Warning ball for overhead electric transmission lines

Abstract: Each shell (1a,1b) making up the ball (1) carries fixed on each of the two opposite plane walls crossed by the wire (2) a part of a vice (3) capable of engaging with the other part of the vice by means of a peripheral hinged coupling (4) having an axis of rotation (I-I) parallel to the wire and the two parts of the vice (3a,3b) are provided with means (5,7,8) capable of realizing a tightening device transverse to and for clamping onto the wire (2) positioned in a seating obtained in the two parts of the vice.

Description: The present invention relates to a warning ball for overhead electric transmission lines. The field of the invention is that of warning signals that, mounted on the topmost wire of an overhead electric transmission line, generally the earth wire, and appropriately spaced and coloured, serve to signal the presence of the transmission line to the pilot of an aircraft or helicopter in areas where the wires are high above the ground, as happens, for example, when the line has to cross a valley; as a general rule, these signals are hollow balls of a suitable diameter and made up of two hemispheres that are generally clamped to each other by means of clip devices; the balls are clamped onto the wire during the construction phase of the transmission line by workmen moving along the wire and employing a item of equipment known as "bicycle". Document US-A-3 362 377 discloses a span marker or warning ball that, according to known practice, comprises a pair of shells movable about a common axis from an open position and a closed position to define a substantially closed hollow body and a central opening through said body for receiving a wire of the electric transmission line. One inner shell is movable into the outer shell whereas an intricate tool connected with the marker has to be used for installing the marker on the wire. Document CH 579 838 is also known that discloses a marker for overhead electric lines made of two substantially identical shells forming, once they are mounted one onto the other in closed position, a spherical body wherein two diametrically opposed parts comprise a passage for the wire and means for clamping the wire. The drawback of state-of-the-art clamping devices consists of the fact that neither the fixing of the two hemispheres to each other nor the clamping of the ball to the wire are either strong enough or sufficiently permanent to satisfy regulations and good practice. The regulations currently in force prohibit use of the "bicycle" at any time after the construction of the electric line, so that the installation of new balls or the removal of old balls have to be effected with the help of robots or helicopters and need to be effected easily and rapidly. Given this situation, the problem underlying the invention is to provide a warning ball with fixing and clamping devices that will ensure good tightness and durability and imply only simple and quick operations. The problem is solved by a warning ball according to claim 1. The angular sweep of each shell in the plane perpendicular to the wire is less than 180°, so that appropriate dimensioning the said seating will render the vice suitable for tightening onto a preselected range of wires of different diameter. Preferably, each shell will also carry a visor or mask to cover the joint between the two shells. Preferably again, the two parts of the vice facing each other will carry, respectively, a projection and a corresponding cavity that will act as a guide during the tightening. The principal advantage of this ball is constituted by its simplicity in use; in fact, the two shells can be hinged to each other before the ball is placed onto the wire, with the two shells kept appropriately apart, and then positioned on the wire in such a way as to make the latter correspond to the said seating, after which the two parts of the vice can be transversely tightened to grip the wire. The invention will now be described in greater detail with the help of an implementation example and a number of drawings, of which Figure 1 shows the side view of a ball mounted on a wire, Figure 2 shows a first and partially sectioned front view of the vice, Figure 2a shows a detail, Figure 3 shows a side view of the vice, Figure 4 shows a second front view of the vice and Figure 5 shows a front view of a ball. Figure 1 shows a plastic ball 1 fixed to a wire 2 by means of the vice 3 ; as can be seen from Figures 2 and 3, the connection between the two hemispheres or shells 1a and 1b that make up the ball 1 is realized by means of the hinge 4 , which is so arranged that its axis I-I is parallel to the wire 2, while the clamping of the ball onto the wire is realized by means of the two parts 3a and 3b of the vice 3 which are tightened by means of the bolt 5 ; in the upper part of the ball there is the handle 1c, made of a strip of plastic and having its two ends riveted to, respectively, the shells 1a and 1b. Examining Figures 2 and 3 together, it can be seen that the two parts 3a and 3b of the vice 3 are connected at the top by means of the hinge 4 ( 4a is the hinge pin that has its axis I-I parallel to the wire 2 ) and that the said two parts are provided at their centre with two curved seatings that face each other to clamp the wire 2 when the shells are tightened; the association of the two curved seatings, jointly indicated by 3c, is suitable for clamping wires of a variable diameter within a preselected range and for this reason the sweep of the two parts 3a and 3b, as also that of the shells that make up the ball, is less than 180°. With a view to making it possible for the two shells to be applied to the wire when they are already connected to each other by means of the hinge 4 and with the tightening device of the vice already prepared to engage the wire, the said device is positioned between the wire and the hinge; a clamping bolt 5 is introduced into a chamber 6 formed within the part 3a , into a first semispherical element 7 housed in a corresponding semispherical cavity in the bottom of the chamber 6 and into a hole in the adjacent wall of the part 3a; it is then passed through a hole in the adjacent wall of the part 3b and screwed into the threaded hole of a second semispherical hexagonal element 8 housed in a corresponding semispherical hexagonal cavity at the bottom of the chamber 9 , which has a hexagonal section. Figure 2a shows that, alternatively, the semispherical elements 7 and 8 may also be semispherical-cylindrical, which prevents them from rotating in their respective seatings and simplifies the machining of the said seating and the chamber 9. Figure 4 shows that, in a position between the hinge 4 and the wire 2, the two parts 3a and 3b of the vice 3 are provided with, respectively, a projection and a corresponding cavity 3d that act as a guide during the tightening of the vice. Figure 5, where the ball 1 can be seen with the two shells 1a, 1b clamped tight against each other, though without a wire between them, shows that the two shells are provided with, respectively, the visors 10 and 11 that serve to cover the upper and lower slits that might be formed between the shells as a result of their incomplete closure. For example, when the ball is mounted on a wire of one of the larger-diameter wires within the envisaged range, the lower slits may be of quite considerable size and the visor 10 will cover it completely. Figure 5 also shows the rivets 12 that fix the two parts of the vice onto the flat surfaces of the two shells crossed by the wire (these surfaces have the form of a circular crown).

Claims: A warning ball (1) for overhead electric transmission lines made up of two substantially hemispherical shells (1a, 1b) that come together in a plane passing through a wire (2) of said transmission line, characterized in that two vices (3) are provided, each having a first part (3a) and a second part (3b), whereby the first parts (3a) are fixed on two opposite walls of the first shell (1a) crossed by the wire (2), whereby the second parts (3b) are fixed on two opposite walls of the second shell (1b) crossed by the wire (2), whereby peripheral hinging means (4) are provided for engaging the first part (3a) of each vice (3) with the respective second part (3b), whereby the hinging means (4) have an axis of rotation (I-I) parallel to the wire (2), whereby the first part (3a) and the second part (3b) of each vice (3) are provided with tightening and clamping means (5, 7, 8) for realizing a tightening transverse to and for clamping onto the wire (2) positioned in a seating (3c) formed in the two parts of the vice. A warning ball in accordance with claim 1, characterized in that the said tightening and clamping means (5, 7, 8) are positioned between the said peripheral hinging means (4) and said seating (3c) for the wire (2). A warning ball in accordance with claims 1 and 2, characterized in that said tightening and clamping means (5, 7, 8) comprise a bolt (5) that crosses the two adjacent walls of the two parts (3a, 3b) of the vice (3) and a threaded element (8) into which there is screwed the threaded end of the bolt. A warning ball in accordance with claim 1, characterized in that the angular sweep of each shell (1a, 1b) in the plane perpendicular to the wire (2) is less than 180°, so that the said seating (3c) may be dimensioned for clamping onto a preselected range of wires (2) of different diameter. A warning ball in accordance with claims 1 and 4, characterized in that each shell (1a, 1b) is provided with a visor (10,11) to cover a slit between the two shells. A warning ball in accordance with the preceding claims, characterized in that the two parts of the vice facing each other (3a,3b) are provided with, respectively, a projection and a corresponding cavity that act jointly (3d) as a guide during the tightening of the vice.

Inventors: BERTOLOTTI ADRIANO, BERTOLOTTI LUCIANO, BERTOLOTTI, ADRIANO, BERTOLOTTI, LUCIANO
Applicants: FLII BERTOLOTTI S P A OFF, OFFICINA FRATELLI BERTOLOTTI S.P.A.
Application year: 1998
Main classification: H02G7
IPC codes: H02G7