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 discussing the comparative performance of platinum versus tungsten for interrupter points, coils and condensers.
| Identifier | ExFiles\Box 35\6\ scan 179 | |
| Date | 30th June 1926 | |
| To Oy. from EFC. c. RJ. EX. WD.{Mr Wood/Mr Whitehead} X 2894 EFC2/T30.6.26. x4652 x1680 We have seen a copy of your letter CY2-Ell.6.26, with reference to the question of platinum versus tungsten interrupter points, coils and condensers. (1) Interrupter Points. (a) Excluding any effect which may be due to the presence of oil vapour, with which we have had a certain amount of trouble, we have not yet been able to obtain tungsten points fitted to our own contact breakers which will run as well as platinum; certainly not better. Platinum points run fairly well (though not ideally well) in the absence of oil vapour. Various steps are being taken still further to improve the running, such as ignition coils with finer primary windings taking less current, and ballast resistances of larger magnitude. (b) As stated, we cannot get tungsten points on our own ignition which will run in the same way as U.S. tungsten points run on their equipment, even in this country. It is our general experience that the U.S. tungsten points on their own ignition run quite well, but we have not been able to obtain the same results with English tungsten points fitted to our ignition. (c) If we run our own ignition entirely, including condenser, with the exception of the contact breaker and points, on an American made contact breaker with tungsten points, we get excellent results on the tungsten points. We are following up a further experiment in this direction, but it is not easy for us to obtain U.S. ignition equipment and particularly to obtain spare levers and points with which to make experiments. So far as we have done, it would appear to be entirely a question of material and to this end we are trying to get the English tungsten makers to supply the same sort of material. (d) We do not think it is a question of coils or condensers. We think there may be a little in the nearly closed iron circuit coil for the reason you mentioned of the increased damping effect on the oscillation due to eddy current and hysteresis losses, though not very much according to our experiments of U.S. tungsten points on our own ignition. Contd. | ||