GB2181606A

GB2181606A - A line end clamp

Info

Publication number: GB2181606A
Application number: GB08622993A
Authority: GB
Inventors: Rolf Eugen Hedendahl
Original assignee: KB AUS REDSKAP INGFIRMA
Current assignee: KB AUS REDSKAP INGFIRMA
Priority date: 1985-10-01
Filing date: 1986-09-24
Publication date: 1987-04-23
Also published as: NO863894L; SE8504540L; SE450181B; SE8504540D0; NO863894D0; GB8622993D0; GB2181606B

Abstract

Conductor (1), which may be an overhead cable for electric trains, is detachably connected to earthing cable (2) by a clamp which can be applied and tightened by an operator. The conductor (1) is inserted into groove (11), and caught in recesses (12), so that it lies obliquely to the groove (11) as the clamp tilts under the weight of the earthing cable (2). Locking screw (5) is then tightened, e.g. by rotation of a clamp-applying rod engaging nut (7). <IMAGE>

Description

SPECIFICATION A line end clamp The present invention relates to a line end clamp primarily intended for detachably connecting a socalled earthing cable, provided with a contact device, to an aerial conductor or line, such as an overhead cable for electrically powered trains, the clamp being intended for manipulation from the ground or like surface and the earthing cable being attached to the clamp so asto hang therefrom.

Clamps of essentially this kind are known to the art.

Forexample, clamps ofthis kind are known in which the conductor is detachably held with the aid of spring-biassed devices. Such spring biassed devices are not absolutely reliable in operation, however, since they are subjected to the stresses of external weather conditions, such as snow, ice etc. Furthermore, such spring biassed devices cannot always be relied upon tO hold the conductor in the clamp, for example in the event of a short circuit. In this regard,the clamp is liable to loosen should a short circuit occur, which is something that cannot be accepted. In order to overcome this problem, the conductor may be held secured by means of a locking screw or some like fastener device, which is tightened or loosened from ground level with the aid of a rod-like tool.This requires the provision of expensive, complicated and heavy constructions however.

The present invention relates to a line end clamp which, through the agency of very simple means, is held automatically and detachably to the conductor when the clamp is fitted thereto, and which is secured to the conductor by means of a locking screw.

Because of its simplicity and because it lacks the aforesaid spring biassed devices, the clamp is cheap to manufacture, light in weight, and extremely reliable in operation.

Thus, the invention relates to a line end clamp which is primarily intended for detachably connecting a so-called earthing cable, provided with a contact device, to an electrical conductor located at a given distance above the ground or corresponding surface, such as an overhead cableforelectrically powered trains, the clamp being intended to be manipulated by an operator and to be fitted to the conductor, and one end ofthe earthing cable being fitted to the clamp so that the earthing cable extends from said clamp, and the conductor being held in the clamp by means of a locking screw arranged in an attachment head orthe like incorporated in the clamp.

The line end clamp is characterized in that the free end of the locking screw is intended for co-action with a rod or like tool operated by the aforesaid operator and projects from one end of the attachment head, said one end being intended to face the operator, said screw extending through the attachment head, preferably to the bottom of a groove located at the other end ofthe attachment head and terminating in a direction away from the operator, the conductor being inserted into the groove at said other end for co-action with the screw in a man nerto retain the conductor; and in that recesses or like cavities are provided in the groove in the proximity ofsaid groove bottom so as to form a channel or like space by means of which the conductor can be positioned obliquely in relation to the direction of outwardly located parts ofthe groove and clamped firmly bythe locking screw; and in that the earthing cable is arranged to project from the clamp in a manner such that through the action of its weight it strives to rotate the attachment head so that a conductor inserted in the groove takes a given position in said channel.

The invention will now be described in more detail with reference to an exemplifying embodiment thereof illustrated in the accompanying drawings, in which Figure 1 illustrates schematically afirstembodiment of a line end clamp according to the invention seen in the direction of the conductor when inserting the same into the clamp, said clamp being shown in a vertical position; Figure2 is a top plan view of the clamp shown in Figure 1; Figure 3 illustrates the earthing cable connection according to Figure 1,seen obliquely from the left and in the plane of the drawing; Figure 4 illustrates schematically a part of a line end clamp which incorporates the guide arrange mentforaligningthe earthing cablewith the clamp attachment head; and Figure illustrates schematically part of another exemplifying embodiment of a line end clamp according to the invention incorporating an earthing cable attachment bolt.

The reference number 1 in Figure 1 designates an electrical conductor which is shown to extend at right angles to the plane ofthe drawing ata given height above the ground or corresponding surface and which may have the form of an overhead supply cable for electrically operated trains. The reference numeral 2 designates a so-called earthing cable by means of which the line end clamp according to the invention is connected electricallyto the conductor 1, the earthing cable 2 being provided with a contact device which is not shown in the drawing.The clamp is intended to be manipulated by an operator (not shown) remotely positioned from the conductor 1 and to be fitted to said conductor, one end 2' ofthe earthing cable 2 being connectedtotheclampsothat the cable extends from said clamp.

In the embodiment illustrated in Figure 2 the earth- ing cable 2 is fitted to the clamp by means of a perforated pole shoe 3, which is secured by some suitable means, such as a nut.

The reference numeral 4 designates an attachment head incorporated in the clamp, whereas the reference numeral 5 designates a locking screw which is provided in the attachment head 4for locking a con ductorthereto. The free end 6 of the screw5 is intended for co-action with a rod or like tool (not shown), e.g. through the intermediary of a nut-like device 7, said rod being manipulated by the operator in a manner to turn the screw 5 about its longitudinal axis. The screw 5 extends from one end 8 of the attachment head 4, this end 8 facing the operator, and passes through the attachment head preferably to the bottom 9 of a groove 11 which is located at the other end 10 ofthe attachment head 4 and which terminates in a direction away from the operator.The conductor 1 is intended to be inserted into the groove 11 from the aforesaid other end 10 of the attachment head, so as to extend substantially transversely to the axial direction of the locking screw, for locking co-action with the screw 5 in a mannerto secure the conductor.

In this regard the groove 11 is provided in the vicinity ofthe groove bottom 9 with recesses 12 or like cavities which form a channel or like space by means ofwhich the conductor 1 can be positioned obliquely relative to outwardly lying parts ofthe groove 11, as illustrated schematically in Figure 2, with the conductor, here shown in broken lines, taking a given position in the channel. The recesses 12 are defined by support and stop surfaces 13 which are located opposite the groove bottom 9 and against which the conductor is held, inter alia, by the screw 5.

In accordance with the invention, the earthing cable 2 is arranged to extend from the clamp in a manner such that the weight of the cable strives to rotate the attachment head 4 in a manner to cause a conductor 1 located in the groove 11 to take a given position in said channel.

The channel is suitably arranged so thatthe direc- tion in which the attachment head 4 must beturned in orderto introduce a conductor 1 in said channel is the same direction as that in which said locking screw 5 must be turned in orderto clamp the conductor in the channel.

According to one preferred embodimentofthein- vention, the earthing cable 2 extends from the attachment head 4 in a direction which forms an angleV1 of about 30 - 60 , preferably about 45", with the direction of the groove 1 1, and an angleV2 of about 60 - 1 20", preferably about with the direction of said channel.

In accordance with one preferred embodiment of the invention, illustrated in Figure 1,the groove 11 widens towards the mouth 11' thereof, at least in the vicinity of said mouth, thereby to facilitate insertion of a conductor 1.

The earthing cable 1 is also preferably connected to the attachment head in a mannerwhich enables the cable to be replaced. To this end, suitable guide means are arrangedforenablingthe earthing cable to be arranged in a predetermined fashion in relation to the attachment head, and therewith the groove 11 and the channel, so that the attachment head is rotated in the manner desired underthe action ofthe earthing cable. In the embodiment illustrated in Figure 3 and 4, the aforesaid guide means has the form of a guide plate 14 arranged on the pole shoe 3 ofthe earthing cable, this guide plate 14 being intended to co act with a corresponding recess 15 provided in the attachment head.

In Figure5there is illustrated an embodimentin which the perforated pole shoe 3 of the earthing cable is intended to be fitted onto a bolt 16 projecting from the attachment head 4, and in which guide means, such as a groove 17 provided on the bolt are intended to co-act with a guide plate orthe like (not shown) located in the hole or perforation of the pole shoe.

The function of the line end clamp according to the invention will be understood to a largeextentfrom the aforegoing. The cable 1 is thus introduced into the groove 1 1,the groove being positioned around the conductor either (obliquely) from above or (obliquely) from beneath. The weight exerted by the earthing cable causes the attachment head 4to rotate, so that the conductor enters the channel, wherewith the clamp is automatically held hanging from the conductor. When the screw 5 is screwed into the attachment head, the screw turns in a direction such as to forcethe conductor into the channel.

It will be understood from the aforegoing that the invention provides a particularly simple and operationally reliable line end clamp which incorporates only one moveable part, namelythe screw 5. The clamp is therefore a great improvement on the clamps forming part ofthe prior art, both with respectto function and with respect to cost.

In the aforegoing the line end clamp according to the invention has been described mainly with reference to one exemplifying embodiment thereof. It will be understood, however, that other embodiments are conceivable within the scope ofthe invention and that minor modifications can be made to the illustrated embodiment.

Forexample,thegroove 11 and the channei can be given a different form to that illustrated and described. For example, the groove may be given a helical configuration so asto cause the attachment head to rotate when the conductor 1 is moved towards the groove bottom 9.

In certain cases, such as when the clamp is to be used in conjunction with copper conductors, the clamp may suitably incorporate a contact insert (not shown) made of copper or brass and intended to constitute at least parts of said channel and forconnection with the earthing cable. The remainder of the clamp is suitably made of aluminium,for reasons of weight. In the case ofaluminium conductors,the whole clamp is suitably made of aluminium. In the majority of cases the attachment head is preferably molded.

Preferably means are provided which ensure that the screw 5 cannot be screwed from the attachment head to an extent greaterthan that the end 5' ofthe screw at the groove bottom 9 substantially connects with the bottom 9. This avoids exaggerated screw movements when loosening the clamp.

Embodiments are conceivable in whichthescrew5 does not extend to the groove bottom 9 but is arranged to acutate, to bear upon, a contact device (not shown) located in the vicinity ofthe groove bottom.

The invention is therefore not restricted to the afore-described embodiments and modifications can be made within the scope ofthefollowing

Claims

claims. CLAIMS

1. A line end clamp primarily intended for detachably connecting a so-called earthing cable, provided with a contact device, to a conductor located at a given height abovethe ground or corresponding sur- face, such as an overhead cable of electrically oper ated trains, the clamp being intended to be manipulated by an operator and to be attached to the conductor, and the earthing cable being attached at its one end to the clamp and being intended to extend from said clamp, the conductor being retianed in the clamp by means of a locking screw arranged in an attachment head or the like incorporated in the clamp, characterized in thatthefree end ofthe locking screwis intendedto co-actwith a rod orlike tool, operated by said operator, for rotation of the screw and projects from one attachment head end which is intended to face said operator, in that the screw extends through the attachment head preferably to the bottom of a groove which is located atthe other end ofthe attachment head and which terminates in a direction away from said operator, said conductor being intended to be inserted into the groove at said other end for co-action with said screw for retention ofthe conductor; in thatsaid groove is provided in the vicinity of said groove bottom with recesses or like cavities which form a channel or like space by means of which the conductor can be positioned obliquely in relation to the direction of mouth wardly lying parts of the groove and be clamped securely by means of a locking screw; and in thatthe earthing cable is arranged to project from the clamp in a manner such thatthe weight exerted bythecable attempts to rotate the attachment head in a manner to cause the conductor located in the groove to take a given position in said channel.

2. Aclamp according to Claim 1, characterized in that said channel is so arranged that the direction in which the attachment head is to be rotated for insertion of a conductor into said channel isthesamedir- ection asthat in which said locking screw is to be turned in orderto clamp the conductor in said channel.

3. Aclamp according to Claim 1 or2,characterized in that the earthing cable projects from the attachment head in a direction which forms an angle (V1) of about 30 - 60 , preferably about 45", with the direction of the groove, and an angle (V2) of about 60 120% perferably about 90 with the direction of said channel.

4. Aclamp accordingto Claim 1,20r3,characterized in that said groove widens towards the mouth thereof, at least in the vicinity of said mouth, therewith to facilitate insertion of a conductor.

5. Aclamp according to Claim 1,2,3 or4,char- acterized in that the earthing cable is replaceably arranged on the attachment head, guide means are provided for positioning the earthing cable in relation to the attachment head, and therewith the groove and the channel, in a predetermined manner so that desired rotation ofthe attachment head is obtained through the intermediary of the earthing cable.

6. Aclamp according to any of the preceding Claims, characterized in that the attachment head incorporates a copper or brass contact insert, while the remainderofthe clamp is made substantially solely ofaluminium.

7. A line end clamp constructed and arranged to operate substantially as herein described with refer enceto and as illustrated in the accompanying drawings.