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 failed outer valve springs from a Phantom III sales trial car.
Identifier | ExFiles\Box 96\2\ scan0122 | |
Date | 29th July 1936 | |
X354 Micro Examination Report. M.1172. Laboratory. To By/Ogh. [text crossed out] c. to Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} o.{Mr Oldham} to Sft{Mr Swift}/Mr.Base. [text crossed out] H1.6/WJ.29.7.36. FAILED OUTER VALVE SPRINGS FROM PHANTOM 111 - 32 EX. - SALES TRIAL CAR. Five of the above springs have been stripped and examined. We have found nothing to indicate the presence of any fault in the original wire. The heat treatment has also been satisfactory, as shown by fractures and hardness tests on two of the springs. From an examination of the fractures it is clear that in each spring, cracking started from the inside of the coil, and in each case the starting point was a small pit or depression in the surface. These marks are on the inside of the spring only, and are undoubtedly due to "pick-up" on the guide rollers of the spring-making machine, since marks found on every spring are identical in shape and arrangement. This is a repetition of the trouble referred to in Report M.1158 - see also photomicrographs Nos. A.1444 - 6. As a check on the above conclusions we have, as requested, stripped two springs supplied by Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}, which have completed a considerable mileage without trouble. These are both free from the defect in question. The pieces of the five broken springs have been collected and labelled A to E and the position of a similar pattern of marks in each has been indicated with pencil on the etched surface. All of the springs from 34 EX. are returned herewith. The two springs supplied by HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} have been returned. As requested, we are de-scaling sample springs from present production. [Signature] H1/EJW. | ||