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).
The causes of gummed-up piston rings, attributing it to gas leakage, and the development of an apparatus to measure it.
| Identifier | ExFiles\Box 66\1\ scan0106 | |
| Date | 6th October 1926 guessed | |
| contd :- -2- We give some results obtained Jehle and Jardine in U.S.A. which show the method of conducting the tests and figures obtained. The quickest and most certain way we know of to produce gummed up piston rings is to allow an artificial leak past the pistons. We have had this frwquently occur on F.X. when the gudgeon pins have rubbed against the cyl. walls. We hold the view that the cause of gummed up piston rings will most probably be found due to gas leakage past the rings. If we consider the case of the Silver Ghost where alum. pistons prove to be worse for this trouble than the cast iron, the cast iron piston has a better chance of being gas-tight due to the fact that the bands between the rings are a much closer fit also owing to the fact that there is no split or drain holes, the skirt of the piston assists in making it gas-tight. Up to the present we have had no means of measuring the amount of leakage past the pistons. We have felt for some time it was a point we ought to have more information on. We have therefore made a simple apparatus which we think will enable accurate comparative results to be quickly obtained. We attach a sketch of the apparatus used. We have carried out preliminary tests on the Phantom engine and it is astonishing to watch the rate at which the water replaces the air in the container in order to make up for the leakage. We have only used it so far on a Phantom engine on which the head was replaced by a flat plate in one cyl. This cyl. had a compression pressure of 250 lbs. contd :- | ||