From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Various properties and manufacturing considerations for road springs, comparing different types.
| Identifier | WestWitteringFiles\T\2July1928-December1928\ Scan059 | |
| Date | 14th August 1928 | |
| FROM R.{Sir Henry Royce} ROAD SPRINGS. ORIGINAL R1/M14.8.28. X7410 X1429 X8410 X3503 I was very interested in your memo. with reference to road springs, but there are one or two points upon which I should like to comment. RUSTING. I think this hardly enters into the experience we have had in tests at the Works on the bumping rig, because there would not be time for rusting to affect the life of the spring, and neither can the rusting effect difference in the life of the springs between Firth's, the American springs, and the French Lemoine springs. GRINDING OF THE EDGES. Though this may have some effect, again I think we should compare with the French and American springs. BEDDING. It is not usually recognised that the load, and therefore the rubbing and friction, only occurs at the ends of the plates, and we can hardly expect heavy bearing marks along the whole length of the plate. (It was some years before I realised this) even with springs having plates of the same thickness throughout. NIP. This appears to be inevitable when the spring plates are graded in thickness, as the curvature of the thin plates must be greater than the curvature of the thick plates to get the maximum stress the same on the maximum deflection. HOLLOW ROLLED PLATES. The last point, and I think the most important, is the hollow rolling of the plates. I think this is decidedly bad. I have the impression that it is done merely for the appearance of making the plates fit close together at the edges, but it must of necessity make the bedding of the spring in small hard places. It must also increase the stresses at the edges of the plates, which is also very bad. This is a point which could be profitably compared with the French and American springs. In conclusion, I am not convinced that it is necessary to make an expensive and elaborately finished article of these springs to bring them in line with the Lemoine springs, but I do think that all reasonable expense should be allowed to make everything about our chassis the superior job we claim for it, and if we can prove that increased life and reliability are obtained with a better finished spring, or if we find that the better life of the Lemoine spring or American spring is due to the superior finish of the surface, or the workmanship, we ought to insist that Firth springs are at least equal, especially as I understand the cost to us of the Firth springs is greater than the Lemoine springs. R.{Sir Henry Royce} | ||