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).
Testing Ram Type silent pistons, detailing issues with over-oiling and piston knock.
| Identifier | ExFiles\Box 77\3\ scan0075 | |
| Date | 9th December 1919 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to BN.{W.O. Bentley / Mr Barrington} c. to E.{Mr Elliott - Chief Engineer} c. to DH.{D. Henderson - Showroom} X.3739 Hs{Lord Ernest Hives - Chair}3/LG9.12.19. <3715> RE SILENT PISTONS - RAM TYPE. x3739 The six pistons of the ram type, which, when fitted to 1.EX gave us trouble with over-oiling, have now been fitted to 49-GB Car. On this car, however, we did not touch the connecting rods which have the two holes feeding the oil to the gudgeon pin and rams. The rams have a single ring fitted. Very much less oil gets past these pistons on 49-GB than did when they were fitted to 1.EX. If we run light with the car standing, the magneto plugs do, however, become over-oiled. There is a little sign of smoke from the exhaust. When we first started the engine up after the pistons had been fitted, there were several piston knocks. These went off after two or three minutes running. Since then, after the car has stood all night in a cold garage, there are piston knocks which disappear after about half-a-minutes running. The bad over-oiling we had with these pistons on 1.EX was greatly due to the fact that we turned an annulus in the big end bearing and had no baffle plates to keep the oil from being flung up into the cylinder. It was nothing to do with the pistons. If we can get the plunger pistons to work without making any alterations to the big end bearing, we think it would be a great advantage. It will enable us to fit these pistons to existing cars very easily. As regards the improved type of piston fitted with a Contd. [Stamp: RECEIVED DEC 11] [Upside down text: R.R. 235 A (100 (T) 18 (L) 576. 16/4/19) G 2384] | ||