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).
Proposal for an electrical speedometer that also registers miles travelled for the chassis.
| Identifier | ExFiles\Box 33\5\ Scan015 | |
| Date | 8th April 1919 | |
| B.B. 285a (500 F) (B.D. 408. 26-4-17.) Bm. 2/156/13. COPY. To R.{Sir Henry Royce} from EH. c. to CJ. EH3/LGS.4.19. 8th. April 1919. SUGGESTION FOR SPEEDOMETER FOR CHASSIS. You will remember sometime ago I suggested that we might use the electrical speed indicator which you designed for registering engine revolutions, as an instrument for registering M.P.H. on the car. You pointed out at that time that it would not be satisfactory because it would not register miles. I suggest that it would not be at all a difficult proposition to make the instrument so that it would register miles travelled. My idea is to use a simple form of contact breaker on the machine itself, as the lowest reading required is a tenth of a mile, this contact breaker need not be run more than one-fifth or one-tenth the engine revolutions so that it could be made quite simple and reliable. The current supplied to the contact breaker would be from the main 12-volt circuit and would be entirely separate from the little speedometer. There should not be much difficulty in getting an ordinary mileage recorder to be operated on the dash board by means of a little magnet, as a matter of fact, I have made up a "Veedee" mileage recorder operated by this means. When one appreciates the troubles with the ordinary speedometer we wonder that this scheme has not been carried out before. We have made inquiries and cannot find that any such instrument is made. The advantages of it are fairly obvious:- Contd. | ||