Railway switches and signals – Switches – Tie bars
Reexamination Certificate
1999-08-30
2001-09-18
Le, Mark T. (Department: 3617)
Railway switches and signals
Switches
Tie bars
Reexamination Certificate
active
06290189
ABSTRACT:
The invention relates to a point-operating device for pressing one switch tongue against a stock rail and for simultaneous withdrawal of another switch tongue from an opposite stock rail.
At high speeds in track points with the passing speed reaching 160 km/h, however, in particular, 250 km/h in points of high-speed section of a straight track, it is necessary that a respective switch tongue, which lies on a stock rail, has a perfect contact both in the stop region of the tongue and in the following bearing studs. This is very important to avoid movement of tongue regions, which do not lie on their support elements, during travelling under load, which practically is equal to track narrowing. Therefore, to prevent the track narrowing, it is necessary that before passing of a train, all of the switch tongue regions are supported on the support elements. It is also necessary that the other switch tongue, namely the tongue spaced from the stock rail, be spaced from the stock rail not less than 58 mm.
The cause of non-observance of a minimum distance of 58 mm or of the tongue not lying over its entire length is a so-called “hanging-up” of the tongue during switching which results from high frictional forces and a possible plastic horizontal deformation.
In order to eliminate both drawbacks, the not-lying of the movable tongue and not sufficiently wide opening between the spaced tongue and the stock rail or not sufficient spacing of the spaced tongue from the stock rail, so-called clamp middle locks or fork-like locks are provided in the region of the narrowest opening, i.e., mainly in the region of a complete face width of the tongue. Thereby, it is achieved that the used tongue lies on the support regions provided therefor, and the minimal distance between the stock rail and the spaced tongue does not fall below a predetermined value.
With the clamp lock, the lying tongue is clamped to the stock rail, whereas with the fork-like lock, the lying tongue is only pressed against the stock rail, and the spaced tongue is pulled off a distance of 58 mm.
In present mostly old point-operating devices, for switching a switch tongue, only a drive, with a point detector the tongue tip, is provided. In order to bring into contact the tongue regions located behind the tongue tip before movement of the contracting tongue and to pull-off the spaced tongue from the stock rail a sufficient distance, clamp and fork-like locks are correspondingly positioned with driving linkages which are adjusted by a tongue tip motor. A respective transmission linkage of a drive linkage and which is arranged in front of the face of the cross-tie makes the necessary compression of the ballast in front of the cross-tie face, which is necessary for increasing the positional stability, practically impossible. Thereby, the positional stability of the cross-tie is reduced which leads to the track distortion and primarily to increased maintenance costs.
The problem of previously made manual packing, from outside, of both cross-tie of a cross-tie box by using a drive or point detector linkage was solved by using of box-type cross-ties for both wooden cross-tie points and concrete cross-tie points, however, here also the use of a drive linkage from the tongue tip motor requires the use of the clamp and fork-like locks with all their, discussed above, drawbacks.
The prior art also discloses the use of so-called bow suspensions for switching tongue in a point. They are arranged in a space between the cross-ties, so that both cross-ties of a cross-tie box are packed only at one side. Neither mechanized nor manual packing from the inner side of both ties of a cross-tie box is possible. A further drawback of the known bow suspension consists in that it has only two spring assemblies. Therefore, when one spring assembly breaks, the bow suspension becomes inoperable. Similarly, with two spring assemblies, when one spring assembly is broken, the remaining spring assembly cannot provide the force necessary for switching of the tongues. Thus, both spring assemblies becomes inoperable with breaking of one spring assembly and the bow suspension should be either repaired, which is costly and time consuming, or be replaced. Further, the drive linkage for the fork-like lock has a drawback which primarily consists in the temperature-dependent length changes of the drive linkage, which takes place at low and/or high temperatures.
Accordingly, an object of the invention is a point-operating device without the above-discussed drawbacks.
This object is achieved, according to the invention, by arranging between the stock rails/switch tongues of a point a moving device with at least four adjustable spring assemblies. The four spring assemblies can, after the preadjustment of the spring assemblies, provide, horizontally, a pressure force of 4×400 N=1,600 N. This enables the switch tongue, which lies on the stock rail, to be reliably pressed against the stock rail and insures that the spaced switch tongue is pulled off the stock rail a sufficient distance. At that, the necessary minimal spacing of 58 mm is exactly retained, and the back of a wheel can pass this open region without descending, which is particular important at high speeds. Because the four spring assemblies provide a high pressure force, it is also possible to use a moving device with six spring assemblies, the clamp and fork-like locks can be dispensed with.
According to an advantageous embodiment of the present invention, the moving device is formed as a bow suspension having a tandem spring assembly in the middle and a spring assembly at its left and right ends. Each spring assembly consists of a spring socket in which a spring arranged on a pressure rod is received. The bow suspension is V-shaped. In its middle, two spring assemblies, located next to each other, are provided. The tandem arrangement insures that with breaking of one of the adjacent spring assemblies, the bow suspension remains operational. Furthermore, the spring assemblies provided at the outer ends of the bow suspension primarily serve for increasing the applied forces. The sockets of the spring assemblies advantageously are arranged in a carrier frame which can easily be fixedly connected with a cross-tie. Push rods connect the outer ends of the bow suspension with the tongues of the point. The bow suspension is operated by moving the tongue with a point drive motor arranged in the region of the tongue tip.
According to a further embodiment of the invention, the push rods are provided each with a toothing. The toothing adjustably connects a tongue with the push rod. Thereby, it is possible to compensate manufacturing tolerances, but particularly, to adapt to predetermined thicknesses of the tongue face, in accordance with the position of the bow suspension, to respective characteristics or parameters, among others, to the prestress of the spring assemblies.
Advantageously, the inventive bow suspension is mounted in a box-type cross-tie. Thereby, it is possible to better maintain the operability of the bow suspension, while protecting it against environmental influences and, besides, packing of the box-type cross-tie can be effected automatically with a point tamping machine. Thereby, maintenance costs and the possibility of a failure of a point are substantially reduced.
For monitoring of both switch tongue, two simple mechanical point detectors can be used because the otherwise necessary signaling monitoring of a drive linkage of a previously necessary fork-like lock has been eliminated.
REFERENCES:
patent: 1637919 (1927-08-01), Sampson
patent: 2046568 (1936-07-01), Lundy
patent: 2316312 (1943-04-01), Bone
patent: 2401294 (1946-06-01), Clymer et al.
patent: 2712914 (1955-07-01), Lavarack et al.
patent: 2730319 (1956-01-01), Arnold et al.
Le Mark T.
Schwihag Gesellschaft fur Eisenbahnoberbau mbH
Sidley Austin Brown & Wood LLP
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