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).
Causes of gummed up piston rings, comparing issues found with aluminium versus cast iron pistons.
| Identifier | ExFiles\Box 66\1\ scan0105 | |
| Date | 6th October 1926 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to OY. +8040 Hsl/LG6.10.26. GUMMED UP PISTON RINGS. X8040 X3996 We think it would be unwise for us to rely solely on the modification of the F.X. cylinders to wet liners in order to overcome the gumming up of piston rings. This fault occurs on all our engines. We have had bad examples of it on the Eagle, Condor and Falcon X. It is also a frequent complaint on the 20 HP., Phantom and Silver Ghost. There are several facts which go to prove that the gumming up of the piston rings is not due to the piston temperature. Our Repair Dept. records at the Works definitely show that they have very much more trouble with the rings gumming up on engines fitted with aluminium pistons than on engines fitted with cast iron pistons. They are frequently handling Silver Ghost engines which have either type of pistons fitted. Experiments have been carried out by several investigators and all go to show that cast iron pistons run at considerably higher temperature than the alum. - approximately 200°F.{Mr Friese} It appears to us that if the aluminium pistons on the Silver Ghost attain a temperature which causes gumming up of the rings to take place, when less than 90 lbs. B.M.E.P. is developed, it is not feasible to expect to be able to reduce the temperature of the Falcon pistons to eliminate this trouble when they are subjected to a B.M.E.P. of 140 lbs. contd :- | ||