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 Vickers hardness testing of a broken contact breaker spring and comparison with other production samples.
| Identifier | ExFiles\Box 61b\1\ scan0210 | |
| Date | 9th January 1937 | |
| To BY.{R.W. Bailey - Chief Engineer} c. Rm{William Robotham - Chief Engineer}/Wst. HL1/AG.9.1.37. 6118 M.1248. Laboratory. Re: Contact Breaker Spring from Ph.III 3AX.49. This broken spring had a Vickers Hardness No. of 644. You will see from the copy of report M.1224 which we send herewith that we have recently dealt with a similar failure. On that occasion the trouble appeared to be due to under tempering, a similar hardness being obtained on the broken spring, whereas a spring unbroken after 300 hours gave a much lower figure, namely 540. As suggested by you we have taken half a dozen springs from present production and have tested these for hardness. The figures obtained were:- 626, 644, 649, 644, 644, 653. You will note that we have already suggested to Mr. West that it would be a good plan to test some more satisfactory springs if these can be obtained. R.S. How are S.S spring proceeding? WSR HL. HC | ||