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).
Comparison of S/CV and American springs, focusing on dimensions, wire properties, and performance in low temperatures.
| Identifier | ExFiles\Box 88\4\ scan0057 | |
| Date | 3rd May 1934 guessed | |
| -3- Springs. S/CV. American. Small end bore - 0.980" 1.002" 0.99" Large end bore - 1.092" 1.099" 1.106" Free length - - 1.990" 2.018" Poundage - - 54 lbs.8 ozs. 60 lbs. A couple of the springs were also measured for wire diameter after the removal of scale. The English S/CV wire was 0.1593" in diameter and the American wire was 0.1617". The American wire when tested in the usual way gave a somewhat greater bend than the English S/CV wire before fracturing. This was confirmed by more accurate bends made with the Tensometer machine. Tests were also made on an S/CV Bentley Spring which had been given the double quench treatment. This treatment improved the bend slightly but did not bring it up to that of the American Spring. With regard to the suggestion that the S/CV Spring failures in America were due to the low temperature running conditions experienced. We have made enquiries as to other engines run under similar conditions. The Repair Department (Mr. Bull) tell us that they can recall no instances of complaints of valve spring failures due to cold running conditions, although some chassis have, they know, been used at temperatures at least as low as -15°F.{Mr Friese} Mr. Dorey tells us that we have had aero engines for at least three winters in Czecho-Slovakia where the temperature falls as low as -30°F to -36°F.{Mr Friese} There have of course been other instances of low temperature work, as, for example, the engines supplied for use with Arctic expeditions. You may perhaps have some information with regard to these, and be able to form an opinion as to the actual running temperatures of the valve springs of the various engines. contd. | ||