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).
Requirements and issues with a dynamo for a 4.5' car engine, comparing Bijur and Lucas systems.
| Identifier | ExFiles\Box 61\2\ scan0088 | |
| Date | 22th August 1917 guessed | |
| To Ry. from R.{Sir Henry Royce} c. to CJ. " " EH. X.3374. R6/G111118. X. 3129 X. 3231 RE DYNAMO FOR 4 1/2" CAR ENGINE. X.3014. X.294.3374. (294 is struck through) As far as I can remember, the best we have installed for a convenient speed, and probably a convenient drive for cutting in at low speed and for not overcharging the battery, is the Bijur system, similar to the one you have sent for the Drawing Office lights at West WitteringHenry Royce's home town. (1) We cannot do with a heavy dynamo. (2) We do not think it is necessary to charge under 15 miles an hour, therefore the "cut in" should act at about 750 on the dynamo and the belt ratio should not be more than 1 1/2 : 1, otherwise the pulley is too small. (3) We think with a starter motor it is necessary to have a 12 volt plant. We should be pleased to know whether we can supply a satisfactory 12 volt non-trembler ignition. With a starting motor it will not be necessary to have a trembler ignition system. The battery/coil should have sufficient resistance to run with a fair economy of current at slow speed, but capable of firing the engine up to 2000 revs., i.e. high percentage of non-inductive resistance. Kindly take this matter up with Mr. Clark. So far Lucas seem to have failed, their original dynamo on 7CA could not be driven because the pulleys were too small. There was also a particular fuse on the switch board which was blown on two occasions. When this happened the dynamo still gave current at a much increased speed. This caused wrong impression, i.e. it was thought belt was slipping P.T.O | ||