BACKGROUND OF THE INVENTION
It is common to use railroad rails to transmit a signal to or from a train. Typical reasons for doing this are to advise the engineer of switch positions and to remotely monitor the location of the train. This requires the rails to be broken at periodic intervals and that the resulting rail ends are electrically isolated from one another. This is accomplished by fabricating track sections having electrically isolated rail ends and installing them at the desired locations. Due to the severe loads placed on the rails by trains running on them, the flanges of the rail ends need to be rigidly tied together. This has been done in the past by placing tie plates which are surrounded by a non-electrically conductive coating across the rail ends on each side of the flange and bolting them to the flange and to one another. While these prior art tie plates do substantially eliminate relative movement between the abutting rail ends, they still allow some movement of the rail ends which with time causes the plastic insert that is placed between the rail ends to wear, causing these track sections to have a limited life.
BRIEF SUMMARY OF THE INVENTION
The subject invention provides a cast tie having a pair of spaced-apart elongate support members cast into it. First and second yoke members are attached to but electrically isolated from both of these support members. A first clamp member associated with the first yoke member is attachable to a first rail end, and a second clamp member associated with the second yoke member is attached to a second rail end which abuts the first rail end but is electrically isolated from it. The yoke members are cast into the tie in a manner such that they are electrically isolated from the tie and from each another.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a perspective view of a railroad track section embodying the rail connection system of the subject invention.
FIG. 2 is an exploded perspective view of yoke members which are an element of the invention.
FIG. 3 is a perspective view of the yoke members together.
FIG. 4 is a perspective view of the yoke members installed on support members which are another element of the invention.
FIG. 5 is a perspective view showing how the track section of FIG. 1 is made.
FIG. 6 is an exploded perspective view of the track section.
FIG. 7 is a perspective view of the track section.
FIG. 8 is a cross-sectional view, at an enlarged scale, of the track section.
FIG. 9 is a perspective view of an insulating spacer which is an element of the subject invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to FIGS. 1-4 of the drawings, an apparatus for connecting aligned abutting rail sections which are electrically isolated from one another includes a pair of spaced-apart, side-by-side, elongate support members 10. The support members shown in the drawings are individual metal bars but many other materials and shapes would work as well. Examples are a bundle of fibers which are held in tension between bulkheads and a bundle of smaller diameter high strength tubes. With bars of the type shown in the drawing, the support members are roughly eight feet long, but the length would depend on the size of the bars and other design factors.
Mounted on the support members are a first yoke member 12 and a second yoke member 14, FIG. 2. In the embodiment illustrated the yoke members have two side-by-side feet 16 with openings 18 at each end which loosely receive the support members 10. The feet 16 are joined together by a clamp member 20 which extends between the top surfaces 22 of the feet 16. The clamp member 20 is located at one end of the feet 16. The first yoke member 12 is reversed relative to the second yoke member, and one of its legs 16 is inserted between the pair of legs of the second yoke member until the openings in the two yoke members are aligned, FIG. 3. The spacing between the legs is slightly less than the width of the legs so that no portion of the first yoke member is in contact with the second yoke member when they are in this position. The support members are then inserted through the aligned openings 18. The support members are joined to the yoke members by an electrically non-conductive joint 24. In the preferred embodiment illustrated the joint 24 is a high compression strength epoxy which is poured in the space between the support members 10 and the inner walls of the openings 18 in the yoke members. A 20,000 PSI compression strength epoxy made by Loctite works well for this purpose. The joint could also be a sleeve which is attached to both the support member and the joint member. Posts 25 protrude from the support members and the yoke members to better embed them into a cast tie, as will be explained later.
Located on one side of each clamp member 20 is a first leg 26 which is an integral piece of the clamp member. Located on the other side of the clamp member 20 is a platform 27 which has a second leg 28 removably attached to it by means such as bolts 30, FIGS. 6 and 7. The top surface of the platform 27 and the bottom surface of the second leg 28 have mating discontinuous surfaces which prevent the second leg from moving laterally relative to the platform. In the embodiment illustrated this is accomplished by placing mating slots 32 in the platform and second leg with keys 34 located in them. Aligned holes 35 extend through the first and second legs. The first and second legs are arranged to fit over the top of the rail base, and under the rail head on opposed sides of the rail, FIG. 8. Typically there would only be a support member/yoke member assembly for one of the rails as shown in FIG. 1, but there could be an assembly under both rails if desired.
The support member/yoke member assembly is cast into a tie 36, FIG. 1. The tie includes a first section which comprises a pair of spaced-apart, side-by-side elongate legs 38. A second section of the tie comprises a cross member 40 which extends between the legs 38 below where the broken rail crosses the tie. The legs 38 preferably are made of concrete, but could be made from any material that is or later becomes common for making cast railroad ties. The cross member needs to be electrically isolated from the concrete legs and from the support members 40. One way to accomplish this is to make the cross member from an electrically non-conductive material. In a preferred embodiment the cross member 40 is made from an epoxy grout. Because the epoxy is electrically non-conductive and surrounds the support member/yoke member assembly it electrically isolates the yoke members and support members from one another and from the concrete legs 38. The epoxy also rigidly connects the yoke members and the support members to the tie. In the embodiment illustrated the support members extend into the second section of the tie which further joins the entire device together. It is also possible to make the cross member from a conductive material, such as concrete, and provide an electrically non-conductive barrier between the cross member and the support members 10, yoke members 14 and legs 38.
Referring now to FIG. 5, the apparatus is made by assembling the support member/yoke member assembly and placing it in a form 42. The form has a partition 44 with holes extending through it that receive the support members 10. The partition locates the support members 10 in the form. The partition also divides the form into a first section 46 in which the first section of the tie is cast, and a second section 48 in which the second section of the tie is cast.
In use the apparatus is placed under a pair of rails, at least one of which has been cut to provide a break which electrically isolates the rail end 50 on one side of the break from the rail end 52 on the other side of the brake, FIGS. 6 and 7. The apparatus is located such that one of the rail ends 50 extends across one of the clamp members 20 and the other rail end 52 extends across the other clamp member, with the flanges 55 of the rails placed against the first legs 26 of the clamp members. The second legs 28 of the clamp members are then placed on the platforms 27 against the opposed sides of the rail flanges, and are attached to the platforms by bolts 30. Bolts 54 are placed through the holes 35 in the legs 26, 28, and aligned holes (not shown) in the rail flanges to clamp the rails between the opposed legs 26, 28.
As is standard with concrete ties, polyurethane tie pads 56 are placed between the bottoms of the rails and the tops of the clamps to cushion the rails. In addition, a separator 58 made from a non-electrically conductive material, such as plastic, is placed between the rail ends, FIG. 9. The separator has a notch 60 located in it and a tab 62, which is attached to one of the clamp members by one of the bolts 30, fits into the notch and pushes the separator against one of the rails. Because the separator is held in place by the pressure of the tab it can easily be replaced.
The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
Patent Application
20070084943
