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).
Improvements for gummed pistons in aero and car engines.
| Identifier | ExFiles\Box 66\1\ scan0135 | |
| Date | 10th March 1927 | |
| To RG.{Mr Rowledge} from R.{Sir Henry Royce} To E.{Mr Elliott - Chief Engineer} To Hs.{Lord Ernest Hives - Chair} To EY. c. to BJ. Wor.{Arthur Wormald - General Works Manager} 48040 R2/M10.3.27. AERO ENGINES, CAR ENGINES - GUMMED PISTONS. X.3996 X.8040 X.2103 X.3866 I am very pleased to hear that it is settled that the above is not a question of oil, and that Castrol R.{Sir Henry Royce} is good, because this is undoubtedly a good lubricator for the mechanical parts. Also it is good to hear that F.10. is our best engine now that it has long direct water cooled cyls. It ought to be our best but we are probably working it harder. So that it now resolves itself into a good gas-tight piston with good wall area of contact, and we go on with piston design and rings. (1) Can we detect any difference if we keep the piston better oiled by moving the scraper ring up to the top group, and can we with such a piston get sufficiently good oil consumption? (2) Are more or less rings better? (3) Are the stiffer rings better? I think so in many ways. The deeper section makes the sides of the rings more gastight. (4) Ought we not to be much better off than the hotter condition of an air-cooled engine; what information can be got? (5) Undoubtedly our practice of pinning should be superior and more reliable, but one also thinks it may be necessary with slack piston to have rings which do not depend on the fit between the rings touching the cyl. Ought we to be particular that this beds though slack, so that the leak only occurs while changing sides? (6) It will be remembered that our F.10. tubes cyl. liners should be easy and inexpensive to change so that re-grinding ought not to be necessary - i.e. this engine can have closer fitting pistons if they are more reliable? (7) "We must conclude that the Condor failure is due to cast pistons or wrong design of cast piston, resulting in poor mechanical strength?" Everyone must agree that the above is right as far as we have got, and I understand that if the mechanical strength of the F.10. piston turns out to be OK. now, this item need not cause us undue anxiety, though we go on trying to make it better. R.{Sir Henry Royce} | ||