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, detailing their effect on fuel economy and engine work with accompanying graphs.
| Identifier | ExFiles\Box 147\5\ scan0079 | |
| Date | 17th June 1925 | |
| H.H. 423A (50) (10.11) 21. 17-6-25) J.H.L. 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. [GRAPH of Petrol Consumption vs{J. Vickers} Road Speed] Y-Axis: PETROL CONSUMPTION M.P.G. X-Axis: ROAD SPEED, M.P.H. Graph Curves Labels: Gear Ratio 3-4 to 1, Gear Ratio 4-2 to 1, Gear Ratio 5 to 1 Text on Graph: EFFECT OF GEAR RATIO ON CAR ECONOMY Text next to Graph: 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 wasted rotating the engine. GRAPH 111. [GRAPH of I.H.P. Mins of Work Done Per Mile vs{J. Vickers} Road Speed] Y-Axis: I.H.P. MINS OF WORK DONE PER MILE X-Axis: Road Speed M.P.H. Text on Graph: OPTIMUM SPEED 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 :- | ||