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).
Oil pressure characteristics and issues with the S.S. relief valve compared to the Phantom model.
| Identifier | WestWitteringFiles\T\2July1929-December1929\ Scan054 | |
| Date | 12th September 1929 | |
| To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X7205. X4160. S.S. RELIEF VALVE. Attached is a curve shewing the characteristics of the S.S. oil pressure. The S.S. oil pump is 7% larger than the Phantom. The relief valve passages also offer more resistance than those on the Phantom. The result is, we get a large pressure rise with increasing engine speed. We cannot get a low enough intermediate pressure for normal running without running the risk of the valve gear being dry when warming up in cold weather. The appended curve shews some of the tests that have been made. Cars on test are being set with an intermediate oil pressure of 1 1/2 lbs. at slow running speed, with anything more than this top over oiling occurs after a bout of speed. The over-load on the oil gauge is likely to be severe in cold weather. We have tried a pump having two thirds of the capacity of the normal pump and it reduces the pressure rise with speed of both the main and intermediate oil pressure by 40%. We think this may be over-doing it, but that a 20% smaller pump would be permissable. The safest move is of course to decrease the restriction across the relief valve. We are not in any serious difficulty with the present cars but should like your views on the subject, as we do not seem to be getting ideal conditions. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||