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).
Piston design modifications, such as the 'letter-box slit' and oval grinding, to prevent splitting.
| Identifier | ExFiles\Box 77\3\ scan0029 | |
| Date | 10th November 1919 | |
| To BN.{W.O. Bentley / Mr Barrington} from R.{Sir Henry Royce} Copy to CJ. " " EH. " " EP.{G. Eric Platford - Chief Quality Engineer} " " WOR.{Arthur Wormald - General Works Manager} R1/G10.11.19. RE PISTONS. X.3651.3432 It is necessary that the bottom pistons ring is pinned on the power side. The vertical split in the piston should be avoided if possible, therefore try Mr. Barrington's letter-box slit on the opposite side to power, and on both sides with oval grind-ing below the slit, the larger diameter being from 0" to .005" smaller than the cylinder size, and the smaller diameter of the oval, say, .020" to .025" below the cylinder bore, or such diameters as are found safe. Allow the piston to become nearly round when suddenly heated. The upper part will be the usual safe clearance, preferably oval. This would be another way of carrying out the same idea, which has advantages, including no risk of split piston claims. R.{Sir Henry Royce} | ||