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).
Design and effectiveness of different types of piston rings for oil scraping.
| Identifier | ExFiles\Box 66\1\ scan0008 | |
| Date | 1st March 1925 | |
| Hs.{Lord Ernest Hives - Chair} from E.{Mr Elliott - Chief Engineer} C.S. C.R. (at Le CanadelHenry Royce's French residence) C.B. C.Rg.{Mr Rowledge} Y8040 E1/W3. 3. 25 SECRET. E.A.C. PISTON RINGS. The explanation advanced for the bevelled piston ring scraping oil apparently in the wrong direction is the same as given by Mr. Royce some months ago, when the phenomenon was first reported. Also it was then suggested by Mr. Royce that the same effect could probably be obtained without bevelling, by making the ring of unsymmetrical section, such as L shaped, so that the pressure was not uniformly distributed across the face of the ring, but that both this and the bevelled ring would tend probably to wear most where the pressure was greatest and in time lose their oil scraping properties. At that time, however, the investigation finally boiled down to using a stronger and wider ring for the oil scraper on the 20 H.P. engine. Now that the question of oil scraping has again arisen, this time in connection with E.A.C., we are bringing to Derby with us a drawing showing a piston machined to Mr. Royce's latest proposals, in which every ring on the piston has a bevelled abutment above it and an oil scraper recess below it. Thus all the rings should act in series to keep down oil, the final and lowest ring discharging into a recess communicating by means of the usual holes with the interior of the piston. Further to this, it might be worth while to make a test of piston rings with a lop sided section, as previously mentioned, such as would be obtained by bevelling the back of the ring. E.{Mr Elliott - Chief Engineer} | ||