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).
Table of dynamo cutting-in speeds against car road speeds at various ratios.
| Identifier | ExFiles\Box 168a\4\ img023 | |
| Date | 23th June 1937 guessed | |
| Dynamos Cutting in Speeds Dyn. Speed Car Road Speed (R.P.M) (M.P.H.) PIII 655 Ratio 1.25 11 Ben. 910 Ratio 1:5 12.9 - 1.25 16.5 - 1:1 19.5 | ||