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).
Laboratory report on the failure analysis of Wraith 26.C.VI KE.965 exhaust valves.
| Identifier | ExFiles\Box 10\3\ 03-page073 | |
| Date | 10th September 1937 | |
| Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. to Rm.{William Robotham - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} c. to HFS. c. to RHC{R. H. Coverley - Production Engineer}/EG. H1/EJW.1/GS.10.9.37. LABORATORY WRAITH 26.C.VI KE.965 EXHAUST VALVES. Your Ref. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}7/MH.{M. Huckerby}1.9.37. The valve with the head broken off after 7000 miles in France and another valve from the same engine have been tested. Hardness and fracture tests and examination of the micro-structure indicated a satisfactory material condition. The valves have evidently been overloaded for the temperature reached during running. This has resulted in local stretching of the neck and consequent development of circumferential oxidised fissures. These are shown in the atteched low-power photo, No. M.1407/1 which is of the unbroken valve in the polished condition, as received from you, and also in the photo No. 1407/2, which is of part of the stem of the broken valve. In this case we removed the scale by pickling in order to avoid loss of surface by polishing. The original fracture is at the top of this photo and the one we made for test purposes is at the bottom. One of the water passages near the broken valve is choked as shown in photo A.1407/3. This passage, however, is small and well away from the valve neck. H1/EJW. | ||