ES2598881A1 - Device to protect from damage the steel cables and avoid their departure, by desalination, from the dumping of the pulleys (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

The device for protecting the steel cables from damage and preventing their exit, by misalignment, from the shearing of the pulleys is based on the oscillation, limited by a stop mechanism, of the side protection plates on the fixed shaft, as well as in the interaction between the cable and the outer sheaves. With the arrangement of the sheaves on the outside of the side protection plates, both the device is kept centered to cushion the whip effect of the cable, and the cable outlet of the channel is prevented, in case, due to lack of tension, misalign The risk of shear cutting of steel cables is completely eliminated and the possibility of the cable being damaged as it passes through the pulley is reduced. Under normal conditions of use, the pulleys rotate freely without the protection device invented becoming operational. (Machine-translation by Google Translate, not legally binding)

Description

image 1

D ESC R IPC IÓN

DEVICE TO PROTECT THE STEEL CABLES FROM DAMAGE AND AVOID THEIR OUTPUT, BY DESALINATION, OF THE CHANNELS OF THE PULSES

5

SECTOR OF THE TECHNIQUE

The present invention is applicable to any sector of the industry where pulleys are used to guide steel cables. This invention has been developed particularly 10 for application in the naval sector. More specifically to increase safety in the launching and recovery of lifeboats, liferafts and rescue boats. It can be used in any type of davit or launching ramps that have pulleys to guide the steel cables. It is also applicable to the pulleys that are used to guide the steel cables that are

15 have for the remote actuation of the brake in the afloat of the rescue devices that equip the ships.

STATE OF THE TECHNIQUE

20 The problem of safety in the launching and recovery of rescue means on ships is quite complex. Among the many conditions to take into account, the characteristics of the devices used are transcendental. The rig generally used in conventional gravity davit consists of a simple pulley system on each arm. The function that is performed with

25 single pulley rigs is double; on the one hand move the arms of the davit outside and on the side of the ship and on the other the launching and recovery of lifeboats and rescue. To perform these synchronized functions in the two arms of the davit, a variable number of guide pulleys are available through which the steel cables work, and can be damaged and / or sheared at rest or at their rest.

30 passed through the mentioned pulleys, in the event that a misalignment took place. If this occurs, the cables may be forced to pass between the edge of the pulley and the normally installed protective device to prevent the cable from exiting the channel. Damaged cables reduce their breaking load and can break by traction or be sheared more easily. The accidents that occur are of

35 catastrophic consequences, including damage to very serious and fatal people.

image2

In the IMO / MSC1326 (International Maritime Organization / Maritime Safety Circular Committee) clarification of rule III-19 of the SOLAS (International Convention for the Safety Of Life At Sea) agreement it was agreed that the assigned crew should not be required to be on board the lifeboat during the launching in training and maintenance exercises 5. The aforementioned recommendation has its origin in the large number of incidents and accidents that occurred during the performance of maintenance tasks and periodic mandatory abandonment and rescue exercises. The periodicity of these operations is determined in the maritime regulations. These tasks are planned in the way that least interferes with the commercial activity of the

10 vessels, generally carrying out operations involving movements of davits, in the calm waters of the port with the ship docked or in anchorages, with good weather conditions.

In the review of numerous published Technical Reports in which they are analyzed

15 accidents caused by the breakage of the suspension cables, the cause is generally attributed to their deterioration due to corrosion, due to poor maintenance or poor quality of the cables used. However, the detailed and critical study of the aforementioned Technical Reports together with the experience accumulated by professionals in the sector, makes it determined that the devices generally

20 employees to prevent the exit of the cables from the throat of the pulleys can cause damage or cutting of the cables by shear, particularly when they are affected by corrosion.

In the 2006 amendments to SOLAS, the maintenance of the power cables is reviewed

25 steel (SOLAS III / 20) introducing a new wording that establishes, among other criteria, that special attention should be given to the sections of steel cables that pass through pulleys. It is recognized in this way that the cables can be damaged as they pass through the guide pulleys or while resting on the throat of the pulleys, in the area of the arc of contact between cable and pulley. Be

30 recommends extreme inspections to detect any damage in advance. These damages can have their origin in different causes: crushing if tension is not released once the boats have been stowed, rubbing the pulleys throat, increased corrosion in the areas where the saltpeter can accumulate, damage or even shearing by misalignment and exit between cable covers or protections

35 arranged to prevent the exit of the gutter.

image3

On May 26, 2006, the IMO published the MSC1206 subsequently revised by the MSC.1 / Circ.1206 / Rev.1 of June 11, 2009. In the first paragraph seven groups are listed in which the accidents with boats are framed Lifeguard and rescue boats. Among the same figures in No. 7, “Design failures other than

5 those related to tension release devices ”. It is explicitly recognized that approved devices may have design flaws. In this context and observing the wide variety of protection devices used to prevent damage from misalignment of steel cables, it can be concluded that an accessory that is effective and safe has not been achieved.

10

TECHNICAL PROBLEM PROPOSED

In conventional davits with two single pulley rigs, a variable number of pulleys are mounted to guide the steel cables. The ends of the two 15 steel cables remain firmly rooted in the davit structure. From the rooted, the cables are guided by a series of pulleys conveniently distributed on the structure and arms of the davit, passing through baffles with rings to attach the rigs to the loose devices installed in the lifeboat at their bow and stern ends . The cables finish their journey

20 winding on both winch drums. The recovery of the boats and movement of arms to the stowage place is achieved using engines that drive the winch.

Steel cables when working on pulleys can be misaligned by different

25 causes, among which are identified: a) Cable without tension - at a given time, riding on the edge of the pulley. This can occur during periodic maintenance tasks in which the cables are left without tension when the boat is suspended by means of the cables arranged for this purpose. The cables may also remain

30 partially without tension if more than necessary is diverted to dock the boat to the side, to the boarding place when this is not the stowage, being suspended from the rigging or approach cables. Another example appears in cases of abandonment in adverse conditions, when the landing speed is affected by the inertia of the ship's movements; be

35 cause variations in the tension of the cables so that they can run out of tension and misalign in tenths of a second. In these cases and according to the davit used, it can happen that, when tension is generated again in the suspension cable, it can jump the pulley from the spout of the davit arm, being stuck between the edge of the pulley and the element

image4

5 protection installed in each case. In the recovery maneuver and just at the moment when the pasteca joins the davit's arm and begins to swing inside, the pulley that had the cable trapped begins to rotate, being able to damage or shear the cable. b) Whip effect - when violent movements induced to the cable, it

10 ditches in such a way that it can mount on the edge of the pulley. This can occur when the suspended boat is affected by violent movements caused by the balances and pitching of the ship in cases of unfavorable or adverse conditions of the sea. Whips are also generated in the cables when the davit's arms are affected by

15 irregular and violent movements. c) Obstruction in the sheave of the pulley - the formation of ice, for example, on and around the tensionless cables, as well as in the sheave of the pulleys, can be the origin of important misalignments.

20 To prevent the cable from leaving the pulley throat, different protection elements are used: straight or curved roof tile with steel plate, round steel cab, U or L shaped steel plate centered and fixed on the shaft from the pulley or welded to the structure, more or less sophisticated cable guards, cable guides, etc. Almost as many types of protective accessories can be found in the sector as

25 different manufacturers of davit. Characteristic of all of them is the adjustment on the pulley, which must be smaller than the diameter of the cable used in each case.

In the peak of the arms there are also guides to avoid misalignment due to variations in the working angle of the steel cables with respect to the gutters

30 of the pulleys installed at that end, which are compatible with the installation of the invention object of the patent. The different angles contemplated originate from the relative movement between the boat and the ship at the time of launching, particularly in adverse conditions of the sea.

35

image5

The mentioned accessories are effective and a priori do not generate risks when used in optimal conditions; absence of balances and headings of the ship, particularly in tests or exercises in calm waters. For example, in the case of a tile-like protection device, if the cable, without breaking, jumps out of the throat and passes between the edge of the pulley and the protective device, it is admitted that the risk can be controlled: the cable is trapped on its axis if it is on the inner side, and if it is on the outside, the guide pulley stops fulfilling its function, so that the cable works on the previous and the next pulley. In addition, if the malfunction is noticed by the operator and immediately stops the drive

10 of the winch, the breakdown can be limited to damage the cable, its change being generally necessary. In other cases, the most likely for a cable in good condition, is that the safety devices automatically stop the operation of the winch, reducing the possibility of breakage of the cable damaged by traction.

15 Extreme danger occurs when the pulleys are protected in their work area by any of the aforementioned accessories, particularly in cases where these accessories are highly resistant to bending and / or bending: in the case where the cable while the pulley rotates, and is forced to pass under the tile or protection, the created shear comes into operation. If also the steel cable

20 has some corrosion or lack of grease, the consequences are exponentially aggravated.

Conventional davits also have a system to activate the winch brake remotely. The most common is that this system is formed by a 25-diameter steel cable, with one of its ends fixed to the brake lever and which, guided by a series of pulleys conveniently distributed on the structure and arm of the davit, end in the boat's steering position, from where the brake is activated for remote afloat. The brake lever on the winch has a calculated counterweight so that when the tension on the cable is released, braking is activated, this being the resting position when there is no intentional action by the operator to open the brake. The cable is maintained with a slight tension only with the counterweight, generally forming the pull handle, at the drive end, calculated so that it does not lift / activate the brake. To be able to apply the brake during the entire movement of the boat, from its stowage place 35 to the float, it is necessary to have a sufficient cable length that

image6

coil in a drum that rotates synchronously with the winch for the suspension cables. The pulleys to guide the remote brake actuation cable are complemented with protections similar to those used in the guide pulleys for the suspension cables. The problems generated by misalignment are similar to those described for suspension cables, except for shear cutting, given that the voltages and the type of pulleys used are of different characteristics. The most frequent consequences are the blocking of the entire remote drive system, both in the position of the brake lever activated and deactivated, which prevents controlling the speed in the afloat or in other cases the drive to remotely lift the brake lever

EXPLANATION OF THE INVENTION

It has been determined as a priority objective to provide a device that is both robust and simple that protects the steel cables from damage and the output by misalignment of the sheave of the pulleys, increasing efficiency, reliability and safety in maneuvers performed with davits. , both in training exercises and in maintenance tasks and in their use in cases of abandonment of the ship in adverse conditions of the sea. The invention is applicable both to the guide pulleys for suspension cables, as well as to the guide pulleys for remote control cables of the winch brake.

Once the conclusion stated in the previous paragraphs is reached, it is determined that there is the possibility of improving the designs of the known systems or accessories for the protection of steel cables within the indicated context. It is considered that the element object of the invention can replace existing protection accessories when it is determined that they may damage the cables or block the entire system for the launching and recovery of the rescue and rescue devices, It could be the cause of serious accidents.

The main advantage of the present invention is that its oscillation makes it possible to reduce and / or eliminate the possibility that the steel cables can be damaged or cut by the shear that is created with the most generalized systems to protect the cable exit from misalignment. Other advantages are:

image7

• The device allows you to realign the cables when, for any of the identified reasons, they have left their alignment, to continue functioning normally.

• The device forms a single element that completely replaces the previous 5, fulfilling the same functions.

• The device only interferes if necessary. Otherwise, the mechanism works normally, being effective for the same heel angles as the conventional mechanism.

10 In order to achieve the objectives and avoid the inconveniences mentioned in the previous sections, the invention proposes a device that essentially comprises a fixed axis, lateral protection plates, rollers, rotation angle limitation elements and elements of swing top. It also retains the following existing components in davit

15 conventional: standard guide pulleys and steel cables. The configurations of the guide pulleys and the alignments of the cables that correspond to each installation are also preserved, so that the cable makes the same route respecting the working angle of the steel cable on each pulley. The aforementioned elements are detailed below.

The standard pulley and the rest of the components comprising the invention are mounted on a new shaft with flange for attachment to the location of the corresponding structure. The shaft has grooves to fix the swing stop elements and the element for closing the assembly on its outermost part.

25 The swing stop elements have the function of interrupting the rotation of the device at the point where the direction of the oscillation must be reversed so that the cable continues to work normally on the pulley. This takes place in the case where the cable itself in contact with the sheaves has not stopped turning. its

30 configuration is circular, with a reduction in its diameter in the sector where the angle of rotation element oscillates. The physical limitation of the turn is necessary to ensure that, in any case, the pulley will work in an ordinary way and to realign the cables preventing them from being damaged.

35 The angle of rotation limitation elements are arranged to limit the oscillation of the

image8

device at a certain angle, when it oscillates to dampen the whip effect. Its geometry corresponds to that of a ring with an outstanding sector inside, whose measurement determines the angle of oscillation allowed. This measure can be variable depending on the angle of rotation you want to allow. The angle of

5 selected swing allows the mechanism to work under the same heel conditions under which it could work with the devices currently installed. The oscillation angle limitation element must be rigidly attached to the side protection plate.

10 The side protection plates are two equal elements, mounted on either side of the pulley, made of stainless steel sheet or other material of similar characteristics in terms of mechanical resistance and oxidation resistance, rigidly joined together. Its geometry is circular and hollow inside with an outstanding sector equal to that of the angle of rotation limitation element, so

15 that in the assembly, both are perfectly aligned. In this way, each plate reinforces the corresponding angle of rotation limitation element in contact with the oscillation stop element. Its main function is to prevent the exit of the steel cables from the pulley, maintaining their alignment on the groove. They have holes in their outermost area for the location of

20 rigid bushings on which the rollers will be mounted. The number of holes in the side protection plates allows changing the arrangement of the sheaves, adapting the invention to the characteristics of each location in terms of working angle of the steel cable on the pulley.

25 The function of the bushings is to maintain the distance between the lateral protection plates and to provide robustness to the assembly against stresses in the axial direction.

The placement of the rollers depends on the angle of work characteristic of each location, so they are installed in the place where the functionality is ensured

30 total of the invention. As many sheaves are arranged as necessary to cover the functions listed below: 1) Prevent the exit of the pulley throat cable (2, 3, 4-Figure 4). These rollers function as a physical limit outside the assembly. The rollers that fulfill this function are those that, in the rest position,

35 are located immediately above the cable at the inlet and outlet of the pulley (2, 4 - Figure 4) and the one or those located between these two (3 - Figure 4).

image9

2) Keep the assembly in its effective position (1, 2 and 4, 5 - Figure 4). Rollers are provided that keep the protection device in the position for which it is designed, so that the axis of symmetry of the assembly coincides with the bisector of the angle formed between the input and output of the resting cable. When the device oscillates, the sheaves in contact with the cable at its point of entry and exit force the mechanism to return to the effective position. The rollers that fulfill this function are those located limiting the cable to its input (1, 2 - Figure 4) and output of the pulley (4, 5 - Figure 4).

3) Cushion the whip effect (1, 2 and 4, 5 - Figure 4). The tensions that are generated by the whip effect, caused by the violent three-dimensional movements of the ship in cases of maneuvers in unfavorable sea conditions, or by any other anomaly, are damped with the oscillating movement of the lateral protection plates, causing the Sheaves exert a force on the same cable, absorbing the tension generated by the whip effect continuously, without causing damage to the cables.

The device has a greasing system to lubricate the moving parts. The lubricant application point can be on the center of the shaft or on the connecting flange, this location being more suitable to have remote grease piano hoses.

In a preferred embodiment, the fixed axis and the swing stop element closest to the davit arm can constitute a single element, simplifying the structure of the device and making it more robust.

In another preferred embodiment, a side protection plate and an angle of rotation limitation element can be replaced by a stamped sheet so that the central part takes the form of the angle of rotation limitation element. When this part remains in a plane higher than that of the surface of the plate, an oscillation stop element is placed inside. This element has a relief that limits the oscillation of the assembly to its contact with the thickness of the stamped sheet.

image10

In another preferred embodiment, the angle of rotation limitation element is not installed. Either the side shield plate of a greater thickness is manufactured to support the loads, or the turning angle limitation element is not necessary because the force distribution can be absorbed by the plate itself, because it

5 inside copies the geometry of the angle of rotation limitation element.

Figure 5 shows the device object of the present invention installed on the arm of a conventional davit. The position of the innovative device in its assembly at each location is determined so that the axis of symmetry of the assembly coincides with the bisector of the angle formed between the entrance and exit of the

10 cable at rest.

BRIEF DESCRIPTION OF THE DRAWINGS

To complement the description that is being made and in order to help a

A better understanding of the features of the invention is accompanied as an integral part of said description, a set of drawings of a preferred example of practical embodiment of the invention where, for illustrative and non-limiting purposes, the following has been represented:

Figure 1 shows a perspective of a possible embodiment of the device according to the present invention. Figure 2 shows a cross-sectional view of the fixed axis, in which the oscillation mechanism of a possible embodiment of the device can be seen. Figure 3 shows a detailed view of a possible embodiment of the device in the

25 that shows the exploded view and numbering of the different elements in which it is composed. Figure 4 shows a sectional view of the detail of the position of the sheaves, in relation to the angle formed between the entrance and exit of the steel cable to the pulley, of a possible embodiment of the device. In the case represented, the cable presents

30 an angle of 90º between the entrance and the exit. The point of application of the resultant contact force between the cable and the pulley is also indicated. Figure 5 shows how a possible embodiment of the device must be mounted on the arm of a davit, keeping the previous anchor point, for a rig with a simple pulley system.

35

image11

PREFERRED EMBODIMENT OF THE INVENTION

Observing Figure 3, and according to the numbering indicated, an example of a preferred embodiment of the invention is shown, which comprises the parts and elements indicated and described below:

-fixed shaft (1) of diameter corresponding to the pulley to be used, with longitudinal grooves (1C), to rigidly join the swing stop elements (3) by means of mechanical key-type fasteners (11). In the outermost part of the shaft a transverse groove (1D) is machined for the

10 Close the entire assembly with a drilled plate (12) and secured in position with screws or tapered pins (13). This component is completed with the flange (1A) for fixing the shaft to the davit's arm using screws

or welding. The flange has two holes in the part where the diameter is smaller (1B), by means of which the oscillation stop element (3) is fixed with screws or conical pins together with the closing disk of the assembly (2) more next to the module to which the device will be fixed. The diameter of the flange in its diameter reduction zone (1B) must be at most equal to the smaller diameter of the oscillation stop element (3), to interfere as little as possible with the oscillatory movement of the side protection plate

20 (4), - oscillation stop element (3), mounted on the fixed axis (1) and integral with it, and of a thickness equal to the sum of thicknesses of the side protection plate (4) and the element of angle of rotation limitation (5). Its circular geometry, with a sector of 180 degrees in its largest diameter, allows to stop

Mechanically, the oscillation of the device, admitting, in the case of the preferred embodiment shown in the figure, the oscillation of the device from an angle of up to 45 °. The material from which it is made must allow the side protection plate (4) and the rotation angle limitation element (5) to slide over it. Two are placed, in the case of the preferred embodiment

30 represented, at both ends of the device and each has two holes to fix to it the closing disk of the assembly (2), both by the innermost and outermost part,

- side protection plate (4) made of stainless steel sheet or other material of similar characteristics, of a thickness sufficient to withstand the maximum effort. It is mounted on the fixed shaft (1) and sits on the

image12

swing stop elements (3). Its development is symmetrical, with two circumferences joined by a rectangular sector whose interior copies the geometry of the rotation angle limitation element (5), so that the projecting sector that acts limiting the rotation coincides with that of the limitation element of angle of rotation (5). Thus, the internal geometry of the lateral protection plate reinforces the angle of rotation element (5) in its contact with the oscillation stop element (3). Inside the standard pulley (6) with its corresponding bush (6A) is mounted. The plate has holes (4A) made, in the case of the preferred embodiment shown in the figure, every 10 degrees, in both circumferences. In this way the device can be used for different working angles of the steel cable that works on the pulley (6), since the holes (4A) allow to install the sheaves (8) in different combinations. The center of the holes is located on a circumference concentric to the fixed axis and of a radius such that the adjustment between the diameter of the sheave and that of the standard pulley is almost total,

- Angle of rotation limitation element (5), is mounted on the fixed axis (1) and sits on the swing stop elements (3). It is a ring made of a stainless material that allows it to slide on the swing stop element (3). Inside, in the case of the preferred embodiment shown in the figure, a 90 degree sector that allows a 45 degree oscillation of the device, thanks to the configuration of the oscillation stop element (3), stands out. Rigidly joined by welding or other method to the side protection plate, on the outermost part, one on each side. The magnitude of its diameter strengthens, to the extent necessary, the lateral protection plate against stresses in the axial direction,

-dams (8) mounted on rigid bushings (9). The bushes (9) maintain the separation between plates, because their diameter is greater than the holes in the holes made in the side protection plate, on which they are mounted. The bushes (9) are fixed to their position by means of screws (10) and screws with internal thread (10A),

-Friction discs (7) mounted on one side and another of the pulley (6) and that function as a physical boundary between it and the device of the present invention. Its diameter is equal to or less than the outer diameter of the swing stop element (3), to reduce interference between the rotation of the pulley (6) and that of the protective element object of the present invention,

image13

- Closing discs of the assembly (2), located at the two ends of the device, in the longitudinal direction of the fixed axis (1), and mounted on it. Ready

5 for the protection of the inside of the mechanism against dirt and atmosphere. They have a hole to be able to insert them on the fixed axis (1) and free the keys (11), and two circular holes coinciding with those of the oscillating stop element (3), to make it fixed to it. Its diameter is equal to the larger diameter of the swing stop element (3).

10-greasing system, consisting of mechanized channels on the shaft to lubricate the moving parts of the assembly.

The assembly of the whole set can be done at the factory. For mounting on the davit, the alignment of the steel cable is taken into account, so that in the resting position the lateral protection plates remain in the center of oscillation (Figure 5). The steel cable is then mounted on the pulley and a protective sheave is arranged in the center of the cable's contact arc according to the angle of variation for which it is arranged. Finally, the alignment rollers of the cable inlet and outlet and damping of the whip effect are mounted in view of the angle of

20 oscillation of the side protection plates, two at the entrance and two at the exit (Figure 4).

Claims (9)

image 1 1. Device to protect steel cables from damage and prevent their exit by misalignment of the throat of the pulleys for which they work, characterized 5 because it comprises: • circular side protection plates (4-Figure 3) provided with holes (4A-Figure 3) and rigidly connected to each other, larger in diameter than a conventional pulley to be protected, located on one side and another of the pulley and mounted on the same fixed axis (1-Figure 3) on which it 10 works,

•

rigid bushings (9-Figure 3), with through axes through the holes (4A-Figure 3) of the side protection plates (4-Figure 3),

•

some elements of revolution (8-Figure 3) mounted on the bushings

rigid (9-Figure 3), arranged to prevent the exit of the steel cable from the groove of the pulley by misalignment,

•

at least one turning angle limitation element (5-Figure 3), integral with the side protection plate (4-Figure 3) and concentric with it, configured to allow the device to oscillate at a certain angle,

•

at least one swing stop element (3-Figure 3) integral to the fixed axis (1

20 -Figure 3), configured to stop the oscillation of the device when the rotation angle limitation element (5 -Figure 3) reaches, in its turn, the oscillation stop element (3 -Figure 3), damping the effect whip in case of cable dimming, • at least one closing element (2 - Figure 3) located at the end of the 25 device, in the longitudinal direction of the fixed axis and mounted on it, arranged for the protection of the interior of the mechanism and of sufficient dimension to cover the oscillation zone. 2. Device according to claim 1 characterized in that the protection plates 30 lateral (4 -Figure 3) make up a single piece and are rigidly joined by folding them in a certain sector 3. Device according to claim 1 characterized in that the elements of revolution (8-Figure 3) have hyperboloid configuration, to reduce and / or eliminate damage due to friction on the steel cable that works on the pulley. fifteen image2 Device according to claim 1, characterized in that the fixed axis (1 -Figure 3) is grooved both longitudinally to make the oscillation stop element (3 -Figure 3) rigid, and transversely to ensure the closure of the entire assembly on the opposite side to the structure to which it is attached. 5 5. Device according to claim 1 characterized in that the holes of the lateral protection plates (4A-Figure 3) are concentric with the fixed axis (1-Figure 3). Device according to claim 1 in such a way that the rigid bushings (9-Figure 3) keep fixed the separation between the lateral protection plates (4-Figure 3). 7. Device according to claim 1 and 2 characterized in that the configuration of The lateral protection plates (4-Figure 3) determine the position in which the invention should be mounted to keep it at its midpoint of oscillation, which is the effective working position; The axis of symmetry of the assembly must coincide with the bisector of the angle formed between the input and output of the cable to the pulley, at rest. twenty 8. Device according to claim 1 and 3 characterized in that, in general, five rollers are installed (1, 2, 3, 4 and 5 - Figure 4): two at the cable entry to the device, two at the exit and one immediately above the midpoint of the contact arc between the cable and the idle pulley. Both at the entrance and at the 25 output, the cable passes between the two sheaves installed. 9. Device according to claim 1 characterized in that the oscillation angle of the invention allows the cable to work through the pulley in the same manner and under the same conditions in which it would do so if the invented device was not 30 installed. 10. Device of claim 1 characterized in that it may not be necessary, according to one of the preferred embodiments, the presence of the rotation angle limitation element (Figure 3). The side protection plate itself (4-Figure 3) 35 fulfills its function in this case. 16