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).
Modifications to a Phantom III gearbox to achieve a higher gear ratio.
| Identifier | ExFiles\Box 94\2\ scan0085 | |
| Date | 25th November 1936 | |
| 328 HPS.{Horace Percy Smith - Experimental Factory Mgr} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}12/R.25.11.36. P.III GEARBOX. We want to try a P.III car with an indirect high gear, some 20% higher than the present 1 to 1 ratio. Will you, therefore, please put in hand gears of the Rolls-Royce type. C/M Driver ...... 32 teeth as on drawing Rm.{William Robotham - Chief Engineer}261. C/M Driven ...... 27 " otherwise to G.81570. 3rd Driver ...... G.81571 ) off 3rd Driven ...... G.84315 ) production. 2nd Driver ...... 25 teeth otherwise to G.82903 2nd Driven ...... 39 " " " G.84800 1st Driver ...... 14 " " " G.81575 1st Driven ...... 34 " " " G.82928 Rev:shaft small end 13 " " " G.81578. Apart from alterations to the gear ratios, a modified mounting of the C/M driver gear for assembly, and a slight modification to the casting in its vicinity are required. Possibly this can be done by machining an existing casting to allow for the large diameter of this gear. It can be assembled through the rectangular hole for passing its mating gear. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||