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).
Increasing the armature winding gauge of a 36 Slot Dynamo for the Standard Wraith.
| Identifier | ExFiles\Box 168a\3\ img068 | |
| Date | 23th June 1939 | |
| 6142 To By.{R.W. Bailey - Chief Engineer} o.{Mr Oldham} to Da.{Bernard Day - Chassis Design} o.{Mr Oldham} to By/RD. RM{William Robotham - Chief Engineer}/NC.12/JH.23.6.39. Re 36 Slot Dynamo (Std. Wraith). As an experiment the effect of increasing the gauge of the armature winding from 19 s.w.g. to 18 s.w.g. has been tried out. The modified machine was found to be appreciably cooler, and at the same time gave, for a given speed, an increased output. The attached performance curves together with the "Heat Test" figures, show the advantage gained. Unfortunately, winding with the thicker gauge in the existing slots is not a production job, and to make it so, would require slots approx. .015 inches deeper. We realise that to deepen the slot in the existing armature may excessively weaken the root of the tooth, also that the resultant greater flux density, accompanied by increased eddy currents, may counteract the advantage gained, however, if it were possible to slightly increase the diameter of the armature these objections would be eliminated. In view of the fact that under certain conditions the standard machine is working near to its limit, we recommend that the possibility of slightly increasing the diameter of the armature and thus permitting the use of a gauge thicker wire for its coils, be investigated. Heating Test. Speed 1440 r.p.m. Voltage 13.5 Volts. Current 20 amperes. The machines completed a 1 1/2 hours run under the above conditions, carcase temperature readings taken at the end of the test were as follows Cont'd.{John DeLooze - Company Secretary} | ||