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).
Out-of-date practices on piston ring clearances for the 25 HP engine.
| Identifier | ExFiles\Box 105\2\ scan0210 | |
| Date | 27th November 1931 | |
| X5040 RHC.{R. H. Coverley - Production Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/AD27.11.31. PISTON RINGS 25 HP. We find that our practice on piston rings is rather out of date as regards clearances. We took this matter up with the Wellworthy people who are acknowledged experts and they have made up some special rings for us. One point they emphasise is that they do not know how we get a ring of .113 thick over the top of our piston without distorting it permanently. Their main suggestion is that the clearance at the back of the ring is very much reduced. We attach their letter to us and also hand you herewith the piston rings and a print of E.57122 with dimensions of the bottom of the groove marked to 3.030 minus 1 which we deduce from their letter is what they require. We are anxious that the next set of pistons made up should have these rings fitted. We are more particularly concerned because we are getting excessive piston blows with the latest high compression engines which we can only attribute to defective rings. Please return letter at your convenience. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||