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).
Proposal for an experimental dynamo modification for Bentley & 40/50 models to improve cutting-in speed and high-speed sparking.
| Identifier | ExFiles\Box 168a\3\ img152 | |
| Date | 15th February 1935 | |
| 16142. E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Wst.8/MA.15.2.35. PROPOSED EXPERIMENTAL BENTLEY & 40/50 DYNAMO WITH IMPROVED CUTTING IN SPEED AND HIGH SPEED SPARKING. Following our discussion with By/HD.{Mr Hayward/Mr Huddy} this morning regarding the above we have given the matter further thought and we think the following specification for the above dynamo will give a cutting in speed of about 500 R.P.M. and give much improved sparking at high speeds. To achieve this we propose to use the smaller diameter armature machine, i.e. 3.100" diameter and rewind it with 4 turns of 17 S.W.G. wire instead of 3 turns per coil of 16 S.W.G. as at present. In order to keep the machine cool we should want the fan and we should require the poles to be chamfered in order to still further improve the high speed performance. The use of a larger field, i.e. 19 S.W.G. wire which we are at present using on this smaller diameter machine, will give the additional advantage of increased resistance for better operation of the voltage regulator. Our proposed specification therefore is as follows :- (1) Smaller diameter armature 3.100" diameter wound with 4 turns per coil of 17 S.W.G. D.C.C. Superfine wire, 2 coils per slot, 24 slots. (2) The use of the fan for extra cooling. (3) The large field wound with 19 S.W.G. D.C.C. Superfine. (4) Chamfered poles with .015" main air gap. The R.R.SCieme 812 dynamo having the above modifications should, we anticipate, give a much better performance than any dynamo we have yet tested of this size, and we think an experimental machine should be put in hand as quickly as possible for test. Hs{Lord Ernest Hives - Chair}/Wst. | ||