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).
Issues with broken Phantom III piston rings and recommending new gap specifications.
Identifier | ExFiles\Box 94\5\ scan0121 | |
Date | 7th August 1936 | |
+ 336 To By.{R.W. Bailey - Chief Engineer} c. to E.{Mr Elliott - Chief Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews}19/JH. 7. 8. 36. Phantom III Piston Rings. We have recently had on Phantom III engines, cases in which the top compression rings have been found to be broken after running. On examining the rings it was evident from the marking on the ends that the rings have had insufficient gap when closed. the drawing calls for a maximum closed gap of .006 and minimum of .002, the minimum dimension is very close and we recommend a minimum gap of .008 and maximum of .010. We know from experience that gaps of .010 have no adverse effect on blow-by or oil consumption and with the gaps recommended we should have no further trouble from ring breakage due to gap closing up. We also recommend that the gap of the scraper ring be increased at the same time since with .002 minimum clearance there is grave danger of the gap closing. It would be perfectly safe to increase the gap to .008 as on the compression ring. HB{C. E. Harcombe}/R.{Sir Henry Royce} Matthews. | ||