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).
Performance and heating comparison between Smith type 2D and C.575 Lucas dynamos.
| Identifier | WestWitteringFiles\E\June1920\ Scan11 | |
| Date | 18th June 1920 | |
| R.R. 199 (250T) (SD676 19-7-17) MP180865 Contd. -3- EFC7/T18.6.20. the control brush nearly complies with our specified performance, but, as previously explained, the heating of the dynamo is considered to be excessive with this setting. Sheet H is a similar set of curves for one of the Smith type 2D dynamos in which the whole system of four brushes is advanced and retarded. The position labelled "Normal" gives only reasonable heating and is better in performance than either the advanced or retarded position, which last itself exceeds our specified performance. The positive and negative control currents do not come out the same, as would be anticipated. One must assume that, owing to slight differences in air gap and due to relatively low resistance of the control circuit, the amount of control on the two sides of the dynamo is not the same. Tables of heating test results are attached, a study of which will show that the differences in heating for the normal outputs of the various machines are not great, but that if anything, the C.575 Lucas and the Smith 2D heating are less for their normal output. For a given output curve, however, the heating of the Smith type dynamos is undoubtedly least. The cutting in points of the C.575 machine will be seen by sheet A to be only slightly better than the Smith 2D, so that taking everything into consideration, it is undoubtedly the case that the general performance of the Smith dynamos in general, and the Smith 2D dynamo in particular, | ||