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).
Comparative test report on rear axle gear ratios for 25 HP high compression cars.
| Identifier | ExFiles\Box 5a\5\ 05-page107 | |
| Date | 7th February 1930 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/AJL. (Held up). YS71 Hs{Lord Ernest Hives - Chair}/AJL.1/MJ.7.2.30. c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} X.5350 c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} X.5771 c. to By.{R.W. Bailey - Chief Engineer} PN.{Mr Northey} X.488 X.1725 REAR AXLE GEAR RATIO FOR 25 HP. HIGH COMPRESSION CARS. -------------------- We have carried out a series of comparative tests on two high compression (5.25:1) 25 HP. cars, 12-G4 and 17-G4., one fitted with 12/50 axle gears and the other with the present standard 11/50 gears. These two cars when fitted with 12/50 axle gears, and when loaded up to exactly the same weight, gave an identical performance as regards acceleration, hill climbing etc. The results obtained from side by side tests 11/50 versus 12/50 axle ratio are as follows:- SIDE BY SIDE ACCELERATION. From 10 m.p.h. 11/50 gets away easily. " 20 m.p.h. 11/50 " " " " 30 m.p.h. 11/50 gets away. " 40 m.p.h. 11/50 still just superior. " 50 m.p.h. Both cars the same. Above 50 m.p.h. the 12/50 ratio is superior, its superiority increasing with the increase of speed; the maximum speed increase appears to be 3 to 4 m.p.h. HILL CLIMBING TESTS. These were carried out on our two standard test hills, Ticknall and Pistera Hill. The conditions were nearly ideal, | ||