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).
Report investigating the failure of spring steel and mild steel fitted dampers (spiders), detailing potential causes and a proposed solution.
| Identifier | ExFiles\Box 73\1\ scan0219 | |
| Date | 31th March 1925 | |
| - 2 - BY7/H.{Arthur M. Hanbury - Head Complaints} 31.3.25. ---------------- to make up two dozen spiders in Mild Steel, as I had satisfied myself it could fulfil the duty imposed upon it. The next point is that both the spring steel and mild steel fitted dampers have failed under exactly the same conditions. I have one of each on my desk at the moment, which were replaced because they failed to operate, shewing clearly that the fault was not in the material. The facts of the case shew that the failure was due to my not calling for the bore of the wheel to be ground to a running clearance so as to remove all friction from centre of wheel and replace it with friction at the point of contact of the spider with the wheel. I have not overlooked Mr.Evans' memo, but there are quite a number of points which would give the effect he describes without at all altering the material of the spring.- a/- failure to nip spider against shaft collar. b/- small burr in bore when testing which would temporarily increase friction. c/- not lubricating bore of wheel before fitting to shaft before test. I have dealt with this matter fully because CJ. and CWB. express themselves as being amazed that we had used Mild Steel, an attitude I would agree with if I had ordered Mild Steel parts all through, but one I cannot endorse when we had only fitted a few spiders in mild steel, and that after carefully testing same to check that their duty was well within capacity of steel as proved by our tests. I have carried out check tests to see if I had been misled originally, but the figures obtained confirm my original ideas, and as both spring steel and mild steel spiders have failed to act in precisely the same manner, it is logical to assume they failed for similar causes, namely, due to the friction of the hub of wheel on its shaft being overlooked, and consequently damping arranged which depended on shaft fit as well as end pressure. In my opinion, the right way to deal with the fault is, as and when cars come to Works for overhaul, to fit ground gears in place of the damping scheme. I return correspondence submitted, herewith. BY.{R.W. Bailey - Chief Engineer} | ||