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).
Conditions to improve the life of tungsten points in battery ignition systems.
| Identifier | WestWitteringFiles\Q\April1927-June1927\ 85 | |
| Date | 16th May 1927 | |
| EFC. } FROM R.{Sir Henry Royce} TO HS.{Lord Ernest Hives - Chair} E.{Mr Elliott - Chief Engineer} C. to BJ. BY.{R.W. Bailey - Chief Engineer} ORIGINAL. R2/M16.5.27. J BATTERY IGNITION. X2894 Y4041 Y4052 I have suggested that the tungsten points may require different treatment to platinum points, that is, they will bear heavier contact pressure and greater scrub. The conditions that may affect the life of the tungsten points must be summed up in the following - (1) Cleanliness would include freedom from oil or oxydising gases from the jump distributor, and as you can remove the distributor, and can run the ball bearing and cam with only the faintest trace of oil, we think you can soon determine how much "cleanliness" affects the life of the points. (2) The second hopeful condition would be when the tungsten points were allowed a certain amount of scrub, as is so usual with most electrical contact surfaces. We are sending you a drawing to shew how this can be arranged, and also shewing alternative springing of the rocker arm, though I should not expect this latter to make any difference in the life of the points. (3) The third point seems to be the electrical condition, in which we ought to reduce the current to the minimum, and therefore the energy at break would be at the minimum, and at the same time increase the capacity of the condenser to the maximum with the shortest and soundest possible connections. It is understood that you will keep an eye on all the other electrical conditions possible, and by continually changing the parts of one ignition for the parts of another ignition, you will be able to find if there is any known unit of any known system that affects the case. I am inclined to think there should be much to be learned from the magneto, where the contact maker points last so much better. You have pointed out that this may be due to the reversal of the current which we cannot get in the battery ignition. Could we run a test with rotating switch, reversing the current four times per minute, just to prove this point? The great point is that our battery ignition must be made not only equal, but superior to all others we can find. R.{Sir Henry Royce} | ||