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).
Examination report on a failed spring, including micro-examination, hardness tests, conclusions, and a note on the investigation.
| Identifier | ExFiles\Box 119\1\ scan0202 | |
| Date | 11th May 1939 guessed | |
| (2). Spring which had run for 13 hours. Micro examination. Part of the fractured surface was polished down and an oxidised seam starting from the extreme edge of the leaf was found. The position of this was indicated with an arrow in photo. M.1840/5. The maximum depth measured of this seam was approximately .031", and, photomicrographs M.1840/6 and M.1840/7 illustrate its appearance. The inner surface of the eye was decarburised to an approx. depth of .006/.009", the outer surface to approximately .005/.006" and the extreme edge .007/.008". Photomicrograph M.1840/8 illustrates decarburisation found on the inner surface of the eye. Hardness Tests. Core 441/448/454 H.2/120. General Conclusion. The methods of manufacture have resulted in a certain amount of decarburisation and roughness on the spring surfaces, also the presence of an oxidised seam close to the point where the fracture has occurred. H1./EJW. Note :- As explained in our telephone conversation and agreed by you, the third spring submitted will not be investigated. This was a main plate made by Firth's, finished by grinding and cadmium plating. Together with part of the black finished spring, (13.hr. failure), reported above, it was borrowed by Mr.Kennington who afterwards informed us that he did not propose to return it as it was now understood by yourself and Rm.{William Robotham - Chief Engineer} that the failure in this case was definitely due to overloading. | ||