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).
Changing the material for low-stress valve springs on the Phantom III from chrome-vanadium to carbon steel wire.
| Identifier | ExFiles\Box 96\2\ scan0154 | |
| Date | 10th October 1936 | |
| 4354 To BY.{R.W. Bailey - Chief Engineer} Copy to BG. RMC. Sft.{Mr Swift} HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} E/PSN.1/MN.10.10.36. Handwritten note: Swd (struck through) Edwards} Please note Rm{William Robotham - Chief Engineer} Low Stress Valve Springs - Phantom III. In order to reduce the stresses in the Phantom III valve springs and enable them to be made from a good quality carbon steel spring wire instead of the much more expensive chrome-vanadium wire which we are at present using, the valve gear has been packed up experimentally by 1/8" to enable more wire to be got into the valve springs. This has enabled the stresses to be reduced to a point where we feel that a plain carbon steel spring wire should be satisfactory. We send you herewith LeC.5323 of the modified valve springs together with details of a modified tappet spring which should also be made in plain carbon steel wire instead of chrome-vanadium, and which has the further virtue of reducing the load between the tappet and base circle of the cam when the valve is closed. This should be beneficial in reducing tappet wear under these conditions. We should be pleased if BY.{R.W. Bailey - Chief Engineer} would arrange for some of these springs to be tested on the production spring rig in addition to instructing a set for a main engine in conjunction with the packed-up rocker gear to LeC.5331. E/PSN. Att: LeC.5323. | ||