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 testing, specifically addressing over-oiling and knocking issues on a 10,000-mile test car.
| Identifier | ExFiles\Box 35\2\ scan 180 | |
| Date | 1st January 1920 | |
| X.2748 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 EP.{G. Eric Platford - Chief Quality Engineer} HS{Lord Ernest Hives - Chair}3/LG1.1.20. X.2748. - RE PISTONS. X.3743. X.3715. We have been endeavouring to find the best piston which is reliable enough to fix on to the 10,000 mile test car. We have not yet received any of the new ram pistons with the three rings on the ram but we have been working on the original type of ram piston with some rams to which we have fitted two narrow rings. This is the best we couldd o with that type of ram. We find that even this does not prevent over-oiling. The over-oiling we complain of is not bad but we know that for the piston to be successful on production we cannot risk any over-oiling at all. Nothing is more objectionable on a car, we consider, than for one cylinder, to be giving continuous trouble and cutting out and up setting the whole running of the car due to the over-oiling. With these pistons we have used the standard big end bearings so that only an intermittent oil supply is fed to the ram. Two of the pistons knock, they knock when picking up even when the engine is hot. The oil pressure is 18 to 20 lbs. The engine also develops a slight rattle at high speeds which we find is due to the pistons. We find, if we have 40 lbs. spring as well as the oil pressure, the knock is over-come but there still remains the over-oiling. We find also, if we have a spring to give 85 lbs. pressure without any oil on at all. Contd. | ||