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).
Continuation page of a letter to The S. U. Company explaining the oil flow and piston mechanism in an engine.
| Identifier | ExFiles\Box 31\5\ Scan006 | |
| Date | 13th January 1933 guessed | |
| THE S. U. COMPANY. CONTINUATION NO. of the piston pushed this up to the top and it seals the oil by any form of suitable valve. When the engine ceases to run the bottom part of the cylinder is, of course, filled with oil which cannot get back owing to the non-return valve. There is a certain amount of clearance round the diameter of the piston, and the piston falls by its own weight, transferring the oil from the bottom to the top of the piston. As soon as the engine is started, of course, the oil pressure at the bottom of the piston forces this up into the cylinder bore. We ourselves calculate that the piston should drop through the oil in about an hour by its own weight, and take about five minutes to exhaust itself when the engine is running cold. The exact amount of oil in the clearance of the piston is, of course, a matter for determination. Kind regards. Yours sincerely, [Signature] | ||