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).
Tests conducted on various scraper and compression rings to control oil consumption.
| Identifier | ExFiles\Box 144\3\ scan0106 | |
| Date | 11th August 1936 guessed | |
| -2- Various forms of supposedly more efficient scraper rings were tried without any appreciable success and consisting of the following. (a) Rings with wall pressure ranging from standard at 20 lbs/sq.in. to 32 lbs/sq.in. (b) Rings with narrow lands and increased width of oil drain slots. (c) Rings with a turned finish instead of a ground finish in the hope that the rougher surface of the turned ring would increase the rate of bedding down. (d) Rings combining a high wall pressure, narrow lands and turned finish. Though in several instances an improved consumption by the various scraper rings were obtained, the results were not consistent and the improvement only slight and not the big alteration we were looking for. Following the tests on the scraper rings it was decided to have a go at the compression rings and here came the surprise of the whole series. On fitting new standard compression rings, retaining the bedded in scraper rings, the oil consumption came down to the starting figures which showed that the scrapers were not controlling the oil to the extent anticipated. Previous to this test we had thought that the scraper was the controlling factor in oil consumption and that the compression rings were left with little to do in oil control, whereas the results show almost a reverse decision. The normal compression rings have a wall pressure of 12-14 lbs/sq.in. and owing to the stresses in the ring, it was only by increasing the radial thickness that higher wall pressure could be safely obtained. This meant an alteration to the ring groove in the piston and would not be a quick getaway for production and is now passed over for future development. Little change was obtained in substituting turned rings in place of the standard ground rings. L section compression rings were tried (No.156) bein machined from standard rings and in the same proportion as the L section rings used on Phantom I. | ||