WO2000068057A1

WO2000068057A1 - Power and free conveyer system using a towing cable

Info

Publication number: WO2000068057A1
Application number: PCT/IT2000/000174
Authority: WO
Inventors: Roberto Impero; Pasquale Impero
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-05-11
Filing date: 2000-05-05
Publication date: 2000-11-16
Anticipated expiration: 2001-11-11
Also published as: IT1308895B1; ITRM990295A1; AU4610900A

Abstract

A power and free conveyer system using a towing cable for the management of loads along the rail path, comprising: a pushing device, which serves to push dollies standing still on the monorail but free to move thereon, in the forward direction; a bumping device, used to automatically open the cable gripping means of a dolly hitting another dolly from behind, the latter standing still on the monorail but being not free to move; and a manual control lever used to stop or start the movement of a dolly. The system is based on the utilization of gripping means having opposed eccentric rollers, which clamp the cable in a manner proportional to the load. The gripping means are interchangeable and bi-directional. The gripping means may interact, if necessary, with appropriate safety cams.

Description

POWER AND FREE CONVEYER SYSTEM USING A TOWING CABLE

Technical Field

The present invention relates to a modular versatile system which may be used in a dollies conveyor plant, in which the dollies are made to slide along monorails and are dragged by means of a metallic rope, in order to transfer products within the factory premises and between several work stations.

The plant to which the present system may be applied may generally comprise manual or robotized work stations, up and down vertically movable devices (elevators), switches, loading and unloading stations, zones used for maintenance works or storage, and ascendant or descendant monorail sections in order to be able to move the dollies at different levels above the ground, along the plant.

Background Art

Presently the dollies are dragged by a chain, or by a metallic rope, or form self-propelled elements moving along the monorail.

The use of a chain is not advisable in those situations in which cleanliness, economy and low noise should be the main features of the plant.

The use of self-propelled dollies requires major investments and electronic means for programming the dolly's movements, and in case of failure, somewhat expensive and complex repair work will become necessary. Moreover, plants with self-propelled dollies make use of electric wiping contacts, which may cause sparks, and for this reason they are not suited for use in explosion endangered industrial environments.

As far as plants with dragging ropes are concerned, that is plants of the same kind as in the present patent application, a remarkable drawback was due to their single grip device (or single pliers), which limited the movement possibilities of the dollies, so that, in certain operative conditions it was necessary to disconnect them from the rope and move them by means of another kind of transfer device. A remarkable progress towards increasing the dragging rope plant versatility has been made by the applicant by providing two separately actuated grip members, as disclosed in Italian patent application NA 98 A000005. By using two grip members (pliers), the dolly does not need to be totally disconnected from the rope: at the time when the dolly has to pass a drive pulley or a turn (snub pulley), a grip member remains always connected to the metallic rope.

Disclosure of Invention

An object of the present invention is to realize a versatile modular system for the management of the loads along the rail path, within plants using ropes for the aerial conveyance of dollies, according to the preamble of claim 1, and which is characterized in that it is provided with a dollies pushing device, comprising front buffers mounted on each dolly of the plant, said device being suited to push forward dollies which possibly stand still and are free to move on the rail; said pushing device comprises elastic means which are sufficiently preloaded in order to push forward said dollies which are free to move along the monorail. A second object of the present invention is to realize a versatile modular system for the management of the load along the rail path, within plants using ropes for the aerial conveyance of conveyor dollies, which is characterized in that it comprises a bumping device which operates in the situation in which a moving dolly hits from behind at least one stationary dolly which temporarily is not free to move. Said bumping device comprises opening means for opening the pliers of the dolly which bumps into the forward dolly form behind, so that the former changes from the movement condition to the rest condition, and wherein the opening of the pliers is caused by a beat portion connected to the pushing device and whose motion is transmitted to the respective pliers control (actuation) means, through said opening means.

A third object of the present invention is to provide a versatile modular system for the management of the load along the rail path, within plants using ropes for the aerial conveyance of conveyor dollies, which is characterized in that it comprises a manually operated lever mounted on each dolly, whose actuation allows the simultaneous opening of both pliers (dolly stops) and also the closing of at least one of the pliers (dolly starts moving) .

A fourth object of the invention concerns the realization of a versatile modular system for the management of the load along the rail path, within plants using ropes for the aerial conveyance of conveyor dollies, characterized in that each of the pliers of a dolly comprises at least a pair of opposed rollers which rotate in synchronism, and which are actuated by the respective control means for the pliers, by the use of cam means and/or a safety stationary element of the plant.

Particular embodiments of the pliers are defined in the dependent claims. The use of this kind of pliers allows to automatically select the clamping force exerted by the rollers on the rope, with respect to the load being carried, so as to reduce the rope deformation to a minimum. Moreover, the pliers will clamp the rope in a bi-directional manner, according to the direction of motion of the rope; for this purpose it will suffice to provide at least four rollers (two pairs of opposed rollers operating in synchronism) . According to the present invention the word "system" indicates the ensemble of devices which are responsible for the management of the conveyance function, as required by the specific plant employing them. The word "modular" indicates that this ensemble comprises a plurality of said devices, associated to the various dollies or stationary relative to the monorail, such as, for instance, a wedge element for opening the pliers in emergency situations.

Brief Description of Drawings

The objects and advantages of the present invention will be illustrated by means of a detailed description of particular embodiments of the system, which are shown in the enclosed drawings only for illustrative purposes, and wherein:

Fig. 1 is a perspective view of a conveyor dolly according to the present invention;

Fig. 2 is a fragmentary view of the only slidable front block of the dolly shown in Fig. 1;

Fig. 3 is a perspective view of the rear pliers support member;

Fig. 4 is a perspective view showing only the front or rear pliers according to the present invention, stationary cam means used for opening the pliers, and the emergency opening wedge element;

Fig. 5 is a perspective view of the pliers of Fig. 4, after removal of the cover portion situated on the right (as seen in said Fig.), in order to show the inner mechanisms ;

Fig. 6 is a plan view of the inner mechanisms of the pliers;

Fig. 7 shows the way of operation of a mechanical bistable device called "flip/flop";

Fig. 8 is an enlarged perspective view of the rear block-and- pliers combination, showing the way it is actuated: for its opening, by the bumping device, and during opening or closing, by the manual lever;

Fig. 9 is an enlarged perspective view of the front block-and- pliers combination, showing how it is actuated for causing the opening thereof, either by the bumping device or the manual lever;

Fig. 10 shows the manually operated control lever used for opening the pliers (dolly stops) or for closing the rear pliers (dolly starts); this lever is also shown in Fig. 1 in the rear part of the dolly. Preferred Embodiments

The dolly 1 includes a slidable front block 2 and a slidable rear block 2', which are both movable on a monorail 3. The two slidable blocks 2, 2' are connected to one another by means of a crosspiece 4, to which is hanged a loading platform (not shown) used to transport items along the monorail 3 of the plant. The plant we refer to, is not shown in its entirety, but it is of a kind known in the art, as has been said in the introductory part, and may include elevators, switches, ascendant or descendant monorail sections, etc. Since such means are known per se and do not constitute - if taken alone - the object of the present patent application, it is useless to describe their structure.

Each slidable block 2, 2' comprises a mounting member 5 of one of the pliers 6 or 6' respectively. Fig. 3 shows the mounting block 5 of the rear pliers 6'. The mounting block 5 of the front pliers 6 (not shown) is wholly similar to the mounting block shown in Fig. 3, the only difference being that the latter also includes the element 7 which engages a corresponding part of the bumping device, as explained later on. Each mounting member 5 has a pair of load bearing wheels 8,8' and a plurality of guide wheels 9 which laterally engage the monorail 3. The pliers is attached onto the disk 10, which may move vertically together with the cylinder 11 guided inside the cylindrical hole 12. The cylinder 11 has at its lower end a wheel (not shown), which by engagement with a lateral cam 13 of the monorail 3, causes the disk 10 to move upwards or downwards. The cam 13, as illustrated, has a minimum extension, but this is obviously only illustrative; the wheel of the cylinder 11 engages the lower surface of the cam 13, and the latter presents two inclined portions 14, 14'. The cylinder 11 is always biased upwards by means of a spring which is not shown. Obviously, in practice, the cam 13 is provided for instance along the whole curve (turn) of the monorail 3, in the presence of a snub pulley, or alternatively, it has the required extension. While moving downwards, the disk 10 allows to totally disengage the respective pliers from the rope 15, after its opening has been carried out by the pliers opening cam means described afterwards.

The pliers 6, 6' open and close in succession when the dolly 1 turns, and they disengage from the rope 15 by moving vertically downwards after opening. Apart from the fact that different mechanisms are used, the operation is generally similar to that disclosed in the above mentioned patent application by the same applicant, according to which the front pliers opens just before the turn, disengaging from (moving downwards with respect to) the rope, and then moving upwards and closing (after the turn) before the opening of the rear pliers. In this way the dolly is continuously dragged. The crosspiece 14 is mounted in an articulated way at 16, 16' and 17, 17', thereby allowing the dolly 1 to turn and move along upward (or downward) slopes. As shown in Fig. 2, the front slidable block 2 has a small box-like frame 18, connected by means of the articulated joint 19 to the front portion of the front block 2. The articulated joint 19 allows the small frame 18 to rotate both in a horizontal plane (parallel to the upper surface of the monorail) and in a vertical plane. The small frame 18 is also provided with guide wheels 9 and a load bearing wheel 8". It is therefore obvious that the small frame 18 does not hinder the movement of the dolly 1 while the latter turns or when it enters a slope inclined upwards or downwards. On the small frame 18 there is mounted the pushing device, comprising a buffer 20, formed by two rods 21 integral with the support 22, which is movable inside the small frame 18. The rods 21 can slide inside the small frame, being guided at the front and rear end of the latter. Helicoidal springs 23, coaxial to the rods 21 and sufficiently preloaded, allow to push forward a front dolly which is stationary but free to move along the monorail 3, by means of the buffer 20, which will engage the portion 24 shown in Fig. 3. The support 22 is integral with the beat portion 25, which also moves backwards (but only temporarily) during the impact with a front dolly.

The beat portion 25 is part of the bumping device. This device will be described later on.

The pliers 6 or 6' and its various mechanisms, and the opening and closing cams with sloping surfaces, are shown in Figs . 4 to 7. The pliers, according to their "standard" form (possible variants will be explained later) include six gearwheels, 26(1) to 26(6), which engage a central rack 27, which we shall also call from now on "pliers actuation member". At one of its ends, the rack 27 is provided with a roller 28 suited to engage cams 29 with sloping surfaces. Said cams 29 may be either of a stationary (fixed) or of a movable kind, and are connected to the plant structure. When the roller 28 moves along the sloping surface 31, inside the respective guide, the pliers opens in consequence of the displacement of the rack 27. When the roller 28 slides along the sloping surface 30, the pliers will clamp the rope 15, due to the displacement of the rack in the opposite direction. These two displacements of the rack in opposite directions, are indicated by the double arrow of Fig. 6. The cam 29 will be located for instance before a turn, in order to ensure that the pliers will open in proximity of a snub pulley. Rollers 33(1) to 33(4) with circular peripheral grooves, are fixed in an eccentric manner, by means of pins 32, onto the gearwheels 26(1) to 26(4). Fig. 6 shows for instance, that when the rack moves to - li ¬

the right towards the position indicated by the solid line, rollers 33(1) and 33(3) approach each other, thereby clamping the rope 15 (Fig. 4). This is due to the fact that the gearwheels and the relative rollers rotate as a single body, and the gearwheel 26(5) induces a rotation of the gearwheel 26(3), opposite to the rotation of the gearwheel 26(1).

Similarly, for the same reason, due to the fact that the device is symmetrical, also the rollers of the second pair 33(2), 33(4) will move in synchronism, thereby clamping the rope 15 by means of their respective groove (the clamping position of the rollers is shown by a continuous line). Therefore, the pliers open when the rack moves to the left in Fig. 6, and closes in the opposite direction of displacement of the rack.

In Fig. 4 and in Fig. 5 it may be noted that the rollers 33(1) and 33(3) have pegs 34 allowing the opening of the pliers in emergency situations, in consequence of the pushing force exerted by the wedge 35 (Fig. 4) which is fixed to the plant structure.

Thus, in the event of a defect of the small roller 28, the wedge 35 - which may be placed e.g. in front of a turn - ensures that the pliers will open by causing the rollers to rotate to the disengagement position.

Otherwise, the pliers would hit the snub pulley or the drive pulley, as the case may be, thereby causing damage to the rope, the motor, etc. The wedge member is a safety device in presence of stationary obstacles. In Fig. 4 it may be noted that a second small roller 37, mounted on the opposite side of the pliers, prevents the pliers from being subjected to the action of a single force, in a single direction, by sliding inside a guide 38 which is parallel to the rope when the rack displaces itself, and thereby acting as a stop. Turning now our attention again to the internal mechanisms of the pliers, the latter comprises also a bistable device (Fig. 7), which we may call a mechanical "flip-flop", including two helicoidal springs 39 mounted on small shafts or spindles 40, freely slidable inside the rotation pins 41 of the gearwheels 26(5), 26(6), but integral at their opposite end with the connection elements 43, which form an articulated joint with the small plate 27(1) fixed onto the rack 27. It may be noted that the rack can assume two stable positions, by passing through a central instable position (maximum compression of the springs 39; axis X-X in Fig. 7). In this manner it is possible to define the two positions associated to the opening and closing of the pliers respectively.

The pliers which have been just described have the advantage of employing a single control means (small roller 28 in Fig. 6) which acts on all inner mechanisms. The pliers are very reliable and allow to distribute the load on separate mechanical components (rollers). Moreover, these pliers form an interchangeable module, and for this reason they facilitate maintenance of a plant using a circulating rope.

The pliers may be used together with emergency opening devices (wedge 35) fixed to the plant structure. Two further important features of the pliers will be described in the following paragraphs, that is: - the clamping force of the pliers is automatically determined by the load which is carried, so as to obtain a minimum deformation of the rope; - the bi-directional feature: the pliers clamps the rope in a bi-directional way, adapting its operation to the direction of movement of the rope.

Suppose first that the rope 15 moves in the direction of the arrows F of figs. 4 and 6 (and imagine that the devices 29, 35 of Fig. 4 are not present).

If the dolly 1 enters an upwardly inclined section, the velocity Vc of the dolly 1 tends to become smaller, and since the rope has a constant velocity Vf , the friction between the rollers 33(1), 33(3) and the rope 15 causes a further small rotation of the rollers towards the rope clamping position, and the rollers 33(2), 33(4) are consequently rotated in the clamping position as well. It follows that the velocity of the dolly automatically adapts itself to the velocity of the rope. The same considerations hold similarly for a downwardly inclined monorail section, where the velocity Vc of the dolly initially tends to exceed the velocity Vf of the rope. It may be deduced that if the arrow F indicates the direction of motion in this case too, but this time the motion occurs along a downwardly inclined slope, the rollers 33(2) and 33(4) clamp the rope due their friction with the rope 15, and the clamping force will be proportional to the load, which in this case comprises the weight of the dolly 1.

It may be observed that Fig. 6 shows the position of the rollers 33 in the condition in which a maximum force is applied to the rope (the pins 32 are located along the line joining the rotation pins 41 of the gearwheels). Actually, the rollers 33 may assume intermediate positions, between the position which is indicated and the position in which the rope is touched for the first time (the latter position is not shown). On the other hand, the bi-directional feature of the pliers implies that they can accomplish all their tasks even if the direction of motion of the rope is inverted. In other words, even if the direction of motion of the rope is inverted, the pliers will clamp the rope by the application of a force which is proportional to the load being carried, as may be easily deduced from the drawings. It may be observed that the bi-directional feature allows one to stop the dolly on a sloping section of the monorail, in the motionless condition of the rope.

The standard form of the pliers which is shown in the drawings, may be modified by including only two opposed rollers, or adding other pairs of rollers (overall number of six or more rollers) or by putting two standard pliers side by side.

Generally, it will be obvious that the load on the rope is distributed according to the number n of rollers 33 being used.

The plant to which the versatile modular system of the present invention is applied comprises, besides the above mentioned stations, also one or more dollies accumulation stations located along the monorail on which the dollies displace themselves. Said accumulation stations serve for a versatile and planned management of the dollies traffic. For this purpose, besides the pushing device allowing to push a dolly (which is motionless and free to move on the monorail), in the forward direction, to an accumulation station, there is also provided a bumping device, which is also included in the system of the present invention. The bumping device intervenes and automatically opens the pliers of the dolly which crashes into the front dolly from behind. In this manner the dollies will automatically become connected to each other, due to the fixed hook 44 of the bumping dolly , which will be "harpooned" by a vertical plane (7) located on the rear part of the dolly which has been hit from behind. The bumping device comprises, as already mentioned, the beat portion 25, which displaces itself until it hits the bell crank 45 provided with the roller 46. The bell crank rotates around the rotation center 47 and in clockwise direction in the representation of Fig. 2, thereby moving the rack 27 of the front pliers 6. Thus, when a stationary dolly which is not free to move, is hit from behind, the rack 27 will be pulled and the front pliers 6 will open. The rear pliers 6' will open as well, due to the fact that a control cable 49(1) connecting the bell crank 45 of the front pliers 6 to the bell crank 45' of the rear pliers 6' (Fig. 1), is pulled. In more detail, the control cable 49(1) is movable inside guide sheaths (similarly to bike brakes). The rotation of the bell crank 45 will produce a traction force on the control cable 49(1), which displaces in turn a rod 50 mounted on the crosspiece 4, in the direction of the arrow A. A control cable 49(4), which is also connected to the rod 50, pulls on the opposite end a spline 51 (Fig. 8), in the direction of the arrow A (opening operation), thereby causing the clockwise rotation of the bell crank 45'; the latter, by rotating around the pin 47 , pushes the rack 27 in the outward direction (Fig. 8, opening direction A).

Note that if the front dolly is free to move, the beat portion 25 will not be able to rotate the bell crank 45, since the springs 23 of the pushing device are not compressed by a sufficient amount. Moreover, in this case the coupling of the dollies will not occur.

Observe that the slotted bell crank 48 has a slot 52 which serves for the purpose of rendering independent the movements of the small roller 28, when the pliers are opened for instance by a cam with sloping surface 29. In other words, when the cam 29 (Fig. 4) which is located at a fixed position with respect to the stationary frame of the plant and at a higher level than the components 45', 48, pulls the rack 27 in the outward direction by means of the small roller 28, the bell crank 48 will stand still due to the presence of the slot 52. This allows to limit the amount of displacement of the components and consequently their wear, and at the same time to reduce the risk of failure.

A dolly arriving at an accumulation station will couple to the preceding dolly. An accumulation station could for instance be a waiting station. The plant may comprise various accumulation stations, serving to distribute the dollies and to avoid the accumulation of a high number of dollies on the same station; this is also important because all dollies in a station will have to be dragged by the first of them. The first dolly in the row, or possibly a single dolly which is present in a waiting station, will be started by means of an electromechanical command, that is by actuating a ratio-motor; the latter moves away a stop which had caused the stopping of the dolly in a predetermined position, and rotates a cam 29 with inclined surface, which at this time is in the opening position. The first dolly of a row of dollies which are present in an accumulation station, drags the other dollies until the second arrives at the waiting position; the first dolly will then be caused to start alone, due to the fact that a beat surface (not shown) lifts the hook which engaged the fixed hook 44 of the rear dolly. A further feature of the modular system of the present invention is the manual lever shown in Fig. 10. The manual lever 53 is mounted on the rear side of the dolly 1, and if it is actuated in the direction of the arrow A, it will open both pliers 6, 6' simultaneously. Instead, if it is rotated in the opposite direction C, which coincides with the normal direction of motion of the dollies, it will cause the closing of the rear pliers 6' alone. Note that an operator can actuate the lever in the direction A even if he keeps his arm still, since the direction A is normally opposite to the direction of motion of the dollies 1. In more detail, the manual lever according to the embodiment shown in fig. 10, operates as follows. We describe first the operation in the direction A, which causes the opening of both pliers.

An elastic pushing means (not shown) biases and positions the lever 53 towards the center of its seat 54. The lever 53 acts on the connection pin 55' of the small block 56 which is connected in turn to a control cable in the sections indicated by 57(1) and 57(2), which, as shown in Fig. 8, exert a traction force on the U-shaped bracket 58, thereby moving the latter in the direction of arrow A. A small quadrant 48 rotates then clockwise around the rotation pin 59 and displaces the rack of the rear pliers in the outward direction. The front pliers open as well, for the following reason: with reference to Fig. 10, the small block 56 is also connected to a slidable rod 60 transmitting the motion through a lever 61, to a second slidable rod 50. The displacement in the direction A of the rod 50 causes -as has been shown for the bumping device - the opening of the front pliers, as a consequence of the traction exerted on the control cable 49(2) (even if for the bumping device the control cable 49(1) controls the movement of the rod 50 and not viceversa). For the closing operation (direction of the arrows C in the figures), the control cable 57(2) acts on the U- shaped bracket 58 of Fig. 8, and through the quadrant 48 (elbow-like lever), it closes the rear pliers. The manually operated lever increases the versatility of the plant, since it allows an operator to stop or start the dolly in any location of the plant which is accessible to the operator. If the operator stops a dolly by means of the manual lever, he need not worry about any second approaching dolly; in fact, the latter will push the first dolly in the forward direction to the waiting or accumulation station. The system may be obviously modified in various ways, without thereby extending outside the scope of the same inventive concept.

The manual lever could also be realized in such a way as to close both pliers simultaneously, even if this is not required because the plant comprises in any case cams having slanted surfaces similar to those indicated by 29, which will be responsible for closing the pliers. In case of failure of the plant, due to the fact that a dolly does not start from a waiting station, the various dollies accumulation stations will be used. The present invention ensures a greater versatility ("flexibility") of operation of plants using a circulating rope, as compared to conventional systems. Further advantages of the invention will also become obvious to those skilled in the art, when the present invention is put into practice. The overall length of the plant may also reach several hundreds of meters and preferably the dollies are moved forward at regular intervals.

Claims

1. A versatile modular system for the management of the load along the rail path, within plants using ropes for the aerial conveyance of conveyor dollies, comprising waiting stations, up and down moving elevators, turns, upwardly inclined sections, downwardly inclined sections, work stations, switches, loading and unloading stations, maintenance and storage stations for the dollies, characterized in that said dollies (1) present a pushing device (20, 21, 22, 23, 24) provided with front buffers (20) mounted on each dolly (1) of the plant, and suited to push in the forward direction dollies which possibly stand still on the monorail (3) and are free to move thereon, said pushing device (20, 21, 22, 23, 24) including elastic means (23) which are sufficiently preloaded, in order to push forward the said dollies (1) which are free to move along the monorail (3).

2. A versatile modular system for the management of the load along the rail path, within plants using ropes for the aerial conveyance of conveyor dollies, characterized in that it comprises a bumping device which intervenes in the event that a dolly hits at least another dolly from behind, and the latter is not free to move on the monorail, said bumping device comprising means (25, 45, 49, 50, 51, 45') for opening the pliers (6, 6') of the dolly (1) hitting the other dolly from behind, so that the former changes from the moving condition to the rest condition, and wherein said opening of the pliers (6, 6') is caused by a beat portion (25) whose motion is transmitted to the respective control members (27) of the pliers (6, 6'), by said opening means (25, 45, 49, 50, 51, 45' ).

3. A versatile modular system for the management of the load along the rail path, within plants using ropes for the aerial conveyance of conveyor dollies, characterized in that it comprises a manual lever (53) mounted on each dolly (1), which serves for the simultaneous opening of the pliers (6, 6') of a dolly, by the transmission (45, 48, 49, 50, 51, 57, 58, 60, 61) of the rotational motion (A) of the lever (53), to the control members (27) of the pliers (6, 6'), or for the closing (57, 58) of at least one pliers (6') in the opposite rotational direction (C) of the manual lever (53).

4. A versatile modular system for the management of the load along the rail path, within plants using ropes for the aerial conveyance of conveyor dollies, characterized in that each of said pliers (6, 6') of a dolly (1) comprises at least a pair of rollers (33(1), 33(3);

33(2), 33(4)) which rotate in synchronism, when they are actuated by a respective control member (27) of the pliers, the said rollers clamping the rope (15) when the pliers is closed , by rotating in an eccentric way with respect to their center (32).

5. A versatile modular system according to claim 2 or 3, characterized in that a dolly comprises two or more pliers (6, 6' ) .

6. A versatile modular system according to claim 5, characterized in that cams having sloping surfaces (29), located in proximity of obstacles, act directly by means of small rollers (28) on the pliers control members (27), without simultaneously actuating the levers (45, 45', 48), and thereby limiting mechanical wear of the mechanisms.

7. A versatile modular system according to claims 4 and 5, wherein safety control means (35) are provided, which act directly on the rollers (33) clamping the rope (15).

8. A versatile modular system according to claim 2, wherein the bumping device is associated to an automatic hooking or coupling device (44) for connecting the dolly which is hit, to the hitting dolly.

9. A versatile modular system according to claim 4, wherein the pliers (6, 6') comprise at least a second pair of rollers (33), in order to clamp the rope in more than a single point, and thereby better distribute the load .

10. A versatile modular system according to claim 4, wherein the pliers comprise a bistable device (39) having springs, defining the clamping and the release position of the eccentric rollers (33) with respect to the rope.

11. A versatile modular system according to claim 9, wherein the pliers are bi-directional, that is, the rollers (33) clamp the rope with a force proportional to the load being carried, independently of the direction of movement of the rope.

12. A versatile modular system according to claims 4, 5, 6, 9, 10, 11, wherein the pliers control member is a rack (27) which engages gearwheels (26) onto which are mounted the rollers (33) in an eccentric way.

13. A versatile modular system according to claim 4, wherein the pliers form interchangeable modules, which facilitate the maintenance of the plant.

14. A versatile modular system according to claim 3, wherein the manual lever is mounted on the rear part of the dolly, and the direction of actuation (A) of the manual lever (53) for opening the pliers (6, 6') is opposite to the direction of motion of the dollies (1).

15. Plant making use of a versatile modular system according to any of the preceding claims, characterized in that it is provided with dollies (1) accumulation stations, for a versatile and planned management of the dollies traffic.