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 memo discussing piston ring design and its effect on oil consumption.
| Identifier | ExFiles\Box 180\M3\M3.1\ img008 | |
| Date | 15th April 1925 | |
| TO HS.{Lord Ernest Hives - Chair} & F FROM R.{Sir Henry Royce} SECRET Copy to Mr. BY.{R.W. Bailey - Chief Engineer} E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. PISTON, & OIL CONSUMPTION. It is very undesirable to have any of the faked systems that I and others have suggested. Very desir- able 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. ring can remain more light- ly 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 ef- fect on its action. So far we seem to only know of one recent im- provement - 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 mark- ed{J. L. Edwards} effect, and if a broad scraper is better than a narrower one; the 20HP said 'yes', and if more rings are better than less. I like plenty of narrow rings because of the gas- tightness, but a very gastight 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 1/4 minute full throttle, 3/4 minute throttle closed. I would much rather use the oil quickly at full throttle, than at light running. R.{Sir Henry Royce} [Handwritten notes] Top right: 9x3 Next to title: 48040 (crossed out) 48980 Left of title: notably Lov{Mr Lovesey} Next to typed R.{Sir Henry Royce}: OR Bottom of page: 90% of this was wasted effort: it was Lov{Mr Lovesey} who unearthed the basic reason, viz the changeover from 40/50 hand bedded crankshaft bearings to the line bored marbel reamed P1 with its significant increase in diametral clearance & thus much greater oil slinging? | ||