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).
Continuation of a letter from Leyland Motors discussing proposed gearbox and axle ratios.
| Identifier | ExFiles\Box 140\3\ scan0152 | |
| Date | 25th March 1938 guessed | |
| Leyland Continuation of a letter From LEYLAND MOTORS LIMITED. -2- On the assumption that you could make a pair of gears to replace the present third speed which would have an overdrive ratio of .625, then we would have a box with ratios:- Overdrive - .625 Direct - 1 to 1. 3 - 2 - 1.96 1st - 2.99 with an axle ratio of 8.66. The overall gear ratio in each gear would then be :- Overdrive - 5.4 Direct - 8.66 3 - 2 - 17.00 1st - 26.00 Comparing this with the overall ratios in our GB.9 with 5.5, we have :- Top or direct - 5.5 3rd - 9.7 1.76 2nd - 16.4 2.9 1st - 26.5 4.8 You will agree that these two combinations are practically identical and give the stepping we desire for public service vehicle work. This re-arrangement of third speed gear would necessitate a slightly awkward change in the gate, but this we do not think would matter at the present stage and for the purpose of obtaining immediate service test. It would also establish a principle in some way that a gearbox of small centre distance could be made to operate just as satisfactorily as a gearbox with large centre distance, incorporating a low bottom gear ratio. As you state in your letter, the clutch centre we are using with this gearbox is going to be somewhat heavy on the cones, and we feel that although up to date we have made 2,000 applications per cone without any material wear appearing, yet this is only equivalent to two service days on test service. We are very desirous of having this box fitted | ||