WO2019058356A1

WO2019058356A1 - Ski boot

Info

Publication number: WO2019058356A1
Application number: PCT/IB2018/057410
Authority: WO
Inventors: Davide Parisotto
Original assignee: Calzaturificio S.C.A.R.P.A. S.P.A.
Priority date: 2017-09-25
Filing date: 2018-09-25
Publication date: 2019-03-28
Also published as: IT201700107006A1; EP3687330A1

Abstract

Ski boot (1) comprising: a substantially rigid shell (2), which is adapted to house the foot of the user and has a lower part structured to be hooked to a ski binding device; a substantially rigid cuff (3), which is adapted to enclose the lower part of the leg of the user and is pivotally joined to the shell (2) to rotate about a reference axis (A) substantially perpendicular to the midplane of the ski boot; and a manually operated cuff locking device (15), which is adapted to selectively lock the cuff (3) onto the shell (2) in a predetermined downhill position, and which in turn comprises: a supporting plate (16) arranged on the cuff (3), above the heel of the ski boot (1); a slider (17), which is fastened onto the supporting plate (16) and is capable of moving freely along the supporting plate (16) substantially parallel to the midplane of the ski boot; a movable arm (18), which is butt hinged to the slider (17) so that it rotates to and from a locking position in which the movable arm (18) extends downwards and is releasably hooked to the shell (2) beneath; and an elastic counteracting element (21), which is adapted to elastically retain the slider (17) in a predetermined operating position.

Description

"SKI BOOT"

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Italian Patent Application No. 102017000107006 filed on 25/09/2017, the disclosure of which is incorporated by reference.

TECHNICAL FIELD

The present invention relates to a ski boot.

More in detail, the present invention relates to a ski mountaineering boot or Telemark boot. Ski boots to which the following disclosure will make explicit reference without however losing its general character.

BACKGROUND ART

As already known, ski mountaineering boots and Telemark boots basically comprise: a rigid shell which is shaped substantially like a shoe so as to accommodate the foot of the user, and whose lower part is specifically structured to be fastened to the back of a downhill ski or the like by means of a special ski binding device; a rigid cuff which is shaped so as to enclose the lower part of the leg of the user from behind, and is hinged to the upper part of the shell to rotate about a transversal reference axis that is substantially perpendicular to the vertical midplane of the boot, and is also locally substantially coincident with the ankle articulation axis; and a protective inner-boot made of a soft and thermal-insulating material, which is inserted in removable manner inside the shell and the cuff, and is shaped so as to enclose and protect the foot and the lower part of the leg of the user approximately up to the calf.

The ski boots mentioned above are moreover provided with a shell closing mechanism and with a cuff closing mechanism, both manually operated.

Finally, ski mountaineering boots and Telemark boots are provided with a manually-operated cuff locking device which is traditionally arranged in the area above the heel of the boot, and is structured so as to be able to, optionally and alternatively,

- rigidly lock the cuff to the shell in a given downhill position, in which the cuff is tilted forward by a predetermined angle with respect to the vertical; or

- completely release the cuff from the shell, thus allowing the cuff to freely pivot forward and backward with respect to the shell.

Unfortunately, the dynamic behaviour of the cuff locking device does not satisfy the needs of some users, who would like the cuff to be able to make small movements (no more than a few degrees) even when the cuff is locked in the downhill position, so as to at least partially follow the ankle movements typical of downhill skiing.

DISCLOSURE OF INVENTION Aim of the present invention is to provide a cuff locking device that can rigidly lock the cuff to the shell in the downhill position while still allowing the cuff to make small movements with respect to the pre-set inclination.

In compliance with these aims, according to the present invention there is provided a ski boot as defined in claim 1 and preferably, though not necessarily, in any one of the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings showing an exemplificative non- limiting embodiment, in which:

- Figure 1 is a perspective view of a ski boot made according to the teachings of the present invention, with parts removed for clarity's sake;

- Figure 2 is a side view on an enlarged scale of the rear part of the ski boot shown in Figure 1, sectioned along the ski-boot midplane and with parts removed for clarity's sake;

- Figure 3 is a front view of the cuff locking device shown in Figure 2, partially exploded and with parts in section and parts removed for clarity's sake; whereas

- Figure 4 is a perspective view of the rear part of a ski boot provided with a different embodiment of the cuff locking device shown in Figure 2, with parts removed for clarity's sake. BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figures 1 and 2, the number 1 denotes as a whole a ski boot that can be advantageously used for practicing ski mountaineering or Telemark.

The ski boot 1 firstly comprises: a substantially rigid shell 2 which is shaped substantially like a shoe so as to accommodate the foot of the user, and preferably has the lower part specifically structured/shaped to couple/fasten in a rigid and stable, though easily releasable manner, to a ski binding device of known type (not shown) which, in turn, is adapted to be fixed in rigid manner to the back of a generic downhill ski or the like; and a substantially rigid cuff 3 which is shaped so as to enclose the lower part of the leg of the user, and is pivotally joined to the shell 2 so as to freely rotate about a transversal reference axis A which is locally substantial perpendicular to the vertical midplane of the ski boot, and is moreover substantially coincident with the articulation axis of the ankle of the user .

More in detail, the lower part of shell 2 is preferably provided with a front tip 4 and a rear heel 5.

Front tip 4 is preferably structured so as to couple/fasten in a stable, though easily releasable manner to the toe- piece (not shown) of a ski binding device which, in turn, is stably secured to the back of the downhill ski or the like. On the other hand, rear heel 5 is preferably structured to couple/fasten in a stable, though easily releasable manner to the heel-piece (not shown) of the same ski binding device which, in turn, is stably secured to the back of the downhill ski or the like.

Preferably, the lower part of shell 2 furthermore has a threaded profile to grip on snow and/or ice, thus allowing the user to walk on snow and ice in relative safety.

In the example shown, in particular, the front tip 4 of shell 2 is preferably structured so as to be able to couple/fasten in known manner to the toe-piece of a ski mountaineering or Telemark binding device, whereas the rear heel 5 of shell 2 is preferably structured so as to be able to couple/ fasten in known manner to the heel-piece of the same ski mountaineering or Telemark binding device.

More specifically, with reference to Figures 1 and 2, the shell 2 preferably comprises: a substantially oblong basin- shaped, rigid casing 6 which is preferably made of plastic and/or composite material and is shaped to accommodate and enclose the foot of the user, preferably approximately up to the ankle; and optionally a lower sole 7 preferably having a threaded profile, which is preferably made of vulcanized rubber or other elastomeric material with a high friction coefficient, and is firmly fixed to the bottom wall of casing 6, preferably by gluing. Preferably, though not necessarily, the shell 2 furthermore comprises a rigid insert 8, preferably made of metal material, which has a substantially plate-like structure and is firmly embedded/incorporated into the bottom wall of rigid casing 6, roughly at the tip 4 of shell 2. The rigid insert 8 is moreover dimensioned so as to surface/emerge outside of the casing 6 on opposite sides of the front tip 4 of shell 2, preferably in a substantially specular position with respect to the ski-boot midplane, so that the two distal ends of rigid insert 8 can couple in known manner to the toe-piece of the ski mountaineering binding device.

With reference to Figures 1 and 2, in turn cuff 3 preferably comprises a rigid casing 9 made of plastic and/or composite material, which is substantially C-bent so as to cover the back of the leg of the user from the ankle substantially up to the calf height, and is moreover provided with two oblong lateral flaps (not shown in the figures) which extend forward on opposite sides of the ski-boot midplane so as to enclose from behind the leg of the user approximately at the height of the calf, and preferably after overlap to one another at the front of the leg, thus forming a tubular structure that encloses the leg of the user at the height of the calf. Furthermore, cuff 3 is preferably fixed in a freely rotatable manner to the upper part of shell 2, or rather of the rigid casing 6, by means of two connection hinges 10 preferably made of metal material, which are arranged on the inner and on the outer side of shell 2 and of cuff 3, and are aligned along transversal axis A so as to allow the cuff 3 to freely swing forward and backward on shell 2 while always remaining on a reference plane orthogonal to axis A and substantially coincident with the midplane of the ski boot.

With reference to Figure 1, preferably the ski boot 1 further comprises a preferably substantially boot- or shoe- shaped, protective inner-boot 11 which is inserted inside shell 2 and cuff 3 preferably in a manually removable manner, and has a soft and thermal-insulating structure shaped to enclose and protect the foot and optionally also the lower part of the leg of the user.

More in detail, in the example shown, the inner-boot 11 is preferably substantially boot- shaped so as to enclose, cover and protect the foot and the lower part of the leg of the user, approximately up to the top of the calf. Preferably, the inner-boot 11 moreover has a thermoformable structure. Furthermore, the ski boot 1 is additionally provided with a shell closing mechanism 12 and/or with a cuff closing mechanism 13, both preferably manually operated.

The shell closing mechanism 12 is structured so as to selectively close/tighten the shell 2 on the foot of the user to immobilize the foot of the user inside the shell 2, or rather inside the inner-boot 11. On the other hand, the cuff closing mechanism 13 is structured so as to selectively close/tighten the upper part of cuff 3 on the leg of the user to immobilize the leg of the user inside the cuff 3, or rather inside the inner-boot 11.

The shell closing mechanism 12 and the cuff closing mechanism 13 are devices widely known in the ski-boot field, and therefore will not be further described.

With reference to Figures 1, 2 and 3, ski boot 1 is finally provided with a manually-operated cuff locking device 15 which is structured to selectively lock the cuff 3 to the shell 2 in a given downhill position in which the cuff 3 is tilted with respect to the vertical by a predetermined angle, while allowing the cuff 3 to perform small oscillations around said downhill position.

In other words, the cuff locking device 15 is structured to selectively and alternatively:

- connect cuff 3 to shell 2 so as to lock the cuff 3 in said downhill position, while allowing the cuff 3 to move/ oscillate by a few degrees around said downhill position; and

- completely unlock/release the cuff 3 from the shell 2 so as to allow the cuff 3 to freely pivot on shell 2 forward and backward about the transversal axis A, always remaining on the ski-boot midplane.

Moreover, in the downhill position the cuff 3 is preferably inclined forward with respect to the vertical by a predetermined angle preferably, though not necessarily, ranging between 3° and 30°.

The small oscillations around the downhill position, on the other hand, have a maximum amplitude preferably smaller than 7° .

Furthermore, the cuff locking device 15 is preferably structured to resiliently oppose the small oscillations of the cuff 3 around the aforesaid downhill position.

More in detail, with reference to Figures 1, 2 and 3, the cuff locking device 15 is preferably fixed on the cuff 3 in the area above the heel of the boot, substantially astride the midplane of the ski boot.

Moreover, the cuff locking device 15 comprises: a preferably elongated in shape, supporting plate 16 which is preferably made of metal material and is rigidly fixed to the cuff 3, above the heel of the ski boot 1 and preferably substantially astride the midplane of the ski boot, with its longitudinal axis L substantially parallel to the ski-boot midplane and also locally substantially close/ tangent to the surface of cuff 3; a movable slider 17 which is preferably made of metal material and is fixed to the supporting plate 16 with the capability to freely move on supporting plate 16 parallel to the plate longitudinal axis L, i.e. parallel to the midplane of the ski boot; and a rigid and oblong movable arm 18 which is preferably made of metal material, and is butt hinged to the slider 17 so as to freely rotate with respect to the slider 17 while remaining on a rotation plane R locally substantially parallel to, and preferably coincident with, the midline of the ski boot, to and from a locking position (see Figures 1 and 2) in which the movable arm 18 extends downwards, preferably substantially skimmed over the outer surface of the cuff 3, and is connected in a rigid and stable, though easily releasable manner to the shell 2 beneath, or rather to the rigid casing 6.

Preferably, the cuff locking device 15 furthermore comprises an elastic member 19 which is preferably interposed between the slider 17 and the arm 18, and is adapted to elastically bring and maintain the arm 18 in said locking position.

More in detail, in the locking position the movable arm 18 extends downwards, preferably so as to arrange its distal end 18a in abutment against an anchoring structure 20 which is stably located on the shell 2, or rather on the rigid casing 6, spaced beneath the cuff locking device 15 and substantially astride the rotation plane R of arm 18, i.e. on the midplane, more or less at the heel of the boot.

The distal end 18a of movable arm 18 is preferably structured so as to couple/hook, when arm 18 is in the locking position, in a rigid and stable, though easily releasable manner, to the anchoring structure 20 so to make the slider 17 integral with the shell 2.

Furthermore, the cuff locking device 15 additionally comprises an elastic counteracting element 21 which is preferably interposed between the slider 17 and the supporting plate 16, and is adapted to elastically retain/ hold the slider 17 in a predetermined operating position on supporting plate 16.

In other words, the elastic counteracting element 21 is adapted to elastically oppose any displacement of the movable slider 17 from said operating position and to elastically bring the slider 17 back into the operating position after any translation of the same slider 17 along the supporting plate 16.

Preferably, the cuff locking device 15 furthermore comprises a manually-operated slider locking mechanism 22 which is adapted to selectively prevent any movement of the slider 17 from said operating position.

More in detail, the slider locking mechanism 22 is preferably adapted to selectively rigidly couple the slider 17 to the supporting plate 16.

With reference to Figures 1, 2 and 3, in the example shown, in particular, the supporting plate 16 is preferably provided with an elongated and substantially straight, longitudinal groove 23 which extends parallel to the longitudinal axis L of plate 16 and to the rotation plane R of arm 18, i.e. parallel to the midplane of the ski boot.

Moreover, supporting plate 16 is preferably firmly fixed/ fastened to cuff 3, or rather to rigid casing 9, by means of at least one transversal anchoring screw 24 that passes through supporting plate 16 before penetrating into the rigid casing 9 of cuff 3.

The movable slider 17 is preferably trapped in axially sliding manner into the longitudinal groove 23, so as to be able to freely move on the supporting plate 16 only parallel to the longitudinal axis of groove 23, i.e. parallel to the plate longitudinal axis L.

The elastic element 21, in turn, is preferably at least partially accommodated inside the longitudinal groove 23. More in detail, the elastic element 21 preferably comprises at least one block of elastomeric material 25 which is arranged inside the groove 23 to deform in elastoplastic manner when the movable slider 17 moves away from said operating position.

In the example shown, in particular, the movable slider 17 is in said operating position preferably when it is located at a first end of longitudinal groove 23, and the block of elastomeric material 25 is adapted to elastically retain/ bring back the movable slider 17 at said first end of the longitudinal groove 23.

More in detail, the supporting plate 16 is preferably fastened on the rear part of cuff 3 in a substantially vertical position, and the movable slider 17 is preferably in the operating position when it is located at the lower end of longitudinal groove 23.

In turn, the block of elastomer material 25 preferably has a first side in abutment against the movable slider 17 and a second side in abutment against the supporting plate 16, at the second end of longitudinal groove 23, so as to compress in elastoplastic manner when the slider 17 moves away from the operating position, i.e. moves towards the second end of longitudinal groove 23.

Preferably, the block of elastomeric material 25 moreover completely occupies/ fills the part of longitudinal groove 23 not engaged by the slider 17.

With reference to Figures 1 and 3, on the other hand, the slider locking mechanism 22 is preferably adapted to selectively prevent any movement of the slider 17 along the longitudinal groove 23.

More in detail, the slider locking mechanism 22 preferably comprises a pawl 26, preferably made of metal material, which is fitted in axially rotatable manner within a complementary housing seat 27 preferably realized on supporting plate 16 or on cuff 3 beside the longitudinal groove 23.

The housing seat 27 is arranged and shaped so as to partially intersect the longitudinal groove 23, and the pawl 26 is shaped so as to selectively protrude or not protrude inside the longitudinal groove 23, depending on its angular position inside the housing seat 27.

More in detail, the pawl 26 is manually positionable in a first angular position in which the body of pawl 26 does not protrude inside the longitudinal groove 23, thus allowing the slider 17 to move freely within the longitudinal groove 23; and in a second angular position in which the body of pawl 26 protrudes inside the longitudinal groove 23, thus preventing the slider 17 from moving within the longitudinal groove 23.

Preferably, when placed the second angular position, the pawl 26 is additionally rotated about 100° with respect to the first angular position.

In the example shown, in particular, pawl 26 is preferably substantially cylindrical in shape and is preferably laterally provided with a secant groove 28 whose shape is preferably substantially complementary to the one of the longitudinal groove 23, so as to form an extension of the longitudinal groove 23.

In the first angular position, the secant groove 28 is aligned to and facing the longitudinal groove 23, therefore the body of pawl 26 does not protrude inside the longitudinal groove 23, thus allowing the slider 17 to move freely along the longitudinal groove 23. In the second angular position, the secant groove 28 is misaligned with respect to the longitudinal groove 23, therefore the body of pawl 26 protrudes inside the longitudinal groove 23, thus preventing the slider 17 from moving freely along the longitudinal groove 23.

Preferably, the side of movable slider 17 is moreover provided with a recess 29 which is adapted to be engaged by the body of pawl 26 when the pawl 26 is arranged in the second angular position.

With reference to Figures 1, 2 and 3, the back of movable slider 17 preferably protrudes outside of the longitudinal groove 23, and the movable arm 18 is preferably butt hinged to the back of slider 17 so as to be able to freely rotate about an axis B locally substantially parallel to axis A and/or substantially perpendicular to the midplane of the ski boot.

More in detail, in the example shown, the proximal end 18b of movable arm 18 is preferably substantially fork-shaped, and each fork prong is preferably separately hinged to the back of movable slider 17 by means of a respective transversal pin 30 extending coaxial to axis B.

The distal end 18a of movable arm 18, on the other hand, is preferably structured to stuck in removable manner astride a second transversal pin 31 preferably made of metal material and which extends coaxially to an axis C locally substantially parallel to axis A and/or B, and is fixed in rigid and stable manner to the rear part of shell 2, or rather of rigid casing 6, astride the arm rotation plane R. More in detail, the anchoring structure 20 preferably comprises the transverse pin 31 and a pair of mutually parallel and facing support winglets 32 which jut out from the rear part of shell 2, or rather from the rear part of rigid casing 6, on opposite sides of the midplane of the ski boot, preferably in a substantially specular position with respect to the midplane of the ski boot, and extend up to the two ends of transversal pin 31 to directly support the transversal pin 31.

With reference to Figures 1 and 2, the elastic member 19 preferably finally comprises an helical spring, preferably made of metal material, which is preferably housed in the throat of the proximal end 18b of the movable arm 18, substantially astride the arm rotation plane R, and has a first end integral with the body of movable arm 18 and a second end integral with the movable slider 17, in an eccentric position with respect to the arm rotation axis B. General operation of ski boot 1 is easily inferable from the above description and thus does not require further explanations .

On the other hand, with regard to the cuff locking device 15, the user manually arranges the movable arm 18 in the locking position when she/he wants to lock the cuff 3 in the downhill position.

Moreover, if desires to let cuff 3 make small oscillations around said downhill position, the user arranges the pawl 26 of the slider locking mechanism 22 in the first angular position, so as to allow the slider 17 to move inside the longitudinal groove 23 deforming the elastic element 21 (or rather compressing the block of elastomeric material 25) . Obviously, any small displacement of slider 17 on supporting plate 16 is elastically opposed by the elastic element 21, and results in a small variation of the tilt angle of the cuff 3 with respect to the vertical.

Alternatively, if desires to let cuff 3 remain stationary in said downhill position, the user arranges the pawl 26 of the slider locking mechanism 22 in the second angular position to prevent the slider 17 from moving inside the longitudinal groove 23.

The advantages connected to the cuff locking device 15 are remarkable .

Firstly, the cuff locking device 15 allows to lock the cuff 3 in the downhill position allowing at same time the cuff 3 to make small oscillations around said downhill position. Moreover, thanks to slider locking mechanism 22, the cuff locking device 15 is additionally capable of rigidly locking the cuff 3 to the shell in said downhill position. Last but not least, the cuff locking device 15 has production costs comparable with those of the known cuff locking devices, with all advantages that this entails.

It is finally clear that modifications and variations can be made to the ski boot 1 described above without however departing from the scope of the present invention.

For example, in a first embodiment, the supporting plate 16 can be made in one piece with the cuff 3. In other words, the groove 23 can be formed directly on the cuff 3, or rather on the rigid casing 9.

Moreover, in a second embodiment, when it is in the operating position, the movable slider 17 is spaced from both ends of the groove 23, whereas the elastic element 21 preferably comprises two blocks of elastomeric material housed inside the longitudinal groove 23 on opposite sides of the movable slider 17.

Preferably, the two blocks of elastomeric material additionally have a different elastic modulus so that the elastic element 21 has an asymmetric behaviour.

Finally, with reference to Figure 4, in a further embodiment, the slider locking mechanism 22 comprises, in place of the pawl 26, a strut rod 36 which is butt hinged to the supporting plate 16 or to the cuff 3, preferably near the upper end of groove 23, so as to be able to rotate to and from a locking position (see Figure 4) in which the strut rod 36 extends downwards so as to arrange its distal end in abutment against the movable slider 17, thus preventing the slider 17 from sliding upwardly into the groove 23.

Preferably, the strut rod 36 is additionally hinged on supporting plate 16 or on cuff 3, so as to be able to rotate about an axis locally substantially perpendicular to the surface of cuff 3.

In this way, the strut rod 36 moves on a plane locally substantially skimmed over the outer surface of cuff 3 and/or locally substantially perpendicular to the midplane of the ski boot.

Alternatively, the strut rod 36 could also be butt hinged to the supporting plate 16 or to the cuff 3 so as to be able to rotate about a reference axis parallel to axis B.

Claims

1. Ski boot (1) comprising: a substantially rigid shell (2) which is adapted to house the foot of the user and has a lower part structured to be connected to a ski binding device; a substantially rigid cuff (3) which is adapted to enclose the lower part of the leg of the user and is pivotally joined to the shell (2) to rotate about a reference axis (A) substantially perpendicular to the midplane of the ski boot; and a manually-operated cuff locking device (15) which is adapted to selectively lock the cuff (3) to the shell (2) in a predetermined downhill position;

the ski boot (1) being characterised in that the cuff locking device (15) comprises: a supporting plate (16) arranged on the cuff (3), above the heel of the ski boot (1) ; a slider (17) which is fixed to the supporting plate (16) with the capability of freely moving along the supporting plate (16) substantially parallel to the midplane of the ski boot; a movable arm (18) which is butt hinged to the slider (17) so as to be able to rotate to and from a locking position in which the movable arm (18) extends downwards and couples, in releasable manner, to the shell (2) beneath; and an elastic counteracting element (21) which elastically retains the slider (17) in a predetermined operating position.

2. Ski boot according to claim 1, characterised in that the supporting plate (16) is provided with an oblong and substantially rectilinear, longitudinal groove (23) which extends parallel to the midplane of the ski boot; and in that the slider (17) is trapped in an axially sliding manner into said longitudinal groove (23) .

3. Ski boot according to claim 2, characterised in that the elastic counteracting element (21) is at least partially housed inside said longitudinal groove (23) .

4. Ski boot according to claim 3, characterised in that the elastic counteracting element (21) comprises at least one block of elastomeric material (25) which is arranged inside the longitudinal groove (23), so as to deform in elastoplastic manner when the slider (17) moves away from said operating position.

5. Ski boot according to claim 2, 3 or 4, characterised in that the slider (17) is in said operating position when located at one end of the longitudinal groove (23) .

6. Ski boot according to any one of the preceding claims, characterised in that the cuff locking device (15) further comprises a manually-operated slider locking mechanism (22) which is adapted to selectively prevent the slider (17) from moving from said operating position.

7. Ski boot according to claim 6, characterised in that the slider locking mechanism (22) is adapted to selectively prevent any movement of the slider (17) along the longitudinal groove (23) .

8. Ski boot according to claim 7, characterised in that the slider locking mechanism (22) comprises a pawl (26) which is fitted in axially rotatable manner into a corresponding housing seat (27) which is located alongside the longitudinal groove (23) and partially intersects the longitudinal groove (23); the pawl (26) being selectively positionable in a first angular position in which the pawl (26) does not protrude inside the longitudinal groove (23), thus allowing the slider (17) to slide along the longitudinal groove (23), and in a second angular position in which the pawl (26) protrudes inside the longitudinal groove (23), thus preventing the slider (17) from sliding.

9. Ski boot according to Claim 8, characterised in that the side of the movable slider (17) is provided with a recess

(29) adapted to be engaged by the body of the pawl (26) when the pawl (26) is arranged in the second angular position.

10. Ski boot according to any one of the preceding claims, characterised in that the cuff locking device (15) additionally comprises an elastic member (19) which is adapted to elastically bring and maintain the movable arm (18) in said locking position.

11. Ski boot according to any one of the preceding claims, characterised in that, in the locking position, the movable arm (18) extends downwards so as to place the distal end (18a) of the arm in abutment against an anchoring structure (20) which is arranged on the shell (2), spaced apart beneath the cuff locking device (15); the distal end (18a) of the movable arm (18) being structured so as to couple/hook to said anchoring structure (20) .