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).
Table of gear ratios and speeds for a 40/50 HP chassis with a four-speed gearbox for various wheel sizes.
| Identifier | ExFiles\Box 75\1\ scan0098 | |
| Date | 6th August 1919 | |
| X 3426 R.R. 235 A (100 T) (S.F. 846 6-8-19) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2460. RATIOS & SPEEDS OF 40/50 HP CHASSIS WITH FOUR SPEED GEAR BOX. Axle Gear. Fourth Direct. Third. Second. First. Reverse. 16 x 52. 3.25 4.83 7.22 11.07 11.07. 17 x 52. 3.06 4.54 6.79 10.42 10.42 18 x 52. 2.89 4.29 6.42 9.84 9.84. SPEEDS IN M.P.H. AT 1000 REVS. OF ENG: 895 mm WHEELS. Axle Gear. Fourth Direct. Third. Second. First. Reverse. 16 x 52 29.85 20.08 13.43 8.76 8.76 17 x 52 31.71 21.35 14.26 9.31 9.31 18 x 52 33.56 22.58 15.09 9.86 9.86 SPEEDS IN M.P.H. AT 1000 REVS. OF ENG: 935 mm WHEELS. Axle Gear. Fourth Direct. Third. Second. First. Reverse. 16 x 52 31.16 20.97 14.03 9.15 9.15. 17 x 52 33.10 22.22 14.89 9.72 9.72 18 x 52 35.04 23.53 15.77 10.29 10.29 SPEEDS IN M.P.H. AT 1000 REVS. OF ENG. 895 mm X 150 WHEELS. Axle Gear. Fourth Direct. Third. Second. First. Reverse. 16 x 52 30.83 20.74 13.87 9.05 9.05 17 x 52 32.75 22.05 14.73 9.62 9.62 18 x 52 34.69 23.33 15.58 10.20 10.20. | ||