Freight wagons

Technical Field

This invention is in the field of railway rolling stock, and in particular freight wagons. In a first aspect the invention is a freight wagon end casting. In a second aspect the invention is a method for manufacturing a freight wagon. Background Art

A typical freight wagon 10 will briefly be described with reference to Fig. 1. Generally, the wagon 10 has a central sill 12 that runs longitudinally under the length of the wagon body 14. Near each end of the central sill 12 is a transverse wagon bolster 16. The wagon bolsters 16 serve two purposes: First, they locate side bearers that provide roll stability by reacting on the bogie 18. Second, they provide a location 20 for lifting or jacking the wagon body. Under the cross formed by the sill 12 and each bolster 16 is a center pin or plate 22 that engages the bogie and allows rotation between the wagon and the bogie.

Manufacture of freight wagons generally involves the fabrication of separate subassemblies for the draft pocket rear stop plates, bolster, transition to center sill member and center plate. These sub assemblies are then brought together and welded to form the end structure of the wagon. The welding requires accurate jigging and setup.

Furthermore, the assembly is required to be rotated during the welding to achieve correct weld positioning. Controlling distortion is always problematic. In addition, welding or bolting the center plate sub-assembly requires very precise setup as it locates the bogie in relation to the wagon. Any misalignment in the attachment of the center plate will result in vehicle dynamic problems and accelerated wear of the bogie and wheelsets. Summary of the Invention

The invention is a monolithic, steel, freight wagon end casting, comprising:

At a first end, draft pocket rear stop surfaces to react against draft gear.

At a second end opposite the first end, a center sill interface to connect to the center sill member.

On either side a bolster interface to connect to a bolster.

And underneath, a center plate to engage the bogie The casting integrates four functional components of a freight wagon into a single monolith. The four functional components are the draft pocket rear stops, center plate, bolster interface and the transition to the center sill member.

The monolithic casting integrates the highest fatigue loaded locations in the wagon structure, and results in superior fatigue performance. Both a lower probability of fatigue failure and a higher fatigue life. Fatigue failure is arguably the highest structural risk on a freight wagon.

The casting process offers flexibility of metal placement which enables more effective mass optimization than can be achieved with the contemporary fabrication approach. Mass savings in the order of 10% are envisaged with optimization. This mass reduction is highly beneficial as it can enable a higher payload for a fixed axle loading.

Perhaps the most important benefit of the casting is the saving of a large amount of time in manufacturing the wagon end assemblies. Time is saved in both the setup and welding processes. The casting is effectively self jigging since it is provided with a locating feature at each interface to the surrounding wagon structure. Each interface may incorporate an inbuilt weld preparation that facilitates the subsequent welding process to enhance fitup, welding and quality. These qualities enable wagon end assemblies to be fabricated in perhaps 25% of the time of conventional configurations.

Another benefit of the casting is greater precision in the dimensions of the finished wagon end assembly.

The casting may also include a draft pocket interface comprising a weld preparation spigot for accepting the draft pocket webs, and top and bottom flanges. The center sill interface may further include a spigot configured to be butt welded to the end of the center sill member.

The bolster interfaces may comprise an upright edge, and optionally, upper and lower horizontally extending edges.

Alternatively a spigot could be provided for, say, a rectangular cross section bolster that would be connected either by welding or mechanical fastening.

In another aspect the invention is a process for manufacturing freight wagons, comprising the steps of:

Casting a monolithic steel body, comprising:

At a first end, draft pocket rear stop surfaces.

At a second end opposite the first end, a center sill interface.

On either side a bolster interface.

And underneath, a center plate to engage the bogie

Then, butt welding or mechanical fastener attachment of the center sill interface to a center sill member.

Welding or mechanical fastening of the bolster interfaces to respective bolsters.

And, engaging the center plate with a bogie. The casting may also include, at the first end an interface to draft pocket webs and flanges.

Brief Description of the Drawings

The existing assembly at a freight wagon end has been described with reference to the pictorial view of Fig. 1.

The invention will now be described with reference to the following drawings, in which:

Fig. 2(a) is a pictorial view of a first end of a freight wagon end casting.

Fig. 2(b) is a plan view of the freight wagon end casting.

Fig. 2(c) is a pictorial view of the other end of the freight wagon end casting. Fig. 2(d) is an elevation of the first end of the freight wagon end casting.

Fig. 2(e) is a side elevation of the freight wagon end casting.

Fig. 2(f) is an elevation of the other end of the freight wagon end casting. Fig. 2(g) is a view from below of the freight wagon end casting.

Fig. 2(i) is a section through A - A shown in Fig. 2(d).

Fig. 2(j) is a section through B- B shown in Fig. 2(e)

Fig. 3 is a pictorial view of the freight wagon end casting in situ in a wagon. Best Modes of the Invention Referring now to Figs. 2, the invention is a bespoke steel casting 100 that integrates four entirely different functional components of a freight wagon into a monolith. The four functional components are: At the second end, the transition 102 to the center sill member 12. At the first end the inclusion of the draft pocket rear stops 104. The center plate 106. The bolster interface 108, including an upright edge 1 10, and upper 1 12 and lower 1 14 horizontally extending edges. A central hollow column 118 passes vertically through the casting 100. Horizontally extending ribs 120 and 122 extend through the casting to strengthen it longitudinally for the high coupler buff loads transmitted via the draft gear into the rear stops 104 of the casting 100.

Transition interface 102 to Center Sill Member 12

This is configured as a spigot 102 that enables the sill member 12 to be both located onto and aligned with the casting 100. The spigot 102 is profiled to achieve a full penetration butt weld to the end of the sill member 12. Alternatively, this could be modified to accommodate a mechanical fastened connection. The direct load path from the dominantly loaded rear stops 104 through the casting 100 to the center sill 12 can be seen in Fig. 3. This feature is responsible for imparting very high fatigue performance by concentrating the coupler load into the sill member 12 without significant diffusion of load into any other structure, for instance a hopper, that is not specifically configured to accommodate it. As the sill member 12 and its connection is sized and configured for high loads, very high fatigue performance is realized.

Bolster Interface 108

The function of the bolster 16 is to provide an interface to the wagon for lifting and jacking, and to react the vertical sidebearer reactions that control wagon roll. In both cases the loading is dominantly vertical. The casting 100 provides an upright edge 1 10 for butt welding to the web of the bolster. Upright edge 1 10 both locates the bolster 16 and provides a weld preparation for the connection. Similarly, the casting provides an interface in the form of upper 1 12 and lower 1 14 horizontally extending edges that both locate and facilitate welding to the upper 18 and lower 20 flanges of the bolster 16. Significant manufacturing setup time is saved relative to conventional full fabrication methods because of this ready interface. Alternatively a spigot similar to 102 could be provided for a rectangular cross section bolster that would be connected either by welding or mechanical fastener. Center Plate 106

Center plates 106 are conventionally either welded or huck bolted to a wide thick base flange. Both processes are slow and tedious requiring careful setup. For bolt on center plates it is usual to machine this flange to ensure correct seating of the center plate casting. There are two downsides to this process; firstly, extra thickness is required to provide for a machining allowance and secondly it is an additional process. Welding the center plate castings is usual, but introduces its own challenges in the form of the weld shrinkage causing misalignment. Careful compensation measures are required, which takes time and is vulnerable to error.

As the center plate 106 is integral with the casting 100, no specific center plate setup is required, nor any joining process. A massive amount of production time is recovered from the elimination of the above setup and joining processes. Rear Stops 104

The rear stops 104 for the draft gear are the most heavily loaded components in a freight wagon. As a consequence heavy gusseting is necessary. This introduces two major problems: First, gusset plates are thick and require full preparation butt welds. This necessitates profiling plates and machining the weld preparations which is expensive. Second, when the gussets are welded into location their spacing is close and the available space makes visibility for welding and indeed welding access somewhat difficult, this can have a negative effect on weld quality and inspection. The casting 100 eliminates any need for welding and in fact provides a homogeneous integration of the stops and gussets into the casting.

Referring finally to Fig. 3, a coupler 204 is connected to each end of the wagon. The draft gear of the coupler (its elastic components) are received in a draft pocket 206 in front of the rear stops 104. It will be appreciated by those skilled in the art that, although this invention has been described with reference to a particular example, a number of variations are possible within the scope of the invention. For instance, the bolster may have a hollow rectangular cross section similar to the sill beam. Also the spigots of the sill beam, bolster and draft pocket may be modified to accept a mechanically fastened connection.