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, oil consumption, and potential solutions for component failure.
| Identifier | ExFiles\Box 16\1\ Scan170 | |
| Date | 23th March 1925 | |
| To E; from R.{Sir Henry Royce} c. to Cj. RG.{Mr Rowledge} BY.{R.W. Bailey - Chief Engineer} c. to Hs.{Lord Ernest Hives - Chair} 4741 (handwritten, crossed out) SECRET E & A.{Mr Adams} C. PISTONS AND OIL CONSUMPTION. Regarding pistons and oil consumption, since tests shew it is not now due to the valves, one cannot think that the bore and stroke, 4½" X 5½" compared with 4½" X 4½", should make any difference in oil consumption. Why not then go on with the 40/50 practice, because I cannot see how 'L' shaped rings can remain right even if they were proved to be better. The pressure per unit area must soon be equalised by wear, or the ring would bind in the groove. It would be more hopeful for a permanent state, to experiment with more or less rings, stiffer or wider rings, baffles, or something to equal the present 40/50 .. which is so good as far as pistons are concerned, and oil consumption. (I hear of 2800 miles without any added oil, and under conditions of extra oil almost always on.) The same applies to the broken piston, about which I have already written to say simply because the diagonal web on the broken side and let the saw nich finish in a large hole close to this web, which will avoid the maximum tension being so great. Test for a tension break which seems easy now we know of the weakness. Moreover I could never understand why these pistons were not heated during assembly, so that the piston pins were a close fit when hot. R.{Sir Henry Royce} | ||