US3368759A

US3368759A - Railway tracks

Info

Publication number: US3368759A
Application number: US531676A
Authority: US
Inventors: Olson Erik
Original assignee: Swedish Rail System AB SRS
Current assignee: Swedish Rail System AB SRS
Priority date: 1965-03-11
Filing date: 1966-03-04
Publication date: 1968-02-13
Anticipated expiration: 1985-02-13
Also published as: SE305007B; GB1097766A

Description

Feb. 13, 1968 E. OLSON 3,368,759

RAILWAY TRACKS Filed March 4, 1966 2 Sheets-Sheet 1 E. OLSON RAILWAY TRACKS Feb. 13, 1968 2 Sheets-Sheet 2 Filed March 4, 1966 United States Patent 3,368,759 RAILWAY TRACKS Erik Olson, Nasbypark, near Stockholm, Sweden, assignor to Swedish Rail System AB-S.R.S., Solna, near Stockholm, Sweden, a Swedish joint-stock company Filed Mar. 4, 1966, Ser. No. 531,676

Claims priority, application Sweden, Mar. 11, 1965, 3,206/ 65 12 Claims. (Cl. 238-83) ABSTRACT OF THE DISCLOSURE Apparatus for connecting two railway tracks, which are preferably mounted on concrete sleepers, for reducing the lateral forces on the sleepers in the curves. An extensible elastic member is connected between the two rails and with each sleeper for receiving the lateral forces on the two rails, these lateral forces being oppositely directed, said elastic member then transferring to the sleepers only the horizontal resultant of said lateral forces instead of the lateral force of each rail per se.

On account of the increasing shortage of good raw materials for wooden sleepers in recent years, the utilization of concrete as structural material for railway sleepers has increased. In the first place the intention was to utilize the good resistance of the concrete to compression stresses and the concrete sleepers have substantially been used for straight tracks or for sections having only slight curves. The continued general utilization of concrete sleepers increases the requirements on the concrete as structural material, as it is desired to utilize concrete sleepers also for tracks with limited'radii of the curves. As well-known, there arises substantial lateral forces when railway vehicles are passing through narrow curves, and these lateral forces first must be received by the anchoring means between rail and sleeper and then have to be transferred from the sleeper to the body of the railway.

According to the hypotheses hitherto adopted for the forces between the railway vehicles and the railway, as occuring in the curves, it generally was supposed that these forces were acting in the direction of the centrifugal force at both rails and could be derived from a simple relation between the mass and the velocity of the railway vehicles. However, in the last years systematic measurements by recently developed methods have rendered the interaction of the forcesbetween the vehicle and the railway empirically accessible, and an analysis made by the inventor as to the force spectra of the predominating guiding forces has led to the surprising result that these forces for each wheel are substantially opposed, as the lateral force on the inner rail is directed inwards, thus opposite to the centrifugal force, the horizontal radial resultant having a value which is only a fraction of the absolute value of the maximum force on each wheel. Thus, the individual connections between the outer rail and the sleeper and between the inner rail and the sleeper are subject to forces which per se are much more p-redominating in value than the summation force existing between the sleeper and the body of the railway.

As mentioned in the introduction, the utilization of concrete sleepers has been limited substantially to straight tracks, because the concrete as structural material is not suitable for taking up tensile forces and on account of its low impact strength or toughness is not well adapted for resisting the strains which may be caused by railway vehicles in narrow curves, and the invention has for its object to create a device which, utilizing the development mentioned above, allows a reduction of the lateral forces transferred to the sleepers in curves.

' Patented Feb. 13, 1968 The device according to the invention is characterized in that between the two rails and below the rail bases, an elastically extensible member is disposed for connecting the two rails with each other and with each sleeper, said member being provided for receiving and taking up the lateral forces of the two rails, these lateral forces being oppositely directed as the lateral force on the inner rail of the curve is directed inwards in the curve, said member being also provided for transferring to the sleepers only the horizontal resultant of these lateral forces (instead of the lateral force of each rail per se).

The invention will be described more detailed in the following with reference to the accompanying drawings, in which embodiments of the invention are illustrated by way of example.

FIG. 1 is a side view of a sleeper together with the two rails and an elastically extensible member according to one embodiment of the invention.

FIG. la is a perspective view of the rail anchoring means as used in the embodiment according to FIG. 1.

FIG. 2 is a side view of a sleeper and an elastically extensible member according to another embodiment of the invention.

FIG. 3 is a plan view corresponding to FIG. 2.

FIG. 4 is a side view of a sleeper and an elastically extensible member according to a modification of FIG. 2.

FIG. 5 is a side view of a sleeper and an elastically extensible member according to a further embodiment.

FIG. 6 is a plan view corresponding to FIG. 5.

FIG. 7 is a transversal cross-section on the line VII VII in FIG. 5, on a greater scale.

FIG. 8 is a side view of an element of the device according to FIGS. 5 to 7.

The sleeper 1 shown in FIG. 1 consists of two end blocks of concrete and an interconnecting tube filled with concrete and containing a through-going reinforcing bar (not shown) for pretensioning the sleeper, as well-known in the art. In this embodiment, the elastically ertensible member consists of a relatively broad flat iron bar 2 which extends along the top surface of the sleeper in contact with the bottom surface of the rail bases (feet) of the rails 3 and has its two ends 2a bent downwards at each side of the ends of the sleeper. Pads 4 of hard rubber or the like can be provided between the flat iron bar 2 and the sleeper. Rail anchoring means 5 are provided between the top surface of the fiat iron bar 2 and the rail bases, said rail anchoring means comprising plates :Sa embracing the rail base, loops 5b attached to the flat iron bar 2 and projecting through slots in the plates 5a, and wedges 5c forced through the loops 5b for pressing upon the flanges of the rail base. If desired, the flat iron bar 2 can be provided with plates 2b welded to the same at the inner sides of the end blocks.

Thus, according to the present invention, the major part of the lateral forces which are developed between a railway vehicle and the body of the railway in a curve is received and taken up by the extensible member 2 before the resultant of these lateral forces is transmitted into the sleeper. At the same time as the lateral forces in this way have been reduced substantially before they are transferred into the concrete sleeper, they also have been distributed into the parts of the concrete sleeper, where the reaction forces are greatest, viz, directly below the rail bases (rail feet). Thus, by the invention the forces acting on the connection between rail anchoring means and concrete .as well as the forces acting between concrete and railway body are reduced, whereby the sleeper will lie more firmly and can be displaced laterally, under the action of the forces of the vehicle, to a much smaller degree than is the case when conventional rail holding means are used.

The elastically extensible member should be designed so as to allow an elongation which, calculated on the width between the rails, has a value between the limits 1 and 10 mm. but usually 2 and 6 mm., preferably 3 to 5 mm., for instance 4 mm. As a matter of fact, based on theoretical considerations as to the guiding forces of the railway vehicles in curves, one can show that one should have a certain and not too high spring force both vertically and laterally between the vehicle and the track. It can also be shown that it is suitable to locate a part of this resiliency in the track. From the experience it is also known that after traflic during a certain period of time there will arise, in the track, irregularities from the circular form and that also the vehicle after some time of wear presents characteristics which further emphasizes the importance of a more weak resiliency between rail and sleeper than attained by a rigid connection.

According to FIGS. 2 and 3, the elastically extensible member comprises a flat iron bar 6 which extends along the top surface in contact with the bottom surface of the rail bases, the two ends of said fiat iron bar not being bent downwards, as according to FIG. 1, but being bent upwards at the outer edge of each rail base. Also in this embodiment, the reference numeral 4 indicates the pads and 5 is the rail anchoring means, the last-mentioned means extending below pegs 7 inserted through holes in the sleeper, and being curved to engage under tension on the top surfaces of the rail bases, as well-known in the art.

In the modification of FIGS. 2 and 3, as illustrated in FIG. 4, the fiat iron bar 6 is slightly corrugated in its central portion for allowing a greater resiliency so that the width between the rails or the rail gauge can be varied.

According to FIGS. 5 to 8, the elastically extensible .member may comprise two round iron bars 8, flat iron bars or profile iron bars, each at one side of the sleeper and extending along the respective side of the sleeper, the two ends of each bar being bent upwards above the outer edge of the associated rail base, rail anchoring means 5 being disposed between the sleeper and the rail bases.

Characterizing for all embodiments is that the elastically

extensible member

2, 6 or 8 takes up the lateral forces of the two rails before these forces are transferred to the sleeper inasmuch as the sleeper receives only the resultant of the oppositely directed lateral forces of the two rails.

The invention is not restricted to the embodiments illustrated and described, many modifications being possible within the scope of the appendant claims.

I claim:

1. In combination with railway track rails supported on sleepers, the improvement which comprises:

an elastic member for reducing the lateral forces transmitted to the sleepers, particularly in the curves, said member being positioned between the rails and below the same and said member being extensible a predetermined distance and disposed for connecting the two rails with each other and withthe sleepers, and

means for sec-uring the elastic member to the rails and the sleepers so that the elastic member receives the lateral forces of the rails, these lateral forces being oppositely directed (the lateral force on the inner rail of the curve is directed inwards in the curve, 7 and the lateral force on the outer rails is directed outwards in the curve), said rails and elastic member being secured to the sleeper so as to be movable during operation relative to said sleeper to permit extension of the elastic member up to said predetermined distance so that said elastic member transfers to the sleepers only the horizontal resultant of said lateral forces instead of the lateral force of each rail, per se.

2. The combination as recited in claim 1 wherein said predetermined distance which said elastic member is extensible has a value between the limits of 2 and 6 millimeters, calculated on the width between the rails.

3. The combination as recited in claim 1 wherein said predetermined distance which said elastic member is extensible has a value between the limits of 3 and 5 millimeters, calculated on the width between the rails.

4. The combination as recited in claim 1 wherein said predetermined distance which said elastic member is extensible has a value of 4 millimeters.

5. The combination as recited in claim 1 wherein the extensible elastic member comprises a relatively broad, flat, iron bar which extends along the top surface of the sleeper in contact with the bottom surface of therailway track rails and has its two ends directed downwards at each side of the sleeper ends, and

wherein said rail securing means is disposed between the top surface of the flat, iron bar and the bases of the rails (FIG. 1).

6. The combination as recited in claim 5 wherein the fiat, iron bar is slightly corrugated in its central portion for providing a greater resiliency for varying the width between the rails (FIG. 4).

7. The combination as recited in claim 1 wherein the extensible elastic member comprises a flat, iron bar which extends along the top surface of the sleepers in contact with the bottom surface of the bases of the rails and has its two ends directed upwardly at the outer edge of each rail base, and

wherein said rail securing means is disposed between the sleeper and the rail bases (FIGS. 2 and 3).

8. The combination as recited in claim 7 wherein the flat, iron bar is slightly corrugated in its central portion for providing a greater resiliency for varying the width between the rails (FIG. 4).

9. The combination as recited in claim 1 wherein the extensible elastic member comprises two iron bars, one on each side of the sleeper, which extend along the respective sides of the sleeper and wherein the two ends of each bar are directed upwardly above the outer edge of the associated rail base, and

wherein said rail securing means is disposed between the sleeper and the rail bases (FIGS. 5, 6, 7).

10. The combination as recited in claim 9 wherein said two iron bars are round.

11. The combination as recited in claim 9 wherein said two iron bars are flat.

12. The combination as recited in claim 9 wherein said two iron bars are profile bars.

References Cited UNITED STATES PATENTS 795,622 7/ 1905 Kneedler 238-111 904,438 11/1908 Jacob 238-113 913,238 2/1909 Ross 238-111 1,012,942 12/1911 Wade 238-88 1,056,201 3/1913 Mobley 238-290 1,086,262 2/ 1914 Allen 238-290 1,112,613 10/1914 Hellstrom 238-89 2,035,933 3/1936 Wilson 238-83 ARTHUR L. LA POINT, Primary Examiner. R. A. BERTSCH, Assistant Examiner.