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 cause and mitigation of 'singing' in a Lucas E.575 dynamo.
| Identifier | ExFiles\Box 36\4\ scan 149 | |
| Date | 21th October 1920 | |
| To R.{Sir Henry Royce} from EFC. c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to En. c. to Da.{Bernard Day - Chassis Design} c. to PN.{Mr Northey} c. to Hy.{Tom Haldenby - Plant Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} X 3014b EFC5/T21.10.20. 6 2 X.3014b - LUCAS E.575 DYNAMO SINGING. X.294 In the case of the E.575 dynamos, the singing does not appear to be due to armature vibration as in the case of the Bijur dynamo which you have. As noticed on the aero dynamo we can reduce the singing considerably on the E.575 machine by bearing upon the carcase hard with a large mass of non-magnetic material, although the improvement does not seem to be as much in this case. On the E.575 dynamo, no singing occurs when this is operated as a simple shunt wound machine, by removing the control brush from the commutator, this being the case either with the dynamo open circuited or charging a battery. The act of retarding the control brush against the direction of rotation towards the negative brush also has the effect of practically removing the singing if taken far enough, but the output of the machine is reduced thereby to a figure which is rather less than we like to allow. On a machine with the control brush set in its normal position, the singing appears to be at its maximum at about 800 R.P.M. this being the speed at which, in the hot condition only, a small current, 3 to 4 amperes, is delivered to the battery. The maximum singing does not occur quite exactly at the Contd. | ||