Third Rail For Current Consumers With Large Current Requirement And High Speed

Abstract

A live rail for the supply of current to movable current consumers movable along the rail includes a metal base and a slide surface formed of a wear-resistant material arranged on and interfitting with the base. The wall of the base facing the slide surface is provided with a longitudinally extending slot, having generally a T-shape, in which fits a correspondingly folded sheet section which forms the slide surface with a leg intermediate its width with an enlarged head fitting into the T-shaped slot and with its longitudinal edges extending beyond the longitudinal edges of the base which are undercut and bent into engagement with the longitudinal edges of the base.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a third rail for a supply of current to movable current consumers, particularly those with high current requirements and moving at high speeds, by a current take-off device movable along the third rail, the third rail consisting of a base member of metal and a slide surface of a particularly wear-resistant metal arranged on the base and connected in interfitting connection with the ground body.

2. The Prior Art

Third rails for movable current consumers, such as electric trains, suspended railways and crane arrangements, as well as main current collectors, trolley connectors and the like which consists of a metallic base and a slide surface element formed of a wear-resistant and corrosion-resistant metal arranged on the base and interfitted therewith are known. (See Lueger, Lexikon der Technik, Vol. 16, Lexikon der Fabrikorganisation und Fordertechnik, page 430 and DBGM 7,114,522. It has been sought to dimension the slide surface, which is made of an expensive metal, as light as possible, which is possible if the base participates in the transport of current and an undisturbed transfer of current from the base to the slide surface is assured. An exceptional excess of current requires an extensive contact between the contacting surface of the base and the slide surface. With small dimensions such as extensive contact can be produced simply by rolling or drawing the U-shaped slide surface on the widened head of the base.

Especially in connection with the latest developments in the field of transportation in the sense of an increase of speed, the transmission of especially large current strengths is already necessary. From this it comes about at increased speeds, especially on suspended railways, where swinging of the current collector about a transverse axis is experienced with consequent departure from its normal level, that contact between the shoe of the current collector and the live rail must be assured at all times. The larger currents may be taken care of through correspondingly heavier design of the rail. For insuring a continuous contact between the rail and the shoe of the current collector, it is possible to provide a wider rail head or a wider shoe. With a shoe which is broader than the head of the live rail there is connected a disadvantage in that the live rail wears a flange groove in the shoe. Such grooves lead to disturbances of operation, especially to interference with the transmission of current from the rail to the current collector. Grooves are not produced if the head of the rail is broader than the shoe.

In a base with a shoe arranged thereon and forming a live rail the broadening of the head of the rail, that is the sliding surface of the live rail, also leads to difficulties, because the customary connection of a U-shaped profiled shoe with the widened head of the base by the breadth in question does not bring about sufficient contact between the base and the live rail and for this reason no satisfactory current transfer from the base to the live rail is produced.

According to another proposal a broad contact between the base and the slide surface element with greater breadth of the head is achieved in that on the surface of the base which faces the slide surface element a plurality of dovetailed grooves are provided extending along the length of the base grip in which the bearing surface of the slide surface element engages, the flanks of which are brought into contact with the corresponding flanks of projections from the base. This multiple clamping of the slide surface with the base gives a very good mechanical connection, a broad surface contact and therewith a good transfer of current from the base to the slide surface. However the reduction of this third rail presents some difficulties, because not only the base but also the slide surface element must be subjected to a pinching deformation. Slide surfaces of steel cannot be worked satisfactorily in this manner.

Such an arrangement is shown in applicant's prior application Ser. No. 388,095, filed Aug. 14, 1973.

SUMMARY OF THE INVENTION

The purpose of the invention is to provide a multiple clamping of a slide surface with a base which makes possible an especially satisfactory construction of a steel slide surface element.

This purpose is achieved according to the invention in a third rail of the previously described type, by providing in the wall part of the base which faces the slide surface a longitudinal groove extending over the length of the base widened to a T-shape, which is filled by correspondingly folded sheet section with a leg widened at its free end, while its longitudinal edges which project from the base with the leg engage in the base

The multiple clamping of the slide surface element according to the invention with for example a base formed of an aluminum alloy, which requires only a compression of the base, gives a good mechanical connection, a broad surface contact and thereby a good transfer of current from the base to the slide surface element even when using a slide surface formed of steel, especially refined steel. The bending of the longitudinal edges of the slide surface element constructed of a sheet cross-section which is necessary presents no difficulties.

The heretofore described use of the clamping principle in connection with the slide surface element of steel naturally does not exclude its use with slide surfaces of copper or other materials, especially because they similarly require a simple working.

In providing a good clamping of the slide surface element on the base, the wall portion of the base, on which the slide surface element is arranged, beginning at the longitudinal edges is preferably undercut.

For manufacturing and shaping reasons there is recommended the use of a rectangular hollow profile for the base with a reinforced wall part on which the slide surface element is arranged.

The installation can be simplified if the base is provided on the side remote from the slide surface element with fastening flanges.

The preceding description of the third rail according to the invention, for high speeds of travel does not exclude its use for lower travel speed. In this case the broader slide surface of the third rail is especially advantageous since it makes possible the use of a broad sliding shoe. Broad sliding shoes give a more satisfactory contact than narrower shoes, because a better transfer of current from the third rail to the electrode results.

The third rail according to the invention is produced by inserting the leg of a slide surface element preshaped by folding a sheet cross-section in the longitudinal slot provided therein for that purpose, in which the leg is received with a certain play and finally bending the longitudinal edge parts of the slide surface element which project beyond the base against the base after previously pressing the base against the leg of the slide surface element which is held in it.

In this way slide surfaces of the customary length of 12 meters can be produced.

In a modification of this mode of production, the bending of the longitudinal edges of the slide surface element and the pressing of the base takes place in one operation.

It has also been found advantageous to carry out the pressing of the wall part of the base which mates with the slide surface element while attaching the other surface part of the base. This manner of operation saves a subsequent straightening of the third rail.

Especially light constructions of the third rail can be produced by a simple drawing process.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings the invention is further explained.

FIG. 1 shows a cross-section through the base of the third rail;

FIG. 2 shows a cross-section through the profiled slide surface;

FIG. 3 shows a cross-section through the base body with a preprofiled slide surface arranged thereon; and

FIG. 4 shows a cross-section through the third rail completed through the pressing of the base and the bending of the longitudinal edges of the slide surface against the base.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The base 11 consists of a generally rectangular hollow profile with a thickened wall part 111 - referred to as a head - for the reception of the constituent of the third rail which forms the slide surface element 21' (FIG. 4). The base has a longitudinal slot 112 of basic alloy T-form and its outer surfaces 114 beginning from the longitudinal edges 116 are undercut (117). On the side remote from the head 111 of the base, fastening flanges 118 are formed.

The preprofile 21 for the slide surface element 21' consists of a sheet section folded into essentially a T-shape, whose stem or leg 211 at its free end by corresponding folding is widened correspondingly with the broadening 113 of the longitudinal slot 112 in the head 111 of the base body 11 is widened, producing a foot 212. The longitudinal edge portions 214 of the legs 213 of the preprofile 21 are slightly bent over.

The longitudinal slot 112 as well as the widened part 113 in the head 111 of the base shape 11 on the one hand and the leg 211 as well as the foot 212 of the slide surface preprofile 21, as well as the thickness of the sheet, from which the slide surface preprofile 21 is produced, are so selected that the preprofile 21 with the leg 211 can be introduced from one end of the base profile 11 because of the play which is provided in the longitudinal slot 112 in the base profile 21.

If the slide surface preprofile 21 is pushed completely into the base profile 21, the head 111 of the base profile 11 through pressure in the direction of the lower arrow A in FIG. 3 is pressed in, resulting in elimination of the play between the leg 211 of the slide surface element profile 21 and the longitudinal slot 112 of the base 11. Simultaneously or thereafter through pressure in the direction of the arrow A the already bent over edge parts of the slide surface element profile 21 are brought against the inwardly sloping surfaces 117 of the base 111 which are constructed by the undercutting of the longitudinal edges 116 of the base 111 and brought into position.

In such a third rail (FIG. 4), the slide surface element 21 has becase of the form-fit a trouble-free grip on the pressed base 11', which assures that the surfaces of the base 11' and the slide surface 21' which are in contact with each other have the desired broad contact resulting in a good current transfer.

A further desirable result of the multiple clamping of the slide surface 21' with the base 11' is the plane surface 216 of the slide surface element 21'.

Claims

I claim:

1. A third rail for the supply of current to movable current consumers movable along the third rail, comprising a base of metal and a slide surface element formed of a wear-resistant metal arranged on and interfitting with the base, in which the wall part of the base facing the slide surface element is provided with a longitudinally extending slot having a generally T-shape, and in which the slide surface element comprises a correspondingly folded sheet metal section with a leg intermediate its width having an enlarged head fitting in the T-shaped slot and having its longitudinal edges extending beyond the longitudinal edges of the base and bent into engagement with the longitudinal edges of the base.

2. A third rail as claimed in claim 1, in which the edges of the part of the base on which the slide surface element is arranged remote from the longitudinal slot are undercut.

3. A third rail according to claim 1, in which the base is formed of an aluminum alloy.

4. A third rail according to claim 1, in which the slide surface element is formed of steel.

5. A third rail according to claim 1, in which the base is formed of a rectangular hollow profile with a reinforced wall part on which the slide surface element is arranged.

6. A third rail according to claim 1, in which the base on the side opposite the slide surface element is provided with fastening flanges.

7. Process for the production of a third rail according to claim 1, which comprises folding a sheet section to provide a slide surface element including an intermediate leg part having an enlarged head and projecting flanges extending longitudinally thereof, inserting the leg part from one end into a slot in a base which extends longitudinally of the base, the leg part of the slide surface element being engageable with play in the slot, pressing the base laterally to bring the walls of the slot into firm engagement with the leg and thereafter bending the longitudinal edges of the slide surface element which project beyond the edges of the base against the base.

8. Process for the production of a third rail according to claim 1, which comprises folding a sheet section to provide for an intermediate leg part having an enlarged head and projecting flanges extending longitudinally thereof, inserting the leg part from one end into a slot in a base which extends longitudinally of the base, the leg part of the slide surface element being engageable with play in the slot, and simultaneously pressing the base laterally to bring the walls of the slot into engagement with the leg part and bending the longitudinal edges of the slide surface element which project beyond the edges of the base against the base.