US3494555A - Rail holddown apparatus - Google Patents

Description

Feb. 10, 1970 F. K. HALL. 3 94 55 RAIL HQLDDOWN APPARATUS Filed Feb. 25, 1968 2 Sheets-Sheet 1 2 INVENTOR; l8 FRANK KENNETH HALL Feb. 10, 1970 F. K HALL 3,494,555

RAIL HOLDDOWN APPARATUS Filed Feb. 23, 1968 2 Sheets-Sheet 2 INVENTOR. FRANK KENNETH HALL |J|lm n v Ji g 531 .40, cum /3 E g/5- United States Patent 3,494,555 RAIL HOLDDOWN APPARATUS Frank Kenneth Hall, Findlay, Ohio, assignor to The D. S.

Brown Company, North Baltimore, Ohio, a corporation of Ohio Filed Feb. 23, 1968, Ser. No. 707,492 Int. Cl. E01b 9/28, 9/62, 9/68 US. Cl. 238-315 10 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention concerns holddown systems particularly adapted to securely position a railroad rail on a support member or underlying structure. The invention particularly concerns the holddown systems adapted for use with concrete ties, concrete beds, metal superstructures, and like rail support structures. It further pertains to other uses wherein one member is to be held in position relative to another member and may be used in lieu of bolt connections, welded connections, etc.

Railroad rails traditionally have been mounted on wooden cross ties spaced at close intervals by the driving of railroad spikes into the ties with the head portion of the spike overlapping the base flange of the rail. This has been true of below ground, and on ground rail systems and above ground, or elevated, rail systems. With the fairly recent advent of improvements in the structural strength of concrete, rail systems embodying concrete ties or concrete beds have awakened the interest of railroad designers. Concrete beds or ties require considerable less maintenance and have a longer useful life than do the traditional wooden ties.

The adaptation of rail systems to the use of concrete ties and concrete road beds, however, also require a departure from the traditional concept of holding the rail on the ties, i.e., by spikes being driven into the wooden ties. Holddown systems for rails on concrete ties and/or concrete road beds or metal superstructures have been developed in recent years. Known holddown systems embody heavy metal structures. Some utilize metal components in torsion stress as the force-exerting members. A specific object of the present invention concerns improvements in rail holddown systems wherein the traditional, wooden tie concept is abandoned in favor of prestressed concrete ties, metal superstructures and/or concrete road beds in below ground, on ground or elevated rail systems.

BRIEF SUMMARY OF THE INVENTION Briefly, the invention concerns holding systems in general, i.e., systems for holding one member relative to another comprising a first member, a second member contiguous thereto to be held in fixed position relative to said first member, and means for transmitting thrust between said members including a compressively deformed bias member, preferably a solid elastomer body having opposite substantially parallel faces exerting an outward elastic recovery thrust against substantially parallel faces with lines of thrust forces in said compressively deformed member being essentially at right angles to said faces. An exemplary use thereof comprises rail holddown systems wherein the railroad rails are secured by a series of "ice holddown devices materially different from and considerably improved over the traditional railroad spike.

In the subject invention the compressively distortable resilient bias member (e.g. solid elastomer body) may be in direct contact with the base flange of the rail. The pressure exerted thereby on the base flange is of a relatively high magnitude, i.e., in the order of several hundred p.s.i. and a total force of at least 2000 pounds. The elastomer body is distorted compressively from its normal, unstressed state whereby the elastic recovery thrust forces resulting from the compressive distortion exerts a pressure thrust force of relatively high magnitude, sufficient to secure the rail tightly on ties or other rail support members.

The elastomer pressure member is inserted in the holddown system on the construction site. As is well known, it is difficult to insert an elastomer member in a highly compressed state. To facilitate such insertion, the elastomer member may be compressively distorted or fiattened, whereafter its temperature is lowered sufficiently to immobilize or freeze the member in the compressed or flattened state when the compression force is removed. It is maintained at this temperature until it is inserted on the job in the holddown system. Upon thawing or warming, the elastomer body regains its elastic recovery property and recovers toward its normal shape, which is the shape of the elastomer member before compressive distortion and low temperature immobilization thereof. The holddown system is dimensioned so that the inserted elastomer member cannot recover fully its original or normal shape, whereby the elastomer member is in a partially compressed state when it exerts its thrust force against the holddown member. Thereby, there exists in effect the elastomer member in a partially compressed state. Through the utilization of the elastic recovery force of said member in attempting to return it to its original or normal state, it functions as the pressure exerting body in the holddown system. i

The elastomer member may also be compressed between opposing, preferably substantially parallel faces of a holddown system or the like by other means. For example, the elastomer member may be inserted in an uncompressed state, and one or more shims may be driven between the body and the contiguous face of the holddown member to compress the elastomer member. Alternatively, the holddown device may be made in separate parts and assembled on the job site in a manner whereby the elastomer member is compressed upon assembly. In rail holddown systems, the holddown units may be mounted on the rail without the elastomer member, which is inserted later.

The advantage of the subject apparatus is that the holddown member or plate and resilient bias member may be positioned on the base flange. Thereafter a downward pressure is exerted against the holddown member sufficient to compress the resilient bias member to a point wherein the curved support arms of the holddown member can be oriented so that the lower ends thereof can be attached to an arm-mounting or holding member, e.g., a stud or pin projecting from the side faces of the rail-supporting cross tie. Though not essential for purposes of the invention, a pressure plate may 'be inserted between the lower face of the resilient bias member and the upper face of the base flange to achieve a distribution of the total thrust of the compressed bias member over the area of. the contacting faces of the inserted plate and base flange.

Description of the Drawings A preferred form of the invention is illustrated in the drawing wherein:

FIGURE 1 is an end elevation of an embodiment of the subject rail holddown apparatus with a railroad rail hown in cross section in the underlying concrete tie hown in fragment;

FIGURE 2. is a top plan view thereof with the rail and ie shown in fragment;

FIGURE 3 is a side elevation thereof with the rail tie ll'ld holddown unit shown in fragment;

FIGURE 4 is an enlarged detail taken on section plane l4 of FIGURE 2;

FIGS. 5-7, respectively, comprise a fragmentary side :levation, top plan, and end elevation of a second em- )odiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated embodiment constitutes a rail holddown lssembly wherein the assembly is attached to a rail sup- )orting structure, which may be a series of railroad cross ies, an elevated, ground level or below ground railroad 78d, or steel structural members of an elevated monorail )r dual rail system. The ties or railroad bed may be of any .uitaible material, but generally will be concrete. The rail t0 has the usual base flange 11, the upper surface 12 of vhich generally slopes outwardly but may be at right tngles to the vertical axis of the rail if desired.

In the illustrated embodiment a rail is shown on an lnderlying concrete cross tie 13. There are two holddown lnits 15, one on each side of the base flange of the rail. Each holddown unit comprises an angle bar 16, which in urn comprises an elongated, press down plate or leg 17 1nd an elongated or vertical plate 18. The latter plate may )e eliminated if desired. The function of the vertical plate )r leg 18 is to provide a retaining structure against outvard displacement from the compressibly distorted, resilint bias member 20. Also, the lower edge of the vertical alate or leg 18 can be received in a transverse groove 19 n the upper face of tie 13 and thereby function as a guide in the correct positioning of holddown unit on he upper face 12 of base flange 11.

The press down plate or leg 17 has a lower face which s substantially parallel with the upper face 12 of the base lange. Substantially parallel orientation of the opposing 'aces of said members is preferred to elfect maximum ltilization of the thrust of the resilient bias member 20, vhich is compressed therebetween.

The resilient bias member 20 is preferably a solid elasomer body or block, preferably of regular parallelepiped :onfiguration in the normal or relaxed state. Further deicription thereof appears hereafter.

Each angle bar 15 is fixedly attached at its opposite :nds to the hook-like head portions 23- of curved holdlown arms 21 and 22.

The curved holddown arms 21 and 22 have overlap- Jing tail portions 24 containing apertures 25. These aperures 25 fit over the projecting ends 26 of a rod or bar 27 :xtending transversely through the concrete tie 13 and ying substantially in the vertical center plane of rail 10. [he arms 21 and 22 hold the angle bar 16 in fixed posiion against outward and upward displacement under the )utward thrust exerted by the compressed 'bias members 50. This result is attained by relating respective ends 26 1nd plates 17 so that outward pivot movement of arms 21 and 22, from the orientation shown in FIG. 1, would iarrow the space between plate 17 and upper face 12, hereby requiring still further compression of bias memers 20. If desired, arms 21 and 22 may be locked together after assembly of the holddown system.

If desired, a rubber insulator cushion pad 28 may be trical conductors of the holddown system is desirable when the rail is used to conduct electricity-operating electrical componentsof railway signals, automatic crossing warnings and gates, and the like.

As can 'be seen in FIGURE 2, the elastomer body 20 is an elongated member which may have a length substantially equal to the width of the cross tie 13 or the distance between pairs of holddown arms 21 and 22. This provides a relatively large thrust-exerting contact with the lower face of the body 20 against the upper face 12 of the flange whereby the holddown systems herein are capable of generating a total thrust of about 2000 or more pounds against the base flange 11.

In lieu of fixedly attaching the pressure plate 17 to the arms 21 and 22, the invention herein also contemplates a hooking of the head portions 23 thereof over the pressures plate 17 to obtain a holding function against upward and outward displacement of the pressure plate 17 under the upward and outward thrust of the compressed bias members 20 against plate 17. In such modification, the arms 21 and 22 need not be separate, and may comprise, if desired, a double arm unitary member.

The preferred method of assembly of the rail and holddown apparatus on the rail-supporting understructure, e.g., the tie 13, comprises placing the rail 10 on the tie 13 with the vertical center plane of the rail substantially in alignment with the rod or bar 27. The lefthand holddown unit 15 (as viewed in FIGURES 1 and 2) is positioned with the pressure plate 17 above the base flange 11 with the resilient bias member 20 between the lower face of the plate 17 and upper face of the base flange. The arms 21 are sprung outwardly so that their tail portions 24 are over the outer ends 26 of the rod 27. A downward thrust is exerted against pressure plate 17, preferably by a mechanical or pneumatic tool or machine with suflicient force to compress the bias member 20 and also move tail portions 24 to a position wherein their apertures 25 align with projecting ends 26 of the rod or bar 27. At this stage, the arms 21 will spring inwardly or can be bent inwardly to mount the tail portions 24 on the rod 27 and thereby provide an assembly of the lefthand holddown unit 15, the rail 10, and the cross tie 13. The righthand holddown unit 15 is thereafter mounted in a similar fashion.

The elastomer bodies 20 preferably are generally rectangular parallelepipeds in the relaxed (undistorted) state having a height or thickness in such state considerably greater than the distance between opposing faces of the pressure plate 17 and upper face 12 in the assembled form of the holddown unit, The aforesaid opposing faces are prefereably substantially parallel, planar faces for achieving maximum effect of the thrust forces of the compressed resilient bias members 20.

As an alternative to the aforedescribed method of the assembly of rail holddown apparatus with the rail and rail-supporting understructure, the holddown units 15 may be mounted first without the resilient bias members in the illustrated positions. Thereafter such bias members may be inserted in a flattened state or driven into the space between the opposing faces of pressure plate 17 and base flange 11. It is difficult to insert compressibly distorted, elastomer bodies between said faces. To facilitate such insertion, it is preferred that the elastomer bodies be compressively distorted in a flattened shape and frozen or immobilized in this state. They are held at the freezing or low temperature immobilization until in serted. As the elastomer bodies warm, their resilient properties are restored and they seek to resume their shape prior to compressive distortion and freezing. In so doing, they become wedged between said faces and thus exert a downward thrust on the holddown members.

The terms freezing and thawing above, are nontechnical descriptions. In practice, the elastomer bodies are formulated so that the elastomer composition will rigidity, through loss of elastic properties, at relatively low temperatures, i.e., in the order of 40 F. and below. The elastomers also should have good resistance to atmospheric deterioration in the presence of sunlight, atmospheric oxygen, and ozone, and should retain their elastic properties also at relatively high temperatures on the order of 100 to 120 F. The elastomer compositions useful for this purpose may be formulated from elastomers which crystallize at relatively low temperatures with the loss *of elastic properties upon crystallization. Exemplary thereof are low crystallization neoprene elastomers. However, elastomers which are usually considered to be noncrystalline elastomers, e.g., natural rubber and most syntheticrubbers, can be immobilized or rigidified in the compressively distorted state at low temperatures in the order of F. to 100 F. or even lower. The invention herein contemplates use of any naturalor synthetic rubber composition wherein such low temperatureimmobilization can be attained. The selection of a particular elastomer composition will depend in part on the climate of the locale where the installation is made, In northern parts of the temperate zone, a low temperature immobilization of 30 F. or below is recommended. In the arctic zone, a low temperature immobilization of -60 F. or below is recommended, whereas in southern parts of the temperate zone and in the tropical zone 0 F. or below would be suitable. In each instance, the low temperatureimmobilization is selected so that it will not be reached and preferably not even closely approached under the coldest climate conditions of the particular locale.

The system embodies substantially parallel, opposed faces against which the compressively distorted elastomer body is positioned with its opposite" faces pressing against said opposed faces to give an elastic recovery thrust force urging said faces apart along lines of thrust force at right angles to said faces. This combination utilizes the elastic recovery forces in thecompressed elastomer body more effectively than would be the case if the clastomer body were subject to twisting. In the latter case, the torque elastic recovery forces in the twisted elastomer adopt a sine curve-like configuration. Such recovery forces are considerably less effective in terms of amount of elastic recovery thrust forces per unit of distortion or deformation of the elastomer body as'compared against the thrust force orientation achieved by this invention.

The embodiment of FIGS. -7 utilizes a pair of U- arms 30 mounted substantially flush against tapered, opposite sides 13a and 13b of concrete cross tie 13, The upper ends of the U-arms are hook-like head portions 32. Each mid-portion 33 of arms 30 has an aperture 34 to receive a projecting end 35 of the rod or bar embedded in and extending transversely through tie 13 substantially directly below the vertical mid-plane of rail 10.

The hook-like head portions hook over the outer edges of base flange 11 and respectively seat intransverse grooves 37 in cross bar or plate 36. Interposed between the lower face of each bar or plate 36 and opposing upper .face 12 of base flange 11 is the compressively distorted resilient bias member 38, e.g., the aforedescribed solid elastomer block or body, which exerts via its resilient recovery stresses a directly applied, downward thrust against each respective upper face 12 of base flange 11. The assembled system of this embodiment, though different in component parts, works as a holddown system very similarly to the holddown system of FIGS. 1-4.

The holddown system of FIGS. 5-7 may. be assembled with the rail and tie by placing rail .10 on thetie as shown. U-arms 30 are loosely hooked around the flange 11 from beneath. Bias members 38 and respective cross bars or plate 36 are placed on upper faces 12, and head portions 31 are placed in grooves 37. The downward pressure is exerted on bars or plates 36 while mid-portion 33 is sprung over projecting ends 35. When the bias members 38 are sufliciently compressed to allow ends 35 to seat in apertures 34, the assembly operation is complete. Alternatively, the bias members 38, in the form of elastomer bodies, may be inserted in the assembled holddown system in the aforedescribed state of low temperature immobilization.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein disclosed being preferred embodiments for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. In a rail holddown system including a rail having a base flange and a rail-supporting understructure, the improvement which comprises a holddown unit embodying a pressure plate above said flange and having a lower face substantially parallel with the upper face of said flange, holddown arms at opposite ends of said pressure plate, said holddown arms being curved arms and each having a head portion positioned above said base flange and holding said pressure plate against upward movement, said holddown arms respectively having a tail portion releasably attached to said understructure below the center portion of said rail, and a resilient bias member compressively distorted between said lower face and said flange and exerting a downward thrust against said flange to press said rai-l against said understructure.

2. The improvement as claimed in claim 1 wherein said bias member is a solid, elastomer body.

3. The improvement as claimed in claim 2 wherein said solid elastomer body is an elongated, substantially rectangular parallelepiped body in the uncompressed state.

4. An improvement wherein the rail holddown system comprises two holddown units as defined in claim- 2, said units being positioned on opposite sides of said base flange.

5. The improvement as claimed in claim 1 wherein said understructure is a cross tie, a rod projecting respectively from each side face of said tie below said center portion of said rail, and each tail portion having an aperture therein and receiving respectively one of said rods.

6. An improvement wherein the rail holddown system comprises two holddown units as defined in claim 5, said units being positioned on opposite sides of said base flange.

7. The improvement as claimed in claim 1 wherein said pressure plate is embodied in an angle bar of which said pressure plate is the upper leg thereof and a vertical plate 18 the outer leg thereof, and groove means in the upper face of said understructure receiving the lower edge of said vertical plate.

8. An improvement wherein the rail holddown system comprlses two holddown units as defined in claim 1, said units being positioned on opposite sides of said base flange.

9. In a rail holddown system including a nail having a base flange and, 'a rail-supporting understructure, the improvement which comprises two holddown units positioned on opposite sides of said base flange, each hold down unit embodying a cross bar above a respective, opposite side of said base flange, said cross bar having a lower face substantially parallel with the upper face of the respective side of said base flange, a resilient bias member compressively distorted between said lower face and said flange and exerting a downward thrust against said flange to press said rail against said understructure, and a pair of U-arms having respective mid-portions attached to said understructure and respective hook-like head portions on the upper ends thereof hooked over respective ends of said cross bar.

10. The improvement as claimed in claim 9, wherein said bias member is a solid, elastomer body.

(References on following page) References Cited UNITED STATES PATENTS Verpianck 23 8-283 Johnson 238283 De Turk 238-283 Chapman 238-315 Olson 238-288 5/1968 Tew 238283 3,417,922 12/1968 .Vavlry 238-283 US. Cl. X.R.

Images