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).
Fatigue failure of a foot switch return spring and recommending a replacement.
| Identifier | ExFiles\Box 168a\2\ img248 | |
| Date | 28th October 1936 | |
| To Rm{William Robotham - Chief Engineer}/Wst. r6139. BY/RD.2/B.28.10.36. FOOT SWITCH. Referring to the failure of the Return Spring DB.{Donald Bastow - Suspensions}811 on the Foot Switch, the failure is a fatigue failure, and we are of the opinion that the high stress together with the shock loading which the spring is receiving on the test rig, have jointedly caused the failure. We have produced some hundreds of these springs on production without any failures, but the operation on the chassis is considerably more gentle and this will materially add to the reliability of the switch. We still think that this spring which gives a load of 1 1/2 pounds, is too strong, - it was strengthened up, from 3/4 lb. to 1 1/2 lbs., at your request, and we suggest that you obtain a supply of the original spring DB.{Donald Bastow - Suspensions}667, for further trial. We think that you will agree that the work the spring has to do is only to return the toggle mechanism to the upper position, and does not demand a spring of such poundage. J.J. Please note & return. BY/RD. | ||