EP0172975B1 - Spreader device for two-piece driving pulley - Google Patents

Description

The invention relates to a free cable lifting device with a drive pulley composed of two half-pulleys, each of which has on its peripheral edge a groove part for cable and one of which is controlled, directly or indirectly, by one motor and supports the other. In order to increase the drive capacity of the lifting device, the half-pulleys are pressed towards each other by a series of pressure devices rotating with them and distributed uniformly along their periphery.

A lifting device of this kind and according to the precharacterizing part of claim 1 is described in German patent DE-C-2 522 033 - by the same applicant - according to which the annular half-pulley is particularly elastic and is separated from the other half-pulley, at the places where the cable enters and exits the groove, using at least one spacer, so that the cable is subjected to a strong localized pressure which would deform it, causing unacceptable heating and wear.

In certain devices of this kind - for example that described in the German patent above - the spacer device may consist of a roller rotating on an axis, parallel to the axis of the pulley, which is fixed to the housing to outside the periphery of the half-pulleys.

In other similar devices - for example that described in German patent DE-429 820 - a spacer device represented by a ring having a diameter a little less than the diameter of the half-pulleys is located between the half-pulleys eccentrically in relation to these.

It is obvious that both these kinds of spacers effectively prevent the cable from being subjected on the part of the half-pulleys to a particularly strong pressure localized at the entry and the exit of the groove for cable, and consequently very heavy wear. However, it is also obvious that both types of spacing device cause friction and a high temperature rise in the contact zone between the caster or spacer ring and half-pulleys. This drawback is caused by the difference in the trajectories traversed by the reciprocally corresponding points of the contact surfaces between half-pulleys and spacer wheel (or ring) - since these trajectories have different radial components and therefore involve a greater or lesser displacement relative in radial direction of the reciprocally contacting surfaces - and is particularly annoying because of the large force concentrated in the contact zone by half of the pressure devices distributed over the periphery of the half-pulleys. Indeed, this limits, on the one hand, naturally the life of the spacer and / or half-pulleys and also, on the other hand, the speed of exercise also as well as the duration of uninterrupted operation of because of the difficulty in dispersing the heat given off (which is proportional to the speed of exercise).

The present invention completely eliminates this drawback by providing a spacing device capable of applying at least one of the half-pulleys, in the cable entry and exit zone, at least one force directed exclusively along the axis of pulley.

An axial thrust is also applied in an elevation device described in the German publication DE-A-2 547 194, but to remove a series of pressure devices which clamp the cable directly against a half-groove of a pulley in one single piece. The axial thrust is thus applied by a stationary cam separate from the pulley to casters which rotate with the pulley and simultaneously separate part of the pressure devices, so that the apparatus does not actually achieve the result of protecting the cable from overheating and wear caused by sudden tightening and loosening.

To overcome these drawbacks, the cable elevation device according to the invention comprises the elements of the characterizing part of claim 1.

It is easy to see that several apparently very different embodiments are possible.

All of these, however, include, on the one hand, at least a series of spacers (balls or studs) arranged uniformly along and near the periphery of the pulley and rotating with it, which exert the '' one after the other on one annular half-pulley, on the opposite side of the throat arch supporting the load, a thrust directed essentially along the axis of the pulley - being therefore free of any radial component (or even peripheral) giving origin to a sliding friction.

All these embodiments comprise, on the other hand, a disc which has at least one inclined surface relative to the half-pulley mounted on the shaft (or on the axis) and which therefore lends itself to actuating one after the other in turn the above spacers, this disc can be stationary relative to a housing of the device or rotate with the pulley.

As for the spacers, both the balls and the discs can be replaced by needle bearings (or cages).

The advantages of the invention appear clearly: since all the embodiments of the invention make it possible to separate the two half-pulleys by applying to one of them - by means, for example, as mentioned above - above, balls or studs - forces directed essentially along the axis of the pulley (therefore comprising no component in the radial direction of the latter), no sliding friction (precisely in the radial direction) intervenes to generate heat and no limitation is placed on the speed of exercise. And as this fact, on the one hand, allows the use of the device in a number of areas from which it would otherwise remain excluded and, on the other hand, substantially prolongs its life, the interest of a lifting device with a free cable endowed with a spacer device according to the invention results increased to a decisive extent.

• - dans les figures 1, 2 et 3 - représentant, respectivement, une section selon la ligne "A - A" de la fig. 2, une vue et une section partielle dans la direction "a" de la fig. 1 - un disque d'épaisseur variable qui est supporté par les demi-poulies à l'aide de deux rangées périphériques de billes et qui est stationnaire relativement au boîtier,
• - dans les figures 4 et 5, une rangée de goujons qui coulissent dans des trous de la demi-poulie montée sur l'arbre, sont articulés à un disque incliné par un galet stationnaire et tournent avec la poulie,
• - dans les figures 6 et 7, une rangée de goujons coulissants creux en deux parties qui coopèrent librement avec un disque incliné tournant sur une butée inclinée stationnaire relativement au boîtier,
• - dans la figure 8, une rangée de goujons coulissants pleins en une pièce qui coopèrent librement avec une butée à aiguilles inclinée stationnaire par rapport au boîtier,
• - dans les figures 9 et 10, une rangée de goujons coulissants qui coopèrent librement avec un disque incliné tournant avec la poulie sur un second disque incliné avec manchon qui est stationnaire relativement au boîtier et qui est supporté par la bride d'un manchon solidaire de l'arbre de la poulie,
• - dans la figure 11, une rangée de goujons coulissants qui coopèrent librement avec une butée à deux rangées d'aiguilles tournant sur une bride d'appui clavetée sur l'arbre de la poulie et dont la plaque médiane est stationnaire relativement au boîtier, et
• - dans les figures 12 et 13 les mêmes éléments de la figure 11, la bride d'appui étant cependant vissée sur l'arbre de la poulie de façon réglable axialement.

Several embodiments of the invention are described below and represented in the drawing, where the object spacing device comprises,

• - in Figures 1, 2 and 3 - showing, respectively, a section along the line "A - A" of FIG. 2, a view and a partial section in the direction "a" of FIG. 1 - a disk of variable thickness which is supported by the half-pulleys using two peripheral rows of balls and which is stationary relative to the housing,
• - in FIGS. 4 and 5, a row of studs which slide in holes in the half-pulley mounted on the shaft, are articulated to a disc inclined by a stationary roller and rotate with the pulley,
• - in FIGS. 6 and 7, a row of hollow sliding studs in two parts which cooperate freely with an inclined disc rotating on a stationary inclined stop relative to the housing,
• - in FIG. 8, a row of solid sliding studs in one piece which cooperate freely with a needle stop inclined stationary relative to the housing,
• - In Figures 9 and 10, a row of sliding studs which cooperate freely with an inclined disc rotating with the pulley on a second inclined disc with sleeve which is stationary relative to the housing and which is supported by the flange of a sleeve integral with the pulley shaft,
• in FIG. 11, a row of sliding studs which cooperate freely with a stop with two rows of needles rotating on a support flange keyed onto the pulley shaft and the central plate of which is stationary relative to the housing, and
• - In Figures 12 and 13 the same elements of Figure 11, the support flange being however screwed onto the pulley shaft in an axially adjustable manner.

1. In a first embodiment of the invention, shown in Figures 1 to 3, the first pulley part 1 is keyed onto the shaft 3, the bearings (not shown) are housed in the housing of the lifting device, while the annular pulley part 2 is carried and rotated by the first part.

The cable is housed in a groove part 4 of the first pulley part 1 and is held there by the other groove part 5 which is located on the annular pulley part 2 and consists of a simple annular surface perpendicular to the axis 3 of the pulley.

Along the peripheral edge of the pulley, several pressure devices 6 are distributed uniformly. They comprise (FIGS. 1 and 3) a compression spring 7 which is wound around a sleeve 8 and bears, at one end, against the annular pulley part and, at the other end, on a flange of the sleeve, the latter being on the other hand retained by a screw 9 fixed in a threaded hole in the first pulley part. In this way the annular pulley part is pressed against the first pulley part.

The two pulley parts 1, 2 both have a zone of their periphery which is arranged radially outside the groove for cable and which is constituted by a circular ring 1 ', 2' provided, on its axially inner side , of a raceway 10, 11.

Between the outer peripheral zones of the two pulley parts is interposed a spacer disc 12, which has its center on the axis of the pulley and a face 13 perpendicular to this axis while its second face 14 is slightly inclined relative to the first. The thickness of the disc is therefore variable and precisely it gradually increases from a minimum located in the center of the cable winding arc to a maximum in the diametrically opposite zone.

In order to allow the passage of the cable at the level of its entry and exit from the cable groove of the pulley, the spacer disc has two parallel holes tangent to its inner peripheral surface.

On each face 13, 14 of the spacing disc is arranged a raceway 16, 17 having the same diameter of the corresponding raceways respectively located, reciprocally opposite, on the circular rings 1 ', 2' of the half-pulleys .

The spacer disc is on the other hand connected to the housing of the lifting device by a bar 18. This is housed in a hole, parallel to the axis of the pulley, which is bored in a lug 19 fixed to the disc on the side opposite to the cable winding arc, and which can slide on the bar. The disc is thus prevented from rotating on its axis (coinciding with the axis of the bar), but not from automatically carrying out, under the action of the clamping devices, a translation parallel to the axis of the pulley.

It is therefore obvious that the disc, because of the reciprocal inclination of its faces, has a thickness which, along the winding arc of the cable, is reduced to an extent such that the balls located opposite screws of the annular pulley part remain away from the indicated raceway and thus allows the cable to be tightened by the pressure devices. On the opposite side, on the other hand, the thickness of the disc is such that the balls, rolling in the path bearing, abut one after the other against the annular half-pulley and thus reciprocally - against the force of the pressure devices and thanks to the particular elasticity imparted to the annular pulley part by its relatively very small section - the sides of the cable groove. This to such an extent that - the distance from the sidewalls gradually decreasing in both peripheral directions - contact with the cable is only made barely beyond its point of entry into the throat and only stops almost where it comes out.

And it is also obvious that the force transmitted to the annular half-pulley by the ball which, while rolling in the raceway, succeeds in turn in making the separation, is directed perpendicular to the bottom part of the way , that is to say also perpendicular to the annular half-pulley - therefore excluding, in accordance with the invention, any unwanted component in a radial and even peripheral direction.

As a result, the speed of exercise as well as the period of uninterrupted operation and the life of the apparatus results therefrom very greatly.

The peripheral arrangement of the spacer disc allows it to intervene against a "creep of the cable" preventing it from climbing in the groove or even so radially - due to the fact that following its unilateral load its tensile stress and its elongation can vary greatly along its course in the throat. The spacer disc thus also functions as a "cable guide" and, in addition, prevents part of the cable wear.

An advantage of this embodiment lies finally in the economic advantage which it presents for its relative simplicity, which very significantly lowers its manufacturing price compared to the other solutions.

Nevertheless, it is necessary, as in any case, to have a particular regard to the tightness of the device in relation to dust, mud and small debris which on the site inevitably adhere to the cable and are introduced by this one in the mechanism.

From this point of view, this embodiment appears rather disadvantageous because, if we consider the relative arrangement of the cable, of the two series of balls and of the sliding bar, which are all arranged in the same plane, we can fear that foreign bodies will hinder, in particular, the longitudinal movement of the various elements and thereby compromise proper tightening of the cable. And, moreover, the same foreign bodies always deteriorate, sooner or later, more or less, the seals and make it necessary to replace them.

On the other hand, and above all, in the case that the lifting device must have an even greater capacity and that it is therefore essential to use two pulleys in tandem - in a manner analogous to that shown, relative to the third embodiment, in FIG. 9 - this embodiment does not lend itself to this because the spacer disk occupies precisely the place which is normally intended for the teeth required for the transmission of the movement of the control shaft to the drive pulley. Unless we admit dimensions for the gear making the size of the lifting device prohibitive.

II. A second embodiment, shown in FIGS. 4 and 5, makes it possible to overcome these drawbacks by replacing the spacer disc 12 of the first embodiment, arranged radially outside the cable, by a disc with parallel surfaces 30 which is placed longitudinally outside the pulley and which can oscillate on a spherical bearing 31 carried by the shaft 3.

This disc 30 is rotated by the half-pulley 1 by means of studs 32 sliding in holes bored in the axial direction in a zone 1 'of its peripheral edge which is arranged radially outside the groove for cable . These studs, at one of their ends, are articulated to the spacer disc by means of a ball joint 33 and, at the other end, are arranged opposite spherical notches 34 in a 2 ′ extension of the half-pulley 2.

As on the other hand, a spacer roller 35 is fixed by its bracket to the housing - in such a way that its axis is parallel to the pulley and perpendicular to the axis of the latter - with respect to the place opposite to the cable winding arc and in such a position that it causes the spacer disc to tilt by a predetermined angle, it is understood that each stud, cyclically in turn, is carried to transmit to the 'respective spherical notch a force (reaction) capable of spreading the half-pulley 2 to such an extent that the sides of the groove begin and stop tightening the cable only near the ends of the winding arc.

It is also noted, on the one hand, that the pressures that the free ends of the spacing studs transmit to the half-pulley 2 are directed exclusively, according to the invention, along the axis of the pulley.

And we note, on the other hand, that the major drawbacks presented by the first embodiment are no longer present - namely, firstly, the serious danger of fouling, since the studs 32 and their joints 33 and surfaces of sliding are almost out of reach for any foreign body.

And on the other hand and above all, the lateral arrangement of the spacing disc eliminates the impossibility of coupling the drive pulley according to the invention with a toothed ring with a second drive pulley (equal or not) - well that the pulley according to the invention can obviously also be used alone (as shown, for simplicity, in Figure 5).

Finally, as a result of this provision, the device elevation is no longer linked, for proper operation, to a determined thickness of cable: the half-pulley 2 can indeed, by approaching more or less than the half-pulley 1, allow the studs to protrude more or less opening their spacing, because by adjusting the advancement of the spacing roller we can now start and gradually end the tightening of the cable at the ends of the winding arc even if the thickness of the cable varies between certain limits .

A danger of crushing remains, however, although to a much lesser extent, also for this second embodiment since, on the one hand, the studs come, in turn, to expose themselves to foreign bodies when they come out gradually of their bores to spread the annular half-pulley - and dust or mud can thus infiltrate the sliding seats and / or in the notches of the annular half-pulley and hinder the spacing thereof.

And, on the other hand, the force of a plurality of pressure devices is now concentrated on the single spacer roller and its stirrup and subjects them to stresses which are hardly compatible with their necessarily reduced dimensions.

III. Also these two drawbacks are however eliminated by the third embodiment (Figures 6 and 7).

On the one hand, in fact, the studs, which, in this form of construction, can slide freely in their axial seats of the half-pulley 1 mounted on the shaft, are produced in two hollow coaxial parts 40 whose end free is provided with a flange 41 and which contain in their internal cavity a compression spring 42. The spacer disc 43 with its notches vis-à-vis the spacer studs, on the other hand, is located in a cavity inside the gear ring 44 for coupling with a second pulley according to the invention and is articulated to the casing of the lifting device by means of a ball cage 45 rolling in raceways on a cylindrical portion 46 projecting from the casing, in the direction of the axis of the pulley, and a needle stopper 47 mounted on a surface in an inclined circular ring integral with the casing.

Since the ends of the two stud parts therefore remain in constant contact, under the action of the springs 42, both with the annular half-pulley 2 and with the spacer disc 43 in notches arranged opposite their ends, it is clear, on the one hand, that fouling of the notches by foreign materials introduced by the cable into the casing is no longer hardly possible. All the more, as regards the notches on the annular half-pulley, that the ends of the studs projecting from their seat on the side of the annular half-pulley are coated with a cap 48 made of an elastically deformable material which, during sliding back and forth of the studs constantly prevents contact with any solid or liquid material introduced by the cable, which could cause the studs to seize and, consequently, the cable to slip.

(For the other end of the studs such a cap 48 is not necessary since the notches of the spacer disc which correspond to it are already protected by the fact that they are located, far from the cable, in the cavity at the inside the above-mentioned toothed crown 44.)

On the other hand, as for the disadvantage of a concentrated pressure on one or two spacers - such as thrust rollers and the like - which is capable of causing a lamination of their limited contact surface, it is completely absent. because the very high pressure produced by the clamping devices 6 is now absorbed by the large number of needles of the inclined stop, having large dimensions, 47.

However, it can be noted that this third embodiment of the pulley does indeed eliminate the disadvantages of the previous ones, but at the cost of a non-indifferent complexity which makes it rather expensive to manufacture. In particular, very tight tolerances and very high resistance characteristics, as well as a correspondingly long working time, are required by all the adjustments and surface treatments relating to the sliding path in the half-pulley mounted on the axis and the notches in the spacer disc, which must be exactly on the axis of the sliding paths, and therefore depend on the adjustment and surface treatment of the bearing to a ball cage supporting the spacer disc, as well as for the adjustment and surface treatment of the inclined seat arranged in the casing for the cage with thrust needles, which must be such as to ensure the correct inclination of the annular half-pulley.

IV. A fourth embodiment (FIG. 8) guarantees the desired result at a cost price which is a fraction of that which must be provided for all of the adjustments and surface treatments mentioned. For this purpose, it suffices to replace the bearing with a bill cage 45 and the needle stopper 47 as well as the spacer disc 43 itself with a simple commercial needle stopper 50 which is to be mounted in a seat. bearing 51, suitably inclined, arranged in the casing of the apparatus. There is indeed no need to make any particular adjustment (the manufacturer indicates a tolerance H 10) with a view to the cooperation between studs 53 and stop, since the surface of the ring 52 of the latter intended to enter cyclically at turn in contact with the studs is already normally designed to withstand loads which, for needle thrust bearings of the diameter of the row of studs, amount to hundreds of thousands of N (while the total force of the springs distributed over the half circumference can be, for example, of a t). It is therefore not necessary to establish on the surface of the inner ring 52 of the stopper, vis-à-vis the ends of the studs, places particularly designed to withstand very high pressures: the surface hardness offered by the manufacturer for loads on the order of those now mentioned - corresponding therefore to another order of magnitude compared to the nominal load of the device - is more than sufficient.

Especially since the contact between studs and stopper is verified, quite desirably, in places which, because of the normal (imperceptible) speed difference between pulley and inner ring of the stopper, change continuously, so that wear of the stop surface is practically not to be taken into account. As well as a wear of the surface, preferably flat with a slight rounding, of the end of the studs, which can obviously be covered by a layer of high hardness - the latter being able to be at will, according to criteria of economically, either slightly less than or slightly greater than the hardness of the surface of the inner ring.

The only criticism which could, if necessary, be made of this form of construction concerns the resistance of the housing to the thrust of half of the pressure devices 6 which is transmitted by the stop 50.

V. But then a fifth embodiment (FIGS. 9 and 10) can be chosen in order to discharge the casing from any function of resistance to thrust in the axial direction pertaining to the use of pressure devices. In accordance with this solution, the pressure devices 6 thrust transmitted by the spacer disc is completely taken up and neutralized by a spacer flange 62 rigidly mounted on the shaft 3 of the pulley.

The invention in fact provides in this case that the spacing disc 60, also provided with notches opposite the spacing studs, is supported, by means of a ball bearing 61, on a flange d 'spacer 62 which has two surfaces in a circular crown, one of which 63 is slightly inclined relative to the second 64. This spacer flange 62 is, on the one hand, fixed relative to the casing by a rod 65 and, on the other hand, articulated to the shaft 3 of the pulley by means of a roller stop 66 and a hub 67 on roller bearing 68, the forces transmitted by this stop and this hub being, in turn, taken up by a support piece 69 consisting of a stop flange with hub which is rigidly fixed to the shaft of the pulley.

All the conditions relating, in accordance with the invention, to the arrangement and operation of the lifting device are thus satisfied. Only one remark could still be made about the non-indifferent complexity of this embodiment and its relatively expensive manufacture: this, again, because of the precision and resistance characteristics, also superficial, very advanced which are essential for all the adjustments and surface treatments in play, a fortiori even, because these now refer - in addition to the sliding tracks, the notches, the bearing 46 of the row of balls 45 and the inclined seat 49 of the stop needle cage 47, as mentioned for the fourth form of construction - also to the spacer flange 62 with inclined surface 63 and to its mounting between the spacer disk 60 and the support piece 69.

VI. Also in this case, however, a sixth solution (Figure 11) achieves all the kinematic and exercise results while avoiding all the necessary adjustments and surface treatments in relation to the sixth solution: it suffices , also in this case, to replace the ball bearing 61, the roller bearing 68 and the roller bearing 66 as well as the spacer disc 60 and the spacer flange 62 with hub 67 themselves by a simple stop with two crowns of needles and median plate with inclined "floating" faces 70 on the market, the outer ring 71 of which can be clamped in a flange 72 with hub 73 rigidly mounted on the pulley shaft using a key and a push ring 74 while the middle plate 75 is fixed to the housing, for example, by a rod 76. The middle plate can, by the use of this stop rod sliding in the radial direction either in its seat fitted in the middle plate or in its seat in the housing, ê be kept "floating" and thus receive its self-centering from the two crowns of needles, themselves normally subject to self-centering.

VII. A seventh solution, finally, does not present, like the sixth now described, the disadvantage of having to cooperate with a cable of a determined thickness, and is therefore susceptible of even more varied uses. Indeed, the spacing device may comprise - instead of the flange 72 provided with a hub mounted on the shaft of the pulley by means of a key in a well-defined position, essentially dependent, unequivocally, on a single cable thickness - a stop assembly 81 (FIGS. 12 and 13) constituted by a threaded end 82 of the pulley shaft, by a stop flange 83 and by an adjusting nut 85.

The stop flange has a threaded hub 84 fixed on the shaft end 82 and its position in the axial direction can obviously be determined by more or less screwing the adjusting nut 85 on the threaded end 82 and tightening the stop flange against the adjusting nut strongly enough so that frictional forces between the surfaces reciprocally with respect to the hub 84 and the nut 85 as well as between the threads of these and the thread of the shaft end 82 are created and, even in the presence of repeated vibrations, effectively oppose loosening of the stop flange. It would, moreover, be easy for any person skilled in the art - in case it is feared that a loosening will occur for unforeseeable or inevitable causes - to provide the stop assembly of any known stop system.

It goes without saying that the stop rod 86 of the "floating" middle plate 87 of the spacer 80 must itself be able to move itself in the axial direction, in one direction and in the other, to the using, for example, a sliding slide (not shown).

Claims (10)

1. Cable hoisting apparatus having a driving pulley consisting of two half-pulleys (1, 2), the one (1) of them being mounted on the shaft or axle (3) of the pulley and the other (2) being ring-shaped and supported by the first one, wherein said half-pulleys are pressed against each other by several pressing devices (6) which are evenly distributed on the surface of the pulley and wherein they are gradually spread apart from each other by a spreading device (12; 30; 43; 60) at a place being located on the side opposite to the winding arc of the cable,

characterized

in that said spreading device comprises a spreading disk (12; 30; 43; 60) which is mounted on the shaft or axle (3) of the pulley,

in such a way that at least one of its faces (14; 52; 63) has its center on the pulley axis and is slightly inclined relatively to the half-pulley (1) being mounted on the shaft or axle (3), and

in that the spreading device further comprises at least one row of spreading elements (32; 40; 53) which are evenly distributed along the peripheral portion of the pulley and which cooperate one after the other with the spreading disk (12; 30; 43; 60)

so as to push the ring-shaped half-pulley (2) apart from the other half-pulley (1), at said place, by transmitting in turn to it a force which is exclusively directed in a parallel direction to the pulley axis.

2. Cable hoisting apparatus according to claim 1,

characterized

in that the spreading disk (12) is stationary relatively in a housing of the hoisting apparatus.

3. Cable hoisting apparatus according to claim 2,

characterized

in that the spreading disk (12) presents a bore whose diameter is greater than the outer diameter of the cable groove (4, 5) of the pulley, and

in that the spreading disk (12) is located between the half-pulleys (1, 2) opposite to two portions (1', 2') of their respective peripheral surfaces which are provided radially outside their respective half cable groove (4, 5), and

in that between each half-pulley (1, 2) and the spreading disk (12) a row of balls rolls in a pair of races (10 - 11, 16 - 17) which are provided in the peripheral portion (1', 2') of each half-pulley (1, 2) and in the face (13, 14) of the spreading disk (12) which is arranged respectively opposite to this portion (1',2'), and

in that the spreading disk is procided with a radial extension (19) with axial bore and is guided in an axial direction by a rod (18) which is fixed to the housing and passes through said bore.

4. Cable hoisting apparatus according to claim 1,

characterized

in that the spreading disk (30; 43; 60) is directly or indirectly coupled for rotation with the half-pulley (1) which is mounted on the pulley shaft (3) between the ring-shaped half-pulley (2) and the spreading disk (30; 43; 60).

5. Cable hoisting apparatus according to claim 4,

characterized

in that the half-pulley (1) is mounted on the shaft (3) and the ring-shaped half-pulley (2) present each one peripheral portion (1', 2') which is arranged radially outside the cable groove (4, 5) and in which are evenly distributed a row of bores being directed in a parallel direction to the pulley axis and, respectively, a row of round notches (34) being arranged respectively opposite to said bores, and

in that the spreading elements consist of spreading studs (32) which are linked with the spreading disk (30) by means of swivel joints (33) and which can slide in said bores, and in that the spreading disk (30) is mounted on the shaft (3) by means of a swivel joint (31) and thus can get an opportune tilt relatively to the pulley, as an effect of the reaction of a roller (35) whose pivot is fixed to the housing on the side opposite to the winding arc of the cable,

in such a way that all the spreading studs (32) remain retracted in their respective axial bores except the one stud which in turn gets in front of said roller (35) and pushes back said ring-shaped half-pulley (2).

6. Cable hoisting apparatus according to claim 4,

characterized

in that the spreading disk (43) and the ring-shaped half-pulley (2) present each a row of round notches (34) which are evenly distributed along the peripheral surfaces being radially inside the cable groove (4, 5), and

in that the half-pulley (1) mounted on the shaft (3) presents a row of bores being directed in a parallel direction to the pulley axis and being arranged respectively in front of said round notches (34), and

in that the spreading elements consist of two- piece hollow studs (40) which may slide in said bores and which are kept in said respective round notches (34) by springs (42) being lodged inside them, and

in that the spreading disk (43) which is driven into rotation by the spreading studs (40) turns on a ball bearing (45) and a thrust needle cage (47) which are lodged in bearing seats being integral with the housing and whose common axis is slightly tilted relatively to the pulley axis,

in such a way that the spreading studs (40) remain retracted in their respective axial bores during the rotation until, on the side opposite to the winding arc of the cable, they jut out one after the other, against the action of the pressing devices (6), so as to push back the ring-shaped half-pulley (2).

7. Cable hoisting apparatus according to claim 6,

characterized

in that the spreading studs do not consist of two hollow pieces, but of only one solid piece (53), and

in that it comprises, instead of the spreading disk (43), of the ball bearing (45) and of the thrust needle cage (47), a thrust needle bearing (50) which also is lodged in a bearing seat being integral with the housing and whose axis is slightly tilted relatively to the pulley axis.

8. Cable hoisting apparatus according to claim 6,

characterized

in that the spreading studs do not consist of two hollow pieces (40), but of only one solid piece (53), and that the spreading disk (60) being driven into rotation by the spreading studs (53) presses, by means of a thrust ball cage (61), against a second disk (62) with sleeve (67) which is stationary relatively to the housing, and

in that this stationary disk (62) is supported by a flange (69) of a sleeve, which is integral with the shaft (3), by means of a thrust needle bearing (66) and of a ball bearing (68) which are respectively lodged in the flange (69) and in its sleeve, and

in that a face (63) of the stationary disk (62) presents an opporune tilt relatively to the pulley,

in such a way that the spreading disk (60) gets the same tilt and pushes back the ring-shaped half-pulley (2), by the intermediary of the studs (53) one after the other, on the side opposite to the winding arc of the cable.

9. Cable hoisting apparatus according to claim 8,

characterized

in that it comprises, instead of the spreading disk (60) turning with the pulley and of the second stationary disk (62) as of the thrust ball cage (61) and, respectively, of the thrust needle bearing (66) and of the ball bearing (68), a two-race thrust needle bearing (70) which leans against the flange (72) of a sleeve (73), and

in that the median plate (75) of this thrust bearing (70) is stationary relatively to the housing and presents a face being opportunely tilted relatively to the pulley, in such a way that the ring plate of said thrust bearing (70) which is located on the side of the pulley pushes back the ring-shaped half-pulley (2), by the intermediary of the studs (53) one after the other, on the side opposite to the winding arc of the cable.

10. Cable hoisting apparatus according to claim 9,

characterized

in that the bore of the sleeve (84) with flange (83) as the shaft portion (82) on which this sleeve (84) is mounted are threaded, and

in that the axial position of the two-race thrust needle bearing (70) relatively to the pulley can opportunely be modified by screwing the sleeve (84) with flange (83) against a regulating nut (85) also being screwed on said threaded shaft portion (82), and

in that the median plate (87) of this thrust bearing (70) is prevented from turning relatively to the housting by a retaining means (86) which allows it to move axially.

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