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).
Letter to A. Taub of Vauxhall Motors discussing factors for achieving gearbox silence.
| Identifier | ExFiles\Box 127\4\ scan0171 | |
| Date | 4th December 1939 | |
| 1097 Rm.{William Robotham - Chief Engineer}13/MH.{M. Huckerby} 4th. December, 1939. A.{Mr Adams} Taub, Esq., Vauxhall Motors Ltd., Luton, BEDS. Dear Taub, Replying to your letter of the 2nd. December, we have two gearboxes, one is a normal box, direct top, the other is what we call our overdrive box with a direct 3rd. and geared top. The three factors which we find most important in getting gearbox silence are - (1) Accurate truth profile obtained by grinding. (2) Fine surface finish obtained by lapping. (3) Maximum overlap obtained by either (a) Fine pitch (b) High helix angle (c) Wide gear. Actually, it is not very practical to use helix angles above 35° due to the difficulty of getting the thrust. As you know, the way the gearbox is mounted has a marked effect on silence. Are you still sold on wide plug gaps ? At the present stage of developments what are they worth in miles-per-gallon? Yours sincerely, | ||