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 rattles, binding issues, and the modification of adding rings to solve the problem.
| Identifier | ExFiles\Box 35\2\ scan 208 | |
| Date | 18th March 1920 | |
| X.2448 TO R.{Sir Henry Royce} from HS.{Lord Ernest Hives - Chair} c. to CJ. c. to Bn.{W.O. Bentley / Mr Barrington} c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} HS{Lord Ernest Hives - Chair}7/LG18.3.20. A.2748. RE PISTONS. A.3715. A.2631. we have had a case of slight piston rattles even when the top band of the pistons has had the extra clear-ance. this has occurred on 49-GB car. the pistons were of the plunger type andowing to them having excess of oil, had formed carbon very rapidly. we think, however, the fact of us having a case where a piston has been binding with the extra clearance, is sufficient proof that we must adopt immediately the ring at the top of the piston. we have received MR. Johnson's permission to do this and the modification is being put through immediately. we have completed 55 hours running on the bench they have given no trouble the rings have not stuck up. with pistons with a ring high up./ there is a bright mark on the very top band of these pistons - this band is .1" which shows the brightness. we cannot imagine that this very narrow band could ever cause the piston to rattle. Acting on your recommendation, besides the ring at the very top of the piston, we have also added another ring above the present four. this will give us five stopped rings and the advantage is that we can have the stops in the desired position both for the top ring and scraper ring which is not possible with an even number. we have a set of pistons running on a car fitted with these rings. HS.{Lord Ernest Hives - Chair} | ||