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).
Secret internal memorandum discussing piston ring designs and their impact on oil consumption.
| Identifier | ExFiles\Box 72\1\ scan0011 | |
| Date | 15th April 1925 | |
| To HS.{Lord Ernest Hives - Chair} & E.{Mr Elliott - Chief Engineer} FROM R.{Sir Henry Royce} c. to CJ. BY.{R.W. Bailey - Chief Engineer} S E C R E T. X8980 E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. PISTON, & OIL CONSUMPTION. R7/M15.4.25. X.8040 X.8980 It is very undesirable to have any of the faked systems that I and others have suggested, but very desirable to try everything and then take a review of the most practical. When we tried the L. shaped rings which were intended to be equal to the bevelled rings, we made these latter ourselves, which may have made some difference. Naturally they are better than the bevel because they have more surface, but I cannot think even this L. [struck through text] ring can remain more lightly loaded in the upper part, since the section revolves round some centre as it is squeezed up or wears, so it should bind in the grooves; even this may have some effect on its action. SEE ORIGINAL FOR SKETCH. So far we seem to only know of one recent improvement - i.e. the L. section. But we have the 40/50 doing about 1000 miles to the gallon with quite simple pistons and rings. We ought to find if stiffer rings have any marked effect, and if a broad scraper is better than a narrower one; the 20 HP. said 'yes' and if more rings are better than less I like plenty of narrow rings because of the gas-tightness, but a very gas-tight piston might, or should, use more oil at full load, and less at light load. Our bed plate test should be road conditions of say 1/2 min. full throttle and 1/2 min. throttle closed. I would much rather use the oil quickly at full throttle, than at light running. R.{Sir Henry Royce} | ||