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).
Technical memorandum comparing the performance of Swedish carbon steel and Chrome Vanadium valve spring wire.
| Identifier | ExFiles\Box 158\5\ scan0057 | |
| Date | 30th January 1940 | |
| 1360 Hs.{Lord Ernest Hives - Chair} . . .from BY.{R.W. Bailey - Chief Engineer} Rm.{William Robotham - Chief Engineer} BY.3/HR.30.1.40. C.P.S See Bull and ask him if these failures were on test or in customers hands - what were Pin's for same period (see our complaint sheet file) Re VALVE SPRING WIRE. Reference:- Rm.{William Robotham - Chief Engineer}9/JH.24.1.40. The evidence, when critically reviewed, does not sustain the view that Swedish carbon steel wire gives as good results as Chrome Vanadium wire on similar designs of springs. It is necessary to point out that, whilst on the Bentley engine, Swedish wire gave the better results, the springs tested were of special design. The Swedish wire was used with damping coils, whilst the Chrome Vanadium was used with the then standard design. The tests were run on the bench, using a Bentley engine at 4250 r.p.m., at which speed the standard form of spring had a persistent surge whilst the new design of spring, for which Swedish wire was used, was free from surge. When similar springs to our original scheme with a regular pitch to the coils, were tried out in the two wires, Chrome Vanadium, as we produce it, had the better record by a good margin. Turning now to actual experience under production conditions, whilst freely admitting the failure of the Chrome Vanadium springs on the Bentley car run by Rm.{William Robotham - Chief Engineer} under particularly severe winter conditions in U.S.A., I am still prepared to maintain that Chrome Vanadium wire used on both chassis and aero engines have given us an unique record for absence of valve spring troubles. We have some 20,000 cars out with a total of something like 250,000 springs, and our actual failures in customers' hands are negligible. In Aero engine work we have never had an epidemic in service, whereas our competitors have -continued- | ||