Letter from a supplier discussing the function of a safety gap in a magneto and issues caused by excessive resistance.
| Identifier | ExFiles\Box 65\3\ scan0414 | |
| Date | 9th July 1930 | |
| X7791 .SPEEDOMETERS & MAGNETOS. THE BRITISH MADE Watford NORTH & SONS, LTD. WHIPPENDELL ROAD, WATFORD. TELEPHONES: LONDON 1346 GERRARD WORKS: 622 & 623 WATFORD. CONTRACTORS TO THE ADMIRALTY, WAR OFFICE, AIR MINISTRY, CROWN AGENTS FOR THE COLONIES, INDIA(Production 20 HP. with 4-speed box and Front Wheel Brakes) OFFICE. TELEGRAMS: AEROMAGS WESTCENT LONDON AEROMAGS WATFORD. Ref. AMA/CT.1/DD Your ref. PN {Mr Northey} 4/WT.30.6.30. 9th July, 1930. SALES DEPARTMENT. Messrs.Rolls-Royce Ltd., Claremont Road, Cricklewood, London, N.W.2. Dear Sirs, For the attention of Mr. Percy Northey. re Chassis No. 1 WJ. With reference to your letter of the 1st inst., reference A17/H.W.30. in connection with the above, and further to our letter reference CT7/DD of the 19th ult., We would state that we do imply an excessive resistance in the high tension circuit external to the Magneto. The object of the safety gap in a Magneto is to take care of an occasional overload, such as a plug fault or a detached high tension cable; a consistently overloaded Magneto will cause a leak across the safety gap in the form of brush discharge; the brush discharge in conjunction with moisture present in the atmosphere, form nitric acid, & a Magneto, under these conditions, must eventually breakdown. | ||
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).