GB2204849A - Winch for the laying of cables, in particular optical fibres - Google Patents

Description

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2 C. n., 0.., 9 ' 0:.

"WINCH FOR THE LAYING OF CABLES, IN PARTICULAR OPTICAL FIBREC In the in an intermed which the same in order to red Such an i prior art is, the pull to layin i a t E of cables; the use is known of a winch position between the storage bobbin on cable is wound, and the main pull winch, uce the pulling force of.this latter.

ntermediate winch of type known from the substantially, a capstan, which transmits cable, wound a plurality of times around the by adherence.

However, such a kind of known art shows drawbacks, above all in the field of optical fibres, wherein cables constituted by stretches of very long size are used, the use of a capstan does not make it possible to pull long enough lengths of cables in one piece only; often very long cable laying time are experienced.

A decidedly problematic aspect is by the difficulty of realizing a between the main pull winch and the capstan the intermediate winch, a synchronism which any time throughout the operation of cable the tubes.

constituted furthermore synchronism acting a s.

must exist at laying inside In the capstan, the cable is wound with adherence on the race of the drum, it is hence under tension.. and under friction; on considering elasticity of the steel rope of the main winch, of the cable to be laid, only be obtained by means of a manual intervention, must result particularly timely, in order to adjust the pulling speed of the capstan as a function of that of the main winch. This means, of course, the need to make use constant always the and that the necessary synchronism can w h i c h I- - 1 1 2.

of suitable manpower. Furthermore, in this case a considerable difficulty exists in controlling the stresses applied to the cable by the two winches used.

The purpose of the present invention is to solve the above reminded problems.

In order to achieve that purpose, and to realize other advantages which will result. cleared from the following disclosure, the present invention proposes a in particular, constituted by f i b r e winch suitable for the laying of cables, for the laying inside tubes of cables long-size stretches, such as optical cables, characterized in that it comprises at least a couple of pulleys superimposed to each other, an upper pulley and a lower pulley, suitable to receive, by adherence, said cables, and mounted on respective horizontal shafts, at least one of which transmits the motion, which shafts extend from a vertical support upright.

In order to better understand the characteristics and the advantages of the invention, hereunder an example of practical embodiment thereof is disclosed, by referring to the figures of the hereto attached drawings.

Such an example is absolutely not to be construed as being li mitative of the purview of the invention, but is only illustrative thereof.

Figure 1 shows a schematic, partially sectional, elevation view of a device according to the present invention.

Figure 2 shows a side elevation view of the device of Figure 1.

Referring to the figures, a winch according to the present invention comprises a couple of pulleys, an upper I_ 3.

pulley 10 and a Lower pulley 11, upright 12 bearing a couple of upper shaft 13 and a Lower siaft of pulleys as, e. g suitable reference. shaf t 13 wheels 18 Lower puL above and pulley, a function of di recti on each other: Lower pull The upright 12 is fastened on a framework 21, mounted on a support plane 22, which is fastened in its turn onto the walls of a well, schematically indicated by the reference numeral 23, inside which the Lower pulley 11 of the winch is "dipped": the Level of said winch inside the well can be adjusted by means of the sliding of a screw rod 24, integral with the column 12, driven by a handwheeL 25; the screw rod 24 inmeshes with, and can slide inside, a female thread 26 which is constituted by screw- threaded hollow seats provided on the stationary framework 21.

The upper pulley 10 has one race only, whiLst the Lower pulley 11 has two races, positioned side-by-side to each other, to be able to receive the cable both when said cable Leaves, and when said cable enters, the well.

supported by a vertical horizontal shafts, an 14, an which tile couple revolve with the aid of suitable means, such ball bearings. The motion is produced by a drive means, schematically indicated by the numeral 15, and is transmitted by means of the to a chain 16 which engages with the sprocket and 17, with which the upper pulley 10 and the Ley 11 are respectively provided. Positioned under the sprocket wheel 18 of the upper couple of pinions 19 and 20 perform the returning the chain 16, so to reverse the pulleys relatively to revolves clockwise, the ey will therefore revolve counterclockwise.

of movement of the two if the upper pulley 4.

1 storage means of in Figure 1, the cable entering the well is indicated by the reference numeral 27: it is received by one of the two races of the lower pultey, is sent to the upper pulley around which it carries out a complete turn, and, when leaves said upper pulley, it returns back to the lower pulley, along a direction crossing its preceding an "8"-shaped path. On the is received by the second race which is free, and is finally the outgoing cable is indicated 28 in Figure 1. operating way of the winch exemplified in the can be summarized as follows: suppose that cables have to be laid, which are constituted by long-size stretches, e.g. , some kilometres long single pieces, inside previously installed tubes, without solution of continuity, e.g. on intercity ot motor-way systems.

that the cable is initially wound on a bobbin, from which it is unwound and pulled by a main winch,-which pulls an end thereof.

In an intermediate point along the path between the bobbin and the main winch, inside a well, an intermediate winch according to the invention is positioned, with the level thereof inside the well being suitably adjusted by acting on the handwheel 25 which drives the sliding of the screw direction, thus running along lower pulley, the cable provided on this latter, sent to the well outlet:

by the reference numeral The drawings oDti ca l-f ibre Suppose the stat the main 24 inside ionary framework 21.

Suppose that winch has operated until has caused the free end of the cable to reach and beyond (by a 9-10 metres) the well on which intermediate winch is installed.

U i t go the 1 5.

The cable recovered, by main pulleys pattern and 2.

run across the well (9-10 metres) will be liberating, and, obviously, stopping, the winch, and the cable will be positioned on the of the intermediate winch, according to the previously disclosed by referring to Figures 1 After putting the cable under pull, adhere w ell to the bottom of the races of the pul without making any loops C'skirC) when entering leaving the well, the drive means 15 of the intermediate winch is started up.

The two pulleys, after the initial starting up, will revolve without pulling the cable (idling).

The two pulleys, linked by the chain 16, by both of them being driving pulleys with the same torque, running at identical, but contrary peripheral speed, at the same revolutions per minute, by not finding the adherence the cable, will be unable to transmitted to the cable will winch will be started up, then and will adhere to the races of it possible the intermediate -operative.

in fact, it will be sufficient that the cable is put under pull, for the intermediate winch "feeL" the conse quent force, and supply, in return, its whole power (even a pulling force as high as 200 kg can be supplied to the cable).

so to make it leys, and o f produce work; the power be zero. When the main the cable will be pulled, the pulleys, thus making winch to become fully The desired synchronism with the main winch is achieved: we could say that the intermediate winch self-synchronized.

thus is 6.

That means that, if during its operation, the intermediate winch should result faster than the main winch, pulling an amount of 'cable larger than required by the main winch, it would immediately no longer transmit any power, and its pulleys would idle.

it should transmision of because cable on r e 1 a t i v e 1 consider ball bearings, to very low va way the cable provided during the Obtaining in an automatic way the synchronism between the intermediate winch and the main winch, according to as above disclosed, constitutes a considerable advantage of the present invention: One should think indeed that such synchronism is generally necessary at any time throughout the laying of the cable inside the tube.

According to the known art, because of the elasticity of the metal rope of the main winch and of the elasticity of the cable, the system used to realize such synchronism has been based, up to now, on the timeliness in intervention by man, consisting in changing the pulling speed of the intermediate winch.

On the intermediate winch according to the instant invention, the intervention by man is not necessary to realize the synchronism. In fact, as it is mentioned in be furthermore power can that the p r e c i s e 1 y the adherence, and hence the friction, of the the pulleys is obtained in a long enough time y to the time of cable progressing. If we then that the bearings used on the pulleys are and reduce the involved rolling friction lues, we can reasonably think is submitted to larger st working step.

observed take place gradually, that in no resses than 1 7.

the foregoing, should the intermediate winch result faster that the main winch (it pulls a larger amount of cable than of the main winchY, the cable'moves away from the bottom of the races of the pulleys, and allows the same to idle until the equilibrium between the cable lengt[s pulled by the two winches is restored; on the other side, if, on the contrary, the intermediate winch results slower that the main winch, on one side (downstream) said intermediate winch will constitute a resistance for the main winch, on the other side (upstream) it will pull the cable,, supplying all of the pulling force it can develop. The balance is always positive.

Furthermore, the possibility is achieved of supplying the cable a constant and controllable pulling f o r c e.

It the application of the present invention, no limits exist., which may derive from the value of the diameter of the optical-fibre cable.

A further considerable advantage yielded by the instant invention is represented by the larger length of cable which can be pulled as a single-piece length.

Above all in the field of optical fibres, we can in fact forecast that in a very near future, industry will be able to produce cables of a considerable length, even Longer than 6 kilometres, so that, if one will wish to lay cable lengths of that-magnitude, without solution of continuity, inside already installed raceways, it will be necessary to be able to use one or more intermediate winch(es) according to the invention, installed in correspondence of an equal number of wells positioned x, - 8.

in cable laying time, known from the prior from the prior art, intermediate along the selected path.

Further advantages are constituted by the reduction as compared to the use of the winch art, and by a considerably improved control of the stresses applied to the cable.

It should be observed that, whilst in the use, known of a capstan, acting as the a plurality of turns around the race and therefore a considerable mutual the various stretches of the same invention, pulleys various on necessary and w i n c h, of the drum exist, friction exists between cable, in the winch the path along which does not involve any stretches of the cable, the race of the pulleys d e s i r e d.

As it has been seen, when applying such force is no longer necessary, the cable moves contact with the bottom of the races of will hence start idling, without pulling the this way, the winch according to the present substantially operates like a clutch.

Furthermore, the winch of the invention can also operate, whenever desired, as the main winch, instead of acting as an intermediate winch, when the pulling force necessary to pull the cable results very limited, or when creating a certain spare length at the end of a cable piece, e.g., when the terminal station inside the has to be reached, is desired.

it is possible to produce, in winch is located, an as long according to the present the cable runs on the two mutual friction between the which exerts a friction force only, when that is f ri cti on away from the pulley, which c a b 1 e: in invention exchanges In such case, point wherein the the spare 9.

length as necessary, without any displacement of the winch having to be carried out.

The winch according to the present invention enables the user to use it also for pulling the nylon rope and the steel rope, instead of pulling the cable. In this case, the pulling direction iscontrary to the cable laying direction.

From the above, one can hence well understand how the present invention makes it possible to achieve a whole set of advantages of considerable impGrtance.

jo f k- C-1-a-i-m-s 1. Winch suitable for the laying of cables, in particular, for the layinb inside tubes of cables constituted by long-size single stretches, such as optical-fibre cables, characterized in that it comprises at least a couple of pulleys superimposed to each other, an upper pulley and a lower pulley, suitable to receive, by adherence, said cables, and mounted on respective horizontal shafts, at least one of which transmits the motion, which shafts extend from a vertical support u p r i g h t.

2. Winch according to claim 1, characterized in that said pulleys are provided with races to receive said cable.

3. Winch according to claim 2, characterized in that one of said pulleys is provided with at least a couple of races placed side-by-side to each other.

4. Winch according to claim 3, characterized in that the other pulley is provided with a single race.

5. Winch according to claim 1, characterized in that one of said pulleys receives the motion from its shaft, and transmits it to the other pulley by means of a suitable transmission.

6. Winch according to claim 5, characterized in that said transmission comprises a chain which engages on respective sprocket wheels integral with said shafts, a couple of pinions being provided for returning the chain between said sprocket wheels, to cause the direction of revolution of a pulley relatively to the other one to change.

7. Winch according to claim 4, characterized in that 1 1 1 1 said pulley provided with one race only houses one substantially complete turn of said cable, and said pulley provided with a coupl of races positioned sideby-side to each other receives on one of said races the winch entering cable, and on the other of said races the winch leaving cable, the path along-which the cable runs between the pulleys being so given an "8"-shaped configuration.

8. Winch according to claim 1, characterized in that said upright can slide along the vertical direction inside a support framework fastened to a well.

9. Winch according to claim 8, characterized in that on said upright a screw rod is integrally fastened, which is suitable-to slide inside a female screw integral with said framework.

10. Use of the winch according to claim 1, as an intermediate winch between a wound bobbin of the cable to be laid, and the main pulling winch.

11. Use of the winch according to claim 1, as the pulling winch to pull the cable to be laid.

12. Winch according to as hereinabove disclosed and illustrated in the figures of the hereto attached 'drawings.

Published 1988 at The aent Office, State House, 6611 High Holborn, London WCIR 4TP. Further copies maybe obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Maxy Cray, Kent. Con. 1/87.