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).
Technical memorandum critiquing a supplied cast iron piston and proposing an alternative trunk type design.
| Identifier | ExFiles\Box 35\2\ scan 185 | |
| Date | 1st January 1920 | |
| X.2948 To Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} Copy to CJ. " " Bn.{W.O. Bentley / Mr Barrington} " " Ck.{Mr Clark} X.3754. - RE PISTONS. RG{Mr Rowledge}/GS.1.20. X.2948 The cast iron piston you have sent us does not appear a very hopeful design should we be obliged to return to cast iron pistons. If we adopted this we should be throwing away most of the experience we have gained during the War, and even some-what previous to the War, because it is a piston with no scraper ring, and therefore would be very danger us for over-oiling in case of ample oil being supplied to the cylinder walls. It would not suit the present length of connecting rod. It has a thick spherical crown which is practically flat in the middle, and might collapse from over-heating, in case of thin speci-mens getting through manufacture. We consider the rings are too high up and they are of the borad type, and pinned by a system that we have now discarded I have therefore asked Mr. Elliott to indicate a trunk type of piston that we think suitable to be constructed in cast iron, that we can have on test. It would be practically like the present standard aluminium piston but of lighter dimensions, that is, it has a large surface for the oil film below the rings. It is fitted with narrow rings rather low down, though not ultra-low down. It has narrow bottom rings as a scraper ring, and a conical surface, as Mr. Elliott points out that the centre of the conical top is better supported when over-heated than is the case with the dome top Contd. | ||