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).
The investigation and rectification of noisy magnetos for the New Phantom chassis.
| Identifier | ExFiles\Box 48\2\ Scan311 | |
| Date | 31th August 1925 | |
| X 8796 U. Wor. {Arthur Wormald - General Works Manager} O.Ma. C. Hs. {Lord Ernest Hives - Chair} G. {Mr Griffiths - Chief Accountant / Mr Gnapp} Hk. {Col. T. Harker - Sales} BY15/H. 31.8.25. NEW PHANTOMCodename for PHANTOM I CHASSIS MAGNETOS. --------------------------- With reference to the question of noisy magnetos, this matter has been under consideration betwixt ourselves and Messrs North & Sons. from a date before the New PhantomCodename for PHANTOM I chassis was issued on production, as the Experimental Dept. have drawn attention to the fact that the magneto caused more noise than any other feature on the new engine. Messrs Norths attempted to grapple with the question as follows:- 1. In the first place, at our request, they introduced a new Duralumin make and break lever which reduced the noise produced by the operation of the make and break gear. 2. As a result of further pressure in regard to quietening the gears themselves, when R's consent was arrived at it was agreed to introduce a different combination of material into the gears, namely, pinions made from Continental Bakelite, and wheels made from aluminium. This proved quite satisfactory. 3. As a result of the increased quietness arrived at by 1. & 2, it was discovered that what we at one time considered to be a noisy make and break mechanism must really have been due in a great many cases to what we now know as "sleeve flopping", this expression meaning that too much clearance was allowed in the end bearings of the sleeve which is rotated by hand to give the advance and retard, and at the position when the primary current was broken a magnetic snatch took place which caused the distinct knock in the end bearing. This matter was taken up at once with Messrs Norths, and it was pointed out to them that two features were considered necessary:- a {Mr Adams} /- A very much reduced clearance between the rotating sleeve and its housing. b/- Stiffening up the housing itself to prevent distortion and obtain accuracy of dimensions. Messrs Norths at once tackled these features and sent some magnetos along in which they had reduced at our suggestion the clearance in the bearings between the sleeve and its Con. | ||