EP0058810B1 - Openable pulley block - Google Patents

Description

The present invention relates to a pulley or opening block, of the type comprising two load-bearing flanges, or two load-bearing fittings supplemented by two flanges, one of which simultaneously supports the axis of at least one sheave over which a cable passes. and, directly or through another part, a pivot axis carrying an opening part, such that the pivoting of this part around said axis allows the introduction of the cable or its release between the two flanges, while that a means of suspending the pulley or of the load, such as a hook, the axis of which passes substantially through the median plane of the sheave, is connected to one of the flanges indirectly by means of a part such that cross with nipples, this cross being located, with respect to the axis of the sheave, on the same side as the opening axis of the pulley or the block, the hook being connected to the opening part and not to the bearing flange the sheave, therefore pivoting with this opening part relative to the flange which carries the sheave, so that the tensile force that a load exerts via the cable on the sheave creates couples whose effect is to close inoperatively the opening part of the pulley / block if it was opened.

An opening pulley of this kind is known from document US-A-2 723 834. The principle is advantageous from the point of view of safety of use, because the weight that a load exerts via the cable tends to close the opening part automatically. However, the embodiment described by the document cited above remains imperfect in practical terms. Indeed, the opening part, connected to the hook, is constituted by an arm mounted to pivot about an axis parallel to the axis of the sheave, which is inserted between two flanges which remain permanently parallel to each other. This structure requires a significant pivoting of the opening part, of the order of 90 °, to obtain a relatively narrow free passage allowing the introduction of the cable. In addition, no means is provided to then keep the pulley in the open position, in particular when the latter remains suspended by its hook. To be able to insert the cable, the operator must maintain the opening part manually in the raised position; he therefore has only one free hand to introduce the cable and put it in place on the sheave and he must possibly be helped by another person if, due to the weight, he cannot hold the opening part with one hand. Furthermore, if the presence of a load effectively causes the opening part to close if it was open, on the other hand in the closed position, the load does not cause any torque on the opening part tending to keep the pulley in place. closed position.

Furthermore, for example, from document US-A-2 235 302, opening pulleys are known in which the opening part is constituted by one of the flanges or by a part of one of the flanges, pivotally mounted around a direction axis perpendicular to the axis of the sheave, and offset with respect to the median plane of the sheave. The axis of this sheave is integral with the non-opening flange, also connected to the hook. This construction method makes it possible to obtain, with a limited pivoting of the opening part, a relatively wide opening of the pulley for the introduction of the cable. However, even in the case of locking means in the closed position, it does not provide absolute security: in the event of forgetting to close and lock, or in the event of failure of these locking means, the flanges tend to be moved away under the effect of the load, hence the risk of opening, cable exit, falling of the load, etc. On the other hand, like the opening pulleys of the kind previously considered, these opening flange pulleys do not include any means making it possible to keep the pulley in the open position, in particular when the latter is suspended, to facilitate the introduction of the cable.

The present invention aims to remedy all the drawbacks described above, by providing a pulley or an improved opening block, which closes automatically and is kept closed under the effect of a load, but can also be kept wide open by itself. in particular by remaining suspended, after removal of the traction due to the load, so that the operator can use both hands to introduce or remove the cable.

To this end, the invention relates to an opening pulley or block belonging to the genus indicated in the introduction, in which the opening part connected to the hook, constituted by that of the flanges not carrying the sheave, has its pivot axis oriented perpendicularly to the axis of the sheave and offset from the median plane of the sheave, so that the tensile force exerted by a carge not only causes the pulley / block to close by bringing its two flanges together, but also to maintain that in the closed position throughout the duration of application of the force due to the load, means being provided to keep the two flanges apart from one another in the absence of force due to the load, without opposing the closing of the pulley / block under the effect of the load. The pulley can thus be temporarily held in the open position, at a relatively small angle but sufficient for the introduction of the cable, without manual intervention.

The arrangement here adopted implies that the axis of the hook, connected to one of the two flanges, forms a certain angle with the median plane of the sheave, when the flanges are separated, that is to say the open pulley; the presence of a load results in a traction which tends to cancel this angle, that is to say, to confuse the axis of the hook in the median plane of the sheave, therefore to bring the pulley in its closed position. In addition, the offset of the pivoting axis of the opening flange makes it possible to keep, in the closed position therefore when the two flanges are parallel, a certain torque which keeps the pulley / block in this closed position, even in the absence of any lock.

• Une première solution consiste à prévoir des moyens à butée, limitant l'angle de pivotement de l'ensemble »flasque ne portant pas le réa + crochet« par rapport à l'ensemble »flasque non lié au crochet+réa«, dans le sens de la fermeture de la poulie/moufle sous l'effet d'une charge, de telle sorte que l'appui d'un ensemble sur l'autre n'engendre pas d'efforts de flexion que les pièces ne pourraient supporter, ces moyens à butée ayant aussi pour effet de supprimer, dans la position fermée de la poulie/moufle, la transmission de l'effort dû à la charge par l'intermédiaire de l'axe de pivotement. Il en résulte que cet axe, n'étant plus porteur de la charge mais seulement accessoire pour permettre l'ouverture de la poulie, peut être sensiblement réduit en diamètre.

Torques of forces, which tend to bring the flanges together and keep the pulley in the closed position, also have the effect, when one flange rests on the other via the axis of the sheave or any other way, to tend to flex the flanges and other parts subject to these couples. These bending effects are variable, depending on the distances between the flanges, the hook axis and the pivot axis of the movable flange, and the invention also provides means making it possible to limit or avoid such bending, if this is necessary:

• A first solution consists in providing stop means, limiting the pivoting angle of the assembly "flange not carrying the sheave + hook" relative to the whole "flange not linked to the hook + sheave", in the direction closing the pulley / block under the effect of a load, so that the support of one assembly on the other does not generate bending forces that the parts could not support, these means with a stop also having the effect of eliminating, in the closed position of the pulley / block, the transmission of the force due to the load via the pivot axis. As a result, this axis, no longer carrying the load but only accessory to allow the opening of the pulley, can be significantly reduced in diameter.

If it is an opening pulley in which a transverse block linked to the hook forms one with one of the flanges, the support in the closed position can be produced between, on the one hand, a face of said transverse block which is secured to the flange not carrying the sheave, and on the other hand, at least one lug secured to the flange which carries the sheave.

If it is an opening pulley in which one of the flanges is linked to a hook-carrying cross-member, the abovementioned abutment means may result from the fact that said cross-member, linked to the flange not carrying the sheave, has a stud engaged in a lumen of the flange which carries the sheave, so that in the closed position of the pulley / block, the support is produced between this stud and the edge of the light, the pivot axis passing through or well through the cross itself, or through the flange not carrying the sheave and linked to said cross.

To completely avoid the bending forces in the closed position, said abutment means require a precise adjustment, which can however be avoided by making, with a certain flexibility in a transverse plane, the connection between the stud cross member, therefore the hook. , and the flange not carrying the sheave, for example by making this connection by means of a nut placed at the end of one of the nipples and pressing at least one elastic washer against the flange not carrying the sheave, or against the bearing hardware of this flange. Alternatively, it is the connection between the pivot axis and the flange carrying the sheave which is produced with a certain flexibility, by means of a yoke whose mounting on said flange uses for example at least one elastic washer interposed between these two elements and held by tightening a nut. By providing such flexible connections, in particular by the use of elastic washers, it is obtained that the forces of the couples liable to cause the bending of the flanges / fittings will press the elastic washers and allow a certain modification of the angle, substantially straight, formed either by the flange not carrying the sheave with the cross member, or by the flange carrying the sheave with the yoke carrying the hinge pin for opening the pulley. It is this slight modification of the angle considered which makes it possible to avoid bending of the flanges / fittings.

According to another characteristic of the invention, in order to facilitate the operations of entering and leaving the cable using two hands, spring means are provided to keep the two flanges apart from one another. , or to bring the two flanges in the separated position and keep them there, until the tensile force exerted by the weight of the cable and / or the load, or the weight of the device resting on the cable and / or of the load, becomes greater than the resistance of said spring means.

• - d'un ressort fixé sur la flasque liée au crochet et comportant une partie incurvée coopérant avec l'extrémité libre de l'axe du réa, porté par l'autre flasque, extrémité sur laquelle sont ménagées une rampe et une gorge aptes à recevoir la partie incurvée dudit ressort;
• - ou d'un cliquet monté pivotant sur la flasque liée au crochet, ce cliquet étant soumis à l'action d'un ressort et coopérant avec l'extrémité libre de l'axe du réa, porté par l'autre flasque, extrémité sur laquelle sont ménagées une rampe et une gorge aptes à recevoir ledit cliquet.

Preferably, other spring means are also provided to ensure automatic locking when closing the pulley / block under the effect of a load, these means requiring manual unlocking to allow the opening of the pulley / muffle. These locking means prevent the opening of the pulley from occurring as soon as the load is removed, if the first spring means are designed to bring the flaccid ones into the separated position and keep them there, or accidentally under the effect of '' involuntary external action. The opening of the pulley by spacing the two flanges can only be done after manual unlocking, by the operator. On the other hand, said locking means are designed to be put in place automatically, when the pulley is closed under the effect of a load. They can be constituted, in particular, in the form:

• - A spring fixed on the flange linked to the hook and comprising a curved part cooperating with the free end of the axis of the sheave, carried by the other flange, end on which are formed a ramp and a groove capable of receiving the curved part of said spring;
• - Or a pawl mounted pivoting on the flange linked to the hook, this pawl being subjected to the action of a spring and cooperating with the free end of the sheave axis, carried by the other flange, end on which are mena a ramp and a groove adapted to receive said pawl.

• Si les moyens de verrouillage automatique et de déverrouillage manuel sont détériorés, l'appareil peut s'ouvrir par exemple lorsqu'il a posé une charge sur le sol et, éventuellement, le câble risque de sortir de la gorge du réa et de tomber au moment où l'opérateur s'apprête à remonter la charge. Ainsi le choix d'une ouverture automatique ne présente pas une sécurité totale, notamment en cas de traction oblique lorsque la tension du câble devient très faible, et si les moyens de verrouillage ne sont pas d'une fiabilité absolue et sont susceptibles de devenir défectueux.

As for the first spring means, according to one embodiment of the invention, they consist of an opening spring, in particular wound around the axis by which the two flanges are articulated and bearing on these two flanges, so to tend to spread them and keep them in the spread position, until voluntary manual or automatic closing under the effect of a load. This spring therefore ensures automatic opening of the pulley, after removal of the load and after manual unlocking, in the case where locking means in the closed position are provided. This version of the device which is the subject of the invention therefore comprises both an automatic closure and locking under the effect of the load, and an automatic opening under the action of a spring, after the load has been canceled and manual unlocking; a disadvantage is however the following:

• If the automatic locking and manual unlocking means are damaged, the device can open for example when it has placed a load on the ground and, possibly, the cable may come out of the sheave of the sheave and fall to the when the operator is about to raise the load. Thus the choice of an automatic opening does not present total security, in particular in the case of oblique traction when the cable tension becomes very low, and if the locking means are not of absolute reliability and are liable to become defective. .

This drawback is eliminated in another embodiment of the invention, no longer comprising a spring to ensure both automatic opening and keeping in the open position, but in which a spring is provided, carried by one of the flanges, such as that carrying the sheave, or by an element integral with this flange, and able to snap onto an element integral with the other flange, such as that linked directly or indirectly to the hook, when the two flanges are separated one from the other, to maintain the two flanges in this separated position, until voluntary manual or automatic closing under the effect of a load. In this other version, which may or may not include means for automatically locking the closure with manual unlocking, the automatic closing of the pulley is guaranteed by the traction force, according to the basic idea of the invention, even if operator failed to close device; the latter is made perfectly safe, and the invention thus provides a high security opening pulley, as it does not currently exist. In this case, the effort to be exerted will be greater to open the pulley until the spring engages, especially if a cable of a certain weight is engaged in the groove of the sheave, but the effort to be provided remains reasonable, while at least for devices with common capacities.

• - selon une première possibilité, il s'agit d'un ressort profilé, porté par l'une des flasques, telle que celle portant le réa, et permettant l'enclenchement d'un téton solidaire de l'autre flasque, telle que celle liée au crochet, lorsque les deux flasques sont écartées l'une de l'autre.
• - selon une deuxième possibilité, il s'agit d'un ressort en forme d'étrier, dont les extrémités sont liées à deux oreilles elles-mêmes liées à la flasque portant le réa et formant une chape sur laquelle est montée pivotante l'autre flasque liée au crochet, la partie médiane dudit ressort en forme d'étrier étant engageable dans une gorge annulaire de l'écrou de retenue du crochet, lorsque les deux flasques sont écartées l'une de l'autre.

Various forms can be given to the spring whose function is to maintain the flanges in the separated position:

• - According to a first possibility, it is a profiled spring, carried by one of the flanges, such as that carrying the sheave, and allowing the engagement of a stud secured to the other flange, such as that linked to the hook, when the two flanges are spaced from each other.
• - According to a second possibility, it is a caliper-shaped spring, the ends of which are linked to two ears themselves linked to the flange carrying the sheave and forming a yoke on which the other is pivotally mounted. flange linked to the hook, the middle part of said stirrup-shaped spring being able to be engaged in an annular groove of the hook retaining nut, when the two flanges are spaced from one another.

Advantageously, in the case of a pulley with a hook-carrying cross member, and when the pivot axis passes through the cross member, the stud of the latter, engaged in a slot in the flange and / or the fitting carrying the sheave, constitutes also the stud which, in the open position, engages in the profiled spring, if this kind of spring is envisaged to keep the flanges apart from one another. In the case where the pivot axis crosses the upper part of the flange or the fitting, the already-mentioned caliper-shaped spring, supported by the hook retaining nut, may be preferable.

In all the embodiments defined above, the spring means which keep the two flanges apart from one another, in the open position of the pulley / block, and the spring means which ensure the automatic locking when closing the pulley / block under the effect of a load, are designed as two entirely separate devices, which must be added one and the other on the basic elements that the pulley / block opening. This results in a certain complexity of production, resulting in particular in a multiplication of parts such as pins and springs, or machining such as those necessary for the production of the various grooves previously mentioned. The present invention also provides other embodiments, comprising a constructive simplification and in particular limiting the number of complicated and subject to wear parts, thanks to a single and simple device, capable of ensuring alone the functions of automatic locking of the pulley / block in the closed position, manual opening of the lock and, by continuity of movement, opening of the flange and then maintaining it in the open position, without opposing the automatic closing of said pulley / block from the open position by a progressive movement, the whole always ensuring a safety of use when a load is applied quée according to the fundamental characteristic of the invention.

To this end, the means provided, on the one hand, for keeping the two flanges apart from one another and, on the other hand, for ensuring automatic locking during closing are constituted by a single pawl mounted pivotally on the flange or its supporting fitting linked to the hook and not carrying the sheave, said pawl, subjected to the action of a spring tending to rotate it in a determined direction, capable of cooperating on the one hand, in the closed position of the pulley / block, with a complementary housing of an element integral with the flange carrying the sheave, and on the other hand, in the open position of the pulley / block, with a bearing surface belonging to this element integral with the flange carrying the sheave, said bearing surface and / or the part of the pawl which cooperates with this surface forming a ramp or a cam which allows, during the application of a load, the sliding of one on the other against the action of the aforementioned jurisdiction, in the sense of bringing together of ix flanges of the pulley / block.

Thus the same pawl pivotally mounted on one of the flanges, and possibly the same part of this pawl, ensures on the one hand the locking when the pulley / block is closed, by cooperating with an element integral with the other flange and placed then in a first position relative to the pawl, and on the other hand the retainer in the open position (without locking but by obtaining a certain sufficiently stable equilibrium), always cooperating with the same element, then placed in a second position relative. The spring also remains unique in this device.

According to one embodiment, the pawl is pivotally mounted on the flange or its supporting fitting linked to the hook and does not carry the sheave along an axis parallel to the pivot axis of said flange, and this pawl, which the aforementioned spring tends to be brought closer to said flange, comprises on the one hand a lever making it possible to move it away from said flange against the action of the spring, and on the other hand a finger capable of cooperating either with a housing or with a boss with curved profile, both belonging to an element integral with the flange carrying the sheave. This element is advantageously constituted by one of the arms of a yoke integral with the flange carrying the sheave and supporting the axis of articulation of the other flange, in which case no additional part is necessary: it suffices to give at one of the edges of this clevis arm a special profile, with a recess which constitutes the housing of the pawl finger in the locked closed position, and with a boss on which the same pawl finger rests, in the open position of the pulley / block.

According to another embodiment, the pawl is pivotally mounted on the flange or its bearing fitting linked to the hook and does not carry the sheave along an axis perpendicular to the plane of said flange, and this pawl comprises on the one hand an operating lever , and on the other hand a head of at least partially conical shape, while the complementary element integral with the flange carrying the sheave has a part folded parallel to the latter flange, so that the head of the pawl can either be engage between said folded part and the flange or its bearing fitting linked to the hook, the aforementioned spring tending to maintain the pawl in this position, or bear externally against said folded part by its conical surface. This folded part is advantageously constituted by a bent extension at right angles to one of the arms of a yoke integral with the flange carrying the sheave and supporting the axis of articulation of the other flange. In the closed position of the pulley / block, the pawl head, interposed between the opening flange and the bent extension of the clevis arm, and held by the spring in this arrangement, prevents any separation of the two flanges. In the open position of the pulley / block, the support of the ratchet head against the bent extension of the yoke arm maintains this position, while the conical shape of said head allows it to slide on its bearing surface when closing the pulley / block.

• Figure 1 est une vue de côté très schématique, avec coupe partielle, rappelant le principe d'une poulie ouvrante connue, avec indication de la position ouverte;
• Figure 2 est une vue de face très schématique, correspondant à la poulie connue de figure 1 mais aussi aux poulies selon l'invention des figures suivantes;
• Figure 3 est une vue de côté très schématique, montrant une autre poulie ouvrante connue;
• Figure 4 est une vue de côté très schématique, avec coupe partielle, illustrant le principe de la poulie ouvrante selon l'invention;
• Figure 5 est une schéma de principe similaire à figure 4, montrant une première réalisation des moyens à butée limitant l'angle de pivotement de l'ensemble »flasque ne portant pas le réa+crochet«, avec indication de la position ouverte;
• Figure 6 est un schéma de principe similaire aux précédents, montrant une seconde réalisation desdits moyens à butée;
• Figure 7 est une vue de côté d'une forme d'exécution de la poulie ouvrante selon l'invention représentée de façon détaillée, avec un cliquet monté pivotant suivant un axe parallèle à l'axe d'articulation des deux flasques, en position fermée et verrouillée par ce cliquet;
• Figure 8 est une vue similaire à figure 7, mais représentant la position ouverte, dans laquelle le même cliquet maintient les deux flasques écartées l'une de l'autre;
• Figure 9 est une vue de face, en position fermée, de la poulie ouvrante des figures 7 et 8;
• Figure 10 est une vue de côté d'une autre forme d'exécution, avec un cliquet monté pivotant suivant un axe perpendiculaire au plan de la flasque liée au crochet, en position fermée et verrouillée par ce cliquet, et aussi avec indication partielle de la position ouverte dans laquelle le même cliquet maintient les deux flasques écartées l'une de l'autre;
• Figure 11 est une vue de face de la poulie ouvrante de figure 10;
• Figure 12 est une vue partielle en coupe, suivant 12-12 de figure 11;
• Figure 13 représente, en perspective, le cliquet seul de la forme d'exécution selon les figures 10 à 12;
• Figure 14 est une vue de face détaillée d'une poulie ouvrante selon l'invention, munie d'un ressort apte à maintenir les deux flasques écartées l'une de l'autre;
• Figure 15 est une vue de côté de la poulie selon la figure 14, représentée en position ouverte;
• Figure 16 est une vue de face détaillée d'une poulie ouvrante selon l'invention, munie d'un ressort apte à amener les deux flasques en position écartée et à les y maintenir;
• Figure 17 est une vue en coupe verticale, suivant 17-17 de figure 16;
• Figure 18 est une vue de côté de la poulie selon les figures 16 et 17 représentée en position ouverte;
• Figures 19, 20 et 21 sont des vues de côté très schématiques, avec coupes partielles, illustrant le principe des poulies ouvrantes selon l'invention incluant une liaison souple pour éviter les efforts de flexion en position fermée;
• Figure 22 est une vue de face détaillée d'une poulie ouvrante munie d'une telle liaison souple, entre la traverse porte-crochet et la flasque ne portant pas le réa;
• Figure 23 est une vue en coupe verticale, suivant 23-23 de figure 22;
• Figure 24 est une vue en coupe horizontale, à échelle agrandie, suivant 24-24 de figure 22;
• Figure 25 est une vue en coupe verticale similaire à figure 23, mais en position ouverte;
• Figure 26 est une vue de face détaillée d'une poulie ouvrante, consituant une variante des figures précédentes;
• Figure 27 est une vue en plan par dessus de la poulie de figure 26, sans son crochet et sans sa partie inférieure;
• Figure 28 en est vue en coupe verticale, suivant 28-28 de figure 26;
• Figure 29 en est une vue partielle, suivant la flèche F de figure 28;
• Figure 30 est une vue en coupe verticale similaire à figure 28, mais en position ouverte.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing which illustrates the principle thereof and which represents, by way of nonlimiting examples, some embodiments of this pulley opening:

• Figure 1 is a very schematic side view, with partial section, recalling the principle of a known opening pulley, with indication of the open position;
• Figure 2 is a very schematic front view, corresponding to the known pulley of Figure 1 but also to the pulleys according to the invention of the following figures;
• Figure 3 is a very schematic side view showing another known opening pulley;
• Figure 4 is a very schematic side view, with partial section, illustrating the principle of the opening pulley according to the invention;
• Figure 5 is a block diagram similar to Figure 4, showing a first embodiment of the stop means limiting the pivot angle of the assembly "flange not carrying the sheave + hook", with indication of the open position;
• Figure 6 is a block diagram similar to the previous, showing a second embodiment of said stop means;
• Figure 7 is a side view of an embodiment of the opening pulley according to the invention shown in detail, with a pawl mounted pivotally along an axis parallel to the axis of articulation of the two flanges, in the closed position and locked by this ratchet;
• Figure 8 is a view similar to Figure 7, but showing the open position, in which the same pawl keeps the two flanges apart from one another;
• Figure 9 is a front view, in the closed position, of the opening pulley of Figures 7 and 8;
• Figure 10 is a side view of another embodiment, with a pawl mounted pivoting along an axis perpendicular to the plane of the flange connected to the hook, in the closed position and locked by this pawl, and also with partial indication of the open position in which the same pawl keeps the two flanges apart from one another;
• Figure 11 is a front view of the opening pulley of Figure 10;
• Figure 12 is a partial sectional view along 12-12 of Figure 11;
• Figure 13 shows, in perspective, the pawl alone of the embodiment according to Figures 10 to 12;
• Figure 14 is a detailed front view of an opening pulley according to the invention, provided with a spring capable of holding the two flanges apart from one another;
• Figure 15 is a side view of the pulley according to Figure 14, shown in the open position;
• Figure 16 is a detailed front view of an opening pulley according to the invention, provided with a spring adapted to bring the two flanges in the separated position and to keep them there;
• Figure 17 is a vertical sectional view along line 17-17 of Figure 16;
• Figure 18 is a side view of the pulley according to Figures 16 and 17 shown in the open position;
• Figures 19, 20 and 21 are very schematic side views, with partial sections, illustrating the principle of the opening pulleys according to the invention including a flexible connection to avoid bending forces in the closed position;
• Figure 22 is a detailed front view of an opening pulley provided with such a flexible connection, between the hook-carrying cross member and the flange not carrying the sheave;
• Figure 23 is a vertical sectional view along line 23-23 of Figure 22;
• Figure 24 is a horizontal sectional view, on an enlarged scale, along 24-24 of Figure 22;
• Figure 25 is a vertical sectional view similar to Figure 23, but in the open position;
• Figure 26 is a detailed front view of an opening pulley, constituting a variant of the previous figures;
• Figure 27 is a plan view from above of the pulley of Figure 26, without its hook and without its lower part;
• Figure 28 is a vertical section view along 28-28 of Figure 26;
• Figure 29 is a partial view, along arrow F of Figure 28;
• Figure 30 is a vertical sectional view similar to Figure 28, but in the open position.

The known opening pulley, the principle of which is recalled by FIGS. 1 and 2, generally comprises: a sheave 1 in the groove of which passes a cable 2, two carrying flanges 3 and 4, and a hook 5. The sheave 1 is mounted rotating on an axis 6 fixed, by means of a nut 7, to the flange 3, the upper part of which is integral with the hook 5. This upper part of the flange 3 is further extended by two ears 8 which form a sort of yoke supporting an axis 9, in a direction perpendicular to the axis 7 of the sheave 1. The second flange 4 is pivotally mounted, by its upper part, around the axis 9, to allow the opening of the pulley (position indicated in lines mixed in Figure 1).

As shown in Figure 2, the flange 4 can be mounted on a support fitting 10, in which case it is the upper part of the fitting 10 which is crossed by the axis 9. In the closed position, the two flanges 3 and 4 being parallel, and the axis 6 passing through an opening of the flange 4, the pulley is locked by a spring 11, carried by the fitting 10 and / or the flange 4, and engaged in a groove 12 produced near the free end of the axis 6, which has a frustoconical conformation 13 constituting a ramp for the engagement of the spring 11.

FIG. 3 shows another known opening pulley, in which the bearing fitting 14 of the flange 3 carrying the sheave 1 has its upper part linked to the hook 5 indirectly, that is to say by means of a cross member 15, one end of which, shaped as a stud or a journal, is linked to the flange 3. The other end of the cross member 15 is linked to an intermediate piece 16, supporting the pin 9 on which the carrier fitting 10 is pivotally mounted flange 4.

Whatever their details of execution, the known opening pulleys, described above, have their hook 5 secured, directly or indirectly, with the flange 3 which carries the sheave 1. As a result, in the unlocked position, or in the event of failure of the locking means 11-12, the flanges 3 and 4 can deviate.

On the contrary, in the opening pulley object of the invention, the principle of which is illustrated by FIG. 4 (where the corresponding parts keep the same references as previously), the hook 5 is connected to the flange 4 which does not carry the sheave 1, therefore pivots around the axis 9 with this flange 4 (see also the line in phantom in Figure 5). It follows that the tensile force f, which a load exerts via the cable 2, tends to bring the flanges 3 and 4 together, therefore tends to close the pulley or to maintain it closed.

The hook 5 can be fixed, as shown in FIGS. 4 and 5, to a transverse block 17 which laterally extends the upper part of the flange 4 (or of its possible supporting fitting 10). The axis 9 can in this case pass through said block 17, as well as the two ears 8 integral with the flange 3. In the fully closed position, one or two lugs 18, which comprise the ears 8 or the flange 3, serve as a stop for the transverse block 17 (see FIG. 5), therefore limit the pivot angle of the assembly "flange 4 + hook 5".

Figure 6 shows, in principle, another embodiment of the opening pulley object of the invention, with a cross member 15 carrying the cross chet 5, according to the design already mentioned with reference to FIG. 3. The flange 4 not carrying the sheave 1 is linked to one end of the cross-member 15, so that this flange 4 will pivot with the hook 5 around the axis 9, which as shown can pass through the crossbar 15. To produce stop means equivalent to the lugs 18 of FIG. 5, the crossbar 15 here comprises, at its end remote from the flange 4, a lug 19 engaged in a slot 20 of the flange 3 which carries the sheave 1. In the closed position, the lug 19 comes to bear against the upper edge of the lumen 20.

Figures 7, 8 and 9 show, in detail, a first embodiment of an opening pulley closing and keeping itself closed under the effect of the load, according to the principle explained above, the two flanges 3 and 4 being here mounted respectively on load-bearing fittings 14 and 10. The fitting 14 secured to the flange 3 supports, at its top, a yoke formed by two parallel arms 8, which are for example welded to said fitting and which support an axis 9, on which is articulated the fitting 10 secured to the other flange 4. The hook 5 is here attached to a cross member 15 which laterally extends the upper part of the fitting 10, and which comprises a lug 19 cooperating with a slot 20 in the fitting 14.

According to the particularity of the embodiment of FIGS. 7 to 9, the fitting 10 of the flange 4 linked to the hook 5 has a lateral recess 52, at the level of which is pivotally mounted, around an axis 53 parallel to the axis pivoting 9 of the flange 4, a pawl designated as a whole by the reference 54. Around the axis 53 is also wound a spiral spring 55, the ends of which rest on one of the flange 4, the other on the pawl 54, so that this spring 55 tends to bring the pawl 54 closer to the flange 4.

The pawl 54 comprises an operating lever 56, extending approximately along a vertical edge of the fitting 10 and making it possible to separate said pawl 54 from the flange 4, against the action of the spring 55. For that the lever 56 can be grasped easily, it has a curved free end, located at the level of a recess 57 of the fitting 10. The pawl 54 also comprises a branch which forms substantially a right angle with the lever 56 and which comprises a locking finger 58 turned upwards.

The finger 58 is located opposite the lower edge of one of the yoke arms 8, the edge which comprises on the one hand by a recess 59 complementary to the finger 58, on the other by a boss 60 with a curved profile.

In the closed position of the pulley (see FIG. 7), the pawl 54 has its lever 56 parallel to the flange 4 and to the fitting 10, while its finger 58 is inserted into the recesses 59 of the clevis arm 8. This engagement finger 58 in the housing that constitutes the recess 59 is held by the spring 55, and a real locking in the closed position is therefore achieved.

To open the pulley, and therefore to move aside the flange 4 from the flange 3, the lever 56 of the pawl 54 must first be pulled to the position indicated in dashed lines in FIG. 7, position which allows the finger 58 to come out completely from the housing 59 and coming into contact with the boss 60. The pulling movement of the lever 56, being continued in the same direction, allows by continuity to open the pulley, by pivoting the flange 4 around the axis 9 .

Once this flange 4 is moved away from the flange 3, the lever 56 of the pawl 54 is released. As shown in FIG. 8, the finger 58 of the pawl 54 then comes into contact with the edge of the boss 60 in its part remote from the recess 59. The system then remains in equilibrium, by the action of the spring 55; the pulley is thus kept in the open position.

In the event of application of a force tending to close the pulley, and acting either on the flange 4 (manual closing force), or on the sheave 1 (automatic closing force by the weight of a load), the action of the spring 55 is overcome. The finger 58 of the pawl 54 slides along the edge of the boss 60 of the yoke arm 8 and "drops" finally into the housing 59, which causes the automatic resetting of the lock when the closed position is reached.

In the embodiment according to FIGS. 10 to 13, the pawl 54a is pivotally mounted, on the assembly constituted by the flange 4 and its supporting fitting 10, around an axis 53a which is perpendicular to the plane of the flange 4 , and offset laterally relative to the axis of symmetry of this flange 4. A spring 55a, shown partially, is wound in a spiral around the axis 53a, while its ends are supported one on an edge of the fitting 10 and the other on the pawl 54a.

This pawl 54a comprises an operating lever 56a, turned downwards, and its upper part forms a head 58a having a conical surface, the conformation of said pawl 54a being clearly visible in FIG. 13.

One of the yoke arms 8 has an extension 60a bent at a right angle and thus coming in front of the fitting 10. In the closed position of the pulley, the extension 60a is parallel to the fitting 10 and to the flange 4, and the distance which separates said extension 60a from the fitting 10 corresponds substantially to the thickness of the head 58a of the pawl 54a.

Thus, in the closed position of the pulley, the head 58 of the pawl 54a is introduced into the housing 59a of corresponding dimension delimited: by a part of the clevis arm 8 considered, by the extension 60a of this arm, and by the external face of the fitting 10. The spring 55a acts on the pawl 54a in the direction of engagement and maintenance of the head 58a in the housing 59a, and the presence of the head 58a in the housing 59a prevents any separation of the two flanges 3 and 4, so that the locking in the closed position is achieved.

To open the pulley, therefore to separate the flange 4 from the flange 3, the lever 56a of the pawl 54a is pushed to the position indicated in phantom in Figure 10; this movement releases the head 58a from the pawl 54a, bringing it below the bent extension 60a therefore out of the housing 59a. The locking being thus removed, the pulley can be opened, by pivoting the flange 4 around the axis 9.

Once the pulley is open, the lever 56a of the pawl 54a is released. As shown in the dashed line in FIG. 10, the head 58a of the pawl 54a then comes into contact with the lower edge of the bent extension 60a of the clevis arm 8, and the system remains in equilibrium by the combined action of the spring 55a and the taper of the head 58a of the pawl 54a.

In the event of application of a force tending to close the pulley, the action of the spring 55a is overcome. The conical surface of the head 58a of the pawl 54a slides on the lower edge of the bent extension 60a of the clevis bracket 8, finally causing the automatic resetting of the locking.

Figures 14 and 15 show, in detail, another embodiment of an opening pulley according to the invention, in which it is a spring 21, in the form of a profiled blade, which keeps the pulley open when the two flanges 3 and 4 have been separated, at the same time as the corresponding fittings 14 and 10. The two ends of the spring 21 are fixed by means of members 22 such as screws or rivets between the two ears 8 forming the yoke located at the top of the fitting 14 which carries the flange 3 and the sheave 1. The other fitting 10, carrying the hook 5, has its upper transverse block 17 provided with a stud 23 intended to be engaged in the spring 21.

A certain manual effort must be exerted to open the pulley, by pivoting the fitting 10 around the axis 9, and to engage the stud 23 in the spring 21. This effort is weakest when the apparatus rests on the ground. , because the operator does not have to overcome the weight of the device and the cable 2.

Locking in the closed position of the pulley according to FIGS. 14 and 15 is ensured by another spring 11, made of steel wire, fixed by a rivet 24 on the fitting 10 and on the flange 4. This spring 11 comprises a curved part , able to automatically engage in the groove 12 of the axis 6, after "mounted" on the frustoconical end 13 of this axis 6. Two stops 25 and 26 position the spring 11 so that it occurs correctly at the end of axis 6, when closing the pulley.

In addition to the opening 27 of the flange 4 and the fitting 10 which allows the passage of the axis 6 in the closed position, the same parts are here pierced, in their lower part, with an additional opening 28 receiving in position closed the free end of an axle 29 which carries a becket 30 and which is fixed to the lower part of the flange 3 and of the fitting 14.

FIGS. 16 to 18 relate to another embodiment, where the two flanges 3 and 4 are devoid of bearing fittings, but which is distinguished above all by the fact that a spring 31 is mounted so as not only to keep the pulley open, but also to bring the two flanges 3 and 4 in the separated position, after unlocking.

The spring 31 is wound around the axis 9 by which the two flanges 3 and 4 are articulated, and it bears against the interior faces of these dermières, by acting in the direction of their spacing, therefore in the direction of the opening of the pulley.

• a) Le ressort 31 peut être choisi suffisamment fort pour que la flasque 4 s'écarte d'elle-même, après déverrouillage manuel, lorsque la charge ne correspond qu'au poids du câble 2 qu'un homme peut soulever à deux mains. La poulie restant ouverte, l'opérateur aura les deux mains libres pour soulever le câbles 2, ou pour remettre ce câble ou un autre câble dans la gorge du réa 1.
• b) On peut aussi concevoir, avec un ressort d'ouverture automatique 31 légèrement plus faible, que sous le seul poids du câble 2 la poulie, même déverrouillée, reste fermée, et qu'elle ne s'ouvre que si le câble 2 a été soulevé manuellement, pour être dégagé. Dans ce cas, inversement, la poulie se refermera d'elle-même lorsque le câble sera remis en place dans la gorge du réa 1.

The automatic locking and manual unlocking means could here be carried out as previously, but FIGS. 16 to 18 make it possible to indicate a variant: on the flange 4 which does not carry the sheave 1 is mounted, near the opening 27 receiving axis 6, a pawl 32 mounted pivoting about an axis 33 and subjected to the action of a spring 34. In the same way as the spring 11 of the previous embodiment, this pawl 32 cooperates with the groove 12 and the frustoconical end 13 of the axis 6. Manual action is necessary to pivot said pawl 32, against the force of the spring 34, in order to release the flange 4 and allow it to move apart if the charge is sufficiently reduced. Depending on the force of the spring 31 which acts in the opening direction, various effects can be obtained for the practical use of the pulley:

• a) The spring 31 can be chosen strong enough for the flange 4 to move away from itself, after manual unlocking, when the load only corresponds to the weight of the cable 2 that a man can lift with both hands. The pulley remaining open, the operator will have both hands free to lift the cables 2, or to put this cable or another cable in the groove of the sheave 1.
• b) It is also conceivable, with an automatic opening spring 31 slightly weaker, that under the sole weight of the cable 2 the pulley, even unlocked, remains closed, and that it only opens if the cable 2 has been lifted manually, to be released. In this case, conversely, the pulley will close by itself when the cable is replaced in the groove of sheave 1.

Of course, in all cases the opening spring 31 must be chosen in such a way that the closing of the pulley, up to the locking position, is perfectly achievable manually by one man, both when the device is suspended by its hook 5 only when it is placed on the ground. However, when the pulley is on the ground (and rests in particular on the ground by its flange 3 carrying the sheave 1), the weight of the device not contributing to the closure, the operator must exert a force slightly greater than that necessary to operate the same manual closing when the device is suspended.

In addition, as shown in FIG. 18, taking into account the spring 31, the opening of the pulley is here necessarily limited by a stop, constituted by a finger 17a of the transverse block 17 which cooperates with part of the flange 3 located at look.

Whatever their details, the embodiments of FIGS. 5 to 18 require a very precise adjustment so that the stop means, constituted either by the lugs 18 cooperating with the transverse block 17, or by the light 20 cooperating with the lug 19, completely avoid bending forces in the closed position. These bending forces can be eliminated by supplementing the opening pulley, object of the invention, with provisions which will first be explained, in principle, by referring to the diagrams in FIGS. 19, 20 and 21:

In the case of Figure 19, where the flange 4 not carrying the sheave 1 is linked to the hook 5 via a cross member 15, a flexible connection is made between this flange 4 and the cross member 15. For this purpose , a nut 35 is mounted on the stud 36 of the cross member 15 which is opposite to the stud 19 cooperating with the slot 20, the nut 35 compressing an elastic washer 37 between itself and the outer face of the flange 4.

In the case of FIG. 20, the connection between the flange 4 and the hook-carrying crosspiece 15 remains rigid. The two ears 8, supporting the axis 9 passing as previously in the cross member 15, here belong to a separate yoke 38, and a flexible connection, always produced by a nut 39 and an elastic washer 40, is provided between said yoke 38 and the flange 3 which carries the sheave 1.

FIG. 21, which again corresponds to a flexible connection produced between the flange 4 not carrying the sheave 1 and the cross-member with hook 15, shows that, as a variant, the axis 9, instead of passing through the cross-member 15, can pass through the upper part of the flange 4.

Figures 22 to 25 show, in detail, an embodiment of an opening pulley produced according to the principle of Figure 19, that is to say with a flexible connection formed between the flange 4 not carrying the sheave 1 and the cross member 15 through which the axis 9 passes. The flanges 3 and 4 being here carried by fittings 14 and 10, this flexible connection is more precisely produced between the fitting 10 and the stud 36 of the cross member 15. It is note that the other stud 19 serves both as a stop means, cooperating with the edge of the light 20 in the closed position, and of a lug cooperating with the profiled spring 21 in the open position. Given that the aforementioned flexible connection guarantees, in the closed position, the support of the stud 19 under the upper edge of the lumen 20, avoiding bending, the axis 9 can be of relatively reduced diameter as shown in the drawing .

Another constructive feature of the embodiment according to FIGS. 22 to 25 lies in the fact that the two ears 8 belong to a yoke 38, distinct from the fitting 14 and fixed to the top of the latter by means of two screws 41 and a rivet 42 which also serves to retain the profiled spring 21.

Finally, FIGS. 26 to 30 show in detail a similar embodiment to the previous one with regard to the flexible connection, but in which the hinge pin 9 crosses the upper part of the fitting 10 (according to the principle illustrated by Figure 21), not the crossbar 15.

Maintaining the pulley in the open position is ensured here by a spring 43 in the shape of a stirrup, the ends of which are linked respectively to the two ears 8, being freely engaged in holes made on these ears 8. The two lateral branches of the spring 43 are articulated around two respective pins 44 and 45, offset with respect to the axis 9, while the middle part of the spring 43 is inserted between, on the one hand, the nut 46 for retaining the hook 5 and , on the other hand, the internal face of the fitting 10. Thus the middle part of the spring 43 slides along the nut 46, during the opening movement and, in the fully open position, as shown in FIG. 30, it is engaged and supported in an annular groove 47 of the nut 46. This groove 47 is obviously shaped in such a way that, under the effect of a load on the cable, the spring 43 disengages from itself to allow automatic closing of the pulley.

In this latter embodiment, the spring 11 has a somewhat modified conformation, which is only an additional variant of the locking means in the closed position: this spring 11 has a bent end 48 positioned in a small hole in the fitting 10 , a straight part located under the fitting 10, between the latter and the flange 4, turns 49 housed in an opening 50 of the fitting 10, and a last curved part located in front of this fitting 10, this part cooperating with the groove 12 of axis 6 as well as with a stop 51.

• - Remplacement du crochet 5 par toute suspente équivalente, qui dans tous les cas sera liée à la flasque 4 et/ou au ferrement 10 ne portant pas le réa 1.
• - Montage de deux ou plusieurs réas sur l'axe 6.
• - Réalisation »monobloc« ou en éléments séparés de l'ensemble constitué par la flasque 4 et/ou le ferrement 10, le bloc 17 et le crochet 5, tournant autour de l'axe 9 qui peut traverser cet ensemble monobloc ou la flasque 4 ou le ferrement 10 ou la traverse 15 ou une pièce intermédiaire quelconque, l'axe 9 étant par ailleurs lié par un moyen quelconque à la flasque 3 et/ou au ferrement 14 portant l'axe 6 du réa 1.
• - Réalisation de la liaison souple entre la fiasque 4, ou le ferrement 10, et la traverse 15 portant le crochet 5, ou entre la flasque 3, ou le ferrement 14, et la chape 38 comportant les deux oreilles 8 liées à l'axe d'articulation 9, par tout autre moyen qu'une rondelle élastique pressée par un écrou.
• - Modification de la forme des cliquets 54 et 54a qui assurent à la fois le verrouillage automatique en position fermée et le maintien en position ouverte, ainsi que modification de la position et de l'orientation de l'axe de pivotement de tels cliquets, dont le montage peut se faire, selon le type de poulie ouvrante concerné, sur une flasque, sur un ferrement, ou simultanément sur ces deux organes associés.
• - Remplacement du ressort 21 ou 43 par tout moyen susceptible de maintenir écartées les flasques 3 et 4 malgré l'action du poids de la partie de l'appareil suspendue à l'axe 9 et, éventuellement, du poids d'une certaine longueur de câble 2, mais permettant la ferme_ture automatique de la poulie ouvrante dès que le câble est mis en place ou quand il est chargé.
• - Conformation du ressort profilé 21 telle que celui-ci puisse maintenir par enclenchement le téton 23 du bloc 17 ou le tourillon 19 de la traverse 15 en position d'ouverture et aussi, éventuellement, en position de fermeture, notamment si l'on n'a pas prévu de système de verrouillage automatique de la poulie fermée.
• - Remplacement du ressort 11 ou du cliquet 32 de verrouillage en position fermée par tout autre moyen de verouillage automatique, coopérant ou non avec l'axe 6 du réa 1, et éventuellement suppression de tout moyen de verrouillage en position fermée, la poulie restant »de sécurité« par le fait qu'elle se ferme d'elle-même sous l'effet d'une charge.
• - Adaptation pour l'obtention d'un déchargement automatique, en prévoyant que la poulie s'ouvre d'elle-même lorsque la charge touche le sol ou lorsque la tension sur le câble tend vers zéro.
• - Application à des poulies et moufles ouvrantes avec des réas de toutes dimensions, et avec des flasques et/ou des ferrements de toutes formes, quelles que soient en outre les techniques de formage et d'assemblage de ces pièces.

It goes without saying that the invention is not limited to the sole embodiments of this opening pulley or block which have been described above by way of examples; on the contrary, it embraces all the variants designed according to the same principles, and it includes in particular all the equivalent means of those described and all the derived applications. Thus one would not depart from the scope of the invention by the following modifications or adaptations:

• - Replacement of the hook 5 by any equivalent hanger, which in all cases will be linked to the flange 4 and / or to the fitting 10 not carrying the sheave 1.
• - Assembly of two or more sheaves on axis 6.
• - "Monobloc" or in separate elements of the assembly constituted by the flange 4 and / or the fitting 10, the block 17 and the hook 5, rotating around the axis 9 which can pass through this monobloc assembly or the flange 4 or the fitting 10 or the crosspiece 15 or any intermediate piece, the axis 9 being also linked by any means to the flange 3 and / or to the fitting 14 carrying the axis 6 of the sheave 1.
• - Realization of the flexible connection between the flange 4, or the fitting 10, and the cross member 15 carrying the hook 5, or between the flange 3, or the fitting 14, and the yoke 38 comprising the two ears 8 linked to the axis articulation 9, by any other means than an elastic washer pressed by a nut.
• - Modification of the shape of the pawls 54 and 54a which provide both automatic locking in the closed position and maintenance in the open position, as well as modification of the position and orientation of the pivot axis of such pawls, including mounting can be done, depending on the type of opening pulley concerned, on a flange, on a fitting, or simultaneously on these two associated members.
• - Replacement of the spring 21 or 43 by any means capable of keeping the flanges 3 and 4 apart despite the action of the weight of the part of the device suspended from the axis 9 and, possibly, the weight of a certain length of cable 2, but allowing the automatic farm _t ure of the snatch block as soon as the cable is introduced or when it is loaded.
• - Conformation of the profiled spring 21 such that the latter can hold the lug 23 of the block 17 or the pin 19 of the cross member 15 in the open position and also, possibly, in the closed position, in particular if n has not provided an automatic locking system for the closed pulley.
• - Replacement of the spring 11 or the pawl 32 for locking in the closed position by any other automatic locking means, cooperating or not with the axis 6 of the sheave 1, and possibly removing any locking means in the closed position, the pulley remaining " security "by the fact that it closes by itself under the effect of a load.
• - Adaptation for obtaining an automatic unloading, by providing that the pulley opens itself when the load touches the ground or when the tension on the cable tends towards zero.
• - Application to pulleys and opening blocks with sheaves of all sizes, and with flanges and / or fittings of all shapes, whatever the techniques of forming and assembling these parts.

Claims (21)

1. Openable pulley or muffle of the type comprising two support flanges (3, 4) or two support brackets (10, 14) with two flanges (3, 4) one of which (3) supports both the sprindle (6) of at least one groove pulley (1) over which there passes a cable (2) and, directly or by means of another component, a pivot axis (9), supporting an openable portion (4) such that the pivoting of this portion (4) about the said axis (9) enables the introduction of the cable (2) or its release from between the two flanges (3,4), whereas a means for suspending the pulley or the load, such as a hook (5), whose axis passes substantially through the median plane of the groove pulley (1), is connected to one of the flanges (4) indirectly via a component such as a stud crossbar (15), this crossbar (15) being located, with respect to the axis (6) of the groove pulley (1), on the same side as the axis of opening (9) of the pulley or muffle, the hook (5) being connected to the openable portion (4) and not to the flange (3) supporting the groove pulley (1) such that the traction effort exerted by the load on the groove pulley (1) via the cable (2) creates torques whose effect is to close the openable portion (4) of the pulley/muffle if it is open, characterised in that the openable portion connected to the hook (5), and constituted by the flange (4) which does not support the groove pulley (1), has its pivoting axis (9) orientated perpendicularly to the axis (6) of the groove pulley (1) and offset with respect of the median plane of the groove pulley (1) such that the traction effort exerted by a load not only causes the closure of the pulley/muffle by closing up its two flanges 3, 4) but also maintains this pulley in the closed position during the entire period in which the effort due to the load is applied, means (21, 31, 43, 54, 54a) being provided so as to keep the two flanges (3, 4) spaced from one another if no effort due to a load is being applied, without opposing the closure of the pulley/muffle under the action of a load.

2. Openable pulley or muffle as claimed in claim 1, characterised in that stop means (17, 18, 19, 20) are provided and limit the angle of pivot of the »flange (4) not supporting the groove pulley (1) and hook (5)« assembly with respect to the »flange (3) not connected to the hook (5) and groove pulley (1)« assembly in the direction of closure of the pulley/muffle under the action of a load such that the support of one assembly on the other does not lead to bending efforts which the components could not support, these stop means also being designed to prevent, in the closed position of the pulley/muffle, the transmission of the effort due to the load via the pivoting axis (9).

3. Openable pulley or muffle as claimed in claim 2, and in which a transverse block connected to the hook forms part of one of the flanges, characterised in that support in the closed position is provided, on one hand, between a face of the said transverse block (17) which is rigid with the flange (4) which does not support the groove pulley (1) and, on the other hand, between at least one catch (12) rigid with the flange (3) supporting the groove pulley (1).

4. Openable pulley or muffle as claimed in claim 2, and in which one of the flanges is connected to a hooksupport crossbar, caracterised in that the said crossbar (15) connected to the flange (4) which does not support the groove pulley (1), comprises a stud (19) engaged in a slot (20) of the flange (3) which supports the groove pulley (1) such that in the closed position of the pulley/muffle, support is provided between this stud (19) and the edge of the slot (20), the pivoting axis (9) passing either through the crossbar (15) itself, or through the flange (4) which does not support the groove pulley (1) and is connected to the crossbar (15).

5. Openable pulley or muffle as claimed in claim 4, characterised in that the connection between the crossbar (15), i. e. the hook (5), and the flange (4) not supporting the groove pulley (1), is provided with a certain degree of flexibility in a transverse plane so as to prevent bending efforts on the flanges (3, 4) and other components, in the closed position, under the action of the load.

6. Openable pulley or muffle as claimed in claim 5, characterised in that the flexible connection is achieved by means of a nut (35) disposed at the end of one (36) of the studs of the crossbar (15) and pressing at least one flexible washer (37) against the flange (4) not supporting the groove pulley (1), or against the bracket (10) supporting this flange (4).

7. Openable pulley or muffle as claimed in claim 4, characterised in that the connection between the pivoting axis (9) and the flange (3) supporting the groove pulley (1) is provided by means of a fork (38) mounted with a certain degree of transverse flexiblility on the flange (3) so as to prevent bending efforts from being exerted on the flanges (3, 4) and other components, in the closed position, under the action of the load.

8. Openable pulley or muffle as claimed in claim 7, characterised in that the flexible connection between the fork (38) and the flange (3) supporting the groove pulley (1) is provided by means of at least one flexible washer (40) interposed between these two components and retained by the tightening of a nut (39).

9. Openable pulley or muffle as claimed in one of claims 1 to 8, characterised in that it comprises, so as to keep the two flanges (3, 4) spaced from one another when no effort is exerted by the load, and to ensure automatic locking during the closure of the pulley/muffle under the action of a load, a single catch (54, 54a) mounted pivotably on the flange (4) or its support bracket (10) connected to the hook (5) and not supporting the groove pulley (1), the said catch (54, 54a), when subjected to the action of a spring (55, 55a) which tends to make it pivot in a predetermined direction, cooperating, on one hand, in the closed position of the pulley/muffle, with a complementary housing (59, 59a) of a component (8) rigid with the flange (3) supporting the groove pulley (1) and, on the other hand, in the open position of the pulley/muffle, with a support surface (60, 60a) belonging to this component (8) rigid with the flange (3) supporting the groove pulley (1), the said support surface (60, 60a) and/ or the portion (58, 58a) of the catch (54, 54a) which cooperates with this surface forming a ramp or cam which enables, when a load is applied, the sliding of one on the other against the action of the said spring (55, 55a), in the direction of closure of the two flanges (3,4) of the pulley/ muffle.

10. Openable pulley or muffle as claimed in claim 9, characterised in that the catch (54) is mounted pivotably on the flange (4) or on its support bracket (10) connected to the hook (5) and not supporting the groove pulley (1) along an axis (53) prallel to the pivoting axis (9) of the flange (4), and in that this catch (54), which the said spring (55) tends to bring closer to the flange (4), comprises a lever (56) enabling it to be spaced from the flange (4) against the action of the spring (55) and a finger (58) designed to cooperate either with a housing (59) or with a boss (60) having a dished profile belonging in both cases to a component (8) rigid with the flange (3) supporting the groove pulley (1).

11. Openable pulley or muffle as claimed in claim 10, characterised in that the said component is formed by one of the arms (8) of a fork rigid with the flange (3) supporting the groove pulley (1) and supporting the axis of articulation (9) of the other flange (4), one of the edges of this fork arm (8) comprising a recess (59) which forms the housing for the finger (58) of the catch (54) in the locked and closed position, and a boss (60) on which the same finger (58) of the catch (54) acts, in the open position of the pulley/muffle.

12. Openable pulley or muffle as claimed in claim 9, characterised in that the catch (54a) is pivotably mounted on the flange (4) or its support bracket (10) connected to the hook (5) and not supporting the groove pulley (1) along an axis (53a) perpendicular to the plane of the flange (4), and in that the catch (54a) comprises an actuation lever (56a) and a head (58a) having a partially conical shape, whilst the additional component (8) rigid with the flange (3) supporting the groove pulley (1) has a portion (60a) folded parallel to this latter flange (3) such that the head (58a) of the catch (56a) may either be engaged between the folded portion (60a) and the flange (4) or its support bracket (10) connected to the hook (5), the spring (55a) tending to retain the catch (54a) in this position, or may have its conical surface supported externally on the folded portion (60a).

13. Openable pulley or muffle as claimed in claim 12, characterised in that the said folded portion is formed by an extension (60a) having a right-angled elbow shape of one of the arms (8) of a fork rigid with the flange (3) supporting the groove pulley (1) and supporting the axis of articulation (9) of the other flange (4).

14. Openable pulley or muffle as claimed in any one of claims 1 to 8, characterised in that spring means (21, 31, 43) are provided in order to keep the two flanges (3, 4) spaced from one another or to bring the two flanges (3, 4) into the spaced position and maintain them in this position, until the instant at which the traction effort exerted by the weight of the cable (2) or the load, or the weight of the apparatur supported on the cable (2), becomes greater than the resistance of the spring means, and in that further spring means (11, 34) are provided in order to ensure automatic locking during the closure of the pulley-muffle under the action of a load, these further means requiring manual unlocking in order to enable the opening of the pulley/muffle.

15. Openable pulley or muffle as claimed in claim 14, characterised in that it comprises a spring (21) supported by one of the flanges, such as the flange (3) supporting the groove pulley (1), or by a component rigid with this flange, and designed to lock onto a component (23) rigid with the other flange, for exemple the flange (4) connected directly or indirectly to the hook (5) when the two flagnes (3,4) are spaced from one another, so as to maintain the two flanges (3, 4) in this spaced position until simple manual or automatic closing takes place under the action of a load.

16. Openable pulley or muffle as claimed in claim 14, characterised in that it comprises an opening spring (31), wound in particular about the axis (9) on which the two flanges ( 3, 4) are articulated and supported on these two flanges (3, 4) so as to keep these flanges apart and to maintain them in the spaced position, until simple manual or automatic closing under the action of a load.

17. Openable pulley or muffle as claimed in claim 14, characterised in that as the automatic locking means, during closure under the action of a load, require manual unlocking, they are provided in the form of a catch (32) mounted pivotably on the flange (4) connected to the hook (5), this catch being subject to the action of a spring (34) and cooperating with the free end of the axis (6) of the groove pulley (1) supported by the other flange (3), on which end there are provided a ramp (13) and a throat (12) designed to receive the said catch (32).

18. Openable pulley or muffle as claimed in claim 14, characterised in that as the automatic locking means require, during closure under the action of a load, manual unlocking, they are provided in the form of a spring (11) fixed to the flange (4) connected to the hook (5) and comprising a dished portion cooperating with the free end of the axis (6) of the groove pulley (1) supported by the other flange (3), on which end there are provided a ramp (13) and a throat (12) designed to receive the dished portion of the spring (11).

19. Openable pulley or muffle as claimed in claim 15, characterised in that the said spring which maintains the two flanges in the spaced position, is a profiled spring (21) supported by one of the flanges, for example the flange (3) which supports the groove pulley (1), and enables the locking on of a stud (23) rigid with the other flange, for example the flange (4) connected to the hook (5), when the two flanges (3,4) are spaced from one another.

20. Openable pulley or muffle as claimed in claim 15, characterised in that the said spring which maintains the two flagnes in the spaced position is a stirrupshaped spring (43) whose ends are connected to two lugs (8) themselves connected to the flange (3) which supports the groove pulley (1) and forming a fork on which there is pivotably mounted the other flange (4) connected to the hook (5), the median portion of this stirrupshaped spring (43) being engageable in an annular throat (47) of the retaining nut (46) of the hook (5) when the two flanges (3, 4) are spaced from one another.

21. Openable pulley or muffle as claimed in claims 4 and 20 taken together, characterised in that the stud (19) of the crossbar (15), engaged in the slot (20) of the flange (3) supporting the groove pulley (1), also constitutes the stud which, in the open position, locks onto the profiled spring (21).

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