The present invention relates generally to the field of railway tracks, and more specifically to cross-ties that are used with railway tracks.
Railway vehicles that use linear induction motors (LIM) as their primary source of propulsion are known in the art. In general, linear induction motors (LIM) used by railway vehicles consist of a primary portion that is supported under the railway vehicle, and a reaction rail that is supported on the railway track. As such, railway tracks built for LIM railway vehicles include a pair of running rails for supporting the wheels of the railway vehicle, and a reaction rail for interfacing with the primary portion of the linear induction motor. In addition, railway tracks for LIM railway vehicles include at least one power rail that is generally positioned above, and perpendicularly to the running rails and the reaction rail. It is the one or more power rails that supply power to the railway vehicle as it travels over the railway track.
Traditionally, railway tracks for LIM railway vehicles are formed by fastening each of the running rails, the reaction rail and the one or more power rails to a concrete guideway of the railway track via separate rail fasteners. As such, each of the rails is secured to the concrete guideway of the railway track independently. A deficiency with this manner of building the railway track is that each one of the rails requires a separate rail fastening arrangement, which makes the railway track time-consuming and expensive to install. A further deficiency with such traditional railway track is that it is difficult to control the relative positioning between the running rails, the reaction rails and the one or more power rails, which is important for the proper operation of the LIM rail vehicle over the track. As such, at the time of installation, the position of each rail must be adjusted such that it is properly positioned in relation to the other rails.
U.S. Pat. No. 5,314,115 describes a cross-tie that attempts to overcome at least some of the deficiencies with such traditional railway tracks. The cross-tie described by U.S. Pat. No. 5,314,115 supports both the pair of running rails and the reaction rail, and is operative for securing these rails to the concrete guideway of the railway track. A deficiency with this cross-tie is that it does not take into consideration the relative positioning of the power rail in relation to the running rails and the reaction rails. As such, the precise positioning of the power rail in relation to the pair of running rails and the reaction rail needs to be adjusted at the time of installation. In addition, the fact that the running rails and the reaction rails are mounted to the guideway separately from the power rail requires additional fastening studs which results in more work for the person installing the track, and additional parts that can be costly.
In light of this background, there exists a need in the industry for a more efficient, less cumbersome and less costly manner of building and maintaining a railway track for LIM rail vehicles.
In accordance with a broad aspect, the present invention provides a cross-tie comprising an elongated body. The elongated body comprises a reaction rail supporting section, two running rail supporting sections and a power rail supporting section. The reaction rail supporting section is adapted for supporting a reaction rail and the two running rail supporting sections are each adapted for supporting a respective running rail. The power rail supporting section is adapted for supporting at least one power rail.
In accordance with another broad aspect, the present invention provides an assembly comprising a cross-tie and at least one stud assembly. The cross tie includes a reaction rail supporting section adapted for supporting a reaction rail, and two running rail supporting sections, each adapted for supporting a respective running rail. The one or more stud assemblies are adapted for securing the cross-tie to a guideway of a railway track, and are operative for electrically insulating the cross-tie from the guideway.
In accordance with another broad aspect, the present invention provides an assembly that comprises a cross-tie and a wedge member. The cross-tie has an elongated body that includes a reaction rail supporting section and two running rail supporting sections. The reaction rail supporting section is adapted for supporting a reaction rail, and the two running rail supporting sections are each adapted for supporting a respective running rail. Each running rail supporting section has a lower surface adapted for facing a rail guideway and an upper surface adapted for supporting a running rail. The upper surface is substantially parallel to the lower surface. The wedge member is adapted to be positioned on the upper surface of the running rail supporting section between the upper surface and the running rail.
In accordance with yet another broad aspect, the present invention provides an assembly comprising a cross-tie and a power rail support. The cross-tie includes a reaction rail supporting section, two running rail supporting sections and a power rail supporting section. The reaction rail supporting section is operative for supporting a reaction rail and the two running rail supporting sections are each adapted for supporting a respective running rail. The power rail support is adapted for being removably connected to the power rail supporting section and is adapted for having at least one power rail connected thereto.
These and other aspects and features of the present invention will now become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying drawings.
A detailed description of the embodiments of the present invention is provided herein below, by way of example only, with reference to the accompanying drawings, in which:
In the drawings, the embodiments of the invention are illustrated by way of examples. It is to be expressly understood that the description and drawings are only for the purpose of illustration and are an aid for understanding. They are not intended to be a definition of the limits of the invention.
Shown in
As shown, the running rails 6 are positioned on the cross-tie 10 in a parallel, spaced apart relationship, such that the wheels of the railway vehicle can travel therealong. The reaction rail 8 is positioned between the two running rails 6, and is operative to complete a flux path with a primary portion of the linear induction motor located on the railway vehicle, so as to propel or retard the railway vehicle along the track. The power rails 12 are positioned perpendicular to the running rails 6 and the reaction rail 8, and are adapted for supplying power to the LIM railway vehicle. It is to be understood that although the power rails 12 are generally positioned perpendicularly to the running rails 6, they could also be positioned parallel to the running rails 6.
Shown in
In a non-limiting example of implementation of the present invention, the elongated body 14 of the cross-tie 10 is formed of steel. It should be understood, however, that other materials can be used without departing from the spirit of the invention. It should also be understood that the two running rail supporting sections 16 and the reaction rail supporting section 18 can be formed as one integral piece via molding or casting. Or alternatively, the reaction rail supporting section 18 and the running rail supporting sections 16 can be separate pieces that are welded together, or assembled in any other suitable manner, in order to form the single elongated body 14.
As shown in
Referring to
As shown in
Referring back to
Traditionally, the running rail supporting sections of prior art cross-ties have angled upper surfaces, such that the running rails secured thereto are positioned at a slight angle in relation to the reaction rail. A deficiency with such prior art cross-ties is that it is difficult to manufacture the angle of the upper surface to the tight tolerances required, which results in a high rate of discarded pieces.
As shown in
Depending on the railway track requirements, the running rails 6 may need to be positioned at different angles of inclination in relation to the guideway 4. As such, instead of using a different cross-tie having a different angle of inclination, each time a different angle of inclination is required, the same cross-tie can be used, only with a different wedge member 38. As such, regardless of the desired angle of inclination of the running rails 6, the same cross-tie 10 can be used by simply using a wedge member 38 having the desired angle of inclination. With traditional cross-ties, a different model of cross-tie for each different angle of inclination needed to be manufactured, which is far more costly than simply manufacturing wedge members having different angles of inclination. Also, along a length of the same track, the angle may vary from one track section to another. Therefore, using different wedge members 38 having intermediate angles of inclination provides a smooth transition from a first track section to a second track section.
In a non-limiting example of implementation, the wedge members 38 are made of an electrically insulating material, such as nylon, therefore providing electric insulation between the running rails 6 and the elongated body 14 of the cross-tie 10.
In the non-limiting embodiment shown in
Shown in
The rail clips 40 used are standard e-clips™ from Pandrol. The rail clips 40 secure the running rail 6 to the running rail supporting section 16 of the cross-tie 10. Rail clips 40, such as the ones shown in
In a non-limiting example of implementation, the rail clips 40 are also electrically insulated. For example, they can be made of an electrically insulating material such as nylon. Therefore, between the electrically insulating wedge members 38, and the electrically insulating rail clips 40, the running rails 6 are completely electrical insulated from the elongated body 14 of the cross-tie 10.
Referring back to
In the embodiment shown, the stud assemblies 44 are adapted to extend through holes in the running rail supporting sections 16, such that they can extend into insulating inserts 54 which are cast in the concrete guideway 4. In the non-limiting embodiment shown in
Referring now to
The insulating inserts 54 for mounting the cross-tie 10 to the guideway 4 of the railway track 2, enable the cross-tie 10 to be electrically insulated from the guideway 4. This prevents stray current from being transmitted into the concrete guideway 4. In addition, the insulating inserts 54 prevent galvanic corrosion of the studs 46. Furthermore, the inserts 54 placed in the concrete guideway 4 do not constitute a safety hazard, as they are flush with the guideway 4 surface. In prior art cross-ties, studs similar to studs 46 would be cast directly in the concrete of guideway 4. Hence, during construction of the guideway 4 and before any cross-tie was installed, a field of studs 46 would stick out of the guideway 4, such that they would often get bent or damaged. In addition, construction workers could trip on the studs, or even worse, fall on them, and get seriously hurt. In accordance with the present design, the studs 46 are only inserted into the insulating inserts 54 at the same time that the cross-ties 10 are installed. As such, there is not a field of studs sticking out of the guideway 4 prior to installation of the cross-ties 10.
Referring back to
The cross-tie 10 is biased toward the elastomeric pads 58 via the coil springs 50 of the stud assemblies 44. As the nut 48 is threaded onto the stud 46 the coil spring 50 compresses, thereby providing the required bias of the cross-tie 10 against the elastomeric pads 58.
As further shown in
As shown in
The power rail support 66 is operative for carrying the power rails 12, such that the power rails 12 can be connected to the cross-tie 10. As shown, the power rails 12 are connected to the power rail support 66 via bolts 68. Although the power rails 12 are each supported to the power rail support 66 via a single bolt 68, it should be understood that more or less bolts could be used without departing from the spirit of the invention. In addition, any other means of securing the power rails 12 to the power rail support 66 could be used without departing from the spirit of the invention.
In the specific embodiment shown in the Figures, the power rail supporting section 64 is located on the left hand side of the cross-tie 10, and is substantially perpendicular to the ground. It should be understood, however, that many other configurations for the power rail supporting section 64 can be used without departing from the spirit of the invention.
In addition, although
As mentioned in the background of the invention, the power rails of traditional railway tracks for LIM rail vehicles are connected directly to the concrete guideway of the track. As such, the power rails and the cross-ties are not connected in any way. A deficiency with such railway tracks is that if there is any movement, or deformation of the cross-ties, or of the structure supporting the power rails, then the positioning of the power rails in relation to the running rails and the reaction rail will change. This could negatively impact a railway vehicle's ability to travel over the railway track 2. A further deficiency with such prior art railway tracks is that when the power rail is bolted directly on the guideway 4, stray current could flow in the guideway, prematurely deteriorating it. In addition, the loss of current is expensive for the companies operating the railway track.
A benefit of having the power rails 12 supported by the cross-ties 10 is that the position of the power rails 12 in relation to the running rails 6 and the reaction rail 8 is more easily controlled than if the power rails 12 were connected directly to the concrete guideway 4. As such, the cross-tie 10 in accordance with the present invention is exposed to less variation in the relative position between the power rails 12 and the running rails 6 and reaction rail 8.
In a specific, non-limiting example of implementation, the position of power rails 12 should not vary by more than 0.25 inch (6.4 mm) both laterally and vertically with respect to the running rails 6. When the power rails 12 are directly installed on the guideway 2, meeting this tight tolerance requires much adjustment. However, with the power rails 12 connected directly to the cross-tie 10, the 0.25 inch tolerance can be more easily and more accurately achieved, by appropriately dimensioning parts and by appropriately manufacturing the same parts.
In the non-limiting embodiment shown, the vertical position and the lateral position of the power rails 12 can be adjusted independently with respect to the cross-tie 10. For example, the vertical position can be adjusted via vertical slots in the portion of the power rail support 66 that mates with the power rail supporting section 64. Alternatively, the vertical slots could be in the power rail supporting section 64. The lateral adjustment of the power rails 12 in relation to the cross-tie 10 may be made through the use of shims (not shown) that can be positioned in between the power rail supporting section 64 and the power rail support 66, or alternatively by adequately positioning power rail 12 using the nuts on bolts 68. However, if manufacturing tolerances are met, it is well possible that no adjustment be required.
The fact that the cross-tie 10 supports the power rails 12 provides an advantage in that fewer fasteners are required to connect the cross-tie 10 and the power rails 12 to the guideway 4. This results in a shorter assembly time and lower installation costs. Another advantage is that the insulated insert 54 of the stud assemblies 44 provides an electrically insulated system for the power rails 12.
Although the railway track 2 shown in the Figures shows two power rails 12, it should be understood that the railway track 2 could have included only a single power rail 12. In the field of railway tracks 2 for LIM rail vehicles, there are two types of power rail arrangements that can be used. The first type of power rail arrangement includes only one power rail, called the “third rail”, and the second type of power rail arrangement includes two power rails, called a “fourth rail”.
The second type of power rail arrangement (i.e. the one with two power rails 12) has one positive rail and one negative rail, while the first type of power rail arrangement (i.e. the one with only one power rail 12), uses the power rail 12 as the positive rail, and uses one of the running rails 6 as the negative return path. The first type of power rail arrangement is the most commonly used, due to the fact that it saves the expense of adding a second power rail 12. However, in order to use the running rail 6 as the negative return path, the running rail 6 must be well insulated from the concrete guideway 4, in order to avoid the loss of current.
In general, cross-ties in accordance with the prior art are not electrically insulated from the concrete guideway 4, and as such, should they be operative to support a power rail 12, they would be restricted to being used in the cases where the railway track 2 uses a power rail arrangement with two power rails.
As such, an advantage of the cross-tie 10 of the present invention is that due to the fact that the elongated body 14 is electrically insulated from the guideway 4, via the insulating insert 54 and the elastomeric pad 58, the cross tie 10 is operative to support power rail arrangements having either one power rail, or two power rails. In addition, the power rails 12 benefit from the fact that the running rails 6 are electrically insulated from the cross-tie via the insulating rail clips 40 and the insulating wedge members 38.
As described above, the cross-tie 10 of the present invention includes an ATC (Automatic Train Control) cable support 62. The ATC cable support 62 is positioned on the reaction rail supporting section 18 of the cross-tie 10, and includes a clamp for preventing the ATC cable from moving around. The ATC cable support 30 can include any type of clamp or securing device known in the art that is suitable for preventing the ATC cable from moving around. Typically, the ATC cable should be located approximately 1 inch below the top of the running rails 6. A sensor on the train then receives a signal from the ATC cable as it travels along the track. In prior art railway tracks, the ATC cable is fixed to the top of an L-shaped bracket, about 4 inches high to bring the cable to approximately 1 inch below the top of the running rails. These brackets are screwed directly to the guideway. In accordance with the present invention, the ATC cable sits at approximately 2 inches below the top of the running rails 6, which is lower than the conventional 1 inch, but still enables the sensor on the train to receive a strong signal from the ATC cable. The fact that the ATC cable is supported directly on the cross-tie 10 avoids having to use an additional bracket, which saves costs, materials, and installation time.
As further described above, the cross-tie 10 in accordance with the present invention is operative to support at least one derailment guard rail 60. In the specific embodiment shown in
In order to create a railway track 2 for an LIM rail vehicle, such as the one shown in
As shown in
Once the cross-ties 10 are mounted to the concrete guideway 4, the running rails 6, reaction rail 8 and power rails 12 are mounted thereto. In general, the reaction rail 8 is formed in sections that are between 3 m and 10 m long. As shown in
As described above, the cross-tie 10 of the present invention is operative to support the running rails 6, the reaction rail 8 and one or more power rails 12, as an integrated assembly. Cross-ties 10 in accordance with the present invention, enable a relatively high stiffness of the assembly to maintain the tight tolerance required in the height of the air-gap between the reaction rail 8 and the vehicle mounted LIM, and enable a relatively low stiffness in the cross-tie 10/guideway 4 interface to ensure an acceptable ride quality, wheel/rail interaction and vibration isolation. Since the running rails 6 and the reaction rail 8 are both supported by the cross-tie the relative deflection between them under operating conditions will be limited, and will be independent of deflection of the cross-tie which is mounted on elastomeric pads to the guideway.
Although various embodiments have been illustrated, this was for the purpose of describing, but not limiting, the invention. Various modifications will become apparent to those skilled in the art and are within the scope of this invention, which is defined more particularly by the attached claims.
This application claims priority from provisional U.S. Patent Application Ser. No. 60/468,096, which was filed on May 6, 2003.
Number | Date | Country | |
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60468096 | May 2003 | US |