GWR Coral wagon

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I picked up a battered 00 wagon at a recent train fair. It's a white metal kit build which I identified as a Coral (GWR telegraph code name). Apparently only 25 were built between 1884 and 1906 so it seems an odd prototype to choose for a model, but nonetheless interesting. They were used for the carriage of large sheets of plate glass in wooden crates. My question is how was the glass packed? A late 19th /early 20th century loose coupled freight train would not be conducive to a gentle ride for such a fragile load, but apparently some Corals survived into BR days so I assume that they worked. Any information on the packing and loading techniques would be welcomed.

[What About The Bee]

Hi Three Link

There is plenty of information on shipping and transporting sheet glass. Perhaps not in Coral wagons...

Glass is shipped standing on edge, never laying down. The box is lifted from the top, and usually not from the bottom. There would be separation packing layers betwixt the sheets.

This is all related to Beam Theory! A thin beam will deform more readily than a thick beam, as the deflection goes by the height of the beam cubed, in the denominator. Once accepted, a sheet of glass on edge has a tremendous beam height, a sheet of glass laid flat has little beam height.

Next, consider how yield strength and ultimate tensile strength affect this. The material bends, until deformation occurs at yield. When the material bends beyond ultimate, it shatters. Materials that have yield and ultimate tensile strength at nearly the same values are brittle. That is glass!

Putting this together, glass deforms under load. The deformation goes by the height of the beam. Orient the glass to maximize beam height to minimize deformation. Minimizing deformation of a brittle material reduces breakages. Separation of sheets reduces scratching.

This will have been very well known to glass factories, for the period you describe.

Bee

[81F]

If you are interested in seeing a real Coral, I recall there was one at the GWS museum at Didcot

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Thank you Bee and 81F. I can understand that glass makers would be well versed in the handling of glass but I do wonder to what extent railway staff would be conversant with the requisite handling techniques. As to packing, I appreciate that a stout wooden crate would offer protection to its fragile contents but I I would love to know what packing material was used inside the crate in Victorian times - I hazard a guess at felt and straw, but would love to know for certain. I believe that the Didcot specimen is the sole survivor of its type and has undergone or is undergoing substantial restoration.

[What About The Bee]

Hi Three Link

Material between glass sheets should be flat and of uniform thickness. Felt would do. Cardboard would as well. Anything that could apply point loads would be rejected, as localized bending and stress concentrations could be created. Even a sheet of paper of requisite size.

I searched for images of your Coral A wagon and there are plenty. One lad did a fantastic job with his model, the wooden crate is loaded. Chains a touch overscale, but acceptable. I also note that "DAZ" has some 3D printed models of Coral A. Some cracking ideas there.

Bee

[Going Spare]

Perhaps railway personnel were not involved in loading/unloading the crates: the wagons may have travelled undisturbed between producer and customer with both using their own specialist facilities and staff to ensure all went well.

It would appear that the Corals that were retained were transferred to South Wales steelworks in the late 1930s for the movement of sheet steel, possibly the advent of pneumatic tyres on lorries causing the railways to lose the glass traffic.

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Again, thanks all for your input. The use for steel sheet conveyance is useful info - it will fit well with my latest modelling project.