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 ratio calculations and weight specifications for an Alfa Romeo car.
| Identifier | ExFiles\Box 124\5\ scan0023 | |
| Date | 1st January 1932 | |
| 84482. Jan:1932. ALFA ROMEO CAR. WEIGHT 20cwt. 2qrs. 21 lbs. Effective tyre circumference at 30lbs/sq.in. = 84.8" Road wheel revs/mile = 1760 x 36 / 84.8 = 747 Top Gear. 4 engine revs = 79.625" Engine revs/mile = 1760 X 36 X 4 / 79.625 = 3180 Top Gear Ratio. = 3180 / 747 = 4.27:1 3rd. Gear 6 engine revs = 90.75" Engine revs/mile = 1760 X 36 X 6 / 90.75 = 4190 3rd Speed Gear Ratio = 4190 / 747 = 5.62:1 2nd. Gear. 8 engine revs. = 84.5 Engine revs/mile = 1760 X 36 X 8 / 84.5 = 6.000 2nd. Speed Gear Ratio = 6000 / 747 = 8.03:1 1st. Gear. 10 engine turns = 65.5" Engine revs/mile = 1760 X 36 X 10 / 65.5 = 9670 1st. Speed Gear Ratio. = 9670 / 747 = 12.95:1 (4450 R.P.M. Top Gear = 84 m.p.h.) (Danger point) Speedometer 15% Fast. | ||