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).
Design and benefits of piston rings and aluminium pistons for car engines.
| Identifier | Morton\M11\ img051 | |
| Date | 5th July 1917 | |
| To E.P. ) from R.{Sir Henry Royce} EH. ) c. to Commander Briggs. c. to J.{Mr Johnson W.M.} After the War - looking ahead ORIGINAL R4/B4:3:17. X.682 Re Wing-Commander Briggs' Car. X.2809. X.2369.? X.2809.? RECEIVED 5 JUL 1917 On a recent occasion during a visit to Commander Briggs re aero engines, I rode in the Rolls-Royce car which he uses. During my visit, he expressed a wish to have (the Admiralty) tested some pistons with narrow rings which they have been using in aero engines. These appear to be the same as those of our recent practice, except that they are still narrower, being only .06" wide instead of .1". I do not think that for a car engine of the usual type that narrower rings than .1" could be considered practical. I suggest therefore, that we fit to Commander Briggs' car a set of pistons similar to those fitted to 7 CA, which consist of four upper rings .1" wide pinned alternately front and back, and a lower scraper ring with some surface below the ring, to retain the oil and reduce the risk of piston knocks. 7 CA was particularly good in this respect although fitted with aluminium pistons. Referring to the type of piston, I think it is highly desirable to retain the Zephyr type for the reason that the distortion is less, and therefore the freedom of the piston is probably greater, and secondly, the top of the piston keeps cooler owing to the heat being carried off more effectively. This is advantageous as, you know Because as it enables the engine to fill up better and therefore give more power, and is also advantageous especially when using aluminium for a piston, to keep it as cool as possible. (Contd.) | ||