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 broken 3 1/2 litre Bentley valve springs.
| Identifier | ExFiles\Box 88\4\ scan0055 | |
| Date | 3rd May 1934 | |
| Rm{William Robotham - Chief Engineer} X254 Micro-Examination Report. 1943. To Mr. Hives (Hives is crossed out) HI2/A.C.3.5.34. Laboratory. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} O.{Mr Oldham} Wor.{Arthur Wormald - General Works Manager} Re: 3 1/2 Litre Bentley Valve Springs. (Your refs: BY/BD{Mr Berend}/J.27.4.34. and HY{Tom Haldenby - Plant Engineer}/Bd{Mr Berend}14/J.1.5.34.) Twenty-eight pieces of chrome vanadium steel springs broken on the Bentley chassis used in America by Rm.{William Robotham - Chief Engineer} were submitted. These have all been stripped of enamel and scale, and the surface and fractures examined. Most of the fractures were of the usual type. A few were of peculiar shape, but these were found to be secondary fractures with one possible exception, where the wire was fractured square across. This latter type of fracture, as you know, has always been associated with some mechanical fault. None of the springs showed any signs of surface flaws associated with any of the fractures. There was in fact almost complete absence of surface flaws of the mechanical type, and no corrosion pits at all. Individual springs were examined in the usual way for seams, slag, decarburisation, micro-structure, bend and fracture. All of these tests gave good results. The Brinell hardness of two of the springs was measured and found to be 427. The single spring sent with your second memo. and which was broken in England, was examined and tested in the same way as the others, with exactly the same results, excepting a slightly higher hardness figure, viz. 437. This hardness is, of course, quite satisfactory. It will be gathered from the above that the material contained no defects and had been heat-treated correctly. Two of the American plain carbon steel springs were also submitted. contd. | ||