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).
The causes of 'EAC' engines over-oiling compared to the standard 40/50 model.
| Identifier | ExFiles\Box 71\4\ scan0084 | |
| Date | 25th March 1925 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. X8980 REF Hs{Lord Ernest Hives - Chair}1/LG25.3.25. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. BJ. c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to WOr.{Arthur Wormald - General Works Manager} S E C R E T. 'EAC' ENGINES OVEROILING. X8980 X8040 We are running a set of sand-cast pistons made to LeC.2030. This is the piston with the stiffer diagonal web on the split side and a boss for the split to finish in. As regards the reason why the EAC. oil consumption is so much more than the standard 40/50, the only obvious differences which we can see in these two engines are :- (1) On the EAC. the trunks of the cylinders extended into the crankcase may collect a lot of oil which would drain on to the crank or connecting rod and get flung up into the cylinder. At present, we are making some baffles to prevent this occurring. (2) The main oil pressure is supplied to all seven brgs. on the EAC. It is only fed to three bearings on the 40/50 and the 20 HP. Originally, the 20 HP. had the main pressure supplied to all seven bearings but because the overoiling occurred, it was finally only fed to three main bearings. We have carried out tests and find on the EAC. engine, if we only supply main oil to the ends and the centre bearing, the oil consumption is reduced. We cannot yet say definitely how much. Our tests are shewing, as you anticipated, that the 'L' shaped ring, when made to the proportions which we have been using, will loose its efficiency owing to wear. We do not recommend that we fit any special type scraper rings. The tests at present being carried out are being made to endeavour to find the reason why with similar pistons to the 40/50, on the EAC. we use much more oil than we do on the 40/50 H.P. We have made a test which demonstrates the efficiency of the 'L' shaped ring as a scraper. contd :- | ||