GB2516273A - Drum of action radial - Google Patents

Abstract

A drum comprises a plurality of edge assembles 10, each comprising a secondary shaft 2, rollers 1 and bearings 3, the edge assemblies 10 being movable radially relative to an axis of rotation of the drum. The edge assemblies 10 may be moved by the movement of nuts 6 threaded on cores 8 and connected to the shafts 2 by hinged rods 5. Alternatively the edge assemblies 10 may be adjusted pneumatically or hydraulically by telescopic secondary pistons 11 actuated by a master cylinder 13. The drum may be used in winch systems or in the manufacture of coils of cables, wires, hoses and other flexible elements. A cable 9 wound around the drum may be taken up by expansion of the drum as the edge assemblies 10 are moved radially outward. The drum may be placed within a number of fixed edge assemblies (14 fig. 6) about which the cable 9 is wound.

Description

"DRUM OF ACTION RADIAL"

1. FIELDS OF APPLICATION OF THE iNVENTION

The invention presents a mechanism designed for acceptance of flexible elements such as ropes and cables. One of its applications is the hoisting of loads; it may operate as a catapult of launch. The invention can be used for the winding of hoses flexible such as those seen for the fire brigades in which the unwinding must occur in a short of time reduced. The invention is useful in the manufacturing of solenoids for transformers and electrical devices.

2. BACKGROUND OF THE iNVENTION

A hoist is a simple mechanical device that associates a set of pulleys in a provision serial. Half him rests on a fixed reference, such as a slab erected few meters from the ground.

The other half moves supportive to a car that carries the load. A cable passes through the pulleys is alternated between a pufley suspended and another fixed one, insomuch that the total length travelled by the rope can be reduced when it is triggered. The load is placed in the car and to raise it of a certain distance s=H, it is necessary that we scroll the rope edge through a distance S= nH, where n expresses the number of times with that rope connects an upper pulley fixed and a bottom driven. [he force f' needed to lift the bale "F" is reduced in proportion f. S = F. s whence f= F. (s/S) = F/n. If the force is applied by the car sustained by the pulleys mobile, we have the hoist operating in reverse condition. In this case a bale "f' placed on the free end of the rope will be raised through an effort of excitation "F", several times greater than the weight of the bale itself. The load, however, will move with speed greater than speed of displacement in the actuation. Unfortunately, however, the frictional effects occur ruthless. The cable presents a stiffness that is its own. The pulleys have their diameters sized within space limitations. Friction between the cable and peripheral surface of the pufleys cause deviations in the gyration. The angie of an interference fit of the cable on the pulley influences for a low performance of efficiency. The pulleys spin on axis of revolution fixed, which generates more friction. Cables suffer from deflation of 180 degrees when they exceed each pulley most of the times, which compromises its durability and limits their parameters of stiffness permissible. The decay of efficiency occurs each time after as the cable passes through a new sheave. In practice, we limit hoists to a maximum set of six to ten pulleys, except some exceptions of applying less frequent.

Winches and cranes are machines involving a combination of mechanical components intended for lifting or moving large bales burly on free end of cables. We can point out three problems in these systems: 1. lack in their mechanical efficiency; 2. number of pulleys is restricted; 3. drums are driven by reducers of gears sprockets. The use of gears in drums raises the capacity of the lifting, but strength to greater decay of efficiency. Furthermore, thc system oftcn is drivcn ncar thc operator, gcncrating noisc and sacrificing conditions of ergonomics.

A conventional device for winding wires, such as for the manufacture of electro magnets for motors or transformers, provides a core rotary turning on his spin. For coils of larger size, this process can become time consuming and counterproductive.

3. SOLUTIONS OF THE INVENTION We drive our machine from the core of a set of pulleys gifted of mobility radial. The result is the fast recoil of the flexible element with no need for the turning. The provision of radial axles containing rollers 1 moving from a nucleus centralized provides that loops be set multi planar, unlike the traditional arrangement existing in conventional pulley hoists. A drum composed by following the requirements of the invention can dispense with the use of gears with the frmnction of transfening torque, angular velocity and speed tangential. The system is more efficient, quiet, environmentally friendly, and significantly more ergonomic than hoists activation in reverse. The principle, we do not make the use of gears for revolving our drum. The invention increases efficiency indexes and we foresee its usefulness in devices aimed at winding of hoses as those used in fire equipment.

We describe a method for the manufacture of drums always devoid of inertial effects that cause expenditures of energy useful during the variation of accelerations of rotation angular.

The manufacture of solenoids is widely used in the industry. Electro dynamos, alternators, transformers, generators, motors, piping for radiators are some of the products obtained these applications. Mainly a core is chosen to rotate on its axis and the beginning portion of the wire is attached in the cylindrical surface of a drum nucleus. The number of revolutions will determine the total length of material curled, implying in adequacy of electrical resistivity or of other parameters initially foreseen. Let's say that a coil is composed of 300 turns of wire and that the transverse diameter of the coil is 120mm. In conventional machines we would set a core with diameter 120mm as to completing 300 laps. In our invention we would do that a nucleus of 40mm rotate of 300 laps. After, it would suffice the actuation of a device to increase the diameter of the drum until it reached 120mm. In fact the "radial" action operates by expansion of the cylindrical surface polygonal, around which a cable is already wrapped in the coils. Hopefully get with this a reduction of approximately 2/3 of the time required to complete the operation, if compared to conventional winding machines.

It is object of the present invention reducing the generation of noise during the operation of drum barrels.

It is also object of the invention, welcome flexible elements by eliminating the movement of revolution required for the winding.

It is further object of the present invention allow the reversal of the movement by eliminating the accelerations due to inertial rotary.

It is object of the present invention the manufacture of drums that dispenses with the to machining of reels of dimensions large.

The present invention describes a method for the manufacture of solenoids, accelerated mode and productive.

4. SUMMARY OF INVENTION

A plurality of rollers I is inserted within a plurality of axis secondary that are arranged circumfercntially around a centered core 8. Secondary shafts 2 are submitted to the expansion of its radial distance relative, through displacement of an actuator joined by means of connectors 4, a plurality of rods 5 radially arranged, both cross-sectional and competitors with relation to the centered core 8. The device uses of rollers 1 to communicate mechanically among the several coils of a cable 9 drawbar. The rollers 1 establish contact mechanical with the duo formed of the spool and the coiled cable.

The device is configured in spools of rays mutants, in which the flexible elements will be housed around a surface prismatic polygonal that, however, does not necessarily rotates on its axis of revolution. An example can be presented: the radius "r" of a hexagonal prism formed by arms of rollers 1, is increased to the value "C. r", where C is a real variable arbitrary module of greater than 1.

The end free of the cable 9 will suffer the linear displacement equivalent to (6 x n) x (C-i) .r, where n is the number of coils contained in the spool from the initial conditions to adjust the machine. The speed "v of expansion or contraction of r" determines the speed "V of displacement "D" of the end free of flexible element. "V' is multiplied by a factor defined by an equation appropriate. Thus, eases C make r vary in 2 units/see, we will have the displacement D (hexagonal) ranging from 12 units/sec. The greater the number of edges of the prismatic surface (and secondary axles, therefore), more the multiplier gets closer of value C. n. (2. it). The invention is graphically displayed through the following drawings.

5. A BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 Rollers installed on spherical bearings in secondary shaft.

Fig.2 Mounting mechanical of a drum radial of action.

Fig.3 Settings mechanical viewed in cross-section.

Fig.4 Settings mechanical viewed in longitudinal section.

Fig. 5 Mounting hydraulic of a drum radial of action.

Fig.6 Settings viewed in cross-section, featuring dual momentary displacement.

6. DESCRIPTION OF TUE EXEMPLARY EMBODIMENTS

A secondary shaft 2 is coated with a plurality of pulleys in the form of rollers 1 with tabs, articulated by bearings 3. The quantity of rollers 1 inserted in each secondary shaft 2 must match the amount of laps of cable wrap around the drum. The plurality of secondary shafts 2 thus formed is mounted in parallel arrangement and distributed distant around a nucleus central. Seen in cross section, the secondary shafts 2 will be represented as vertices of a polygonal figure preferentially regulate. Each secondary shaft 2 receives at least a pair of connectors 4 in order to communicate with rods 5 of elevation. The rods 5 converge coinciding with the centered core 8 of the system. Tf seen in cross section, the resultant of forces that act on each one of the rods 5 coincide concurrently at the center of the circle circumscribed by polygonal figure. The rods 5 can suffer its displacement with respect to the centered core 8 in two ways foreseen: 1-by moditring the slope of one of its ends and 2-by modifying their ends two in displacement radial orthogonal to the centered core 8. The first mode facilitates drives mechanical as essential. Is expected the use of central shaft threaded and truss rods 5 attached on nuts 6 such that the nuts can skid along the centered shaft. The second provides for telescopic drives essentially hydraulic or pneumatic. A characteristic interesting of our drum is that he does not necessarily suffer of rotation. Drums conventional are made of iron cylinder shaped, wood and other materials. Their brims bring an increment to the flywheel effect while subject to revolution of spin. Consider the additional effect of a gear wheel in the shape of a crown that surrounds the inner wall of a drum or that locates next to one of your tabs. This peripheral mass increased provokes a momentum in the acceleration angular when we want halting or reversing the direction of rotation. This is the case in drums encountered in cranes or freight elevators. As we invert direction of operation, a large portion of energy will be wasted to overcome the inertia of motion, before which the drum reaches a speed of regimen capable of removing from the machine bit useful work. The invention presents a second useful application. If we want to develop a solenoid containing for example coils with a radius of 10 cm. The cable 9 length coiled will be 10 x it x 20 cm. and we would havc to offcr 10 laps to thc nucleus of a machinc including with 20 cm in diamctcr.

With our invention we could offer 10 laps in a coil of radius 2.5 cm. and the cable 9 would travel along course it x 10 x 5 cm. Then we would do radius expand up to little more than 10 cm. The result is hollowing out the coil with only 25% of the course of their displacement perimetral. We present three variants constructive for the invention. The first specifies a device that provides the mechanical drive by rotation of a threaded shaft that mobilizes nuts 6 and rods 5 arrangcd in truss hinged. Thc sccond configures an apparatus that can opcratc with hydraulic drivc in telescopic rods providcd with cylindrical pistons 11 of stagcs multiple. The third shows a provision that doubles the power of displacement in the machine. This description will be subdivided with the purpose of facilitating the understanding for the examples in question.

6.1 Device with drive mechanical: Fig. 1 illustrates a set of rollers 1 inserted in secondary shafts 2. Each roller is equipped with at lcast onc sct of bearings 3 that act with the objective of reducing the friction. Connectors 4 are installed in ends of secondary shafts 2 that will communicate with rods 5 hinged so to establish a kinematic coupling. Once assembled, rollers 1, shaft secondary 2 and bearings 3 henceforth we will call simply "edge assembly". Fig 2 shows a fitting endowed with a plurality of edges assemblies 10. For illustrative purposes we take the edges assemblies 10 in number six. Nothing would prevent us, however, take a number distinct like three, five or 12 units, for example. The set of edges assemblies 10 is willing equidistant of an imaginary circle centered on the centered core 8 so that a transversal view submit a configuration such that they constitute a regular polygon. In the example shown by Fig 2 we would see therefore a hexagonal prism regular. We aim to make vary the relative distancing between the edges assemblies 10 without changing its parallelism on. For both, the centered core 8 is properly threaded in order to receive a plurality of nuts 6 each which provided with vanes 7. In This way, each rod 5 communicates through one of its ends with a vane 7 of the nut 6 and by another of its ends with one of the connectors 4 to each of edge assembly 10. We prevent the nuts 6 of revolving and by printing rotation on the centered core 8 we see that nuts 6 will swing away in rectilinear displacement along centered core 8 lines, if the nuts 6 are built with threads counter clock to pairs, we will have that their travel relative to each other possess opposite directions (Fig.4). i.e.: we take the centered core 8, print it in rotation direction exclusive, and we obtain as a result the remoteness or approximation relative between the nuts 6 (and between edges assemblies 10 as a result). The effect achieved is a prismatic surface that varics in sizc. Wc makc cablc 9 to wrap around this prismatic surfacc. Each fraction of cable 9 connects exclusively one piece of roller 1 existing in the entire arrangement. A complete loop on cable 9 foresees m+1 roller are contacted where m expresses the number of edges assemblies 10. Fig. 2 expresses as the provision of cable 9 in which each coil connects to a separate roller keeps the coupling with the flexible element. Through the example of Figure 3, we can see that the perimeter of a regular hexagon is calculated by the formula p=6.R and cxprcsscd approximatcly thc lcngth of a cablc 9 wrappcd in its surroundings (wc do not considcr cabic cmbraccmcnt by pullcys of thc form of an arc). Thc total cablc 9 lcngth wrapped in hexagonal drum will be estimated by the value n. p, where n responds by number of loops. If we do r vary up to R we have p ranging until P. It is known Li = n. 6.R and knowing Lf= n. 6.R where Li and Lf express the initial length and end of the free end of the cable 9. Thus, (Lf -Li) = 6. (R-r) or AL = 6.Ar. The formula summarizes that for talking about a load Q stuck on cnd of cablc 9 for displaccmcnt of 60 units, wc must rcstrict thc variation of r as the fraction 10/n units. Making V = dl. / dt, v = dr / dt, speeds respectively of thc cablc cnd and thc displaccmcnt of thc radius, wc scc that V = 6.nv Thc strcngth of action orthogonal to thc ccntcrcd corc 8 is dcmonstratcdby Fig. 3. If a load Q hangs frccly from rollcr 1, thc uppcr rollcr will suffcr thc dual cffcct of Q in dircctions symmetrical with rcspcct to its radial direction, at an angle of 60° of an intcrfcrcncc fit of thc cable 9. Each component of force radial exerted on a secondary shaft 2 is Q. sin (30) and thus the radial force F = Q for each edge, considering a single lap of the flexible element. The rcsulting forcc total theoretical T radially imposcd for thc systcm in opcration will bc cxprcsscd as 6.n.Q, n being thc number of coils. Wc must considcr at least two additional forces of friction acting on the system, however. Rj is inherent to the winding and unwinding of cable 9 on thc pulleys and thc moment of friction shaft-hub Rae inherent to thc rotation of rollers 1. Rj = Q. 2.ö/p, where 6 is the coefficient of stiffliess of the material (steel or hemp, for example) that is expressed in metric units and also depends on the cable 9 diameter. The radius of the roller has been designated by p". The multiplier factor 2 is explained by the fact that thc cablc 9 dcforms when cntcring and dcforms whcn cxiting from contact with thc roller.

We should also consider the friction axle hub that will be calculated for each application. A formula usually employed in convcntional hoists is Rec= p!.2.Q. sin (cii 2) whcrc Rec expresses the friction pulley shaft hub of a common, t is the coefficient of friction by sliding shafts exposed (usually 0.08) and a is the angle of an interference fit of the cable 9, which violates the component of the normal force "N to the contact of shaft-hub. However wc build our rollers 1 employing bearings 3 brokering with the secondary shaft 2, and we will have a value calculated differently, favoring the mechanical efficiency.

The rotation of the roller by means of the rotation of bearings 3 including spherical or cylindrical pins with diameter 0. The forcc R of opposition by friction bcaring will be: Q. (2.a/0).2.sen (a! 2) where a is the coefficient of friction by bearing (steel-steel = 0.005 cm, pins assemblies = 0.001cm) and, as has previously been said, a is the angle of an interference fit of the cable 9. Whereas "m" is the number of edges assemblies of the polygon, we can see that a = 180-(360/rn). With this, we get formula most general: R = Q. (2.c/0).2.sin (90°-180° /rn) The tangential force of opposition by friction transferred by time of mechanical advantage on the pair roller/shaft is approximating for greater by cxprcssion: Rae (di! De).Rec, where di is the diameter outer of the inner ring of the bearing ( shaft diameter secondary 2 + ring thickness) and D = 2p is the diameter of the roller.

With this we get: Rae = Q. 2.sin (90°-180° /m). (2.a/0). (di! 2p) whence: R = Q. 2.sin (90°-180° /m). (cdi) / (p.0) Finally, the increases in tension due to stiffness and friction axle hub summed will be: Fat = Rj+Rae = Q. (2/p). (8 + sin (90°-I 80° /ni). (c.di /0)) The diameter "d" of the cable 9 will be chosen as a function of the magnitude of the charge Q and the material used. In general d 0.1 l'JQ for ropes of hemp. For steel cables we seek d in charts and tables for each model of torsion and soul. The radius p must overcome point 12.d to l5.d for steel cables and s.d for ropes ofhemp. We getS = 0.12 x dx L-1 forsteel and 6 = 0.06 x d2 x L-1 for hemp. The unit metric of length L was represented in formulas for 6 and 6'. The force tangential effective of cable outlet in each roller 1 can then be calculated: F = F° + Fat = Q. (1+ (2/p). [6 + sin (90°-180°!m). (ad1 /0)]}; we can designate the second factor of the sum by letter ic and we have F = Q. (1+ic) where ic can be considered as the coefficient of friction of a roller/cable system. Note that one of the parameters of that depends Ofl IC is "rn', the amount of edges assemblies 10.

Assuming that "n is number of turns involving the drum, we will have force T1 for the actuation of the cable by its end by suspending the load Q stuck in initial end as being: Ti = Q. e in which 3 expresscs the angle, in radians, of an interference fit of the cable on the drum, being "e" the base of the exponential Neperiano. For example: if we give 1.5 turns of cable around the drum we have f3° = 360 +180 = 540° whence f3 = 9.4247 rad.

In the descent -Q of load, Ti' would act as retention force so that T1' = -Q. e'< To illustrate what was seen consider a practical example with the following parameters: Q=500 kg d0,Scm (steel cable) 60,O3cm p=8,Oem o=0,00lcm (steel-steel bearings) i=0,8cm di=8,Ocm m6 (edgcs) n=lO (loops)> 13°=3.600°> f3=62,S3rad ic= (2/p). [6 + sin (90°-180°/m). /)I 0,00966 We have: Ti= Q. (1.83) = 917 kg Mechanical Efficiency: = (1/ 1.83) = 54% (lirst result) Capacity reduction: (F = 6 x n = 60 We note that the parameter "p' does not depend on the material used and that increasing your value will decrease K proportionally. We note that K acts exponentially for the result ofT1 we can choose Pb as being 15.0cm, for better improvement in the example.

We found Kb. = 0.005 1 and we infer Tlh= Q. (1.38) = 691 Kg, augmenting the mechanical efficiency to lb = 72% (*final result) for the same capacity in the reducing of (F = 60 for the drum drive radial. Thus, it is recommended that "p" is exaggerated intentionally always that "n' is reasonably large.

It should be stressed that the exponential formula for Ti does not depend on the radius r for the drum. Thus, the chosen value radial between the edges assemblies, we would have the expected reduction of (F=60 times, with the efficiency latent of 72% for the invention configured as for our example improved mode.

We can compare our results whereas a conventional hoist would present the following diagnosis: Ic (1+/c)0 = ((i+ic) -1) where k = 0.065, 1=60 and we would have P = Q. 6.65% as force practical effective.

Po = Q/ J = Q! 60 = Q. 1.66% as thc soicly thcorctical forcc. Wc would havc lie = Po/P whence] = 25% as little. It is clear that the low income, resulting from even whole modus opcrandi thc employment of 60 sheaves on a hoist.

Fig 4 summarizes a configuration mcchanical morc functional for thc polygonal drum of edges assemblies 10. Each end of secondary shaft 2 suffers the coupling of two rods 5 which shall bow down in divergent directions, forming an angle of opening. Their lower ends of rods 5 arc attachcd to vanes 7 of two nuts 6 distinct (each sidc). Assuming rotation of ccntcrcd corc 8, wc have activated four nuts 6 that if ever closer together two by two, provokes that secondary shafts 2 move in displacement mutually equal. Each edge assembly 10 will be free of compressive forces of inflection along its longitudinal profile, eventually caused during the activation.

6.2 -Device drive with hydraulic or pneumatic: We can conceive of a fitting represented in Fig. 5 in which the radial movement of edges assemblies 10 is triggered by means of hydraulic drivc. In this assembly we anticipate using rods 5, fittcd with a dcvicc telescopic of one or two stages inside of cylindrical pistons 11. At least two rods 5 activates each edge assembly 10, but a plurality of joints can be built, interspersing them among a group of rollers 1, in order to increase the support of efforts. The pistons cylindrical 11 are interconnected, inside a container, with a master cylinder 13 central, capable of shutting down a certain volume of hydraulic fluid in an airtight manner. For that to happen, a plunger master 12 is dynamically coupled with the inner wall of the master cylinder 13. It is evident that the movement of the plunger compressive master 12, with respect to the master cylinder 13, fixed statically, will cause the increase of the pressure of the hydraulic fluid contained in the container. The fluid expansion will feed the expansion of various cylindrical pistons 11 which constitute the rods 5 and that sustain the secondary shafts 2. It is evident that we could also use a pneumatic device for this drive, by simply adding an air compressor to the assembly.

6.3 -Doubling travel of cable with equal variation Ar: Fig 6 shows the profile in cross sectional view of a drum of radial action which can be mechanical or hydraulic actuation. We alternate a battery of edges assemblies fixed 14 around the core of the drum, built, however with the lacking of mobility. The polygonal cylinder mobile is in angular opposition of phase symmetrical about its edges assemblies 10; in relation to the edges assemblies fixed 14. Cable 9 is inserted so that its end toggles roller to roller, between the external region of an edge assembly 10 mobile and the internal region of a rolling edge assembly fixed 14, as shown in the figure. When we actuate rods 5, distancing r of Ar, we will have as an effect the approximate displacement of 2.Ar in each branch of drum radial. This result in doubling the capacity of theoretical power provided for in examples 6.1 and 6.2 described above. It is obvious that the calculations of efficiency, however, should be reviewed.

Even though the invention has been described in few major variants, it should be understood that modifications can be redesigned in the shape, number and arrangements in the provision of parts so that, however, the spirit of protection the scope of this invention remains assured.

Claims (5)

1. CLAIMSI. Drum for the reception of cables and flexible elements comprising a plurality of edges assemblies that arc moving in radial movement with respect to an axis of symmetry and central that alter their mutual distancing when activated by devices mobile.
2. 2. Drum device in accordance with claim I comprising a plurality of rollers inserted in a shaft secondary, communicating mechanically with the interposition of bearings; said secondary shafts are longitudinally arranged around a main core of central position; said secondary shafts, provided with rollers, constitute edges assembled; actuator devices for provoking the displacement of said edges assembled; said edges assemblies, provided with connectors installed in at least two of its extremities; a plurality of radial rods coupled, each one by one of its ends, in the said connectors; said radial rods coupled, each one by another of its ends, in said actuator devices; said edges assemblies constitute a polygonal prism around the main axis of symmetry of core; said edges assemblies, they can move with radial displacement with respect to the axis main, altering its distancing mutual when excited by said actuator devices; coils of a flexible clement are curled around the polygonal surface formed by said edges assemblies; each roller contained in said edges assemblies communicates mechanically with said flexible element only once.
3. 3. Drum device in accordance with claims I and 2 wherein connectors located in secondary shafts are provided with fins; nuts containing a plurality of fins are inserted into a threaded shaft; said threaded shaft has center coincident with the axis of symmetry of the central core of machine; the fins of these nuts are interconnected with the fins of said connectors by means of rods in radial disposition; nut pieces and said threaded shaft constitute the actuator; the pair swivel of nuts and connector does modify the distancing of at least one of the ends of said edges assemblies with respect to the axis of symmetry main when the threaded shaft suffers spin rotation; said edges assemblies change their mutual distancing by moving radially with respect to the main core axis; the radius with which the flexible element wraps on the drum undergoes modification while thc nuts moving to pairs, in oppositc directions, in rectilinear displacement along thc threaded shaft; free end of the flexible element coiled suffers variation of displacement that is proportional to the variation of the radius of the drum and to the quantity of loops prepared by adjusting the initial conditions of the machine.
4. 4. Device of drum in accordance with claim I activated by hydraulic or pneumatic operation wherein connectors located in secondary shafts is coupled tightly on top of pistons secondary; said secondary pistons move radially with respect to main central core; a master cylinder is placed on the main core axis of a container; said container is hermetically sealed for purposes of pressurization of fluids and provided with rods castings, radially arranged, which constitute the course for the handling of said secondary pistons; said master cylinder allows the movement of a plunger compressive master that actuate the pistons secondary through the internal distribution of the pressure of fluid in the master cylinder; said plunger compressive master constitutes the actuator; the actuation of plunger compressive master moves the pistons secondary what makes with that said edges assemblies modify its distancing mutual moving radially with respect to the main core.
5. 5. Device of drum in accordance with claim 1 comprising a plurality of edges assemblies fixed of equivalent number of edges assemblies mobile; said edges assemblies called fixed constitute a polygonal surface formed around the main core; the two figures understood by polygonal cross sectional view between the edges assemblies fixed and edges assemblies mobile, arc arranged centered but in alternation of angular phase symmetric; coils of flexible element are arranged so that the flexible element communicates mechanically either by region outside of an edge assembly mobile, or by the region inside of an edge assembly fixed; each roller contained in said edges assemblies and said edges assemblies fixed, communicates mechanically with coils of said flexible element only once; free end of the flexible element coiled suffers variation of displacement proportional to trigonomctric secailt of value twice the variation of the radius of the drum, considering the angle formed between the radius of the drum and the flex cable, and also proportional to the amount of coils arranged around the drum, on the rollers of said edges assemblies and under the rollers of said flxed edges assemblies.U