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 Messrs. North & Sons detailing a proposed practical test for magneto magnets, specifically for the R.O.1. Magnetos.
| Identifier | ExFiles\Box 4\5\ 05-page254 | |
| Date | 14th February 1924 | |
| X.430. EFC1/LG. c. to WD.{Mr Wood/Mr Whitehead} c. to BY.{R.W. Bailey - Chief Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} 14th. Feb. 1924. Messrs. North & Sons, Whippendell Rd., Watford. Dear Sirs, For the attention of Mr. North. TESTING OF MAGNETO MAGNETS. During the recent visit of your Mr. North to our premises, he enquired of the under-signed for a suggestion for a suitable practical test of the efficacy of magnets, more particularly, we think, for the R.O.1. Magnetos. We now have pleasure in giving our ideas of such a test, which is as follows :- That a dummy magneto without magnets or contact breaker be permanently arranged with suitable brushes so that a sound electrical connection can be made from the low tension armature winding to an external circuit, the external circuit to consist at will of (1) An alternating current voltmeter of high resistance - or (2) An alternating current ammeter of very low resistance. The magnetic circuit of the magneto to be so arranged that magnets, a test of which is required, may be readily slipped into position and removed after the test by hand. It would then be possible to take characteristic curves of - Open circuit volt-speed on the one hand - and Short circuit ampere-speed on the other hand, and a copy of such curves for three magnetos, one of which is your R.O.1. is attached for your interest. It is not, however, suggested that such curves should be taken in the practical testing of magnets but that the dummy should be continually driven at one convenient speed which might be - say - 2000 or 2400 R.P.M. and that for every set of magnets placed on the dummy, a reading of open circuit voltage and short circuit amperes should be taken and noted. It is well-known that the important properties of a magnet from the point of view of supplying a permanent field contd:- | ||