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).
New piston design defects, including a thick skirt and long ring pins, with modifications suggested by Mr. Hives and Mr. Royce.
| Identifier | ExFiles\Box 35\2\ scan 072 | |
| Date | 1st May 1919 | |
| R.R. 235a (500 T) (S.D. 408. 26-4-17.) Bm. 2/156/13. X.3400. Extract from E6/G1.5.19. (14) PISTONS - Mr. Hives brought a sample of the new piston with low position of piston pin to West WitteringHenry Royce's home town. This sample was defective in being too thick in the skirt, and in not having enough metal opposite to-the oil accumulating groove under the scraper ring. Mr. Hives thought this was due to using a lower position of rings than was originally intended for the first castings that were made, and that no trouble would be experienced with this on the later sets of pistons in hand. It was thought that if any trouble were experienfed with over-oiling an increase in the number of drainage holes from the oil collecting groove might prove beneficial. The original intention was that the Experimental Dept. should continue to drill drainage holes until they found out the limitations at this point. Mr. Royce thought that the ends of the piston ring pins were too long inside the piston, and that it was not necessary to have so much length for opening up the ends of these pins with a screw driver or other suitable tool. Further, Mr. Royce instructs that it should be made quite clear that the heads of these pins were cleared away sufficiently below the surface of the piston so as to avoid galling the cylinder. .010" would not be too much to take off for effecting this purpose. E.{Mr Elliott - Chief Engineer} | ||