub concerned is fixed erlkotation, at least one braking member capable of acting on this rotary member to be braked , elastic clamping means, springs or washers of the Belleville washer type for example, which, supported by an axial end bearing on an axially fixed part, at least in service, are capable, by an axial end of action, provoking the entry into action of said braking member, and controlled retaining means, which, in use, when active, abut said elastic clamping means, for inactive maintenance of said braking member.

 In the event of a failure on the vehicle or machine concerned, the retaining means become inactive, and, thus released, the elastic clamping means cause the braking member to come into effective action.

 One of the problems to be solved in the production of this type of lack of energy brakes is to enable them to be released manually, as conveniently as possible, when the retaining means being inactive, the braking is in action, in particular to allow, the vehicle or machine concerned being otherwise immobilized, a movement to a breakdown station of this vehicle or machine.

 Unlocking means are usually provided for this purpose, which, more often than not, include at least one unlocking screw.

 The latter, by a first portion, called here for convenience, support portion, is able to bear axially on an axially fixed part, and, by a second portion, said here for convenience, action portion, is able to control 1 action of the braking member.

 The problem, then, is to make access to this release screw as easy as possible.

 To date, the lack of energy brakes concerned are most often drum brakes, and their control is ensured by a separate pot, which, outside the wheel hub concerned, can be easily made accessible without it being necessary to disassemble anything for this, and, in particular, without the need to disassemble the corresponding wheel.

 For such drum brakes, the problem of accessibility to the manual release screw therefore does not arise.

 But it is not the same when the lack of energy brake concerned is a disc brake, and more precisely when such a disc brake is integrated in the wheel hub with which it is associated.

 By disc brake is meant, here, in the usual way, a brake comprising at least one disc locked in rotation on the rotary member to be braked, for axial tightening of this disc during braking.

 In practice, and this is the case, for example, in the French patent filed under No. 79 22648 and published under No. 2,439,907, several discs, called here by convention brake discs are set in rotation on the rotary member. brake, alternating with other discs, which, here called by interlayer discs, are fixed in rotation relative to the previous ones, while being, like them, mounted axially movable in translation.

 In practice, as regards, in the French patent mentioned above, a parking brake intended to be mounted at the end of a shaft to be braked, the bearing portion of the manual release screw used is, in the usual way, formed by its head, the latter resting on the brake casing, on the face of the wall of this casing opposite to that on which the axial bearing end of the elastic clamping means concerned also bears , and, in parallel, the action portion of this manual release screw is formed by its threaded barrel, the latter being engaged with a plate, in which is provided for this purpose a tapped hole, and which, established at a distance of the preceding wall, parallel to the latter, is capable of retaining axially, by means of an annular piston, the axial end of action of said elastic clamping means.

 Thus, in this embodiment, the support portion of the manual release screw extends from the side of a first of the axial ends of the elastic clamping means, in this case the axial support end of the latter. , and its action portion extends from the side of the opposite axial end of said elastic clamping means, and, therefore, in this case, from the action end thereof.

 In other words, in this embodiment, the elastic clamping means are sandwiched between, on the one hand, the casing wall on which the bearing portion of the manual release screw is supported, and, on the other hand , the annular piston subjected to the plate with which the action portion of said manual release screw is engaged.

 Therefore, for manual release of the brake concerned when the retaining means that it comprises are inactive, it suffices to act by screwing on the manual release screw provided for this purpose, and, in practice, this does not is actually put in place that on the occasion of such a manual release, a plug being substituted thereon on the brake housing concerned in normal service.

 When, as in this case, the brake is disposed at the end of a rotary shaft, such an arrangement can be satisfactory, the manual release screw can then be installed on the wall of the housing of this brake which, opposite said shaft, transversely closes said casing, and thus being easily accessible.

 It is not the same, as underlined above, when the brake concerned must be incorporated in the wheel hub with which it is associated, either that this wheel hub is at the end of one of the arms of a bridge motor, either that it is directly controlled by an autonomous hydraulic motor, and, even more, in particular in the latter case, when the wheel reducer usually associated with such a wheel hub is disposed at the end of the corresponding wheel shaft .

 The present invention generally relates to a provision which makes it possible, in particular in such a case, to overcome this difficulty, and which also leads to other advantages.

 More specifically, it firstly relates to a lack of energy brake, of the kind comprising a rotary member to be braked, at least one brake disc locked in rotation on said rotary member to be braked, elastic means of clamping, which, bearing on an axial end of bearing on an axially fixed part, at least in service, are capable, by an axial end of action, of causing an axial clamping of said brake disc, controlled retaining means , which, in service, when active, abut said elastic clamping means, for inactive, that is to say loosened, maintenance of the brake disc, and release means capable of causing a loosening of the disc. brake when, the retaining means being inactive, said brake disc is applied by the elastic clamping means, said release means comprising at least one release screw, which, by a first portion, here said for convenience, bearing portion , is able to take ap then axially on an axially fixed part, and which, by a second portion, called here for convenience, action portion, is capable of controlling the possible application of the brake disc, this lack of energy brake being characterized in that the the support portion and the action portion of the release screw are both axially arranged on the side of the axial end of action of said elastic clamping means.

 It also relates to a wheel hub, in particular for an industrial vehicle, public works machine, or agricultural machine, with which there is associated such a lack of energy brake.

 In practice, several brake discs mounted axially movable being provided in the lack of energy brake according to the invention, alternating with intermediate discs fixed in rotation relative to said brake discs and mounted axially movable like these, the unlocking screw is carried by the rotary member to be braked, or a part integral in rotation thereof, its bearing portion is formed by its threaded barrel, and its action portion is formed by the end of said barrel , the nearest brake disc, forming a reaction plate, carrying axially, in service, on said end of said barrel.

 Jointly, according to a characteristic of the invention, the controlled retaining means comprising a piston mounted mobile in a cylinder capable of celestial connection to a source of pressurized fluid, the release screw is axially disposed on the other side of said piston by relative to the elastic clamping means.

 In other words, and unlike the arrangement described in French patent No 79 22648 mentioned above, these are the brake discs and the intermediate discs, on the one hand, and the piston of the retaining means, on the other hand , which, when said retaining means are inactive, are jointly sandwiched between the elastic clamping means and the release screw.

 Anyway, to ensure, when the retaining means are thus inactive, the manual release of the brake has a lack of energy according to the invention, it is sufficient, according to a characteristic of the invention, to act by unscrewing on the release screw provided for this purpose, it being understood that, in fact, several release screws, suitably distributed circularly, are provided in parallel.

 Such unscrewing is easier to drive than a screwing.

 Certainly, on certain energy-lacking brakes already known to date, manual unlocking is also obtained by an unscrewing action on one or more unlocking screws.

 But it is then a question of screws against which bears the axial support end of the elastic clamping means, and, in practice, such an arrangement would only be difficult to apply to a wheel hub with integrated lack of energy brake. of the kind mentioned above, and it could only lead to the implantation of the release screw (s) in an area that is difficult to access without prior disassembly of the corresponding wheel.

 On the contrary, thanks to the arrangement according to the invention, the screw or the release screws used can advantageously protrude, parallel to the axis, on the side of the wheel hub concerned facing outwards, and they are of this fact easily accessible without any disassembly.

 In addition, by their location, they lend themselves advantageously to assume other functions than that, if necessary, of a manual release of the lack of energy brake concerned.

 Indeed, offering axial support to the brake disc forming reaction plate, they allow, by adjusting the axial position thereof, a prior adjustment of the clamping stroke of the assembly, and therefore, of the braking torque. capable of being developed, when, the elastic tightening means being formed of at least one elastic washer of the welleville washer type, this torque depends on the stroke, when braking, of the axial end of action of such elastic means of Tightening.

 Likewise, they make it possible, in service, to compensate for the effects due to wear of the friction linings usually occurring between the brake discs and the intermediate discs.

 Thus, unlike the locking screw used in the lack of energy brake described in French patent No 79 22648 mentioned above, the presence of which is unnecessary, or even harmful, in service, the unlocking screws provided in the lack of energy brake according to the invention are useful, and even necessary, in service.

 During the manual release of the brake concerned, the unscrewing action to be exerted on this (s) release screw can be sufficiently pushed so that the corresponding stroke of the action end of the elastic clamping means leads to a total relaxation of these, thereby rendering them inactive.

 However, preferably, to limit this stroke, and thereby limit the unscrewing action to be exerted on the release screw (s), the piston of the retaining means provided in the lack of energy brake according to The invention preferably comprises, transversely, a support shoulder, on the side opposite to the elastic clamping means, for cooperation with an abutment shoulder provided for this purpose in the cylinder in which it is movably mounted.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended schematic drawings in which
Figure 1 is a view, partly in elevation, partly in axial section, of a wheel hub equipped with a lack of energy brake according to the invention;
Figures 2, 3, repeat the part in axial section of Figure 1 and illustrate the mode of operation of this lack of energy brake;
Figure 4 is a view similar to that of Figure 1 for another type of wheel hub.

 FIGS. 1 to 3 illustrate the application of the invention to a drive wheel hub 10, attached, with the interposition of bearings II, 12, at the end of a fixed wheel rocket 13.

 In the embodiment shown, this wheel spindle 13 is of the flare type with flange, that is to say that it comprises 1 in a single tenan-t, on the one hand an axial sleeve 14, on which are engaged the bearings 11, 12, and on the other hand a transverse flange 15.

 In the embodiment shown in FIGS. 1 to 3, the wheel hub 10 generally constitutes a hollow body, which is in practice formed by several successive parts.

 First there is a first part 16 by which it is engaged on the axial sleeve 14 of the wheel stub 13, this first part 16 itself comprising on the one hand, around said sleeve 14, an axial sleeve 18 , by shoulders from which the llf bearings 12 are buttressed, and, on the other hand, at the axial end of said sleeve 18 opposite the transverse flange 15 of said wheel stub 13, a transverse flange 19.

 There is then a second part 20, essentially consisting of a transverse flange 21, by which it is applied to the transverse flange 19 of the first part 16, said transverse flanges 19, 21 being suitably secured to one another by screws not visible in the figures and jointly forming the flange 23 to which, as shown diagrammatically in broken lines, the web 24 of the rim of the wheel concerned can be attached to the wheel hub 10.

 There is finally, on the side of the flange 23 facing outwards, a third part 25, which is suitably attached to the second part 20, by screws not visible in the figures, and which internally forms a compartment for end in which is disposed, in a manner known per se, a wheel reducer.

 The shaft 27 of this wheel reducer, which forms the planetary, is, by a splined mounting, rotationally locked on a wheel shaft 28 disposed coaxially in the axial sleeve 14 of the wheel stub 13, with interposition of bearings 29, 30.

 In the embodiment shown in Figures 1 to 3, this wheel shaft 28 forms the output shaft of a hydraulic motor 32, suitably attached by screws not visible in the figures, on the transverse flange 15 of the rocket wheel 13, on the side thereof opposite the wheel hub 10.

These arrangements are well known in themselves, and, not being part of the present invention, they will not be described in more detail here.
The wheel hub 10 is associated with a lack of energy brake 33.

 In the embodiment shown in FIGS. 1 to 3, this lack of energy brake 33 is arranged outside the wheel hub 10, in a compartment 34 formed between the axial sleeve 18 of this wheel hub 10, on the one hand, and a crown 35 attached, by screws not visible in the figures, on the transverse flange 15 of the wheel stub 13, on the other hand.

 Overall, and in a manner known per se, the lack of energy brake 33 comprises a rotary member to be braked, formed in practice by the axial sleeve 18 of the wheel hub 10, at least one brake disc 37 fixed in rotation on said rotary member to be braked, elastic clamping means 36, which, bearing by an axial end of support 39 on an axially fixed part, at least in service, formed in practice by the transverse flange 15 of the wheel stub 13, is capable, by an axial end of action 40, of causing an axial tightening of the brake disc (s) 37 and of the controlled retaining means 42 which, in use, when active, disrupt said elastic means clamping 36, and more precisely the axial action end 40 thereof, for holding it loose, and therefore inactive (s) of the brake disc (s) 37.

 In the embodiment shown in Figures 1 to 3, two brake discs 37 are used, alternating with intermediate discs 38 fixed in rotation relative to them.

 By a grooved mounting at their internal periphery, the brake discs 37 are set in rotation on the axial sleeve 18 of the wheel hub 10 forming the member to be braked, while being mounted axially movable along the latter.

As will appear below, the one of these brake discs 37 which is closest to the flange 23 of the wheel hub 10 melts a reaction plate for the whole of the low-energy brake 33
In addition, in the embodiment shown in Figures 1 to 3, it is integral with a crown 44 which, disposed radially between the edge of the transverse flange 19 of the first part 16 of the wheel hub 10, of a part, and the crown 35 carried by the wheel spindle 13, on the other hand, is intended to seal the compartment 34 in which the lack of energy brake 33 is arranged
To this end, in the embodiment shown, a seal 45 is provided between this ring 44 and the transverse flange 19, on the one hand, and, in the compartment 34, this ring 44 carries a seal at lips 46 for contact with the crown 35, on the other hand.

The interposed discs 38, which in practice are two in number, one between the brake discs 37, and one outside of them, are, in the embodiment shown, engaged, by passages 47, on pins 48 carried for this purpose, parallel to the axis of the assembly, by the crown 35, or more precisely, by a radial return 49 thereof
While thus being fixed in rotation, they are therefore, like the brake discs 37, mounted axially movable relative to the rotary member to be braked.

 Between brake discs 37 and successive intermediate discs 38, friction linings 50 operate in a manner known per se.

 In the embodiment shown in FIGS. 1 to 3, these friction linings are carried by the intermediate discs 38.

Although such an arrangement is preferred, because the discs to be subjected, under braking, to the highest temperature rise are then the brake discs 37 and that, for these, the risks of jamming along the rotary member to be braked are the weakest, since the corresponding groove mounting takes place on an inner diameter on the one hand, and on a relatively small diameter, on the other hand, it is not imperative
In other words, and in a usual manner, the friction linings 50 may as well, as a variant, be carried by the brake discs 37.

 Anyway, and according to one aspect of the invention, an odd number of friction faces, three in the embodiment shown, are in practice thus implemented.

In the embodiment shown in Figures 1 to 3, the elastic clamping means 36 used are essentially constituted by a washer, of the washer type
Belleville, unique, arranged in an annular housing 52 formed for this purpose recessed in the transverse flange 15 of the wheel stub 13
At the same time, in the embodiment shown in FIGS. 1 to 3, the associated controlled retaining means 42 comprise a piston 53, on which bears the axial action end 40 of the elastic clamping means 36, and which is mounted to move in a cylinder 54, which, formed in the radial return 49 of the crown 35 carried by the transverse flange 15 of the wheel stub 13, is able, by a passage 55 provided for this purpose therein, to be connected to a source of pressurized fluid not shown
By its axial end opposite the elastic clamping means 36, the piston 53 is able to act on the nearest intermediate disc 38.

 In the embodiment represented in FIGS. 1 to 3, and for reasons which will appear hereinafter, this udder 53 comprises transversely, on the side opposite to the elastic clamping means 38, a support shoulder 56, for cooperation in limitation stroke with an abutment shoulder 57 provided transversely for this purpose in the cylinder 54 in which it is movably mounted.

 The lack of energy brake 33 thus formed further comprises unlocking means capable of causing a release of its brake discs 37 when, the retaining means 42 being inactive, these brake discs 37 are applied.

 In a manner known per se, these unlocking means comprise at least one unlocking screw 60, which, by a first portion, alyte here by this modity support portion, is able to bear axially on an axially fixed part, and which , by a second portion, called here for convenience, action portion, is capable of controlling the possible application of the brake discs 37.

 In practice, several release screws 60 are provided, which are circularly distributed around the aspe of the assembly.

 According to the invention, the bearing portion and the action portion of these release screws 60 are both axially arranged on the side of the axial action end 40 of the elastic clamping means 36.

 In practice, in the embodiment shown in Figures 1 to 3, these release screws 60 are axially disposed on the other side of the piston 53 of the controlled retaining means 42 relative to the elastic clamping means 36, and they are carried by the rotary member to be braked or, more precisely, by an integral part in rotation of this.

 In this embodiment, this is the flange 23 which the wheel hub 10 has radially.

Indeed, according to the invention, the release screws 60 protrude, parallel to the axis of the assembly, on this flange 23, on the side of the wheel hub 10 facing outwards, around the end compartment 25 thereof, using passages 61 provided for this purpose in the web 24 of the rim of the wheel concerned
They are therefore easily accessible, without any disassembly, neither of this wheel, nor of anything.

 The threaded barrel 62 of each unlocking screw 60 crosses with clearance a passage 63 provided for this purpose in the transverse flange 21 of the wheel hub 10 participating in the constitution of the radial flange 23 thereof.

 By cons, it is engaged in screwing in a threaded bore 64 of the transverse flange 19 of the wheel hub 10 also participating in the constitution of the radial flange 23 thereof.

 Due to its screw engagement in this threaded bore 64, the threaded barrel 62 of a release screw 60 constitutes, according to the invention, the bearing portion of such a release screw 60.

 Jointly, the action portion of each release screw 60 is, according to the invention, formed by the end 65 of the threaded barrel 62 thereof, the brake disc 37 closest carrying axially, in service, on said end 65 of each of the release screws 60.

 Preferably, and as shown, the axial position of each of the release screws 60 is confirmed by a locking nut 67 engaged on its threaded barrel 62, at the end of the wheel hub 10, for support on the radial flange 23 of it.

 In service, the cylinder 54 of the controlled retaining means 42 is under pressure.

 Counterbutted by the corresponding piston 53, the elastic clamping means 38 have no action, FIG. 1.

 A free axial clearance then remaining overall for one set of brake discs 37 and intermediate discs 37, the brake discs 37 are not applied, and the lack of energy brake 33 is thus inactive.

 As will be noted, by appropriate action on the release screws 60, it is possible to adjust to the desired value the axial play thus left free for all of the brake discs 37 and the intermediate discs 38, and, therefore, to adjust the initial value of this clearance, and, by successive adjustments, to bring it back to this initial value as the friction linings 50 wear.

 If, for parking the vehicle or machine concerned, for example, the pressure in the cylinder 54 is released, or if, as a result of any failure, this pressure comes of itself to relax, the elastic means of clamp 36 come into action, Figure 2.

 Pushing back, by their axial end of action 40, the piston 53 of the controlled retaining means 42 in the direction of the release screws 60, they cause, by absorption of the play initially left free between the brake discs 37 and the intermediate discs 38, the axial clamping of said brake discs 37, and thereby the braking of the wheel hub 10 on which the brake discs 37 are rotated.

 To ensure manual release of the lack of energy brake 33 thus become active, it suffices, in FIG. 3, to unscrew the release screws 60.

 In fact, as soon as, under the stress of the elastic clamping means 36, the piston 53 of the controlled retaining means 42 comes, by its support shoulder 56, to bear against the abutment shoulder 57 of the cylinder 54 in which it is mounted mobile, said elastic clamping means 36, thus again butted, again become inactive.

 Therefore, and provided that the unscrewing of the release screws 60 is sufficiently accentuated, an axial play can again develop freely between the brake discs 37 and the intermediate discs 38, so that the brake discs 37 are again released.

 Alternatively, no support shoulder is provided for the piston 53 of the controlled retaining means 42, and the unscrewing of the release screws 60 is made sufficient for the elastic clamping means 36 to be completely relaxed.

 FIG. 4 illustrates the application of the invention in the case where the wheel hub 10 is reduced to a flange attached by screws 70 on a transverse flange 71 provided for this purpose at the end of the corresponding wheel shaft 28, the end of one of the arms 72 of a drive axle, to which, at a distance from the wheel hub 10, is usually associated with a wheel reducer, not shown.

 Canme previously, the lack of energy brake 33 according to the invention is arranged in a compartment 34 formed between the collar 71 and a ring 35 attached to a transverse collar 75 provided for this purpose at the end of the arm 72 of the bridge concerned .

 For a splined mounting, the brake discs 37 are set in rotation on the transverse flange 71 of the wheel shaft 28, while being mounted axially movable.

 The release screws 60, which include a head 76 to facilitate maneuvering, are arranged around the screws 70, and are engaged by screwing in threaded holes 77 provided for this purpose in the flange constituting the wheel hub 10, at a distance of the web 24 of the rim of the wheel concerned.

 In addition, in the embodiment shown, the axial support end 39 of the elastic clamping means 36 used is supported on the bottom of the corresponding housing 52 by means of one or more wedges 78 suitable for allowing to adjust the initial stiffness of these elastic clamping means 36.

 Alternatively, these wedges 78 can be replaced by screws, which, of course, in use, are axially fixed.

 The other arrangements implemented in this embodiment are also identical to those described above, and the operation of the lack of energy brake 33 considered is also identical to that described above.

 Of course, the present invention is not limited to the embodiments shown, but encompasses any variant.

 It also includes any variant of implementation.

 In particular, if, as described, the brake applied essentially constitutes a lack of energy brake, for parking and / or rescue, it can also constitute a service brake, by appropriate modulation of the pressure of the fluid sent into the cylinder of its controlled retaining means.

Claims (10)

 1) Lack of energy brake, of the type comprising a rotary member (18) to be braked, at least one brake disc  (37) locked in rotation on said rotary member (18) to be braked, elastic clamping means (36), which, supported by an axial end of support (39) on an axially fixed part (15), at least in service, are capable, by an axial end of action (40), of causing an axial tightening of the brake disc (37), controlled retaining means (42) which, in service, when they are active, buttress said elastic clamping means (36), for holding the brake disc (37) inactive, and release means capable of causing a release of the brake disc (37) when, the retaining means (42) being inactive, the brake disc (37) is clamped by the elastic clamping means! 36), said release means comprising at least one release screw (60), which, by a first portion (62), said here for convenience portion of support, is able to bear axially on an axially fixed part, and which, by a second portion (65), called  here for convenience portion of action, is able to control the  possible tightening of the brake disc (37), characterized in  that the support portion (62) and the action portion (65) of the  the release screws (60) are both axially available  placed on the side of the axial action end (40) of said elastic clamping means (36).  2) brake according to claim 1 and in which are provided several brake discs (37) mounted axially movable, alternating with intermediate discs (38) fixed  in rotation relative to said brake disc (37), and mounted axially movable like these, characterized in that  the release screw (60) is carried by the rotary member (18)  to brake or an integral part in rotation thereof, its  support portion (62) is formed by its threaded barrel, and its por  tion of action (65) is formed by the end of said barrel, the  nearest brake disc (37), forming re plate  action, carrying axially, in service, on said end  said barrel.  3) Brake according to claim 2, characterized in that  that the number of friction faces between the successive discs (37, 38) is odd.  4) Brake according to any one of claims 1 to 3, in which the controlled retaining means (42) comprise a piston (53) mounted movably in a cylinder (54) capable of being connected to a source of pressurized fluid, characterized in that the release screw (60) is axially disposed on the other side of said piston (53) relative to the elastic clamping means (36).  5) Brake according to any one of claims 1 to 4, characterized in that several release screws (60), distributed circularly, are provided.  6) Brake according to claim 5, characterized in that, on the side opposite to the elastic clamping means (36), the piston (53) of the retaining means (42) comprises transversely a support shoulder (55), for cooperation in stroke limitation with an abutment shoulder (57) provided for this purpose in the cylinder (54) in which it is movably mounted.  7) Wheel hub, in particular for an industrial vehicle, public works machine, or agricultural machine of the kind with which it is associated a lack of energy brake (33), characterized in that said lack of energy brake (33) is in accordance with any of claims 1 to 6.  8) Wheel hub according to claim 7, characterized in that the release screw (60) protrudes, parallel to the axis, on the side of the hub facing outwards.  9) Wheel hub according to claim 8, and in an end compartment (25) of which there is disposed a wheel reducer, characterized in that, several release screws (60) being provided, said release screws are distributed circularly around said compartment (25).  10) Wheel hub according to any one of claims 7 to 9, characterized in that the lack of energy brake (33) is arranged outside of said wheel hub, in a compartment (34) formed between the 'rotary member (18) to brake and a crown (35) integral with the wheel spindle or the corresponding bridge arm.