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).
Unsatisfactory output of the Lucas Dynamo for the 40/50 chassis, comparing cutting-in speeds with different axle ratios.
| Identifier | ExFiles\Box 180\M1\8\ img003 | |
| Date | 7th July 1921 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to D.{John DeLooze - Company Secretary} c. to BY.{R.W. Bailey - Chief Engineer} ORIGINAL <4352 X4211 <3014b DYNAMO FOR 40/50 CHASSIS. From experience we cannot agree that the output of the present Lucas Dynamo will be satisfactory when a reliable cut-out is fitted. One does not, of course, expect to receive complaints as regards the dynamo not supplying suffic-ient current during the summer-time but we know from past experience that ever since we have fitted generators we have received complaints from customers of the difficulty of keeping the battery charged in Winter-time in town. We have had an insistent demand from the Sales Dept. for years for a dynamo which cuts in at a lower speed. On a car which is run from 0 to 20 M.P.H. with the 1" longer Lucas Dynamo we get 90% more current into the battery than we do with the present dynamo. It is necessary to take into account that we are likely to be using lower axle ratios in future. The following are the cutting-in speeds with the standard and 1" longer Lucas Dynamo with different axle ratios. Type of dynamo. Axle ratio. Cutting-in speed. Standard E.575 16 X 52 12.8 15 X 52 11.9 14 X 52 11.1 1" longer 16 X 52 10.7 armature. 15 X 52 10.0 14 X 52 9.3 contd:- | ||