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).
Letter to Mr. W.H. Glaser regarding the burning of platinum points on a Phantom, discussing condenser capacity and a new contact breaker design.
| Identifier | ExFiles\Box 70\3\ scan0184 | |
| Date | 7th March 1928 | |
| X8783 EFC4/T. 7th March, 1928. Mr. W.H. Glaser, C/o Messrs. C.A.Vandervell & Co.Ltd., Acton, London, W.3. Dear Mr. Glaser, I have your letter of yesterday's date with regard to the burning of platinum points on Mr. Vandervell's Phantom. You ask me to tell you the capacity of the condenser. This, at 18oC, lies somewhere between the limits 2.75 and 3.25 mf, but the capacity increases with temperature in such a way that at 45oC it will lie between the limits 4.1 and 5.2 mf. You will not find, however, that any alteration in the capacity of the condenser within possible limits will improve the action of the points. We have been all over this ground and the result has been quite definitely that the burning of the contact points is not primarily a function of the constants of the electrical system, but much more to do with the mechanical arrangement of the contact breaker. We have recently standardised an improved contact breaker which gives a very slight scrubbing action of the points in a certain way, and it is this that makes the difference and not an alteration in the circuit quantities. We can, with this new arrangement, use tungsten points to greater advantage than platinum. It should also be mentioned that this pre-supposes that condensation of oil vapour has been previously eliminated. We have had some trouble which is directly traceable to this cause, and at an earlier time than the change of contact breaker and the introduction of tungsten contact points, we had introduced a better form of oil vapour excluder which probably is not contained on Mr. Vandervell's Phantom. It may be quite possible that the bad results he is getting are due to the presence of oil vapour. We do not of course want this information broadcast. If Mr. Vandervell is really seriously troubled Contd. | ||