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).
Gear ratios, showing their effect on petrol consumption and indicated horsepower.
| Identifier | ExFiles\Box 147\5\ scan0091 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31. 12-6-25) J.H.D. EXPERIMENTAL REPORT. -7- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG21125 GEAR RATIO. It is for this reason that a high gear GRAPH 11. PETROL CONSUMPTION M.P.G. ROAD SPEED. M.P.H. GEAR RATIO 3.5 TO 1 GEAR RATIO 4.42 TO 1 GEAR RATIO 6 TO 1 EFFECT OF GEAR RATIO ON CAR ECONOMY. Typical curves taken from American Journals. ratio reduces the petrol consumption; though the actual work required to drive the car is the same. With a high gear less work is watsed rotating the engine. GRAPH 111. I.H.P. MINS or WORK DONE PER MILE OPTIMUM SPEED ROAD SPEED. M.P.H. ROAD SPEED. We have actually plotted the indicated horse power expended driving a Phantom at various road speeds. It will be seen from this that its most economical speed is likely to be contd ;- | ||