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 seizure, recommending design alterations and cross-testing between aero and car engines.
| Identifier | ExFiles\Box 77\3\ scan0021 | |
| Date | 11th November 1919 | |
| Contd. -5- seizure under normal running conditions. We consider that the seizures we have had on the bench test are something quite apart from the fact that the pistons were split. We do not consider it serious, especially as the clearance on the top hand has been increased right away. We still leave a narrow band of reduced clearance to protect the top ring from hot gases. The rings did not suffer at all on the 25 hours run at 2000 R.P.M. full throttle with these increased clearances. We also recommend that we alter the pistons as soon as possible to avoid the top running out into the counter bore. We can do this we suggest, by adopting the connical crown similar to what is being used on the new ram piston. It is a fact that on the aero engine we never got the least signs of any marks or bearing on the top band. The clearance on the top band on the aero engine is the same as we are using on the present car engine pistons. The top band never touched on the aero engine. It used to become coated with a hard layer of carbon which had an enamel-like surface. We find that it is possible for us to test same "Eagle" engine pistons in a car engine and likewise we can test some of the present car engine pistons in an "Eagle" engine. This ought to tell us whether it is the design of the piston or whether it is due to the different conditions in the car engine cylinder. As regards the tests run on split pistons we have completed:- Contd. (R.R. 235 A (100 S) F.S (T). 576. 16-4-19) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2354) | ||