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, engine revolutions, and dynamo revolutions at various speeds for the 20 HP chassis.
| Identifier | ExFiles\Box 75\1\ scan0201 | |
| Date | 13th June 1919 | |
| R.R. 235A (500 T) (S.D. 408. 28-4-17.) Bm. 2/156/13. 13.6.19. X 350T - 4247 X. 3481 20 HP. CHASSIS GEAR RATIOS Miles per hour at 1000 R.P.M. Reverse. 1st. 9.40 2nd. 15.78 3rd. 24.0 M.P.H. Engine revs. Dynamo revs. 1st. 2nd. 3rd. on top gear. 10 1063 635 417 667 12 1275 763 500 800 15 1593 953 625 1000 20 2126 1267 833 1333 25 2657 1586 1042 1667 30 ---- 1901 1250 2000 40 ---- 2538 1667 2667 50 ---- ---- 2083 3333 | ||