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).
Tests and remedies for valve faults caused by two types of grit formation.
| Identifier | ExFiles\Box 109\4\ scan0214 | |
| Date | 18th August 1939 | |
| 666a To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} c. Da.{Bernard Day - Chassis Design} Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}2/MH.{M. Huckerby}18.8.39. 30.G.VII TESTS. In reply to your By.II/G.17.8.39. We have started to remedy the faults you mention. (1) There are two kinds of grit which are formed in the damper. One is coarse chippings off the splines and the other is fine powder off the brass bearing thrust face. It is the fine dirt that has caused the valve to stick and this fine dust is held in suspension in the oil, so that it will get into the valve wherever it is situated. We had some of the fine dirt analysed on a previous occasion and it proved to be chiefly copper, indicating its origin as the brass bearing. There are two possible ways of preventing the trouble: one is to stop excessive wear of the bush thrust face and the other is to make the valve less liable to stick. We have a By/Ald.{F. Allwood - Experimental Design} scheme of a better thrust face (the heavy car imposes a heavy duty on this component, B.V. was trouble free). As regards the valve it has reached its present complicated state due to its development history. (a) It is very small because this was thought better if it was to be controlled. We are circulating a memo explaining why we do not think we shall ever need to control it, so that there is now no reason why the area and spring load should not be increased thus reducing the likelihood of sticking. (b) It is a dual purpose valve because, again, we did consider controlling it. We now prefer two separate valves as these need not have such fine fits. Modifications on these lines are being drawn and we think the sooner a change can be made on B.V. production, the less trouble we shall get in service. | ||