Safety ski binding

Description

1. Introduction

[0001] 

1.1. The invention, whose description follows, is the mechanical element of a step in safety ski binding which allows a ski-boot with a prominent welt, to be held securely to a ski and yet release the boot, omnidirectionally, when subjected to the forces experienced in a fall. It is a development of the invention described in GB-A 8 519 346, GB-A 8 520 679, GB-A 8 528 932 and GB-A 8 601 235.

1.2. Mechanical ski-bindings to secure ski-boots are well known, and work on the principle of a spring force being overcome, somehow, in order to affect the release of the ski-boot, before the forces are large enough to cause injury.

1.3. These bindings do not, however, take into account, the problem of accurately monitoring the rate at which a force is applied to a binding. It is a well known fact that a force, which can be non-injurious if gradually applied, can cause serious injury if suddenly applied, and that trying to decrease the rate of application of this force, by using springs, produces a compromise, which results, either in loss of "feel" by the skier, or a continuation of the risk of injury, depending on the degree of reluctance offered by the spring. The invention, as claimed in GB-A 8 519 346, GB-A 8 520 679 and GB-A 8 528 932 overcame this problem by accurately measuring the rate of increase electronically, and initiating release electrically, when the rate of increase was sensed to be potentially injurious. Unfortunately, the electronic components can be expensive, and, should the electronic unit fail, the stand-by mechanical release, although having excellent release properties, is not discriminating as to the rate of increase of the release force.

1.4. A mechanical safety ski binding with the features of the pre-characterizing portion of claim 1 is disclosed in CH-A 581 481. The piston arrangement of that prior art safety ski binding comprises a first piston coupled to the retaining element and closing one end of one compartment of the liquid-filled cylinder chamber, and a second piston closing the opposite end of the other compartment of said cylinder chamber and being supported by the restraining spring. Accordingly, any movement of the retaining element causes said first piston to displace liquid from said one compartment through the flow restrictor into the second compartment, displacing said second piston against said restraining spring. In addition, the cylinder chamber as a whole is axially movable against a second restraining spring in response to applied shocks which cannot be accomodated by displacement of the liquid from said one compartment through said flow restrictor. Thus, the release mechanism of said prior art safety ski binding comprises two sub-mechanisms actually arranged in parallel, one of those sub-mechanisms (piston arrangement with liquid-filled cylinder chamber compartment and first release spring) accomodating gradual applied forces,. and the second sub-mechanism (cylinder chamber housing and second release spring) accomodating suddenly occuring forces. However, in case of suddenly applied shock forces, actual release requires a corresponding amount of displacement of the cylinder chamber housing against the action of that second spring what, as mentioned above, produces just a compromise which, while allowing resiliant response to shocks, results in a continuation of the risk of injury in case of suddenly occuring heavy shocks.

1.5. This invention is intended to overcome the above problems. Accordingly, the invention resides in a safety ski binding as characterized in claim 1.

1.6. According to the present invention, there is provided, a potentially low-cost, mechanical step-in safety ski-binding, whereby a ski-boot is secured by its prominent welts to a ski, between arms, mounted on two spheroids, each in seperate bindings. Release of the ski-boot, is achieved, by the forces acting on the ski-boot, rotating the spheroids against the pressure of spring-loaded plungers, bearing in recesses in the spheroids, shaped, so as to give a different reaction in different directions, until the plungers are no longer contained. The action of the plungers is controlled by detents, which unlock the constraint of the plungers on the spheroids rotation, when a piston is moved by an anti-freeze fluid, because the rate of flow of the fluid exceeds a by-pass system's capability.

1.7. The advantages offered by the invention are:

1.7.1. The invention provides a cheaper, mechanical alternative, to electronically monitoring the rate of increase of release forces and electrically effecting release.

1.7.2. By utilizing the non-compressible property of a flowing fluid, an accurate response, to a potentially injurious increase, in rate of application of release forces, can be achieved.

2. Description

[0002] 

2.1. A specific embodiment of the invention, will now be described, by way of example, with reference to the unscaled accompanying drawings, in which:

2.1.1. Figure 1 illustrates the Mechanical Release Unit.

2.1.2. Figure 2 illustrates the Mechanical Release Unit (Fixed).

2.1.3. Figure 3 illustrates the Manual Release.

2.1.4. Figure 4 illustrates a 3/4-view of a typical housing arrangement for a Mechanical Release Unit.

2.1.5. FiÇlure 5 illustrates 3/4 views of a typical housing arrangement for a Mechanical Release Unit (Fixed).

2.2. The design consists of the following principle components:

2.2.1. Mechanical Release Unit (Fig. I)

[0003] A spheroid (3), into which two retaining arms (39) and a positioning leg (2) are fixed, and whose rear has a shaped recess (36), is mounted in a cylindrical container (34). The container's closed end is hemispherical. It has a slot (I) and a shaped aperture (38) cut in it, to allow limited movement in any direction of the ski-boot's two retaining arms, and up and down movement of the positioning leg. The arms and leg move, due to forces acting on them, via the welts and sole of the ski-boot. They can only move because the spheroid rotates in its container. A spring-loaded (20) plunger (48), is in three sections, two of which are concentric (10) (13), locked together by inserts (14). The hemispherical head (4) of the third section (48), bears in the shaped recess in the spheroid and acts as a constraint on its rotation. The section of the plunger containing the hemispherical head, is separated from the two concentric sections by a compressible fluid seal (9). The seal is forced against the walls of the containing cylinder (49), by the action of the release spring. Rotation of the spheroid can only occur, because of a relative displacement between the spheroid, and the plunger, against the release spring (20). Sufficient rotation will take the plunger outside the constraint of the shaped recess (36). The inserts (14) are locked in place by a shaped piston (30). The rear part of the plunger also forms a piston (25). As it moves, due to movement of the plunger, caused by the spheroid rotating, or moving, anti-freeze fluid will be displaced, by this piston, from the decreasing volume occupied by the release spring (20). This fluid, will either flow through the restrictable by-pass, formed, by the control rod (22), and the ports (18) (17) in the shaped piston (30), and plunger (13), or, if the flow is too great, it will cause displacement of the shaped piston (30), against its return springs (8) (21). Momentary changes in volume, as the shaped piston (30) moves, is compensated for, by inflation of the compensating bag (29). Due to the shape of the control rod and the by-pass ports (17) (18), in the shaped piston and plunger, movement, of the shaped piston beyond a certain limit, is regenerative. Prior to that, it is degenerative (para 2.2.6. refers). When the middle portion of the plunger (10) is unlocked from the rear portion (13), the release spring (20) restraint on rotation of the speroid, will be removed. The spheroid will then be free to move, to the limits imposed by the slot and aperture, in the closed end of the cylindrical spheroid container (34). This movement is against the opposition of the relatively light return springs (8) (21).

2.2.2. Mechanical Release Unit (Fixed) (Fig. 2)

[0004] The Mechanical Release Unit (Fixed), is similar in its action to the Mechanical Release Unit described in para 2.2.1., in that release forces, acting on the retaining arms (39) and positioning leg (2), will cause the spheroid (3) to rotate. Because the plunger (4) is fixed, rotation of the spheroid can now only occur, by the spheroid and its container being displaced away from the plunger, by compressing the relatively light spheroid casing return spring (41). This displacement, will be transmitted through the ski-boot, to the Mechanical Release Unit, against its release spring. It will cause release of the constraint of this spring, either as described in para 2.2.1., para 2.2.4., or by the rotation of the spheroid, taking the fixed plunger (43) (4), outside the limit of the shaped recess (36).

2.2.3. Controls

[0005] There are two controls affecting release:

2.2.3.1. Release Spring Tension Control

[0006] The release spring (20) tension is set, by adjusting the retaining cap (24). Displacement of fluid due to adjustment, is taken up, by the compensating bag (29). This control is pre-set, according to the physical properties of the skier.

2.2.3.2. Rate Of Increase In Release Force Control

[0007] Control over the rate of increase in release force is set, by controlling the rate at which fluid can be displaced, by the piston part of the plunger (25), through the by-pass ports (17) (18). It is set by adjusting the position of the control rod (22), to set the by-pass dimensions according to the physical properties of the skier.

2.2.4. Manual Release

[0008] Mannual Release is achieved by sliding the release unit housing (47). The release unit housing is coupled to the piston (30), by the connecting rod (46) acting through the mounting block (5), the spring (8), and fluid seal (32). Sliding the housing will displace the piston (30), until the second shaped portion (50), allows the inserts to unlock the two concentric portions of the plunger from each other, and thus remove the release spring's influence on the spheroid's rotation. The spheroid can thus move the plunger, against the relatively light return spring (16), so that the retaining arms no longer retain the ski-boot.

2.2.4.1. The limit of movement of the Connecting Rod Mounting Block (5) is set by the dimensions of the slot (40) in the Fixed Base Unit (45) through which the-connecting rod passes. The slot dimensions are such that there is sufficient clearance to prevent fouling when the plunger is displaced by the spheroid.

2.2.4.2. The second shaped recess (37) in the spheroids, is so that, after release, the spheroids can remain in a position, suitable for reinserting a ski-boot.

2.2.4.3. The return springs (16) (21) (8), ensure that when a ski-boot is not in the binding, then the plunger and piston will adopt a position, which allows the two parts of the plunger to be locked together by the inserts (14).

2.2.4.4. After release in an upward direction, as when stepping out of the binding, the spheroid container return spring (41), by forcing the spheroid against the fixed plunger, will cause the second shaped recess to rotate the spheroid, to a position, suitable for reinsertion of the skiboot.

2.2.4.5. To minimize fluid loss, those moving parts in contact with the fluid, are isolated by seals (9) (32), which are compressed by the release and return springs.

2.2.5. Summary of Components

[0009] The Binding consists of a front and rear unit, at least one of which is a Mechanical Release Unit. The second unit is either a Mechanical Release Unit (Fixed), or another Mechanical Release Unit, depending on the experience of the skier.

[0010] 2.2.5.1. Either the Mechanical Release Unit, or the Mechanical Release Unit (Fixed), can be in the Front or Rear position.

2.2.5.2. Comoensatina Bag

[0011] The Compensating Bag is a non-permeable, elastic bag (29), filled with a permeable, sponge-like material (26), which will allow changes in pressure and volume inside the fluid container, to balance against atmospheric pressure. It is secured to the casing (49) by a grub scew (28) and washer (27) which are drilled to allow atmospheric compensation.

2.2.5.3. Comoensatina Ports

[0012] Compensating Ports (II) are drilled through applicable moving components to facilitate a free flow of fluid when these components move and to prevent seepage having a detrimental effect.

2.2.6. Resoonse of ShaDed Piston

2.2.6.1. Deaenerative Response

[0013] For combined positions of the control rod (22) and the shaped piston (30), where the dimensions of the by-pass are accumulatively increasing, the resulting increase in fluid flow, will tend to reduce the amount of movement of the shaped piston. This is a degenerative response.

2.2.6.2. Regenerative Response

[0014] For combined positions of the control rod (22) and the shaped piston (30), where the dimensions of the by-pass are accumulatively decreasing, the resulting decrease in fluid flow, will tend to increase the amount of movement of the shaped piston. This is a regenerative response.

2.2.7. Adjustments

[0015] 

2.2.7.1. The release spring tension control (para. 2.2.3.1. refers) is adjusted for a given depth of the retaining cap (24) in the housing (49), and is set according to physical properties of the skier, by using the adjusting sockets (23).

2.2.7.2. The rate of increase in release force control (para. 2.2.3.2. refers) sets the reluctance of the binding to release. It is adjusted by:

2.2.7.2.1. Applying pressure to the release spring and operating the manual release, by sliding the binding housing against the return springs until the resistance of the release spring is felt, and holding it there until the operation described in para. 2.2.7.2.2. is completed. This sets the extended rod (31) to a known reference position to facilitate setting the control rod (22) to give the required reluctance.

2.2.7.2.2. Screwing the control rod (22) in until it fouls the end of the extended rod (19). This sets the position at which the response is fully regenerative (para. 2.2.6.2. refers).

2.2.7.2.3. Unscrewing the control rod (22) from this position covers the complete range of response from fully regenerative to fully degenerative (para. 2.2.6.1. refers).

2.2.7.4. The control rod (22) is set according to the properties of the skier, and is set for a number of turns of the control rod from the fully regenerative position.

[0016] 3. Identification and Location of Item Numbers

Claims

1. A safety ski binding comprising front and rear binding units having retaining elements adapted to engage the prominent welt of a ski-boot, at least one of said binding units having a release mechanism adapted to release said retaining elements in response to the occurance of injurious forces acting on the ski-boot, said release mechanism comprising a piston arrangement (10, 13) mounted within a cylinder (49) and being coupled (38, 36, 4, 48) to the binding unit's retaining elements (39) in a manner so as to translate any movement of said retaining elements into an axial displacement of said piston arrangement against a restraining spring (20), said cylinder (49) including a liquid-filled cylinder chamber which is subdivided into two compartments, said two compartments being in flow communication with each other through a flow restrictor (22) of limited flow capacity, characterized in that said cylinder chamber is subdivided into said two compartments by a piston element (25) of said piston arrangement (10, 13), and said piston arrangement has two telescopic sections (10, 13) and a detent mechanism (14, 30, 8) associated thereto, said detent mechanism locking said two sections together and being hydraulically operable to unlock said two sections when a displacement of said piston arrangement (10, 13) causes the liquid pressure in the compartment behind said piston element (25) to exceed a predetermined value.

2. A safety ski binding as claimed in claim I, characterized in that said detent mechanism comprises a number of detent elements (14) for locking said two sections (10, 13) together and a locking member (30), said locking member being spring-biased (8) into a locking position retaining said detent elements in their locking engagement, and being hydraulically displaceable against its bias spring (8) into a position allowing said detent elements to move out of their locking engagement.

3. A safety ski binding as claimed in claim 2, characterized in that said detent elements are detent balls (14) and said locking member (30) is a piston having radial recesses (12) which are moved into register with the detent balls (14) when the locking member is displaced from its locking position so as to allow the detent balls to be radially displaced out of their locking engagement.

4. A safety ski binding as claimed in any of claims I to 3, characterized in that a compression spring (16) is located between said two sections (10, 13) so as to bias them into an elongated position.

5. A safety ski binding as claimed in any of claims I to 4, characterized in that said retaining elements (39) project from a spheroid (3) mounted for omnidirectional rotation and cooperating with said piston arrangement (10, 13) through a hemispherical piston head (4) bearing against a spherical recess (36) of said spheroid.

6. A safety ski binding as claimed in any of claims I to 5, characterized in that said cylinder (49) has an adjustable cap (24) serving as an adjustable support for said restraining spring (20).

7. A safety ski binding as claimed in any of claims I to 6, characterized in that said flow restrictor has an adjustable member (22) for varying its flow resistance.

8. A safety ski binding as claimed in any of claims I to 7, characterized in that the cylinder compartment in front of said piston element (25) has associated therewith an elastic compensating member (29) allowing for compensation of liquid volume variations.

9. A safety ski binding as claimed in any of claims I to 8, characterized in that said detent mechanism (30) is coupled (5, 35, 6, 8) to a manually operable member for manual release of the retaining means.

10. A safety ski binding as claimed in any of claims I to 9, characterized in that only one of said front and rear binding units includes a release mechanism, and that the other binding unit (fig. 2) has its retaining elements (39) coupled to a fixed member (42, 43) in a manner so as to translate any movement of said retaining elements into a displacement of said retaining elements towards said first-mentioned binding unit.

Ansprüche

1. Aus einer vorderen und einer hinteren Bindungsbaugruppe bestehende Sicherheitsskibindung, die mit so angepaßten Halteteilen ausgestattet ist, daß sie den hervorstehenden Randwulst eines Skistiefels umgreifen, wobei mindestens eine Bindungsbaugruppe einen Freigabemechanismus aufweist, der als Reaktion auf gesundheitsschädliche Kräfte, die auf den Skistiefel einwirken, die Halteteile freigibt, wobei der Freigabemechanismus eine Kolbenanordnung (10, 13) enthält und in einem Zylinder (49) angebracht und mit den Halteteilen (39) so verbunden ist (38, 36, 4, 48), daß jede Bewegung der Halteteile in eine axiale Bewegung der Kolbenanordnung gegen eine Druckfeder (20) umgewandelt wird, und wobei der Zylinder (49) eine mit Flüssigkeit gefüllte Zylinderkammer beinhaltet, die in zwei Kammern unterteilt ist, welche mit einem Flußbegrenzer (22) so verbunden sind, daß ein begrenzter Fluidstrom stattfinden kann, dadurch gekennzeichnet, daß die Zylinderkammer durch ein Kolbenelement (25) der Kolbenanordnung (10, 13) in zwei Kammern unterteilt ist, und die Kolbenanordnung zwei ausziehbare Glieder (10, 13) und eine Arretierungsvorrichtung (14,.30, 8) aufweist, wobei die Arretierung die beiden Glieder verrastet und hydraulisch im Sinne einer Entrastend betätigbar sind, wenn eine Bewegung der Kolbenanordnung (10, 13) den Flüssigkeitsdruck in der Kammer hinter dem Kolbenelement (25) über einen festgelegten Betrag hinaus ansteigen läßt.

2. Sicherheitsskibindung nach Anspruch 1, dadurch gekennzeichnet, daß die Arretierungseinrichtung aus mehreren Arretierungselementen (14) für die Verrastung der beiden Glieder (10, 13) und einem Raststab (30) besteht, der von einer Feder (8) belastet in einer verrasteten Lage verharrt und die Arretierungselemente in ihrer verrastenden Funktion beibehält, und hydraulisch gegen den Druck der Feder (8) in eine Lage bewegbar ist, die ein -Herausbewegen der Arretierungselemente aus ihrem verrasteten Zustand zuläßt.

3. Sicherheitsskibindung nach Anspruch 2, dadurch gekennzeichnet, daß die Arretierungselemente Kugeln (14) sind und der Raststab (30) ein Kolben ist, der runde Vertiefungen (12) aufweist, welche mit den Arretierungskugeln (14) genau zusammenpassen, wenn der Raststab aus seiner verrastenden Position weg bewegt wird, so daß die Arretierungskugeln aus ihrer verrastenden Lage radial herausrutschen.

4. Sicherheitsskibindung nach den Ansprüchen 1 bis 3, dadurch gekennzeichnet, daß eine Druckfeder (16) zwischen den beiden Gliedern (10, 13) angebracht ist, die die beiden Glieder auseinanderdrückt.

5. Sicherheitsskibindung nach den Ansprüchen 1 bis 4, dadurch gekennzeichnet, daß die aus einem Kugelkopf (3) herausragenden Halteteile (39) so angebracht sind, daß sie in alle Richtungen schwenkbar sind und mit der Kolbenanordnung (10, 13) mittels eines halbkugelförmigen Druckkolbenkopfes (4), der gegen die kugelförmige Vertiefung (36) des Kugelkopfes drückt, zusammenwirken.

6. Sicherheitsskibindung nach den Ansprüchen 1 bis 5, dadurch gekennzeichnet, daß der Zylinder (49) mit einem justierbaren Deckel (24) versehen ist, der als verstellbares Gegenlager der Druckfeder (20) dient.

7. Sicherheitsskibindung nach den Ansprüchen 1 bis 6, dadurch gekennzeichnet, daß der Durchflußbegrenzer zur Variierung des Strömungswiderstandes ein verstellbares Teil (22) aufweist.

8. Sicherheitsskibindung nach den Ansprüchen 1 bis 7, dadurch gekennzeichnet, daß der Zylinderkammer vor dem Kolbenelement (25) ein elastisches Ausgleichselement (29) zugeordnet ist, um den Ausgleich von Volumenänderungen der Flüssigkeit zu gestatten.

9. Sicherheitsskibindung nach den Ansprüchen 1 bis 8, dadurch gekennzeichnet, daß der Rastmechanismus (30) mit einem manuell zu betätigenden Element zur manuellen Freigabe der Halteteile verbunden (5, 35, 6, 8) ist.

10. Sicherheitsskibindung nach den Ansprüchen 1 bis 9, dadurch gekennzeichnet, daß nur eine der beiden (vordere und hintere) Bindungsbaugruppen einen Freigabemechanismus aufweist, und daß bei der anderen Bindungsbaugruppe die (Fig. 2) Halteteile (39) so mit einem festen Teil (42, 43) verbunden sind, daß jede Bewegung der Halteteile als eine Bewegung derselben in Richtung der erstgenannten Bindung erfolgt.

Revendications

1. Fixation de sécurité pour ski comprenant des blocs de fixation avant et arrière munis d'éléments de retenue conçus pour s'engager sur la trépointe proéminente d'une chaussure de ski, l'un au moins de ces blocs de fixation comportant un mécanisme de libération conçu pour libérer les éléments de retenue en réponse à l'apparition, sur la chaussure de ski, de forces risquant de provoquer des blessures, le mécanisme de libération comprenant un dispositif à piston (10, 13) monté à l'intérieur d'un cylindre (49) et couplé (38, 36, 4, 48) aux éléments de retenue (39) des blocs de fixation de manière à transformer tout mouvement de ces éléments de retenue en un déplacement axial du dispositif à piston, contre l'action d'un ressort de retenue (20), le cylindre (49) comprenant une chambre de cylindre remplie de liquide et subdivisée en deux compartiments, ces deux compartiments étant en communication de fluide l'un avec l'autre par l'intermédiaire d'un dispositif de restriction de débit (22) à capacité de débit limitée, caractérisé en ce que la chambre de cylindre est subdivisée en deux compartiments comme indiqué ci-dessus, par un élément de piston (25) du dispositif à piston (10, 13), et en ce que le dispositif à piston comporte deux parties télescopiques (10, 13) et un mécanisme de détente (14, 30, 8) associé à celles-ci, ce mécanisme de détente verrouillant les deux parties ensemble et pouvant être manoeuvré hydrauliquement pour déverrouiller les deux parties lorsqu'un déplacement du dispositif à piston (10, 13) amène la pression du liquide se trouvant dans le compartiment derrière l'élément de piston (25) à dépasser une valeur prédéterminée.

2. Fixation de sécurité pour ski selon la revendication 1, caractérisée en ce que le mécanisme de détente comprend un certain nombre d'éléments de détente (14) pour verrouiller les deux parties (10, 13) ensemble et un élément de verrouillage (30), cet élément de verrouillage étant poussé par un ressort (8) dans une position de verrouillage retenant les éléments de détente dans leur engagement de verrouillage, et cet élément de verrouillage pouvant être déplacé hydrauliquement, contre l'action de son ressort de poussée (8), pour venir dans une position permettant aux éléments de détente de sortir de leur engagement de verrouillage.

3. Fixation de sécurité pour ski selon la revendication 2, caractérisée en ce que les éléments de détente sont des billes de détente (14) et en ce que l'élément de verrouillage (30) est un piston muni de cavités radiales (12) déplacées pour venir en coïncidence avec les billes de détente (14) lorsque l'élément de verrouillage est écarté de sa position de verrouillage, pour permettre aux billes de détente d'être déplacées radialement de manière à sortir de leur engagement de verrouillage.

4. Fixation de sécurité pour ski selon l'une quelconque des revendications 1 à 3, caractérisée en ce qu'un ressort de compression (16) est placé entre les deux parties (10, 13) de manière à pousser celles-ci dans une position allongée.

5. Fixation de sécurité pour ski selon l'une quelconque des revendications 1 à 4, caractérisée en ce que les éléments de retenue (39) partent d'un sphéroïde (3) monté de manière à pouvoir effectuer une rotation omnidirectionnelle et coopérant avec le dispositif à piston (10, 13) par l'intermédiaire d'une tête de piston hémisphérique (4) venant s'appuyer contre une cavité sphérique (36) du sphéroïde.

6. Fixation de sécurité pour ski selon l'une quelconque des revendications 1 à 5, caractérisée en ce que le cylindre (49) comporte un capot réglable (24) servant de support réglable pour le ressort de retenue (20).

7. Fixation de sécurité pour ski selon l'une quelconque des revendications 1 à 6, caractérisée en ce que l'élément de restriction de débit comporte un élément réglable (22) permettant de faire varier sa résistance au débit.

8. Fixation de sécurité pour ski selon l'une quelconque des revendications 1 à 7, caractérisée en ce que le compartiment de cylindre se trouvant en face de l'élément de piston (25) comporte un élément de compensation élastique (29) associé à celui-ci pour permettre la compensation des variations de volume du liquide.

9. Fixation de sécurité pour ski selon l'une quelconque des revendications 1 à 8, caractérisée en ce que le mécanisme de détente (30) est couplé (5, 35, 6, 8) à un élément manoeuvrable manuellement les moyens de retenue.

10. Fixation de sécurité pour ski selon l'une quelconque des revendications 1 à 9, caractérisée en ce que l'un seulement des blocs de fixation avant et arrière comprend un mécanisme de libération, et en ce que les éléments de retenue (39) de l'autre bloc de fixation (figure 2) sont couplés à un élément fixe (42, 43) de manière à transformer tout mouvement des éléments de retenue en un déplacement de ces éléments de retenue vers le premier bloc de fixation indiqué ci-dessus.

Drawing