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 wear, lubrication, and testing for the 10,000-mile test car.
| Identifier | ExFiles\Box 35\2\ scan 181 | |
| Date | 1st January 1920 | |
| R.{Sir Henry Royce} R.{Sir Henry Royce} 235 a (100 T) (S.F 846 6-8-19) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2460 Contd. -2- HS{Lord Ernest Hives - Chair}3/LG1.1.20. we do not get any piston knocks. This scheme with the spring without any oil fed to the ram is the most reliable pistons of this type we can fit to the 10,000 mile test car, but we do not feel happy about it. On our test it runs alright and there is no sign of wear but we feel that if a car is being run with poor lubricating oil and is left to stand for some time, the oil will be squeezed out by the continuous pressure and that when the engine is started with excess of petrol, there is a risk of seizure. We also are not sure that the ram will not wear the cylinder bore. We know, for instance, that the pistone rings wear the bore considerably. It is also noticeable that the wear takes place very much less on our test engine than it does with cars which are run on the road. We think this is due to the fact that we use better oil and are free from the dirt and grit which must be sucked into the cylinders when the car is on the road. Apart from the ram pistons, we have some more of the split type. We should be glad if Mr. Royce would wire which type of pistons he considersre should be fitted to the 10,000 mile test car. We should like to have this information at least by Saturday. Apart from the tests on the car, we have done a fair amount of work with the plunger piston on the bench with oil fed to the ram on the pressure. We have tried several schemes to try and make it oil tight but we have not been very successful. We think that the most hopeful scheme X. 3765 is the one sent through by Mr. Royce in which Contd. | ||