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).
On modifying the 20/25 Dynamo's pole tips to improve high-speed commutation and reduce sparking.
| Identifier | ExFiles\Box 168a\3\ img157 | |
| Date | 25th February 1935 | |
| E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wat. c. to Hy.{Tom Haldenby - Plant Engineer} (603) Hs{Lord Ernest Hives - Chair}/Wat.G/MA.25.2.35. 20/25 DYNAMO. We have been trying out on the bench a set of poles with chamfered tips to improve high speed commutation. In order to regain cutting in speed we also increased the polar arc, in fact the cutting in speed with these new poles is slightly better than standard. The improvement in sparking was so marked that we feel this feature ought to be introduced on production as soon as possible as a road testwill in this case not be of much value. The result of the dynamo on 21.G.IV. during the last test indicated clearly the necessity for this modification. We attaching herewith our experimental sketch shewing the milled chamfer on the poles with a .015" main air gap. Hs{Lord Ernest Hives - Chair}/Wat. | ||