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 suggestions and potential issues for E.A.C. pistons.
| Identifier | WestWitteringFiles\M\Jan1925-March1925\ Scan59 | |
| Date | 3rd March 1925 | |
| TO-E.{Mr Elliott - Chief Engineer} HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} SECRET. Copy to CJ. RG.{Mr Rowledge} BY.{R.W. Bailey - Chief Engineer} re. E.A.C. PISTONS. X8040 Re. scraper rings we do not know any scheme of ring that can have one edge more heavily loaded than another, because they would soon wear to an equal loading. (1) I have suggested grooves under each ring stopped opposite joint of ring above. E.{Mr Elliott - Chief Engineer} has not got this idea quite correctly; the groove should follow its ring all round except for say 1/4 of its split. This has not been proved to be good or useless; first test was thought good. (2) I have suggested double rings side by side in one groove, one being stiffer or more cut out than the other. This has not been acknowledged - it is worth testing. (3) E.{Mr Elliott - Chief Engineer} has suggested the possibility of the inertia at high speed causing binding, which suggests narrow ring with plenty of set. The vertical bolt preventing piston breaking at the slot does not seem necessary. Possibly the die cast one that broke was defective, cracked, or poor metal for tension when set so that with the increased section etc it should be quite safe. If die castings are likely to be wrong for any reason we should use sand ones until die cast are reliable. I have never heard any report of the piston with a single vertical bolt each side right through the pin from the screws to the crown. This would do many things and could be modified to give slightly more tightness when hot. To lighten. Less so that expansion difference small. Plugged piston pin. It is undesirable to have a special ring for scraper either in width or otherwise. It makes for confusion and wrong fitting, but if necessary I would certainly fit it, but it should not lose its effectiveness under 2 years work. R.{Sir Henry Royce} 2 | ||