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).
Experiments on Bentley scraper rings to improve engine oil consumption.
| Identifier | ExFiles\Box 87\2\ scan0184 | |
| Date | 25th May 1936 | |
| To Hy.{Tom Haldenby - Plant Engineer} c. to R.{Sir Henry Royce} c. to Mx.{John H Maddocks - Chief Proving Officer} Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews}4/JH. 25.5.36. Bentley Scraper Rings. We have recently been carrying out experiments with a view to improving the oil consumption of Bentley units and have come to the conclusion that for the moment we cannot do better than fit scraper rings having a fine turned finish on the lands. Rings finished in this manner of course bed down and conform to the cylinder shape much quicker than rings having the normal finish. From our experience with experimental test bed and car engines we find that the standard R.60621 scraper ring gives an excellent oil consumption providing it has been "run-in" sufficiently. We now know that there are cases of engines starting the 10,000 miles test with an oil consumption of approximately 400 miles/gallon and after 5000-6000 miles this improves to 1500 miles/gallon. On the test bed engines we have known a case of the standard ground finish rings starting with a consumption of approx. 8 pints/hr. and after 100 hrs. at 3000 r.p.m. the consumption had dropped to 1.5 pints/hr. We have fitted a set of turned rings in B-21 unit for Le Mans and this unit after the normal 'running-in' period was using more oil than normal so that we decided to run an oil consumption test for an hour at 4000 r.p.m., the consumption over this hour was 2.75 pints. This consumption was rather more than we wished and in order to find about what rate the consumption was improving we repeated the test and found the consumption had improved to 2pints/hr. This means that by running approx. 85 miles on the road the consumption had improved by .75 pints/hr. The turned rings are made to exactly the same dimensions as the standard ground finish rings but are produced by the heat forming process and not by hammering as in the case of the standard R.60621 rings. The rings have a butt joint and not the scarf joint at present in use. Hs{Lord Ernest Hives - Chair}/R.Matthews. | ||