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).
Piston ring performance, specifically 'L' section rings, in relation to engine over-oiling and oil consumption.
| Identifier | WestWitteringFiles\O\2April1926-June1926\ Scan107 | |
| Date | 1st May 1926 guessed | |
| contd :- -5- on the test bench and ran perfectly well without any signs of insufficient oil to pistons. When shut down it was quite free to turn over by hand and examination of the cylinder bores shewed even lubrication without excess. This seems proof that oil flow as low as this is quite sufficient and reliable for successful operation of the engine! PISTON RINGS. We have demonstrated that rings exert an influence upon over-oiling the worst offenders being those which are slack, i.e. possess up and down movement, in the grooves as they seem to have a pumping action on the oil. 'L' section rings are excellent when new and even with an engine having excessive oil flow will usually correct over-oiling only unfortunately their high efficiency rapidly decreases, as would be expected, with wear. When their efficiency reaches a minimum constant value they should still be equal to plain rings or even superior to new plain rings because they would have 'lapped' themselves to the cylinder bore. Therefore from consideration of the above we see no reason why 'L' section rings should not be employed. There are various other factors exerting slight, but unappreciable, influence on oil consumption, such as pistons - see previous reports. It should be mentioned in passing that we have met with no success by employing various forms of oil baffles. Numerous types have been tested but not a single one has lessened the over-oiling tendency and in the majority of cases they have contd :- | ||