The present disclosure relates to railway ties which are typically made of concrete and embedded within grade material for supporting railway tracks. In particular, the present disclosure relates to a resilient boot for surrounding the railway tie to dampening vibrations from passing trains, and to a method of constructing such railway ties.
Railway ties of the type used in many modern railway systems include a tie block made of concrete or other rigid material which includes embedded rail clip mounts or other mounting structures for connecting and securing railway tracks. The tie blocks are embedded in surrounding grade material such as aggregate or concrete, for example, which forms the railway bed. A resilient boot, typically made of rubber or other elastomeric material, substantially surrounds the tie block and is embedded in the surrounding railway bed. A separate resilient pad, typically made of foam or rubber, is disposed between the bottom wall of the boot and the bottom surface of the tie block. The boot and pad dampen vibrations from passing trains to prolong the service life of the tracks and the mounting hardware by which the tracks are secured to the tie blocks.
In one known process for manufacturing railway ties, the concrete tie block is poured using a mold with track mounting structures, such as rail clip mounts and plastic anchors, embedded within the upper portion of the concrete for later securement of rails. After the concrete has cured, the tie block is inserted within a surrounding resilient boot, with the upper edge of the boot disposed at a vertical distance beneath the upper surface of the tie block.
For aid in embedding the tie block within a surrounding railway bed, a band of resilient material is then installed around the upper portion of the tie block above the upper edge of the boot, such that substantially the entire vertical sidewalls of the tie block are covered. The tie block and boot are then embedded in surrounding railway bed material to a depth at which the railway bed material is disposed near the top of the boot and at the junction between the boot and the resilient band, such that the upper surface of the tie block sits proud of the surrounding railway bed material. In this manner, the resilient band provides a visual locator for the desired depth that the tie block should be embedded in the railway bed. In a final step, the resilient band is cut away from the tie block and surrounding railway bed and removed.
What are needed are improvements in the vibrational dampening effect of the railway tie boots and a simplified process for constructing and installing railway ties.
The present disclosure provides a vibration dampening boot for railway tie blocks and a method of manufacturing railway tie block assemblies. The boot includes a bottom wall with resilient tie block contact structures disposed at different heights for initial tie block support and variable vibration dampening. The upper portion of the boot terminates in a removable wall connected to the side walls of the boot by a relatively thin tear strip to enable direct pouring of cast material, such as concrete or epoxy, into the boot for casting the tie block, with the wall removable after installation of the tie block assembly into a railway bed. In this manner, the boot may be used with pre-cast tie blocks as well as accommodate direct casting of the tie blocks within the boot to form a tie block assembly.
In one form thereof, the present invention provides a railway tie block boot, including a bottom wall made of a resiliently deformable material, a plurality of side walls extending upwardly from the bottom wall and terminating in an upper lip extending around a periphery defined by the side walls, such that the bottom wall and the plurality of side walls cooperate to form a generally rectangular box-like structure with an open upper end, and a removable wall extending upwardly from the upper lip and extending around the periphery of the side walls, the removable wall tapering inwardly from the upper lip toward the open upper end.
In another form thereof, the present invention provides a railway tie block boot, including a bottom wall sized and configured to support a railway tie block, the bottom wall having a ribbed structure formed on an upwardly-facing surface thereof and defining a plurality of lands and valleys, and a plurality of side walls extending from the bottom wall and terminating in an upper lip spaced from the bottom wall and extending around the side walls.
In yet another form thereof, the present invention provides a method of assembling a tie block to a tie block boot, the tie block boot having a bottom wall, a plurality of side walls extending upwardly from the bottom wall and terminating in an upper lip extending around a periphery defined by the side walls, and a removable wall extending upwardly from the upper lip. The method includes folding the removable wall down around the side wall, seating the tie block into the tie block boot such that the tie block is support by the bottom wall and abuts the plurality of side walls, and unfolding the removable wall such that an inwardly-tapered portion of the removable wall is allowed to conform to an adjacent inwardly-tapered portion of the tie block.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.
The above-mentioned and other features of the disclosure, and the manner of attaining them, will become more apparent and will be better understood by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the disclosure and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
The present disclosure provides railway tie assembly 10, shown in
In the illustrated embodiment, tie block 12 is a cast structure which may be formed, e.g., of concrete or an epoxy polymer material such as CASTINITE available from Precision Polymer Casting, LLC of Perry, Ohio. Such polymer materials may, in some cases, be molded directly within boot 30, as described below, thereby saving the step of installing tie block 12 into boot 30. Tie block 12 may include a plurality of cast-in anchors 20, such as four anchors 20 as illustrated, which may have eyelets (not shown) attached thereto for lifting and spatial manipulation of tie block 12. Rail clip retainers 16 are also cast in to tie block 12, and form an anchor point sized to receive rail clips 18. Rail clips 18 can be attached to rail clip retainers and thereby engaged with a lower flange of rail 14 to affix rail 14 to tie block 12. Rail pad 22 may also be disposed between rail 14 and tie block 12.
Turning now to
The overall dimensions of boot 30 may vary according to the intended railway application. In one exemplary embodiment, boot 30 may be about 31.5 inches long, 11.8 inches wide, and 5.9 inches deep, with a total interior depth (i.e., the distance between the upper surface of lip 40 and the upper surface of ribbed structures 42) of about 5.3 inches. These dimensions comport with an application in rail beds for light rail applications, as further described below. Other dimensions may be used for other applications, such as freight or heavy rail applications.
As best seen in
For purposes of the present discussion of lands and valleys, the nomenclature of waves may be employed, with lands 44 and valleys 46 cooperating to form a trapezoid wave form in cross section, as shown in
In an exemplary embodiment, boot 30 is made of a monolithic structure consisting of a single piece of material, such as natural or synthetic rubber having a durometer as little as 45, 55 or 65 and as large as 70, 75 or 80 on the shore A scale, or may have any durometer within any range defined by any of the foregoing values. Exemplary rubber materials for use in forming boot 30 include ethylene propylene, styrene-butadiene (also known as Buna-S), synthetic or natural isoprene, nitrile rubber (also known as Buna-N), isobutyl isoprene, and chloroprene neoprene.
With this type of material and in the context of railway tie assembly 10 utilized in a light rail application, frequency F may be between 0.65 inches and 1.0 inches, such as 0.90 inches, and height DH may be between 0.2 and 0.3 inches, such as 0.24 inches. In addition, the lateral extent DL of each upper surface of lands 44 may be between 0.30 and 0.45 inches, such as 0.38 inches, while the width DV of each valley 46 may be between 0.2 and 0.3 inches, such as 0.25 inches. Angle α defined by the upward and downward slopes flanking each land 44 may be between 50 degrees and 70 degrees, such as about 60 degrees, resulting in an overall base width DF of each land 44 being between 0.60 and 0.70 inches, such as about 0.65 inches. This set of parameters for the trapezoid wave form formed by the grid of lands 44 and valleys 46 throughout ribbed structure 42 provides a suitable resilient force profile, in conjunction with the aforementioned materials and durometers, which is commensurate with currently accepted cushioning requirements for railway tie assemblies including a resilient pad disposed at the bottom of a boot, as may be found in existing light rail applications. For example, ribbed structure 42 as described herein may provide an effective spring constant designed to be appropriate for railway applications.
As best seen in, e.g.,
The material and structure of lands 54 may be tailored to provide a desired reaction force to such external lateral forces. In an exemplary embodiment designed for light-rail applications, lands 54 and valleys 56 may have a frequency of about one land per inch, and an amplitude of about 0.050 inches.
Referring to
In an alternative embodiment, two sets of lands set at differing heights may be provided such that a relatively soft initial resiliency gives way to a firmer subsequent resiliency as loads increase sufficiently to deform the upper set of lands enough to bring tie block 12 into contact with the lower set of lands.
Boot 130 is substantially similar to boot 30 described above, with reference numerals of boot 130 analogous to the reference numerals used in boot 30, except with 100 added thereto. Structures of boot 130 correspond to similar structures denoted by corresponding reference numerals of boot 30, except as otherwise noted herein. Moreover, references to either boot 30 or boot 130 herein may be taken as a reference to both boots, except where differences between boots 30 and 130 are made explicit. Therefore, all features ascribed to boot 30 may also be ascribed to boot 130 except as otherwise noted herein, and vice versa.
As best shown in
In the illustrated embodiment, lands 144 have the same spatial, size and material configuration as lands 44, except frequency F′ (
However, height DH′ of lands 144′ is reduced in order to create the desired height differential between the upper and lower tie block contact structures 134, 136. In order to accommodate this reduced height while maintaining the other spatial variables the same as noted above, lower lands 144′ define an angle β between the sloped surfaces flanking lands 144′ that is larger than the analogous angle α derived from lands 144. In an illustrated embodiment, angle β between 65 degrees and 85 degrees, such as about 76 degrees. In an embodiment particularly suitable for integration in to a light rail system, the difference between height DH of lands 144 and the reduced height DH′ of lands 144′ may be between 0.04 and 0.08 inches, such as 0.06 inches. Because the vertical deformation of upper tie block contact structure 134 needed to initially engage lower tie block contact structure 136 is equal to the difference between DH and DH′, this height differential can be used to set the amount of force needed for the ribbed structure 142 to transition from a first, relatively lower spring constant influenced only by lands 144, to a second relatively larger spring constant influenced by both lands 144 and lands 144′.
For the above described durometer rages and the illustrated and described spatial configuration and structural sizes of lands 144, lands 144′ and valleys 146, the illustrated configuration of ribbed structure 142 may result in a first spring constant set by upper tie block contact structure 134 that is commensurate with industry-accepted values for a particular application, such as railways applications. Once sufficient pressure is applied to upper contact structure 134, lands 144 of upper tie block contact structure 134 will deform sufficiently to allow the lower surface of tie block 12 to come into contact with lands 144′ of lower tie block contact structure 136. At this point, a second spring constant of ribbed structure 142 is set by both upper and lower tie block contact structures 134, 136, and may be commensurate with industry-accepted values for extreme or limit loading conditions for a particular application, such as railway applications.
Turning to
Turning now to
As best seen in
Assembly 10 is placed into a desired position within a prepared railway bed, including the creation of an appropriate canter (e.g., a 40:1 slope) in the upper surface of tie block 12. In the case of a polymer tie block 12, the appropriate canter may be set by molding tie block 12 within boot 30 as noted herein. Aggregate or other material is filled in around boot 30. In a typical installation, such aggregate is not intended to completely submerge tie block 12, but rather, a portion of tie block 12 should extend upwardly out of the aggregate. To this end, lip 40 is positioned at the proper location for aggregate fill depth, and may serve as a visual marker for proper fill depth upon deployment of assembly 10. Particularly where concrete is poured around boot 30 to fix assembly 10 in its deployed position, a resilient and tight fit of removable wall 50 against the abutting surfaces of tie block 12 may protect the inner cavity of boot 30 from infiltration of such concrete or other poured materials.
After boot 30 is buried in an appropriate amount of aggregate and therefore fixed at a desired position and orientation within the railway bed, removable wall 50 is ready for removal in order to leave only the material of tie block 12 exposed above the aggregate. To facilitate easy removal without tools, tear strip 52 is provided at the junction between removable wall portion 50 and lip 40. As best seen in
Thickness T of tear strip 52 is sufficiently thick to prevent separation of removable wall portion 50 from the remainder of boot 30 during installation and/or pouring of tie block 12 into the inner cavity of boot 30 (as described below), and during handling of assembly 10. For example, thickness T is large enough to support the weight of boot 30 as railway tie assembly 10 is lifted and moved into place during deployment. On the other hand, thickness T is thin enough to allow a user to grasp a portion of removable wall 50 and tear it away from tie assembly 10 by hand, and without the use of tools. In other embodiments, removable wall 50 may facilitate removal with a tool such as a knife via tear strip 52.
Tie block 12 may be pre-cast and then placed within boot 30. To seat tie block 12, removable wall 50 may be resiliently deformed or folded down around the adjacent portion of sidewalls 28 to allow tie block 12 to pass into boot 30, and tie block 12 may then be advanced downwardly into the cavity of boot 30 until the lower surface of tie block 12 contacts at least the upper tie block contact structure 134 as shown in
Alternatively, tie block 12 may be cast directly into boot 30, such that boot 30 serves as a casting mold. For this application, a casting plate 60 (
While this disclosure has been described as having exemplary designs, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.
This application claims the benefit under Title 35, U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 62/669,761, entitled VIBRATION DAMPENING RAILWAY TIE BOOT and filed on May 10, 2018, the entire disclosure of which is hereby expressly incorporated by reference herein.
Number | Date | Country | |
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62669761 | May 2018 | US |