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).
Micro-examination report on an American plain carbon steel valve spring from a 3½ Litre Bentley.
| Identifier | ExFiles\Box 88\5\ scan0214 | |
| Date | 22th October 1936 | |
| FILE UNDER VALVE SPRING INFORMATION 8 254 Micro-Examination Report. M1210. To Rm.{William Robotham - Chief Engineer} BY HL1/AG.22.10.36. Laboratory. Re: American Plain Carbon Steel Valve Spring from 3½ Litre Bentley. This is one of the two American springs which were dealt with in our Micro-Examination Report M943 - HL2/AG.3.5.34. The remarks we made in that report are fully confirmed by a re-examination of the spring which we have just made at BY's request, using the latest methods. Two photomicrographs of cross sections of the wire are sent herewith. The first, No. A1,515, X150, illustrates the general condition of the surface, and should be compared with A1,450 (Brunton's cold-drawn C.S. wire), and A1,396 (Stubs C.V.S. wire), taken at the same magnification. You will note that the American spring, although lacking the smoothness of our C.V.S. spring, is definitely better than the Brunton's wire as the small fissures are more rounded, whereas those in the Brunton's wire each terminates in a sharp apex, and would be much more likely to start a fatigue crack. The second photomicrograph, No. A1,516, X500, demonstrates the absence of decarburisation in the American spring. Hl. He Photomicrographs Nos. A1,515/6 att. | ||