This invention relates to a compromise rail for effecting a transition between two rails having different profiles.
Within a railway network of a given gauge, rails of different sectional profiles may be used. For example, such profiles may vary in the base to head height, the width of the web, the width of the head or the width of the base. One prior art approach to effecting a transition between two rails having different profiles is to provide a compromise joint bar which is attached to the two rail sections of differing profiles. The compromise joint bar is typically wedged into and secured to the fishing areas of the two rails to be joined. FIG. 1 illustrates such an approach. The compromise joint bar approach suffers the disadvantage of being a mechanical joint in track work, and as is the case with such joints, this results in discontinuities between the rail ends, broken bolts and high wear and maintenance costs.
With the advent of continuous welded rail, an alternative approach has been to provide a compromise rail which is inserted between the running rails having different profiles. As shown in FIG. 2, the compromise rail includes a first section 12 having a profile matching the profile of a running rail to which one end of the compromise rail is to be attached. A transition section 14 is formed at the end of the first section 12. The end of the transition section is flash butt welded at 16 to a section 18 having a uniform profile matching the running rail to which the other end of the compromise rail is to be attached. The transition section 14 therefore has a profile that varies between the profiles of the two running rails. This is done by forging, bending and machining one end of the compromise rail over a distance of approximately 10 or 11 inches. The forging creates the change in profile. The bending and machining ensures that the gauge lines will match up. Bending and machining are used so that the web of the forged section will also match up with the web of the uniform profile section.
The use of a uniform profile section 18 in the compromise rail of the prior art provides a length of rail which can be cut in the field so as to match the length of the compromise rail to the length of the gap between the two running rails and provides a reliable match to the profile of one of the running rails. It also allows the forged portion to be very short.
Typically, thermite welding is used to weld the compromise rail to each running rail. But thermite welding is time consuming. In order to avoid disruptions in rail traffic, installers sometimes provide a temporary joint between the compromise rail and the running rail and defer thermite welding until traffic conditions improve. The temporary joint is accomplished by providing holes in the web of the uniform profile section of the compromise rail and using a standard joint bar to temporarily secure the uniform profile section of the compromise rail to the running rail.
A disadvantage of the compromise rail of the prior art is that the flash butt welding which is typically used to attach to uniform profile section to the forged section is very expensive.
It is therefore an object of the present invention to provide means for establishing an effective transition between two rail profiles that avoids the expense of flash butt welding a uniform profile section to a forged section, yet still provides the advantages of a compromise rail which may be cut in the field to the match the gap between two running rails to be matched.
It is a further object of the invention to accommodate a temporary joint between the compromise rail and the running rails.
According to the invention, the uniform profile section of the compromise rail is essentially eliminated so as to avoid the need for a flash butt weld operation. In order to accommodate a temporary joint between the compromise rail and a running rail, the forging is extended such that it includes a segment matching the profile of one of the running rails and being at least 19 inches long. This is the approximate minimum length required for the use of a typical joint bar. The extended length of the forging also ensures that sufficient space will be available for eventual thermite welding to the running rail in the field.
Accordingly, this invention comprises a compromise rail for providing a transition between two running rails having different profiles said compromise rail being entirely forged and having a first section having a substantially uniform first profile along the length of said first section, a second section having a substantially uniform second profile along the length of said second section, and an intermediate section effecting a transition from said first profile to a second profile, said second section having a length of at least 19 inches.
Although forging a length of 19 inches is more difficult to achieve than the prior art forging which extends a distance of perhaps 10 inches, the cost saving in avoiding the use of uniform profile rail section that needs to be flash butt welded justifies the extra effort involved in producing a longer forging.
Other aspects and features of the invention will be appreciated by reference to the detailed description of the preferred embodiment which follows and to the claims.