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).
Report comparing Lucas and Smith dynamo cut-outs, including details of a dismantled Lucas unit.
| Identifier | WestWitteringFiles\D\March1920\ Scan52 | |
| Date | 16th March 1920 | |
| Contd. -8- Ck{Mr Clark}2/T16.3.20. with the dynamo balancing speed, which is of course accentuated in the case of Lucas C. On the other hand, in the case of the Smith combinations, this delay is nowhere near so marked as in the Lucas case, showing that the Smith cut-outs with their greater bulk are less susceptible in this respect - in fact, of course, they do not get so hot. It will also be noticed that a Smith cut-out, otherthings being the same, takes rather less reverse current than a Lucas to make it fall out. We have your R5/G12.3.20 and I will bring down a Smith cut-out when I come tomorrow. We have taken up the matter of the want of uniformity in the Lucas cut-outs with Messrs. Lucas but so far have not received their reply. At the same time we are taking up the matter in the works that these shall be tested with a dynamo for uniformity of operation. We dismantled a Lucas cuteout and found the series winding to consist of 55 turns of No.15 S.W.G..072" enamelled copper wire in three layers. The shunt winding consisted of 1680 turns of No.35 S.W.G..008" enamelled copper wire in nine layers. Length of shunt winding 200 ft. Length of series winding 11 ft. 3 ins. It is difficult to say exactly when a cut-out should be set to operate to give the best alround result, as it depends so much on temperature conditions. If the Contd. R R 'B' 332 V (100 L) (& E) 842 6 9-19 C 3400 | ||