US3386657A - Resilient rail hold- down - Google Patents

Description

J1me 1968 J. H. KRAMER 3,386,657

RESILIENT RAIL HOLD-DOWN Filed Dec. 27, 1966 2 Sheets-Sheet l fill 14 i i 16 w} f/3% t \9 l l r g 2 L Ill "MYNm /Q //\0 19 F IG. 3

18 4 O \i 300 INVENTOR. 12/7 JAMES H. KRAMER 7 Z/A/la w I 3Q lw& 5 y T Y.

June 4, 1968 J. H. KRAMER 3,386,657

RESILIENT RAIL HOLD-DOWN Filed Dec. 27, 1966 2 Sheets-Sheet 2 INVENTOR. JAMES H. K RAMER By%%%ti TTY- United States Patent 3,386,657 RESILIENT RAIL HOLD-DOWN James H. Kramer, Akron, Ohio, assignor to The B. F. Goodrich Company, New York, N.Y., a corporation of New York Filed Dec. 27, 1966, Ser. No. 604,835 11 Claims. (Cl. 238-310) ABSTRACT OF THE DISCLOSURE A rail hold-down means which receives a rail between a pair of elastomeric springs each having radially extending arm means adapted to contact and exert a resilient downwardly directed retaining force upon the rail when the springs have been pre-stressed.

Background of the invention This invention relates to a device for anchoring a railway rail to a supporting member and, in particular, to a device for use on railways on which high vehicle speeds are encountered, such as rapid transit systems and particularly electric rail installations. Railways for this type require track gauge and rail deflection tolerances which are much more restricted than those permitted for freight line and general service tracks. In effectively holding the rails in place within the required tolerances for precisiongauge high-speed tracks, it has long been known that conventional rail spikes are inadequate. This is due to the fact that, although the spikes are initially driven tight, they soon loosen under repeated rail stressing until a condition develops where the spikes are no longer in direct contact with the rail in the unstressed state. In such a condition, no retaining force against rail displacement is developed until rail deflection occurs and the heads of the spikes make contact with the rail base-flange. This unrestrained deflection often exceeds the tolerances allotted for precision track installations designed to sustain high vehicular speeds.

One method of attacking the problem of excessive rail deflection has been the utilization of a resilient rail holddown means. For example, metal spring devices have been used for rail hold-down means on track installations in foreign countries. In addition, the use of an elastomeric dampening pad under a rail and/or under the heads of the rail spikes has been proposed.

Summary of the invention The principal object of this invention is to provide an improved rail hold-down device in which the force necessary to retain a railway rail is resiliently applied by an elastomeric material in a manner such that the retaining force is substantially constant during deflection and/ or displacement of the rail.

Another object of the invention is to provide an improved rail hold-down means as defined in the preceding paragraph in which, under normal rail loads and deflections, any horizontal movement of the rail is resisted by the resiliency of the elastomeric springs and, under severe loading, excessive displacement of the rail is constrained by rigid stops.

Another object of the invention is to provide electrical isolation of the rail from the hold-down means without the need for separate insulators.

Other objects and advantages of the invention will be apparent from the following description of the presently preferred embodiment described with reference to the acompanying drawings forming a part of this application.

Brief description of the drawings FIG. 1 is a top plan view of the presently preferred 3,386,657 Patented June 4, 1968 Detailed description In providing tracks for high speed inter-urban transit systems, it has been found preferable for track stability to utilize ties made from material other than wood, as for example, concrete. This is due to the fact that the loosening of hold-down bolts or spikes, which permits excessive rail deflections, is more frequently experienced when the ties are made of wood. Therefore, the use of rigid concrete or metal ties together with a means of resiliently mounting the rail on the tie to absorb rail vibrations induced by vehicle loads is preferred, since this reduces vibrations and/or other deflections of the rail which tend to loosen the holding means thereby causing subsequent failures in the rail. The present invention permits resilient mounting by providing a hold-down structure in which a resilient elastorneric pad is provided under the base of the rail between the latter and a rigid portion of the structure which also performs the function of a tie plate. In addition, the rail is resiliently constrained from displacement by rail hold-down members which bear upon the top of the rail base flange with sufficient force to retain the rail under the restoring action of deformed elastomeric material so that movement of the rail causes movement of the members increasing the restoring force. The elastomeric pad under the rail also serves to electrically isolate the rail from the tieplate portion of the structure while the hold-down members are electrically isolated from the housing means of the hold-down structure by the same elastomeric material which provides the force resisting rail displacement so that the entire rail may be very simply electrically isolated.

Referring now to FIG. 1 and FIG. 2, which illustrate the presently preferred embodiment of the invention, the rail 10 with base-flange portion 10a rests on a resilient dampening pad 11. The dampening pad is intermediate rail 10 and the rigid tie-plate portion. 12 of the holddown means. This plate portion has a pair of rigid cylindrical hollow spring housings 13 mounted thereon in spaced relationship so that the housings are located one on either side of the pad 11. The housings and tie-plate portion are preferably made of steel. Rigid gussets 14, also preferably of steel, are welded to the upper surface of the plate portion 12 and the exterior of the spring housings 13, thereby preventing relative displacement of the housings 13 with respect to the plate 12.

Means are provided for securely anchoring the tieplate portion 12 to the rail support or tie 15 which is preferably made of concrete. As illustrated, this anchoring in the preferred embodiment comprises a threaded stud 16, washer 17 and nut 18 at either end of the hold-down. The unthreaded end of each stud is embedded in or otherwise securely anchored to the concrete rail tie 15 so that the hold-down structure is rigidly anchored thereon by assembling the plate portion 12 onto the support or tie 15 with the studs passing vertically through holes provided in the tie-plate. Rigid stops 13', preferably right angle steel sections extending generally the length of the housing 13, are attached to the plate 12 with one angle of the section positioned vertically and laterally spaced from the rail-base edge a distance which provides a maximum limit to lateral rail movement under severe loads.

Instead of providing the stops 19 as separate sections, they may be formed by shaping the housings 13 such that the side of each housing adjacent the rail is formed with a vertically extending portion spaced from the edge of the rail base a distance to limit lateral rail movement. Incorporating the stops into the sides of the housings eliminates the necessity of providing separate members for this function.

A pair of rigid arms 20, extending generally radially from each housing 13, are provided as rail holding members. Each of these arms has one end in contact with the top surface of the rail base-flange a to exert a downward force thereupon for maintaining the rail firmly mounted on the dampening pad. The horizontal frictional force produced by the pressure of each arm on the area of contact with the rail-base also serves to hold the rail in laterally spaced relation between the housings. The opposite end of each arm for each housing 13 is removably mounted on one end of rigid shaft means 21 extending from the housing by a means preventing relative rotation between the arm and shaft means. In the preferred embodiment, each arm has a hexagonal opening therethrough near one end and is adapted to slip over a hexagonally shaped end 21a formed on each end of the shaft means 21. The shaft means, as shown in the preferred embodiment, is hollow tubing with the central portion substantially cylindrical and with the ends 14a forged to the aforementioned hexagonal shape. The invention is not, however, limited to any particular manner or way for attaching the arms to the shaft means; for example, the arms 20 may have integral studs polygonal in cross section projecting from the sides thereof and received in complementary shaped openings in the ends of ths shaft means. Alternatively, the shaft means and arms may be provided with cooperating keyways and keys or other commonly employed expedients.

Each .pair of arms 20 is rotated into rail-holding position by elastomeric spring material 22 positioned intermediate the shaft means 21 and the surrounding portion of the housing 13. In the preferred embodiment, the elastomeric material 22 has the surface surrounding the cylindrical portion of the shaft means securely bonded thereto. The outer periphery of the elastomeric material 22 is securely bonded to the inside surface of a thin, rigid cylindrical shell 23, having a pair of axially extending radial lugs 23a on its outer surface. The lugs 23a are adapted to axially slip-fit in cooperating parallel grooves in the bore wall of the housing 13 to prevent relative rotation between the shell and housing. Preferably the elastomeric spring material 22 is first securely bonded to shell 23 and shaft means 21 and then the assembly is inserted into the housing bore by sliding it longitudinally therein with the lugs 23a on the shell engaging in the cooperating grooves in the housing 13.

A torsional preload on the elastomeric sprin material 22 of magnitude suflicient to prevent said displacement is necessary to hold the rail securely in place under normal vehicle loads. Therefore, the structure comprising the arms, housing, gussets and tie-plate must be designed sufficiently rigid to withstand the torsional load imposed on them by the elastomeric spring and by the rail deflecting stresses. In the preferred embodiment, each elastomeric spring 22 is capable of being rotated through an arc of 2065 and resistin torsional loads of substantially 6,000 in.-lbs. The method of installing the rail on the hold-down device and providing preloading of the elastomeric spring, in general, comprises first positioning the rail between the housings 13 after which the clastomeric springs 22 are torsionally deflected and then the arms 20 are installed.

More particularly, the resilient pad 11 is first placed on the top surface of the tie-plate portion 12 between stops 19. The rail 10 is then positioned on the pad and centered between the housings 13. One of the hexagonal shaft ends 21a is engaged with a wrench (not shown) and rotated through an arc of range 20-65 away from the rail thereby applying a minimum torsional preload of 5,600 in.-lbs. to the elastomeric spring material 22. While the shaft means 21 is held in the rotated preloaded position with the wrench, one of the arms 20 is engaged with the hexagonal portion 21a on the other end of the shaft, with the free end of the arm 20 as close as possible to contacting the top surface of the rail baseflange 10a. The shaft means 21 is then permitted to rotate under the restoring force of the sprin material 22 until the arm 20 makes contact with and presses upon the surface of the base flange 10a, exerting a retaining force thereupon and preventing further rotation of the shaft means 21. The wrench is then removed from the free end of the shaft means 21 and applied to the installed arm 20 to raise the arm, thus rotating the free end of the shaft an amount suflicient to permit installation of an arm 20 on the free end of the shaft. Finally, the shaft means is again permitted to rotate until both arms contact and exert a restraining force upon the rail base-flange 10a. The procedure is then repeated for the elastomeric spring device 22 for the opposite side of the rail. With the application of the specified torsional preload, the elastomeric spring will cause each arm 20 to exert a hold-down force of approximately 2,800 lbs. on the base-flange 10a.

Any rotational or lateral movement of the installed rail will cause movement of the arms 20 and any movement of the arms will thus cause movement of the shaft means 21 relative to the housings 13. This will produce deflection of the elastomeric spring material 22 in each housing creating further elastic restoring forces therein, which will tend to return the shaft means to their free positions.

In the present embodiment, the tie-plate portions 12, housings 13, gussets 14 and stops 19 are fabricated separately and joined by welding. However, the invention is not limited to this form, and these parts may be made integrally, as for example by casting. Also, although the shaft means 21 is illustrated as unitary and hollow, the invention is not limited to this form.

Referring now to FIG. 3, another embodiment is shown in which those parts similar to the embodiment of FIGS. 1 and 2 have like reference numerals. In FIG. 3, a portion of the arm has been broken away to expose the end of the elastomeric spring to view. In the present embodiment, the rail engaging arms, designated 30, each have a downward projecting lug 30a forming a corner notch with the portion of the arm in contact with the top of the rail base-flange. Each lug 30a extends downward in spaced relation to the adjacent edge of the rail base-flange for limiting the horizontal rail movement. The lug 3011 replaces the stops 19 of FIG. 2 for limiting rail displacement, and therefore, separate stops are not required in the present embodiment. Any severe horizontal displacement of the rail suflicient to create frictional break-away of the hold-down force on the top surface of the baseflange, causes the rail 10 to come in contact with the lug 30a nearest the side of the rail in the direction of displacement. The force exerted by the rail on the lug 30a is transmitted, via the arm 30, to shaft means 21 and absorbed by restoring forces created in deflecting the elastomeric spring 22. The horizontal line of action of the rail force on the lug 30a passes underneath the axis of shaft 21. Therefore, any horizontal rail displacement creates a force-moment about the axis of the shaft 21 which tends to increase the contact force of the arm 30 on the top surface of the base flange.

The present embodiment of the invention electrically isolates the rail from the tie-plate by means of the pad 11 and the elastomeric spring 22. Thus, neither the arm 30 nor the lug 30a make contact with the tie-plate or housings 13 and complementarily shaped surfaces 21a on the shaft means 21 and arms 30 are so formed as to keep the arm 30 axially spaced from the housings 13 sufficiently to precent electrical contact with the housings. Additionally, protection from electrical shorting due to foreign objects lying between the rail and housings can be provided by extending the elastomeric pad 11 laterally on each side beyond the edge of the rail and vertically upward over the top of each housing. Also, by extending the portion of the pad over the ends of the housings 13 vertically downward between each end of the housings and each arm 30, protection can be provided against foreign objects causing electrical shorting between the arms 20 and the housings 13. The embodiment of FIG. 3 thus eliminates the need for separate rail displacement stops and provides an improved resilient rail mounting which is adaptable for electric rail applications, without requiring separate insulators to isolate the hold-down device from the rail.

Referring now to FIG. 4, another embodiment of the invention is illustrated wherein the tie-plate portion 40 is made integral with housings 40a. Similar to the embodiment of FIG. 2, the housings are spaced on the tie-plate sufficiently to permit a rail to be mounted between them upon a resilient pad 11 similar to the embodiment of FIGS. 1 and 2. The vertical sides 40b of the housings adjacent the rail serve as stops to limit lateral displacement of the rail under severe vehicle loads, similar to the rigid stops 19 in the embodiment of FIGS. 1 and 2. Elastomeric spring material is also employed in the present embodimerit to provide the force required to retain the rail; however, the spring is of a different construction than that of the "embodiment of FIGS. 1 and 2. Thus, in the present embodiment, each of the housings 40a has a longitudinal bore centrally therethrough which is generally rectangular in cross-section and parallel to the rail. A rigid shaft means 41, preferably hollow having a uniform polygonal cross-section preferably square, passes centrally through the bore in each housing. Strips of elastomeric material 42 are placed longitudinally intermediate the shaft means 41 and the interior surfaces 40c of the housing here with the elastomeric material deformed in cross-section such as to exert a generally radial pressure on the shaft means. The ends of the shaft means extend exteriorly from the ends of the housing bore and are adapted to have rail holding arms removably mounted thereon. A pair of arms 20 is provided for each shaft means with each arm having a non-circular hole in one end adapted to positively engage in a slip-fitting manner the complementarily shaped end of the shaft means 41. The arms are assembled onto the shaft means and preloading of the elastomeric springs for providing the necessary hold-down force is performed in the same manner as the embodiment of FIGS. 1 and 2. The arms are assembled onto the shaft ends in a position such that the arms extend in parallel spaced cantilever arrangement having their free ends making contact with the top surface of the rail base flange and pressing thereon. Movement of the arms causes the elastomeric material to be compressed between the shaft and the inner periphery of the bore 400 by the rotation of the shaft means 41, and elastic restoring forces are created in the spring material which tend to return the shaft means to its original position.

The embodiment of FIG. 4 is shown as having tie-plate portion 40 and the housings 40a cast as one integral piece. However, the invention is not limited thereto since the tie-plate, housings, gussets and stops may be fabricated of separate pieces joined together, as for example by welding similar to the embodiments of FIGS. 1, 2 and FIG. 3. These and further modifications and adaptations of each of the embodiments, not expressly disclosed herein but which may be made by those skilled in the art are deemed encompassed within and may be made without exceeding the ambit of the invention which is limited only as required by the spirit and scope of the appended claims.

Having thus described the invention, I claim:

1. A mounting means for a railway rail comprising a plate-like portion adapted to be secured to a rail support and extend under a rail with portions extending laterally beyond the rail on either side thereof, a pair of rigid housings immovably mounted one on each of said extending portions with each housing having a bore extending centrally therethrough parallel to the rail when the latter is supported on said plate-like portion, rigid shaft means passing centrally through the bore in each housing with at least one end of said shaft means extending axially exteriorily from its housing, at least one body of elastomeric material in each bore intermediate each of said shaft means and the housing through which. it extends, said elastomeric material cooperating with said shaft means and the walls of the bore in which it is positioned to resiliently resist relative rotation therebetween, and a rigid arm mounted on the said extending portion of each of said shaft means in a manner preventing relative rotation between said shaft means and said arm and with each arm extending generally radially from its shaft means for contact with the top surface of the base-flange of a rail supported on said plate-like portion between said housings.

2. A mounting means as defined in claim 1 wherein the said extending end of each shaft means and the said arm mounted thereon are provided with cooperating disengageable interfitting surfaces which prevent relative rotation when engaged.

3. A mounting means as defined in claim 1 wherein the bore through each of said housings is substantially circular in cross-section and each of said shaft means has the axially central portion substantially cylindrical with the said elastomeric material secured within each bore and to the related shaft means in a manner such that rotation of the latter about its axis deforms the elastomeric material without relative movement at the interfaces of the elastomeric material with the related shaft means and bore.

4. A mounting means as defined in claim 3 wherein each of said shaft means is bonded to the related elastomeric material, a rigid cylindrical shell removably fitted in each bore concentric with the axis of each of said shaft means and having its inner periphery surrounding and securely bonded to the said elastomeric material in the bore for preventing relative rotation therebetween, and cooperating interfitting surfaces on the outer periphery of each shell and the interior of the bore in which it is located to prevent relative rotation between said shell and said housing.

5. A mounting means as defined in claim 4 wherein the said interfitting surfaces on said shell and bore comprise an axially extending radial projection on one and a complementarily shaped axially extending radial recess on the other.

6. A mounting means as defined in claim 1 wherein each shaft means has the portion thereof within the related bore po'lygonally shaped in cross-section and the said elastomeric material within the bore is formed of a plurality of separate longitudinal portions disposed intermediate the polygonal surfaces on the shaft means and the inner periphery of the bore in a manner causing the said elastomeric material to be compressed radially between said shaft means and said bore upon relative rotation therebetween.

7. A mounting means as defined in. claim 1 wherein the said plate-like portion is provided with vertically extending rigid surfaces on opposite sides of the region adapted to receive a rail with said surfaces spaced to limit the horizontal displacement of said rail.

8. A mounting means as defined in claim 1, wherein each of said arms has a lug projecting downwardly therefrom and adapted to extend vertically closely adjacent the opposite edges of the base-flange of a rail positioned on the mounting means whereby horizontal displacement of said rail causes contact thereof with one of said stops so that the force of horizontal rail displacement is resiliently resisted by deflection of said elastomeric material.

9. In the combination of a rail and mounting means therefor adapted to secure the rail to a support comprising: a rigid base-plate, a pair of rigid housings immovable upon said plate in lateral parallel relation spaced sufficiently to receive a rail therebetween, a resilient elastomeric pad resting on said base plate between said housings, a railroad rail having a base flange supported upon said pad between said housings, each of said housings having a horizontal bore centrally therethrough with its axis parallel to the length of the rail, rigid shaft means passing centrally through the bore of each one of said housings with each end of each of said shaft means extending axially exteriorly from its housing, a thin cylindrical shell disposed in the bore of each housing with each shell having surfaces for cooperatively interengaging mating surfaces in said bore for preventing relative rotation therebetween, elastomeric spring material intermediate each of said shells and the shaft means thereon with the elastomeric material securely bonded to both the said shaft means and shell thereby enabling said elastomeric material to resist relative rotation between said shaft means and said housing by deflection of said elastomeric material, a pair of rigid arms re movably mounted upon the opposite ends of each shaft means in a manner such that relative rotation is prevented therebetween, each of said arms having a free end extending radially into engagement with the top surface of the base flange of said rail, the said elastomeric material being torsionally prestressed in a direction such that the free end of each arm exerts a rail-holding force upon said rail.

10. The combination as defined in claim 9 and further comprising means providing rigid, laterally spaced stops on either side of said rail to limit lateral displacement thereof.

11. The combination as defined in claim 9 and further comprising integral projections on each arm normally laterally spaced from said rail and positioned for engagement by the latter upon excessive lateral displacement thereof.

References Cited UNITED STATES PATENTS 2,591,281 4/1952 Musschoot 2671 2,03 6,200 4/ 1936 Eastburn 238-292 1,126,526 1/1915 Liebmann 238331 968,156 8/1910 Holden 238-291 ARTHUR L. LA POINT, Primary Examiner.

R. A. BERTSCH, Assistant Examiner.

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