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).
Comparison of cross web and diagonal web piston designs, concluding that the diagonal web piston is the superior design for car work.
| Identifier | WestWitteringFiles\R\January1928-March1928\ 66 | |
| Date | 18th February 1928 | |
| FROM E.{Mr Elliott - Chief Engineer} ORIGINAL E1/M18.2.28. C. to BJ. HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} PISTONS. X8040 (crossed out: X7040) It is understood that we are testing pistons of both cross web and our old diagonal web pattern. The cross web are however found to be some 4 or 5 ozs. heavier than the standard diagonal, in spite of lighter scantlings in the body of the piston. Additionally, Mr. Bailey, who has gone into the matter with the die casters tells us that the cross web piston is not a practical die casting job. We have demonstrated how the die can be made so that the side pieces of the core can be held up, and will withdraw after the centre piece is withdrawn, but it is not considered practical. You will no doubt remember that the reason on which your suggestion of the cross web piston was based was the alleged distortion of pistons endways due to tight fitting piston pins. I find now that this trouble has disappeared from the mind of the Exp. Dept. and HS.{Lord Ernest Hives - Chair} thinks that distorted cylinder bores may have been the real cause of the complaint. The diagonal web type is inherently strong at the inner ends of the horizontal split. Weighing the whole of the evidence at the moment the diagonal web piston is the best design we have for car work. E.{Mr Elliott - Chief Engineer} | ||