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).
Letter to The Perfect Circle Ring Co. in the U.S.A. asking for help with engine oil consumption problems.
| Identifier | ExFiles\Box 148\3\ scan0159 | |
| Date | 13th October 1936 | |
| -1256 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews}16/KW. 13th October, 1936. The Perfect Circle Ring Co., Hagerstown, Ind., U.S.A. For the attention of Mr. Ralph R.{Sir Henry Royce} Teetor. Dear Sirs, We are taking the liberty of writing to you in the hope that you might be able to help us with our oil consumption problems. The engine we are troubled with is a six cylinder unit of 4 1/4 litres capacity, having a bore of 3.500" and a stroke of 4.500", and maximum speed of 4500 R.P.M. The cylinder block has detachable head and is mounted separately on an aluminium crankcase. The pistons are in R.R.53 aluminium alloy, and have a fully split skirt, and two compression rings, and one scraper ring are fitted. Our main problem is to get the rings "run in" quickly, we know that the consumption can be quite satisfactory providing the unit runs sufficiently long, but this running-in period is far too long and it takes about 4,000 miles running before we can get anything like a reasonable consumption. The rings we use are of course to the usual British proportions. They are centrifugally cast, with ground finish on the periphery, the radial thickness is D/26.9 for the compression rings and D/29 for the scraper ring. The free gap of these rings is 3.5 x radial thickness. The rings are formed by hammering and the En value of the material is approximately 16,500,000 lbs/sq.in. before hammering. The wall-pressures measured by closing the gap are 12.0 lbs/sq.in. for the compression rings and 18.0 lbs/sq.in. for the scraper ring. The oil supply is by pressure feed to crankshaft & conn.rods. | ||