DEVICE FOR SUSPENDING ELECTRIC TROLLEY WIRES TO MESSENGER CABLES

Abstract: A device for the suspension of electric wires (lO) to messenger cables (ll), in particular for the electrification of railways. The device comprises a first suspension element (l5) and a second suspension element (l6) adjust­ ably coupled together; the two suspension ele­ ments (l5, l6) are provided with toothing on at least one outer face, with the teeth (l9) of one element directly engaged with the teeth (2O) of the other element, or indirectly, by means of a securing clamp (l7).

Description: This invention refers to a suspension device for suspending electric conductors to messenger cables, in particular for adjustably suspending trolley wires in lines for the electrification of railways and the like. In carrying out electric trolley wires for railways and the like, the trolley wire usually runs parallel to the rails, since it is suspended from a messenger or supporting cable by means of stay wires or other suitable suspension devices. Unlike the electric trolley wire, the messenger cable is arched between two adjacent anchorage points; consequently, the distance between the messenger cable and the electric wire varies from point to point, ranging from a maximum in correspondence With the anchorage points of the cable to a minimum at the centre. It is necessary therefore to provide suspension devices of different lengths or which can be adapted or adjusted on the site in order to suit the various requirements. Moreover, the suspension device must in general permit the insulation of the supporting cable from the overhead electric line and, in the case of electric contact lines for railways, allow a certain amount of upward movement of the electric wire in order to compensate for the thrust exerted by the trolley, without the tensile stress on the electric wire undergoing sudden variations. Use is currently made of suspension devices of various types and shapes, that is to say, of fixed length or which can be adjusted for example by means of stay bolts, or having a particular shape. From US-A-1.643.749 a hanger or suspension device for overhead trackways is known, comprising a suspension element in the form of an inverted U shaped element provided with heads on each end, which are adjustably clamped within holes or recesses of two mating members of reduced length, rigidly engaging a track rail ; a clamping bolt is provided at the lower end of said mating members and a retaining finger is placed in an hole provided at the upper end of said members. Although the hanger according to US-A-1,643,749 allows to reduce the adjustment by providing steppered holes on the mating members, neverthless the mechanical strength are totally concentrated on the two head portions of the suspension element and on the edges of corresponding holes. Therefore in an hanger according to the document, it is impossible to obtain a wide range of adjustement positions while maintaining the required mechanical strength, unless to use hangers of suitable material, having several members of complex design and more difficult in use. To date, no-one has yet put forward a solution to the problem of suspending an electric wire and of adjusting the length of the suspension device which, in addition to ensuring the required characteristics of electrical insulation and mechanical strength under widely varied environmental conditions, is also easy and cheap to produce with reinforced plastic materials, and which at the same time is also easy to use and to adjust at the site. Therefore an object of present invention is to provide a suspension device for adjustably suspending electric conductors, which may be moulded with fiber reinforced plastic material, allowing an adequate electrical insulation and an appropriate distribution of mechanical strengths along the entire length of the same device. This can all be obtained by means of a suspension device according to this invention, as defined in the main claim. Particular embodiments are defined in the dependent claims. The device according to this invention will be described in greater detail hereunder, with reference to the examples of the accompanying drawings, in which: Fig. 1 shows a frontal view of a first embodiment of a device for supporting electric wires for railway systems; Fig. 2 shows a side view of the device of figure 1; Fig. 3 shows a cross-sectional view along the line 3-3 of figure 1; Fig. 4 shows a longitudinal cross-sectional view of the securing clamp, along the line 4-4 of figure 3; Fig. 5 shows a longitudinal cross-sectional view along the line 5-5 of figure 2; Fig. 6 shows a front view of a second embodiment; Fig. 7 shows a side view of figure 6; Fig. 8 shows a front view of a third embodiment; Fig. 9 shows a side view of figure 8; Fig. lO shows a cross-sectional view along line lO-lO of figure 8; Fig. ll shows a longitudinal cross-sectional view of the clamp along the line ll-ll of figure lO. As shown in the figures from l to 5, an electric wire lO of an electrification line for railways and the like, is suspended from a messenger cable by means of a plurality of supporting devices l2 which are pivoted or connected to hanging clamps l3 and l4 designed to secure themselves to the electric conductor or wire lO and to the messenger cable ll, as shown. The suspension device l2 must be able to adapt its length to the variable distance between conductor lO and messenger cable ll; it must consequently be adjustable in length in order to enable it to be assembled and adjusted at the site with the utmost ease, and to adapt to any situation. The supporting device l2, in the example shown, is made up of two toothed elements l5 and l6 which are elongated in the direction of their longitudinal axes and provided on at least one face with a plurality of crosswise teeth aligned in the direction of the longitudinal axis of each individual element. One or more intermediate clamps l7 serve the purpose of connecting or keeping the two toothed elements l5, l6 engaged with each other in a coplanar or overlapped condition according to the lateral or frontal disposition of the teeth. In particular, in the embodiment shown in figures l to 5, the two elements l5 and l6 are identical and each consist of a U-shaped element, with legs l5a, l5b and respectively l6a, l6b, provided on one side with teeth l9 and 2O. In the case shown, in which each leg is provided with only one row of teeth, the teeth of both legs l5a, l5b and l6a, l6b of each element are disposed on the same side of the legs. The two U-shaped toothed elements are positioned in the same plane, one next to the other, with the corresponding toothed legs l5a, l6a and l5b, l6b opposite each other and with their teeth reciprocally engaged over at least part of the length of the legs, passing through grooves 22 and 23 in the securing clamp l7. The clamp l7 is preferably made up of two matching halves l7a and l7b which are disengageably secured together by means of one or more bolts 24. The device l2 is completed by a movable link member 25 connecting it to one of the hanging clamps, for example to clamp l3 connected to the electric conductor lO, so as to allow the conductor lO a certain amount of lateral and relative upwards movements, which are necessary in order to compensate for the thrust exerted by the pantograph trolley or by the current collector which runs along the conductor wire lO whenever a train passes. In the case shown, the link member 25 consists of a double eyelet element having a first circular eyelet 26 which connects with the clamp l3 and a second elongated eyelet 27 lying in a plane at right angles to that of the eyelet 26 which connects with the previously described suspension device l2. The suspension device according to this invention is used as follows: the two opposing U-shaped elements are placed close together in the same plane to form a loop, with their teeth engaged after having passed the toothed element l5 through the elongated eyelet 27 of the lower link member 25; then the relative position of the two U-shaped elements is adjusted according to the desired length of the suspension device, and the clamp l7 is fitted onto them and tightened with its bolt 24. After having assembled the device, the two end clamps l3 and l4 are fitted on and then secured respectively to the conductor lO and the cable ll. It will be clear, from what has been described and shown, that by arranging U-shaped, or other suitably shaped, toothed elements in the desired length, it is possible to make up supporting devices variously adjustable in length and adaptable to the most widely varied requirements. The entire suspension device, preferably the two toothed elements l5, l6 and the lower link member 25, are advantageously made of fibreglass reinforced plastic material, for example of compact polycarbonate with a fibreglass filler, so as to give the whole assembly a highly resistant rigid structure which electrically isolates the cable ll from the electric conductor lO. Figures 6 and 7 of the drawings show a second embodiment. In this case, both of the U-shaped toothed elements l5 and l6 are provided with toothing l9a, l9b and 2Oa, 2Ob on both main faces, as shown; in particular, the teeth on one of the faces of each element l5, l6 can be aligned with the teeth on the other face, or can be shifted in a longitudinal direction by half a pitch, that is to say, by half the distance between one tooth and the next, in order to enable the device to be adjusted in length more easily. The device of figures 6 and 7 can be made in exactly the same way as the previous example, however, as shown, in certain cases the upper clamp l4 can be eliminated due to the fact that the upper U-shaped element l6 can be provided with a saddle and placed directly astride the suspension cable ll. In this case, the lower element 25 is modified in such a way that both the eyelets 26 and 27 are coplanar instead of at right angles to each other, as shown by the dotted line 26′ in the same figure and in the previous ones. The remainder of the device of figures 6 and 7 is made up and used in a wholly identical way to the previous one; consequently, the same numerical references have been used to indicate similar or functionally equivalent parts. A third embodiment is shown in the figures from 8 to ll of the accompanying drawings. Here too, the supporting device l2 is likewise made up of two toothed elements l5 and l6 sliding in the direction of their longitudinal axis and provided on at least one of the front and/or rear faces with a plurality of crosswise teeth l9, 2O, disposed aligned in the direction of the longitudinal axis of each individual element. One or more intermediate clamps l7 serve as before to connect the two suspension elements together in the coplanar condition of the elements l5 and l6 and positioned as shown in figures 8 and 9. In the embodiment shown, the two elements l5 and l6 are identical, of equal length and each consisting of an U-shaped element, with legs l5a, l5b and respectively l6a, provided with teeth l9 and 2O on both of the front and rear faces. The two U-shaped toothed elements are disposed side by side in the same plane, as in the first case, with the corresponding toothed legs in contact, and with the teeth aligned with one another so as to permit their engagement with an identical double toothing 2l provided on opposing sides of two through slots 22 and 23 in the securing clamp l7. The clamp l7 is preferably made up of two matching halves l7a and l7b which are disengageably secured together by means of one or more bolts 24. The device l2 is completed by a link member 25 to connect it to the lower clamp l3 of the electric conductor, in such a way as to permit lateral movement and relative upward movement, as in the previous cases. The same numerical references have also been used in this latter case to indicate similar or functionally equivalent parts.

Claims: Suspension device, in particular for adjustably suspending an electric conductor (10) from a messenger cable (11) by means of suspension elements (12) connected to the aforesaid conductor (10) and cable (11), said device comprising a first suspension element (15) and a second suspension element (16) each having a longitudinal axis parallel to outer faces of the aforesaid elements, characterised by the fact that the two suspension elements (15, 16) are identical and each consist of a U-shaped element having parallel legs provided with toothing (19, 20) on at least one of its sides, said toothing having teeth (19, 20) aligned in the direction of the aforementioned longitudinal axis, said two toothed elements (15, 16) being disposed side by side, and that it further comprises at least one securing clamp (17) to connect one toothed element (15) to the other one (16). Device as claimed in claim l, characterized by the fact that each suspension element (l5, l6) comprises a U-shaped element having parallel legs (l5a, l5b; l6a, l6b) in which toothing is provided on both legs (l5a, l5b; l6a, l6b) of said U-shaped element (l5, l6). Device as claimed in claim l or 2, characterized by the fact that the teeth (l9, 2O) are provided on at least one lateral face of each suspension element (l5, l6). Device as claimed in claim l or 2, characterized by the fact that the teeth (l9, 2O) are provided on at least one of the main faces of each suspension element (l5, l6). Device as claimed in the previous claims, characterized by the fact that the two U-shaped elements (l5, l6) are positioned opposite each other, with the corresponding legs (l5a, l5b; l6a, l6b) side by side and with the toothing (l9, 2O) of the legs directly engaged with each other, said legs (l5a, l5b; l6a, l6b) passing through slots (22) in the securing clamp (l7) to form an elongated loop in the direction of the longitudinal axis of the suspension device. Device as claimed in the previous claims, characterized by the fact of comprising a link member (25), said link member (25) comprising a first (26) and a second (27) eyelet one of which (27) is inserted in the loop defined by the two opposing U-shaped elements (l5, l6). Device as claimed in claim 6, characterized by the fact that the two eyelets (26, 27) of the link member (25) lie in planes at right angles to each other. Device as claimed in claim 6, characterized by the fact that the two eyelets (26, 27) of the link member (25) are disposed in the same plane. Device as claimed in claim 6, characterized by the fact that one of the eyelets (27) of the link member (25) is in the form of an elongated loop. Device as claimed in any of the previous claims, characterized by the fact that the intermediate securing clamp (l7) is made up of two halves (l7a, l7b) each half being provided with longitudinal grooves defining seats for the legs (l5a, l6a; l5b, l6b) of the aforesaid U-shaped suspension elements (l5, l6). Device as claimed in claim 2 or 3, characterized by the fact that the teeth (l9, 2O) on one face of each leg of the U-shaped elements (l5, l6) are displaced by half a pitch with respect to the teeth (l9, 2O) on the opposite face of the same leg of the U-shaped element (l5, l6). Device as claimed in claim 2, characterized by the fact that toothing (l9, 2O) is provided on at least one main face of each U-shaped element (l5, l6) and by the fact that a securing clamp (l7) is provided, said clamp having toothed grooves for the legs of the U-shaped elements, with the teeth (2l) of each groove (22) in the clamp (l7) which engage with both of the toothings of two adjacent legs of said U-shaped elements (l5, l6). Device as claimed in claims 2 and 7, characterized by the fact that one of the U-shaped suspension elements (l6) is connected to the suspension cable (ll) by means of a supplementary clamp (l4). Device as claimed in claims 2 and 8, characterized by the fact that one of the suspension elements (l6) is positioned directly astride the suspension cable (ll), and saddle means (28) are disposed between said suspension element (l6) and said cable (ll).

Inventors: MORARA, FERDINANDO
Applicants: POLIECO S.R.L.
Application year: 1987
Main classification: B60M1
IPC codes: B60M1