EP0007813B1

EP0007813B1 - Rail fastening assemblies

Info

Publication number: EP0007813B1
Application number: EP79301531A
Authority: EP
Inventors: Graham Mcleod Fee
Original assignee: True Temper Railway Appliances Inc
Current assignee: True Temper Railway Appliances Inc
Priority date: 1978-08-02
Filing date: 1979-07-31
Publication date: 1984-01-25
Also published as: IN152851B; JPS5520900A; BR7902934A; EP0007813A1; AR223346A1; MX148362A; ATE5982T1; DE2966577D1; CA1148913A; ZA791950B

Description

The present invention relates, generally, to assemblies for securing a rail to an anchoring support or crosstie therefor. More specfically, the present invention relates to a simplified drive-on rail fastening assembly including a torsional spring rail clip having a generally S-shaped geometrical configuration, and a cooperating chair designed to engage a tie anchor portion of the clip and restrain a rail bearing portion thereof in proximate engagement with the base flange of a railway rail.
Various and diverse types of rail fastening assemblies are well known in the prior art. For example, it has become commonplace to secure sections of railway rail to a support (i.e. a sleeper or tie) by means of a generally planar fixture secured to the support by a fastener, with a portion, or extension, of the fixture in contact with the base of the rail. Such clips are commonly termed compression type rail spring clips.
Within the recent past, rail clips have been proposed for anchoring rail sections which eliminate the need for a fastener passing directly through the clip or rail-contacting structure itself by employing separate clip and fastener structures. One such class of rail anchoring devices has become known in the art as "Pandrol" clips, which are multi-element clips having a plurality of linear sections joined by convolute sections, whereby the overall profile of the clip may be best described as toric in nature.
With respect to rail fastening assemblies of the prior art employing separable rail clips and chairs therefor (the term "chair" is used herein to denote tie securing means adapted to engage the rail clip in secure engagement therewith), the same offer various drawbacks. Although generally effective in terms of their ability to secure the rail to the tie or sleeper, frequently the fabrication and installation thereof are cumbersome and complex. Typically, toric profiles resultant from convolute intermediate sections as related in certain prior art rail clips require considerable forming operations in order to obtain a serviceable device. Likewise, chairs employed in conjunction with this type of clip also require special casting.
British Patent No. 1,305,871 discloses a drive-on rail fastening assembly comprising a separable rail clip and chair. The clip has a central leg, a tie anchor portion and a rail bearing portion which is adapted for proximate engagement with the face of one laterally projecting flange of a railway rail; the chair is adapted to be positioned adjacent the rail and to have the tie anchor portion of the rail clip driven into seating engagement with a portion thereof. The clip is, overall, of a shape which is approximately equivalent to a fraction more than one complete turn of a helical coil spring, although not of constant radius; the central leg, which is opposite the two free ends of the clip, may be straight, as are the tie anchor and rail bearing portions which are near the free ends of the clip. If the clip is placed on a horizontal surface, resting on its tie anchor and rail bearing portions, with the central leg uppermost, and is viewed horizontally from one end, the clip looks like an inverted V. If it is viewed in that position vertically from above, the central leg appears in the projection so obtained to lie between the free ends of the clip, so that the whole appears rather like a horizontally elongated S, however, the clip is not in fact S-shaped, since it is on the contrary essentially helical with the central leg lying opposite the two free ends.
In use, this clip is driven into engagement with the chair in substantially the same orientation, with the rail bearing portion lying over one of the rail flanges, the tie anchor portion lying over a fixed base plate and the uppermost central leg lying under a hook-shaped part of the chair. The central leg is compressed downwardly by the hook so that the spring clip is bent to a smaller radius in the curved arcuate portions that connect the central leg with the tie anchor portion and the rail bearing portion respectively.
Because of the shape of the clip, this rail fastening assembly must have a high profile. Its holding power is achieved predominantly through bending in the spring clip, as described above.
It is an object of this invention to provide a drive-on rail fastening assembly which achieves a high holding power on the rail in combination with a low profile to the fastener. In the fastening assembly provided by the invention, the spring clip is generally S-shaped and achieves its holding power predominantly by torsion.
German Auslegeschrift No. 1,534,017 describes a rail fastening assembly in which a generally S-shaped torsion spring is used. However, this clip cannot be driven on to the chair, and a special tool is necessary to twist the ends while the clip is inserted into the chair.
In accordance with the deficiencies of prior art rail fastening assemblies, it is a principal object of the present invention to provide a drive-on rail fastening assembly which is of simplified construction, but which operates effeciently under all conditions of use.
Another object of the present invention is to provide a versatile, drive-on rail fastening assembly which may be manufactured and installed in a materially easier manner than prior art rail clips.
Still another object of the present invention is to provide a drive-on rail fastening assembly which eliminates the need to employ any threaded parts.
Yet another object of the present invention is to provide a drive-on rail fastening assembly including a chair which establishes an anchoring-effective torsional force on the generally S-shaped torsional spring clip. Whereby anchoring efficiency of the assembly is enhanced.
A further object of the present invention is to provide a rail fastening assembly for use in conjunction with concrete ties, where forces exerted on the tie by the assembly are uniformly distributed to improve service life of the tie.
The present invention provides a drive-on rail fastening assembly for securing a railway rail, having laterally projecting base flanges, to an anchoring support therefor, said assembly comprising a rail clip including a central leg, a tie anchor portion and a rail bearing portion, the tie anchor portion and rail bearing portion being spaced on opposide sides and extending from opposite ends of the central leg, the rail bearing portion being adapted for engagement with the face of one laterally projecting flange of a railway rail, and chair means adapted to be positioned adjacent said rail and to have said tie anchor portion of said rail clip driven into seating engagement with a portion thereof, wherein the rail clip is a generally S-shaped torsion spring rail clip, in which the axis of the central leg and the axial centre of the tie anchor portion where it is to be engaged with the said portion of the chair means lie in a first plane, and the axis of the central leg and the axial centre of the rail bearing portion where it is to be engaged with the face of the flange of the rail lie in a second plane, the angle of intersection between said first and second planes being not more than 45° in the unstressed condition of the clip, whereby the chair means cooperates with the rail bearing portion of the clip for establishing a torsional spring force on said central leg.
The invention also provides a drive-on rail fastening assembly for securing a railway rail, having laterally projecting base flanges, to an anchoring support therefor, said assembly comprising a rail clip, including a central leg, a tie anchor loop portion and a rail bearing loop portion, the tie anchor loop portion and the rail bearing loop portion being spaced on opposite sides of and extending from opposite ends of the central leg, and a chair positioned adjacent a railway rail adapted to have said tie anchor loop portion of said rail clip driven into engagement therewith in which the rail clip is a generally S-shaped torsional spring rail clip in which the axis of the central leg and the axial centre of the tie anchor portion where it is to be engaged with the said portion of the chair means lie on a first plane, and the axis of the central leg and the axial centre of the rail bearing portion where it is to be engaged with the face of the flange of the rail lie in a second plane, the angle of intersection between said first and second planes being not more than 45° in the unstressed condition of the clip, and the chair comprises means for receiving said tie anchor interiorly of the clip and is adapted to have the rail clip driven thereon in latching engagement therewith, said chair further including means for applying a torsional spring force on at least a first end of said central leg.
The invention further provides a railway rail clip adapted to be driven on to the upwardly projecting head of a cooperating chair, for securing a railway rail to an anchoring support therefor, said rail clip comprising a generally linear central leg, a tie anchor portion and a rail bearing portion, wherein said tie anchor portion comprises a first loop defined by a tie anchor arcuate leg and a tie anchor terminal leg having an upwardly divergent free distal end, said tie anchor portion extending from a first end of said central leg and lying on one side thereof, and said rail bearing portion comprises a second loop defined by a rail bearing arcuate leg and a rail bearing terminal leg having a free distal end, said rail bearing portion extending from the second end of said central leg and lying on the opposite side from said tie anchor portion, in which the rail clip is a generally S-shaped torsional spring rail clip, in which the axis of the central leg and the axial centre of the tie anchor portion where it is to be engaged with the said portion of the chair means lie in a first plane, and the axis of the central leg and the axial centre of the rail bearing portion where it is to be engaged with the face of the flange of the rail lie in a second plane, the angle of intersection between said first and second planes being not more than 45° in the unstressed condition of the clip.
The invention still further provides a chair for cooperating with a spring rail cip for securing a railway rail to an anchoring support therefor, and comprising anchoring means for anchoring said chair to said support in which the chair is adapted to have a generally S-shaped torsional spring rail clip as set out above driven thereon, and comprises an upwardly projecting head for receiving a tie anchor loop portion of the rail clip interiorly of said clip in seating engagement therewith, said head including a jaw formed on a first side thereof, said jaw being configured to receive and embrace both upper and lower surfaces of a central leg of said rail clip and provide a restraining force thereon.
The invention will be more particularly described with reference to the accompanying drawings, in which:-

Figure 1 is an isometric view of a pair of rail fastening assemblies in accordance with the present invention shown anchoring a railway rail to a concrete support;
Figure 2 is a top plan view of the assemblies of Figure 1;
Figure 3 is an end elevational view along the line 3-3 of Figure 2;
Figure 4 is a side elevational view of one of the assemblies shown in Figure 1;
Figure 5 is a side elevational view of a chair employed in the rail fastening assembly of the present invention;
Figure 6 is a side elevational view of the chair shown in Figure 5, rotated 90°;
Figure 7 is a top plan view of the chair shown in Figure 5;
Figure 8 is an isometric view of a torsional spring rail clip employed in the rail fastening assembly of the present invention;
Figure 9 is a side elevational view of the rail clip of Figure 8;
Figure 10 is a top plan view of an insulator pad employed in the rail fastening assembly of the present invention; and
Figure 11 is a side elevational view of the insulator pad shown in Figure 10.

The present invention relates to drive-on rail fastening assemblies for securing a railway rail to a tie or sleeper. Rail fastening assemblies are designed to effectively force-couple the-railway rail to the tie or sleeper in order to anchor the rail for effective use. In terms of the present invention, this is achieved by embedding the shank of the chair member of the boltless fastener type within the concrete cross tie, securing the rail clip to the chair head disposed above the tie, and securing the clip to the base flange of the rail. Consequently, the rail is force- coupled through the rail clip/chair/tie.
By virtue of this cooperative assembly, complex forces come into play under dynamic conditions in addition to static forces existing between the components, including forces due to expansion and contraction of the rails. The rail fastening assembly must firmly restrain the base of the rail under static conditions and must also operate efficiently under those dynamic conditions which occur during passage of a train along the railway tracks. It is important that the rail fastening assembly maintains a positive restraining force on the railway rail under all conditions of use, regardless of longitudinal or wave motion of the railway track.
Referring to the figures, in all of which like parts are designated by like reference characters, Figures 1-4 show a rail fastening assembly, designated generally as 10, anchoring a section of railway rail 12 to a concrete tie 14. The rail 12, as is conventional, includes a base 16 having laterally projecting flanges 18. A tie pad 20 is interposed between the tie 14 and base 16 of the rail.
The assembly 10 is comprised of a generally S-shaped torsional rail clip, designated generally as 100; a chair, designated generally as 200, adapted to have the clip driven thereon; and a shimming pad designated 300 interposed between the base flange 18 and clip 100. For convenience, that side of the chair 200 facing rail 12 (as viewed in Figure 2) will be termed the "inner side", while the opposite side will be termed the "outer side". Similarly, that end of the chair 200 from which the clip 100 is driven on (as viewed in Figure 4) will be termed the "front end", while the opposite end will be termed the "back end".
The rail clip 100 is a torsional spring rail clip having a generally S-shaped geometrical configuration. The simplicity inherent in this design facilitates both the fabrication of the clip as well as application thereof, as described more fully hereinbelow. The clip 100 is comprised of a central leg 102 and a pair of loops 104 and 106 on opposite sides and extending from opposite ends thereof. Loop 104 comprises the tie anchor portion of clip 100, while loop 106 comprises the rail bearing portion thereof, as viewed in Figure 2. Loop 104 includes an arcuate leg 108 and a terminal leg 110. Similarly, loop 106 includes an arcuate leg 112 and a terminal leg 114. Each of the terminal legs 110 and 114 has a free distal end, 116 and 118, respectively. Preferably, the legs have divergent ends of the junctures of terminal legs form protruberant elements 120 and 122.
The dimensioning and cross-sectional configurations of the elements comprising rail clip 100 may vary widely without departing from the scope of the present invention; provided the overall S-shaped geometry is maintained. Accordingly, the central leg and terminal legs might be linear or have a slight curvature imparted thereto. The central axes of each of these members might lie on a common plane or on different planes. For example, the central axes of the central leg 102 and terminal leg 110 might lie on a first plane, while the central axes of the central leg 102 and terminal leg 114 might lie on a second plane, wherein the angular displacement between the two planes may vary up to about 45°, but preferably less than about 15°. In another variation, the three central axes may be skewed with respect to one another. Similarly, the linear distance between successive axes might be the same or different and the relative sizes of the loops 104 and 106 comprising the clip 100 tailored to accommodate the same.
The foregoing variants in geometrical orientations and configurations permit a considerable range of versatility for the S-shaped clip 100, provided the overall S-shape is maintained. For example, holding power may be varied as can adaptability for different rail flanges by appropriately altering the geometric angularity and dimensions of the central axes of the elements.
The chair 200 which cooperates with rail clip 100 is comprised of a downwardly projecting shank 202 adapted to be embedded within concrete tie 14. The cross-sectional profile of the shank or stem 202 is preferably rectilinear, preferably rectangular. The outer surface of the shank 202 is shown in Figure 6 as provided with a stepped wedge configuration resulting from a plurality of laterally projecting ridges 204 which define spaced recesses 205. Accordingly, the shank or stem 202 as shown in said embodiment has a somewhat undulating geometry which materially improves pull-out resistance of the chair 200 from concrete tie 14.
The shank 202 projects downwardly from a shelf 206, which is preferably reinforced at the rear end of chair 200 by a gusset 208 extending between the shelf 206 and the stem 202. Projecting upwardly from the shelf 206 is a head 210.
Head 210 is adapted to receive the tie anchoring portion of rail clip 100, the head cooperating with the loop 104 of clip 100 interiorly thereof to receive the same in latched engagement. The head 210 is formed with a jaw 212 on the inner side thereof; the bight of jaw 212 being provided at its upper end with a projecting lip 214 and at its lower end with a ledge 216 on shelf 206. Preferably, the ledge 216 is comprised of a pair of spaced ledge members. The bight of jaw 212 is configured to receive central leg 102 in close engagement, as best viewed in Figure 3, and the same are complementary.
A ramp 218 is formed on the shelf 206 on the outer side of head 210. The ramp 218 comprises a sloped leading edge 220 which rises vertically to a flattened, substantially horizontal ledge 222. The terminal leg 110 moves upwardly on the ramp 218 as the clip is driven into its seating engagement with the chair and is lifted thereby.
A latching feature as shown may be provided to firmly secure the clip to the chair head 210. Said latching means comprises a recess 224 formed in the head 210 vertically above the ramp 218 which mates with a protruberance 120 on the side of the terminal leg 110, as best viewed in Figure 2. The protruberance 120 in such case functions as a detent which snaps into the recess 224 when the clip 100 is driven into engagement with head 210. The recess 224 could, if desired, be provided on the head 210 in another location; or the latching means could consist of a recess in the leg of the rail clip 100, with mating detent means in the chair structure.
The front end of head 200 preferably includes an overdrive protector 226, as best viewed in Figures 2 and 7, in the form of an outwardly projecting arcuate face 227. Said overdrive protector 226 ensures accurate positioning of the clip 100 on the head 210 during drive-on application of the clip by forming an abutting stop for the arcuate leg 108 comprising the tie anchor portion 104 of the clip. Thus, during application, if this feature is provided, the clip will be limited in its drive-on by abutment of the overdrive protector 226 with the leg 108.
An internal pocket 228 is formed on the inner side of head 210 configured for receiving a projecting central portion of the shim or insulator pad 300, as described hereinbelow. Preferably, the pocket 228 extends between the spaced ledges 216 defining the lower terminus of jaw 212, as described above. Pocket 228 ensures accurate placement and alignment of insulator pad 300, while preventing any displacement thereof during dynamic operating conditions which occur as a train passes over the railway tracks. The internal configuration of the pocket 228 and the complementary formation of the pad thus improves the structural integrity of the overall assembly and provides a more efficient cooperation of the elements comprising the same.
A shim or insulator pad preferably is interposed between the top, upwardly sloped face of flange 18 and the rail bearing portion 106 of clip 100. This pad, designated generally as 300, is restrained and positioned by cooperation with internal pocket 228 of chair 200.
A principal purpose of such a pad 300 is for the electrical insulation of the railway rail from those parts securing it to tie 14. The pad must also aid in transmitting an upwardly directed tensional force on terminal leg 114 of clip 100 as described below. Depending upon design requirements for the rail fastening assembly 10, the pad 300 may accomplish either or both of these objectives.
Pad 300 is preferably comprised of a coated metallic shim 302 having a layer of encapsulating, insulation-effective polymer 304 coated thereon in order to afford both a force transmitting structure and one which advantageously electrically insulates the rail and fastening assembly. Pad 300 is susceptible, however, to modification if either feature is not desirable; for example, the polymer coating might be eliminated should electrical isolation of the parts be unnecessary. A highly preferred insulator coating is high density polyethylene; although other similar polymeric materials capable of withstanding the forces to which the insulator pad will be subjected might be selected by the skilled artisan.
The metal shim 302 is comprised of an outwardly projecting center tab portion 306, which includes an upstanding leg 308 and a lower leg 310 substantially perpendicular thereto. A leg 312 is formed as a continuous extension of the leg 310, and joins an upstanding leg 314 substantially parallel with leg 308. Accordingly, the legs 308, 310, 312 and 314 define a somewhat rectangular channel 316 extending transversely across metal shim 302, the channel having a pair of recesses 318 formed at the bottom corners thereof. A leg 320 extends obliquely from leg 314; the upper longitudinal and transverse edges thereof having a taper 322 and 324, respectively.
Metal shim 302 is preferably encapsulated by the insulation-effective, high density polyethylene material. As shown, the polyethylene coats the edges of legs 312 and 314 to provide an outwardly directed skirt 326 adjacent the tab 306. The tab 306 may thus be inserted within pocket 228 up to the skirt 326. Channel 316 as shown is filled with polyethylene insulator flush with the top surface of leg 308 for the portion of the channel corresponding to leg 312. Beyond that point, denoted 328, the polyethylene surface slopes upwardly corresponding to the upward slope of leg 320. The outer face of leg 314 as well as the bottom face of leg 320 are also provided with a layer of polyethylene 330 which overlaps the top face of leg 320 in the form of a transverse bulbous element 332. Accordingly, the area of contact between the base flange 18 of rail 12 and the rail fastening assembly 10 is effectively electrically insulated, while forces necessary to restrain the rail 12 may nonetheless be effectively transmitted therebetween.
From the foregoing, it is evident that the rail fastening assembly 10 of the present invention enjoys numerous advantages over rail fastening devices known in the prior art. One particularly advantageous feature is the ease with which the respective components may be fabricated.
Fabrication of the S-clip of the present invention is materially simplified over the clips heretofore proposed. For example, standard bar stock of appropriate length and cross-section to form a single clip can be heated and bent around a mandrel in order to achieve the overall S configuration. Subsequently, the detent and required specific angularity between central axes can be imparted to the preformed clip by way of a forging or similar operation. Unformity of cross-sectional dimensions permits the attainment of uniform metallurgical properties throughout the clip.
Preferably, a mechanical feeder for round stock introduces a piece of steel bar heated to about 1800°F to a two-stage forming press. The steel, preferably AISI 1060-1095, is preheated and sized in order that the length of the bar is suitable for yielding a single S-clip. The bar stock is fed to the first stage of the press which imparts the overall S-shape thereto by longitudinally bending the stock about appropriately dimensioned mandrels. Thence, the S-shaped bar is rotated 90° and transferred to the second, final forming stage, where the sides and top geometries are imparted to the clip by a transverse bending operation. Lastly, the formed clip is ejected to a quenching bath and tempered as may be desirable. Because of the uniformity of cross-section, homogeneous metallurgical properties are obtained in the finished clip.
The same may be said with respect to the chair 200, which is preferably cast from malleable cast iron. The lack of through bores or other complex re-entrant design reduces the complexity of the casting process by eliminating cores which must be employed in the casting of known chair designs.
Once the individual components are fabricated, installation thereof is also quite simple. The chairs 200 may be embedded in a concrete tie prior to a full cure thereof, with the plane of shelf 206 substantially level with the top surface of the tie. As shown in Figures 1-3, a pair of chairs will be positioned adjacent to the area of the tie which receives rail 12. When the tie has been positioned, an elastomeric tie pad 20 can then be disposed over the tie and rail 12 positioned between the opposing chairs. Shim or insulator pad 300 is then inserted with lip 306 located in pocket 228 of chair 200. The assembly is completed by driving rail clips 100 into seating engagement with head 210, as illustrated in Figure 4. Application of the clips 100 may be manual; although automated apparatus for applying the clips is desirably employed.
As the tie anchor portion 104 is driven onto head 210, the terminal leg 110 will engage the sloped portion 220 of ramp 218. Simultaneously, the rail bearing portion 106 of the clip 100 will begin riding upon the upwardly sloped face of the flange 18 of the rail. Consequently, as the clip is driven on, upward tensional forces will be exerted on the two terminal legs 110 and 114. When the clip 100 is fully seated on chair 200, with detent 120 engaging recess 224, the static upwardly directed tensional forces will reach their maximum on these terminal leg members of the clip. The magnitude of these forces can be tailored by appropriate design of the geometrical configuration of the clip structure, taking into account the relative lateral placement of the chair 200 and dimensioning of ramp 218. The projecting lip 214 of jaw 212 will provide a counteractive, downwardly directed restraining force on central leg 102, firmly securing the clip against any longitudinal or rotational displacement. Consequently, the upward force exerted on terminal leg 114 by virtue of the sloping face of flange 18 will be resolved as a counterclockwise torsional force at one end of central leg 102; the tensional force being coupled to the central leg by arcuate leg 112. Similarly, the upward tensional force exerted upon terminal leg 110 by ramp 218 will be resolved into a clockwise torsional force on the other end of central leg 102; the tensional force in leg 110 being transmitted by arcuate leg 108. In this manner, both ends of central member 102 are wound up yielding a torsional spring clip.
Due to the manner in which the torsional forces are applied to central leg 102, the rail fastening assembly 10 provides a positive downward restraining force on the flange 18. Any motion of the rail, whether it be longitudinal or transverse (including any wave or rocking motion) will not diminish the efficiency of the rail fastening assembly, and that rail motion will be positively counteracted by the downward force on the base flange. Consequently, the rail is efficiently force coupled to the tie or sleeper.
Moreover, the forces (whether static or dynamic) are efficiently distributed by virtue of the rail fastening assembly 10. This is a very important consideration when concrete ties are employed since any stress concentration between the fastening assembly and the tie contributes to enhanced degradation and/or premature failure of the latter. Conversely, uniform force distribution such as that provided by the present invention materially increases the life expectancy of these concrete ties.
While the invention has been described with reference to certain preferred embodiments, the skilled artisan will recognize that various substitutions, modifications, changes and omissions may be made within the scope of the appended claims.

Claims

1. A drive-on rail fastening assembly for securing a railway rail, having laterally projecting base flanges, to an anchoring support therefor, said assembly comprising a rail clip (100) including a central leg (102), a tie anchor portion (104) and a rail bearing portion (106), the tie anchor portion and rail bearing portion being spaced on opposite sides and extending from opposite ends of the central leg, the rail bearing portion being adapted for engagement with the face of one laterally projecting flange (18) of a railway rail (12), and a chair means (200) adapted to be positioned adjacent said rail and to have said tie anchor portion of said rail clip driven into seating engagement with a portion (210) thereof, characterised in that the rail clip (100) is a generally S-shaped torsion spring rail clip, in which the axis of the central leg (102) and the axial centre of the tie anchor portion (104) where it is to be engaged with the said portion (210) of the chair means (200) lie in a first plane, and the axis of the central leg (102) and the axial centre of the rail bearing portion (106) where it is to be engaged with the face of the flange (18) of the rail (12) lie in a second plane, the angle of intersection between said first and second planes being not more than 45° in the unstressed condition of the clip, whereby the chair means cooperates with the rail bearing portion of the clip for establishing a torsional spring force on said central leg.

2. A drive-on rail fastening assembly according to claim 1 further characterised in that said generally S-shaped rail clip (100) includes:

(a) a first arcuate leg (108) and a first terminal leg (110) having a free distal end (116), defining a first loop (104) comprising said tie anchor portion; and

(b) a second arcuate leg (112) and a second terminal leg (114) having a free distal end (118), defining a second loop (106) comprising said rail bearing portion.

3. A drive-on rail fastening assembly according to claim 2, further characterised in that said means for establishing said torsional spring force comprises:

(a) means for applying an upward force on said first terminal leg (110);

(b) means for applying an upward force on said second terminal leg (114); and

(c) means for applying a downward restraining force on said central leg (102).

4. A drive-on rail fastening assembly according to claim 2 or 3 further characterised in that said chair means (200) comprises a head (210) having:

(a) means (212, 224, 226) for receiving said first loop (104) in seating engagement therewith;

(b) means (218) for applying an upward force on said first terminal leg (110); and

(c) means (214) for applying a downward restraining force on said central leg (102);

whereby said upward force on said first terminal leg is resolved as a torsional spring force applied at a first end of said central leg.

5. A drive-on rail fastening assembly according to claim 4, further characterised in that said second terminal leg (114) proximally engages an upwardly sloped top face of said flange (18), said face comprising means for applying an upward force on said second terminal leg which is resolved as a torsional force applied at the second end of said central leg.

6. A drive-on rail fastening assembly according to claim 5, further characterised in that the torsional forces applied at either end of said central leg (102) have opposite rotational senses.

7. A drive-on rail fastening assembly for securing a railway rail, having laterally projecting base flanges, to an anchoring support therefor, said assembly comprising a rail clip (100) including a central leg (102), a tie anchor loop portion (104) and a rail bearing loop portion (106), the tie anchor loop portion (104) and the rail bearing loop portion (106) being spaced on opposite sides of and extending from opposite ends of the central leg (102), and a chair (200) positioned adjacent a railway rail (12) adapted to have said tie anchor loop portion of said rail clip driven into engagement therewith, characterised in that the rail clip is a generally S-shaped torsional spring rail clip, in which the axis of the central leg (102) and the axial centre of the tie anchor portion (104) where it is to be engaged with the said portion (210) of the chair means (200) lie in a first plane, and the axis of the central leg (102) and the axial centre of the rail bearing portion (106) where it is to be engaged with the face of the flange (18) of the rail (12) lie in a second plane, the angle of intersection between said first and second planes being not more than 45° in the unstressed condition of the clip, and the chair comprises means (212, 224, 226) for receiving said tie anchor loop interiorly of the clip and is adapted to have the rail clip driven thereon in latching engagement therewith, said chair further including means (218) for applying a torsional spring force on at least a first end of said central leg.

8. A drive-on rail fastening assembly according to claim 7, further characterised in that:

(a) said tie anchor portion comprises a first loop (104) having a tie anchor arcuate leg (108) extending from a first end of said central leg (102), and a tie anchor terminal leg (110) having a free distal end (116) extending from said tie anchor arcuate leg; and

(b) said rail bearing portion comprises a second loop (106) having a rail bearing arcuate leg (112) extending from the second end of said central leg (102), and a rail bearing terminal leg (114) having a free distal end (118) extending from said rail bearing arcuate leg.

9. A drive-on rail fastening assembly according to claim 8, further characterised in that each of said terminal legs (110, 114) is formed with a divergent end (116, 118).

10. A drive-on rail fastening assembly according to claim 9, further characterised in that said divergent ends (116, 118) are outwardly divergent ends, said outwardly divergent end (116) on said tie anchor terminal leg (110) having a protruberance (120) comprising a detent for latching said rail clip on said chair.

11. A drive-on rail fastening assembly according to any one of the preceding claims, further characterised in that said chair includes an upwardly projecting head (210) having a jaw (212) on a first side thereof for receiving said central leg.

12. A drive-on rail fastening assembly according to claim 11, further characterised in that said chair further comprises ramp means (218) for applying a static, upwardly directed force on said tie anchor portion (104).

13. A drive-on rail fastening assembly according to claim 12, further characterised in that said ramp means (218) comprises an upwardly sloped ramp (220) formed on a second side of said chair, opposing said first side.

14. A drive-on rail fastening assembly according to any one of the preceding claims, further characterised in that

(a) said tie anchor portion (104) of said rail clip includes detent means (120); and

(b) said chair includes an upwardly projecting head (210) having a recess (224) formed therein adapted to receive said detent means for latching engagement therewith.

15. A drive-on rail fastening assembly according to claim 14, further characterised in that said detent means (120) comprises a protruberance on said tie anchor portion.

16. A drive-on rail fastening assembly according to claim 8, or any claim 9 to 15 when dependent upon claim 8, further characterised by a pad (300) disposed intermediately said rail bearing portion (106) of said rail clip and an upwardly sloped face of a base flange (18) of a railway rail (12).

17. A drive-on rail fastening assembly -according to claim 16, further characterised in that said pad (300) is a shim pad interposed between said rail bearing portion (106) of said rail clip and said face of said base flange (18).

18. A drive-on rail fastening assembly according to claim 17, further characterised in that said shim is a metal shim (302) coated with a layer of an electrical insulation effective polymer (304) to yield an insulator pad (300).

19. A drive-on rail fastening assembly according to claim 18, further characterised in that said polymer (304) is high density polyethylene.

20. A drive-on rail fastening assembly according to claim 18, further characterised in that said chair includes an upwardly projecting head (210) having an internal pocket (228) formed on a first side thereof for receiving one end of said insulator pad (300) and positioning the other end thereof adjacent said upwardly sloped face.

21. A drive-on rail fastening assembly according to claim 20, further characterised in that:

(a) said means for applying a torsional force on said first end of said central leg (102) comprises a ramp (218) for applying an upwardly directed force on said tie anchor terminal leg (110); and,

(b) said upwardly sloped face of said base flange (18) comprises means for applying an upwardly directed force on said rail bearing terminal leg (114), whereby a torsional force is applied to the second end of said central leg (102).

22. A drive-on rail fastening assembly according to claim 8, or any claim 9 to 21 when dependent upon claim 8, further characterised in that said chair includes an upwardly projecting head (210) having a jaw (212) for receiving said central leg (102), said jaw having a bight defined at its upper end by an outwardly projecting lip (214) and at its lower end by a pair of spaced ledges (216) defining a pocket (228) therebetween.

23. A drive-on rail fastening assembly according to claim 22, further characterised by an insulator pad (300) having a tab (306) at a first end thereof inserted within said pocket (228) and a rail contacting portion (320) at the opposite end thereof interposed between said rail bearing portion (106) of said rail clip and the face of the base flange (18) of said rail.

24. A drive-on rail fastening assembly according to claim 23, further characterised in that said insulator pad (300) comprises:

(a) a metal shim (302) having a transverse channel (316) with a recilinear cross-section at one end thereof comprising a tab (306) for insertion within said pocket (228), said channel having a pair of side walls (308, 314) joined by a bottom wall (310, 312), and an oblique leg (320) extending from a first of said side walls (314) for contacting the face of said flange ( 18).

(b) a coating of an electrical insulation-effective polymer (304) on said metal shim.

25. A railway rail clip adapted to be driven on to the upwardly projecting head of a cooperating chair, for securing a railway rail to an anchoring support therefor, said rail clip comprising a generally linear central leg, a tie anchor portion and a rail bearing portion, wherein said tie anchor portion comprises a first loop (104) defined by a tie anchor arcuate leg (108) and a tie anchor terminal leg (110) having an upwardly divergent free distal end (116), said tie anchor portion extending from a first end of said central leg (102) and lying on one side thereof, and said rail bearing portion comprises a second loop (106) defined by a rail bearing arcuate leg (112) and a rail bearing terminal leg (114) having a free distal end (118), said rail bearing portion extending from the second end of said central leg (102) and lying on the opposite side from said tie anchor portion, characterised in that the rail clip (100) is a generally S-shaped torsional spring rail clip, in which the axis of the central leg (102) and the axial centre of the tie anchor portion (104) where it is to be engaged with the said portion (210) of the chair means (200) lie in a first plane, and the axis of the central leg (102) and the axial centre of the rail bearing portion (106) where it is to be engaged with the face of the flange (18) of the rail (12) lie in a second plane, the angle of intersection between said first and second planes being not more than 45° in the unstressed condition of the clip.

26. A rail clip according to claim 25, further characterised in that each of said terminal legs (110, 114) is a substantially linear leg wherein each of said linear legs has a central axis, the axes of said central leg (102) and said tie anchor terminal leg (110) lying in a first plane and the axes of said central leg (102) and said rail bearing terminal leg (114) lying in a second plane, the angle of the intersection between said first and second planes being not more than 45°.

27. A rail clip according to claim 26, further characterised in that each of said linear legs (102, 110, 114) has a central axis, the axes of said terminal legs (110, 114) lying in a common plane.

28. A rail clip according to claim 27, further characterised in that the axis of said central leg (102) is parallel with the axes of said terminal legs (110, 114), and is spaced from the plane of the axes of said terminal legs.

29. A rail clip according to claim 25, further characterised in that said clip (100) comprises a unitary member fabricated from spring steel.

30. A rail clip according to claim 26, further characterised in that said terminal legs (110, 114) are spaced from said central leg by unequal distances.

31. A rail clip according to claim 25, further characterised in that said angle is not more than 15°.

32. A rail clip according to claim 26, further characterised in that each of said linear legs (102, 110, 114) has a central axis, at least two of said axes being askew.

33. A rail clip according to claim 32, further characterised in that the three axes are skewed.

34. A rail clip according to claim 25, further characterised in that said tie anchor portion (104) includes detent means (120) for latching said rail clip on an upwardly projecting head (210) of a cooperating chair (200).

35. A rail clip according to claim 34, further characterised in that said detent means comprises a protruberance (120) defined by an outwardly diverging end (116) of said tie anchor terminal leg (110).

36. A chair for cooperating with a spring rail clip for securing a railway rail to an anchoring support therefor, and comprising anchoring means (202) for anchoring said chair to said support characterised in that the chair (200) is adapted to have a generally S-shaped torsional spring rail clip (100) as claimed in any one of claims 25 to 35 driven thereon, and comprises an upwardly projecting head (210) for receiving a tie anchor loop portion (104) of the rail clip interiorly of said clip in seating engagement therewith, said head (210) including a jaw (212) formed on a first side thereof, said jaw being configured to receive and embrace both upper and lower surfaces of a central leg (102) of said rail clip and provide a restraining force thereon.

37. A chair according to claim 36, further characterised in that said jaw (212) has a bight defined at its upper end by an outwardly projecting lip (214) to extend directly above the upper surface of the central leg (102) and at its lower end by outwardly projected ledge means (216) to extend directly below the lower surface of the central leg (102).

38. A chair according to claim 37, further characterised in that said ledge means comprise a pair of spaced ledges (216) defining an internal pocket (228) therebetween.

39. A chair according to claim 36, further characterised by ramp means (218) for applying an upwardly directed force on a tie anchor terminal leg (110) of a generally S-shaped rail clip (100).

40. A chair according to claim 39, further characterised in that said ramp means (218) is formed on a second side of said head (210) opposite from said first side, said ramp means including a sloped ramp face (220).

41. A chair according to claim 40, further characterised in that said sloped ramp face (220) terminates at a generally flat ramp ledge (222).

42. A chair according to claim 36, further characterised in that said head further comprises overdrive prevention means (226) for locating a said rail clip (100) on said chair.

43. A chair according to claim 42, further characterised in that said overdrive prevention means (226) comprises an outward projection formed in a face of said head (210) for mating with the tie anchor portion (104) of a generally S-shaped rail clip (100).

44. A chair according to claim 43, further characterised in that said overdrive prevention means (226) is formed on a third side of said head (210) adjacent said first side.

45. A chair according to claim 36, further characterised in that said head (210) further comprises a recess (224) for mating with a detent (120) on the tie anchor portion (104) of a generally S-shaped rail clip to establish locking engagement therebetween.

46. A chair according to claim 45, further characterised in that said recess (224) isformed on a second side of said head (210) opposite from said first side.

47. A chair according to claim 36, further characterised in that said anchoring means comprises a downwardly projecting shank (202).

48. A chair according to claim 47, further characterised in that said shank (202) has a rectilinear cross-section.

49. A chair according to claim 47, further characterised in that a pair of opposing faces of said shank (202) are formed with a plurality of longitudinally spaced laterally projecting ridges (204) to yield a stepped wedge outer surface thereon.