Patent Application
20240068173
The present disclosure relates generally to a direct fixation fastener for track rail, and more particularly to such a fastener configured to limit undesired movement of a rail clip in service.
Rail equipment is used globally for transporting persons and all manner of goods and equipment. Rail lines for freight, passenger, or commuter trains are formed by parallel track rails supported upon a substrate, as will be familiar to many. Many different mechanisms are known for positioning, supporting, and fastening the track rails as well as managing loads and vibrations transmitted by way of the rail and fasteners between rail equipment and the underlying substrate. Rail fastening and fixation systems include simple plates attaching rails to wooden ties, as well as highly engineered direct fixation fasteners formed from an assembly of metallic and non-metallic parts.
During service, fasteners can be subjected to significant loads and vibrations as they accommodate transit of locomotives and rail cars upon the supported rails. The rails themselves are often secured to the fasteners by way of rail clips, commonly so-called “E-clips.” In one typical example, a section of rail is placed upon a surface of a rail plate, and rail clips hammered into receptacle holes in the fastener to engage a toe portion of the rail clip in contact with the base of the rail. In this general way, friction and spring clamping force of the rail clips secure the rail to numerous fasteners spaced longitudinally along the rail.
During service, loads and vibrations, including longitudinally directed loads on the track rail, vertical loads, and lateral loads can cause connections among the various components to shift, degrade in performance, or even fail. One known direct fixation fastener strategy is set forth in U.S. Pat. No. 10,081,915 to Constantine.
In one aspect, a direct fixation track rail fastener includes a fastener body having a first clip shoulder, a second clip shoulder, and a rail plate having an upward facing rail contact surface positioned laterally between the first clip shoulder and the second clip shoulder and extending in a fore-aft direction between a fastener body forward edge and a fastener body back edge. The first clip shoulder and the second clip shoulder include a first clip tunnel and a second clip tunnel, respectively, each formed in part by a plurality of clip contact faces, finite in number, oriented to react an upward clamp load from a rail clip prong and defining a first prong contact line and a second prong contact line, each extending in a fore-aft direction.
In another aspect, a track rail fastener includes a fastener body having a lower, substrate-facing side, and an upper side, and including a heel support surface upon the upper side extending in a fore-aft direction between a fastener body forward edge and a fastener body back edge, and in a lateral direction between a clip shoulder and a fastener body lateral edge. The clip shoulder includes a clip tunnel extending in a fore-aft direction and formed in part by a plurality of clip contact faces. The plurality of clip contact faces define a first prong contact line and a second prong contact line on a cylinder extending in the fore-aft direction through the clip tunnel. The first prong contact line and the second prong contact line together define an upwardly opening angle having a vertex at an axis of the cylinder.
In still another aspect, a direct fixation track rail fastener includes a rail plate having a lower, substrate facing side, an upper side, a clip shoulder having a clip tunnel formed therein to receive a prong of a rail clip, and a heel support surface adjacent to the clip shoulder. The clip tunnel includes a floor, and a plurality of clip contact faces, finite in number, located vertically above the floor and defining a first prong contact line and a second prong contact line extending through the clip tunnel. The first prong contact line and the second prong contact line define a cylinder extending in a fore-aft direction through the clip tunnel and are located less than 180° apart on the cylinder.
Referring to
Fastener 10 includes a fastener body 18 having a first clip shoulder 20, a second clip shoulder 22, and a rail plate 24 having an upward facing rail contact surface 26 positioned laterally between first clip shoulder 20 and second clip shoulder 22 and extending in a fore-aft direction between a fastener body forward edge 30 visible in the view of
First clip shoulder 20 and second clip shoulder 22 include a first clip tunnel 34 and a second clip tunnel 36, respectively, each extending in the fore-aft direction. Focusing now on
Each rail clip 16, hereinafter referred to at times in the singular, may include a toe 46 that contacts track rail 12, a heel 48 contacting a corresponding one of heel support surfaces 54 and 56, and a prong 50 received and supported in a corresponding one of first clip shoulder 20 and second clip shoulder 22. Rail clip 16 may be hammered into place to position prong 50 within the corresponding clip tunnel 36 and thereby provide a downward clamping force via toe 46 on track rail 12. An upward clamp load from rail clip prong 50 is reacted by clip shoulder 22 within clip tunnel 36.
When positioned for service, heel 48 contacts heel support surface 56 and counteracts rotation of the respective rail clip 16. Clip prong 50 within clip tunnel 36 provides the clamping force to toe 46 and heel 48. In service, track rail 12 may move longitudinally due to thermal expansion and contraction or car braking forces transferred to track rail 12 by frictional forces. Based on the clamping of toe 46, against track rail 12, toe 46 tends to also engage in longitudinal movement. One rail clip may be urged out of its respective shoulder while another rail clip on the opposite side of the track rail is urged into its shoulder. In conventional strategies, a clip heel has a single point of contact with the heel support surface, and single line contact between the clip prong and clip tunnel. Over the course of time, the rail clip tends to rotate during longitudinal rail movement. Combined longitudinal and rotation forces can cause a rail clip to be pushed entirely out of the clip shoulder and leave the rail unclamped. As will be further apparent from the following description, the present disclosure addresses these and other phenomena.
Referring also now to
In an embodiment, each of first clip shoulder 20 and second clip shoulder 22 forms an arch 75. Each respective plurality of clip contact faces 60 and 62 may be within the respective arch 75. As can also be seen from the drawings clip contact faces 60 and 62 may include an inboard clip contact face 60 closer to track rail 12, and an outboard clip contact face 62 closer to lateral edge 44. Clip contact faces 60 and 62 may be planar in some embodiments. In other embodiments, and as illustrated in
Referring to
Referring now to
Referring to the drawings generally, as discussed above when placed in service traditional fasteners may have a single point of contact between a cylindrical or partially cylindrical clip tunnel surface and a cylindrical prong of a rail clip. The single line of contact in known designs can fail to prevent wiggling of a rail clip in response to dimensional changes in components, vibrations, and other forces.
According to the present disclosure, a rail clip including a prong that is held via clamping forces in contact along two lines of contact with a top surface or roof of a clip tunnel will tend not to wiggle in the manner associate with prior designs. In this general way the present disclosure can provide desirable performance with regard to clip retention and overall improved rail stability and service life.
The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
