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).
History of valve spring changes and development for the Phantom III engine.
| Identifier | ExFiles\Box 96\2\ scan0140 | |
| Date | 10th September 1936 | |
| (sheet 3) The history of the valve spring changes on Phantom III production as we understand it took place is as follows:- Spring No.(1). E.87952 - This is the highest load spring and was changed after some failures were experienced to (2). Spring No.(2).E.87498 - Medium load changed on account of faulty material. Spring No.(3). E.87498 - These continued to fail and were changed to Brunton's wire. Spring No.(4) E.87498 - These springs in Brunton's proved unsatisfactory, and then changed back again to Chrome Vanadium which are still running on 1st batch of production. Spring No.(5) E.87498 - Production was then switched over on to a No.(6) spring E.88325 of the same nominal stress figures as E.87498, but with graduated coil spacing. The inner spring continues unaltered from the beginning. In our present development work we have first had some of the latest type of springs E.88325 tested in Brunton's wire with the object of getting a value for this spring, as reported in By.9/G.10.9.36. Personally I did not expect these to stand up after all that BY.{R.W. Bailey - Chief Engineer} has said about this wire. Our next move will be to run a Phantom III engine with at least .5" longer springs in plain carbon steel, with the valve gear packed up. We shall also produce a new cam for this test. These springs will also be tested on a rig with different cam forms. We shall also order some of these springs from America to compare with the home produced article. Finally it is now appreciated more particularly in America that valve gear systems require careful rig development, using the whole of the mechanism, including the crankcase as part of the rig to ensure that the actual valve movement bears a sufficiently close resemblance to | ||