heraldcoupe Posted February 5, 2021 Share Posted February 5, 2021 (edited) I'm trying to model in CAD the axleboxes on a GWR locomotive bogie with ouside frames. This is specifically for a Bulldog or Duke, but the axleboxes will be common to other types, standardisation and all that... I am struggling to reconcile the dimensions I've measured from drawings to what I can observe in photographs. I theorised that they may match tender axleboxes, but the drawings I have are contradictory. In more normal times I would visit a museum or preserved railway and take my own measurements, but that's not going to be possible for some time. Can anyone point me to good references for with this part? Larger scale drawings, particularly with an image from above, would be particularly helpful. The drawings below are for an Atbara or City, which share these components. Cheers Bill Edited February 5, 2021 by heraldcoupe Link to comment Share on other sites More sharing options...
Miss Prism Posted February 5, 2021 Share Posted February 5, 2021 44 minutes ago, heraldcoupe said: I am struggling to reconcile the dimensions I've measured from drawings to what I can observe in photographs. I theorised that they may match tender axleboxes, but the drawings I have are contradictory. In what sense? Link to comment Share on other sites More sharing options...
heraldcoupe Posted February 5, 2021 Author Share Posted February 5, 2021 The drawings I have are approx 10mm/ft, and rather thickly drawn. There is no view from above and when drawn in CAD, I am struggling to get the proportions to look right without deviating widely from what I can measure in the drawings. Good images of an axlebox out of it's guides, or properly dimensioned drawings would help me see where exactly things are going wrong. The width across the hornguides differs between the tender and bogie axleboxes in the drawings I have. Scaling differs between them, but once I've adjusted the figures according to known dimensions within each drawing, there is a significant mismatch. Cheers Bill. Link to comment Share on other sites More sharing options...
Miss Prism Posted February 5, 2021 Share Posted February 5, 2021 These are tender boxes: 1 Link to comment Share on other sites More sharing options...
heraldcoupe Posted February 6, 2021 Author Share Posted February 6, 2021 Thanks, the two major castings appear to be the same those on City of Truro's bogie. The top section is different, I'm going to make an assumption that the hornguide spacing matches though and that one or other of my drawings is in error, Cheers Bill. Link to comment Share on other sites More sharing options...
Miss Prism Posted February 6, 2021 Share Posted February 6, 2021 I think the CoT bogie box castings are slightly different, probably a bit lighter than the tender box castings. Link to comment Share on other sites More sharing options...
heraldcoupe Posted February 6, 2021 Author Share Posted February 6, 2021 Yes, there are differences. I scoured images of preserved locos and could see interchanging of different axlbeox types into identical applicatiosn, so I made the leap of faith that the running dimensions are the same. In the grand scheme of things, it only has to 'look' right at 4mm scale, but I'm always happier to start from good data, Cheers Bill. Link to comment Share on other sites More sharing options...
JimC Posted February 6, 2021 Share Posted February 6, 2021 (edited) There's also the GWR policy of improvement. The GA shows the locomotive as built. According to the tender drawing register tender axle boxes, for instance, changed in 1915 and 1937 on new construction, and there were two different designs in use between 1884 and 1915. There were certainly different bogie designs used on 4-4-0s, but I don't have data on whether axle boxes changed. Edited February 6, 2021 by JimC 2 1 Link to comment Share on other sites More sharing options...
heraldcoupe Posted February 6, 2021 Author Share Posted February 6, 2021 (edited) I've put together the basic shapes on the left of screen, it's quite a bit more substantial than my initial effort on the right. I'l refine the curves and add detail and see how it looks, Cheers Bill. Edited February 6, 2021 by heraldcoupe Link to comment Share on other sites More sharing options...
Miss Prism Posted February 6, 2021 Share Posted February 6, 2021 http://www.gwr.org.uk/4-4-0-bogies.html Link to comment Share on other sites More sharing options...
heraldcoupe Posted February 6, 2021 Author Share Posted February 6, 2021 2 minutes ago, Miss Prism said: http://www.gwr.org.uk/4-4-0-bogies.html Thanks, I'd not seen that particular page, though the guide to outside frame 4-4-0s has been much used! Link to comment Share on other sites More sharing options...
Rail-Online Posted February 7, 2021 Share Posted February 7, 2021 (edited) All I can say is the Martin Finney castings for the outside frame 4-4-0 axleboxes and springs are completely different to those for the 2500/3000 gallon Dean tender. I would not base dimensions on tender items, the prototype weights to be carried and rotation speeds were completely different. The 3521 class are also different to other OF 4-4-0s. Tony Edited February 7, 2021 by Rail-Online additional info 1 1 Link to comment Share on other sites More sharing options...
heraldcoupe Posted February 8, 2021 Author Share Posted February 8, 2021 On 07/02/2021 at 18:35, Rail-Online said: All I can say is the Martin Finney castings for the outside frame 4-4-0 axleboxes and springs are completely different to those for the 2500/3000 gallon Dean tender. I would not base dimensions on tender items, the prototype weights to be carried and rotation speeds were completely different. The 3521 class are also different to other OF 4-4-0s. Tony Ys, as I've found this as I've gradually uncovered more images without inconvenient shadows. I'm on my fourth draft of the part now, and getting closer... Cheers Bill. Link to comment Share on other sites More sharing options...
JimC Posted February 8, 2021 Share Posted February 8, 2021 Does this help at all. Its from an 1898 drawing tittled "passenger engine" but which appears t be a 4-2-2. 1 Link to comment Share on other sites More sharing options...
heraldcoupe Posted February 9, 2021 Author Share Posted February 9, 2021 The face is a bit fat here, I will come back to this once I have some of the other bogie detail completed. Once I can get some test prints done I'll have a better idea of how it looks in context. Cheers Bill Link to comment Share on other sites More sharing options...
heraldcoupe Posted February 9, 2021 Author Share Posted February 9, 2021 1 hour ago, JimC said: Does this help at all. Its from an 1898 drawing tittled "passenger engine" but which appears t be a 4-2-2. That's great, thanks. Link to comment Share on other sites More sharing options...
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