Patent Application
20220136177
The present disclosure is related to the field of direct fixation fasteners designed to attenuate wheel impact from train wheels while providing structural stability to railroad track and electrical insulation between the rail mainly in passenger rail transit applications.
Design of direct fixation fasteners could involve different design approaches. One of them involves bonding two steel or cast ductile iron plates bonded with a vulcanized rubber layer in between, designed to provide certain amount of resilience to the assembly in the vertical and horizontal directions. Another design approach is to use a non-bonded elastomer pad between the top metallic plate the bottom one, providing resilience in the vertical direction. All designs incorporate different elements to maintain structural stability and electrical insulation. Concrete blocks held in rubber boots supported on elastomeric pads are another form of direct fixation.
Direct fixation fastener plates may also be categorized based on their location of utilization. For example, installation in continuous tangent track involves repeating the same design in a linear continuous pattern. Design features such as location of hold-down clips for rail on tangent track fasteners are fixed and variability is not desired.
However, such continuity is not available in special trackwork areas where train tracks merge or cross. Special plate designs are needed in these areas to accommodate track geometry. Special trackwork plates are usually designed in different lengths, while holding their width constant, where the width is defined by the dimension aligned with the rail direction. Furthermore, special trackwork plates require flexibility with hold-down clip position, which could be unique from plate to plate due to varying track geometry. The need for geometric variation creates a challenge for manufacturing as multiple tools would be required to accommodate different lengths and clip attachment locations, and costs are higher than fixed designs.
Another way to categorize direct fixation fasteners is based their resilience (or stiffness), which stands for the amount deflection a fastener displays under unit load (Kips). While there is no absolute definition, fasteners having ˜150 kip/in stiffness under vertical loading would be considered as fasteners with “standard stiffness” in North America. Fasteners having a stiffness between 40 kip/in and 80 kip/in would be considered as “high-resilient”. High resilient fasteners are more challenging to design because higher deflections tend to create higher stresses in the product and designs must incorporate features to keep such stresses in check while providing the desired stiffness. Higher resilience is a desired feature for noise and vibration mitigation.
The present disclosure is directed to a novel and unique design approach for a high resilient special trackwork fastener plate, to be used in special trackwork areas mainly in passenger railroads. It aims to reduce manufacturing complexity and cost while maintaining desired high resilience and geometrical adjustability. The present disclosure is thus directed to a novel and unique design for a high resilient special trackwork direct fixation fastener having slotted holes in the top plate, and that uses off-the-shelf, commonly available structural shapes for making the top and bottom plates provides the desired ability of making such special trackwork direct fixation fastener in various lengths as needed.
Many other variations are possible with the present disclosure, and those and other teachings, variations, and advantages of the present disclosure will become apparent from the description and figures of the disclosure.
One aspect of a preferred embodiment of the present disclosure comprises a direct fixation fastener comprising: a top plate; a bottom plate made of metal structural channel providing two spaced-apart side walls, wherein the bottom plate has a first end and a second end and wherein each of the first and second ends terminate in a first flat edge section and a second flat edge section, respectively, without spaced-apart side walls; first and second angle bars, wherein the first angle bar is attached to the first flat edge section and the second angle bar is attached to the second flat edge section; and an elastomeric layer disposed between the top plate and the bottom plate, between the top plate and angle bars and between the angle bars and the spaced-apart side walls.
In another aspect of a preferred direct fixation fastener of the present disclosure, the top plate defines one or more key-shaped slotted openings.
In yet another aspect of a preferred direct fixation fastener of the present disclosure, each of the first and second angle bars is disposed perpendicularly to the spaced-apart side walls.
In another aspect of a preferred direct fixation fastener of the present disclosure, the bottom plate and first and second flat edge sections are machined out of a single steel C-channel.
In a further aspect of a preferred direct fixation fastener of the present disclosure, the spaced-apart side walls are disposed vertically with respect to a bottom surface of the bottom plate.
In another aspect of a preferred direct fixation fastener of the present disclosure, the bottom plate defines a central opening.
In yet another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer has a hardness in the range of 55 to 65 Shore A durometer wherein the elastomeric layer has a hardness in the range of 55 to 65 Shore A durometer around the first and second angle bars, and wherein a remainder of the elastomeric layer has a hardness in the range of 45 to 55 Shore A durometer.
In another aspect of a preferred direct fixation fastener of the present disclosure, each of the first and second angle bars comprises A36 L 3×2-½×⅜.
In an additional aspect of a preferred direct fixation fastener of the present disclosure, the first angle bar is welded to the first flat edge section and the second angle bar is welded to the second flat edge section.
In another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer has at least one opening under the top plate to provide the desired stiffness under vertical loading.
In yet another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer comprises rubber.
In a further aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer defines one or more stiffness relief holes.
In another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer has a hardness in the range of 45 to 55 Shore A durometer.
In yet another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer has a hardness in the range of 55 to 65 Shore A durometer.
In a further aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer covers the space between the top plate and the first flat edge up to the first angle bar and wherein the elastomeric layer covers the space between the top plate and the second flat edge up to the second angle bar.
In another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer covers the space between the top plate and the first flat edge up to and surrounding the first angle bar in-whole or in-part and wherein the elastomeric layer covers the space between the top plate and the second flat edge up to and surrounding the second angle bar in-whole or in-part.
In yet a further aspect of a preferred direct fixation fastener of the present disclosure, the bottom plate comprises C-Channel A36 C10×20.
In another aspect of a preferred direct fixation fastener of the present disclosure, the top plate defines one or more slotted openings.
In yet another aspect of a preferred direct fixation fastener of the present disclosure, the first angle bar and the first flat edge section to which it is attached define one or more holes and wherein the second angle bar and the second flat edge section to which it is attached define one or more holes.
In another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer defines one or more dimples, wherein each dimple forms an elongated trench running part way or the full way across elastomeric layer.
In a further aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer has a hardness of about 62 Shore A durometer.
In another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer is disposed between first and second sides of the top plate and the respective opposing side wall of the bottom plate.
In yet another aspect of a preferred direct fixation fastener of the present disclosure, the elastomeric layer is disposed between a bottom surface of the top plate and a top surface of the bottom plate and wherein a portion the elastomeric layer partially fills the central opening around a perimeter of the central opening and the portion of the elastomeric layer disposed in the central opening has a bottom surface that is flush is with a bottom surface of the bottom plate.
The present disclosure is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which:
The following description, taken in conjunction with the referenced drawings, is presented to enable one of ordinary skill in the art to make and use the disclosure and to incorporate it in the context of particular applications. Various modifications, as well as a variety of uses in different applications, will be readily apparent to those skilled in the art, and the general principles, defined herein, may be applied to a wide range of aspects. The present disclosure is not intended to be limited to the aspects disclosed herein. Instead, it is to be afforded the widest scope consistent with the disclosed aspects.
It is to be understood that the descriptions of the present disclosure have been simplified to illustrate elements that are relevant for a clear understanding of the present disclosure, while eliminating, for purposes of clarity, other elements that may be well known. Those of ordinary skill in the art will recognize that other elements are desirable and/or required in order to implement the present disclosure. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present disclosure, a discussion of such elements is not provided herein. Additionally, it is to be understood that the present disclosure is not limited to the embodiments described herein but encompasses any and all embodiments within the scope of the description and the following claims.
Preferably, the bottom plate 20 is made of metal structural channel such as machined steel C-channel bar 22 having vertical sides 24 and flat edge sections 21 where the spaced-apart side walls 24 have been machined away. Bottom plate 20 also preferably defines at least one opening 25 which preferably may be centered in the bottom plate 20. More preferably, bottom plate 20 is made of C-Channel A36 C10×20. Bottom plate 20 may also comprise metal structural channel such as machined steel U-channel bar.
Preferably, top plate 12 is fabricated out of flat A36 grade structural steel and defines key-shaped slotted openings 14 for clip housing attachment at various positions on top plate 12. Also, preferably, top plate 12 may be left flat without holes or openings 14 for welded clip housing attachment in the field. Further, top plate 12 is preferably 1.25 inches thick
Each of the angle bars or sections 30 are preferably attached to the bottom plate 20 on the flat edge section 21 thereof where the vertical sides 24 have been cut or machined away. Preferably, each angle section 30 is attached to bottom plate 20, preferably by welding. Angle sections or bars 30 are preferably made of commercially available angle-section A36 L 3×2-½×⅜. Preferably, holes 32 are drilled through the side of each angle bar 30 and the flat edge section 21 to which it is attached for mounting the direct fixation fastener to rail road ties or other rail road track foundations with fasteners such as bolts, spikes or screws (not shown).
Preferably, the elastomeric layer 40 is made of rubber and has at least one large opening 41 under the top plate 12 to provide the desired stiffness under vertical loading. The inside corners 43 of in opening 41 of elastomeric layer 40 preferably are beveled or radiused as shown in
It should be understood that while the present disclosure has been described herein in terms of specific embodiments set forth in detail, such embodiments are presented by way of illustration of the general principles of the present disclosure, and the present disclosure is not necessarily limited thereto. Certain modifications and variations in any given material, process step or chemical formula will be readily apparent to those skilled in the art without departing from the true spirit and scope of the present disclosure, and all such modifications and variations should be considered within the scope of the claims that follow.
