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).
The testing and development of the B.V. Gearbox, focusing on overcoming noise and gear issues.
| Identifier | ExFiles\Box 99\4\ scan0286 | |
| Date | 23th May 1939 | |
| 428 400 D To Sg.{Arthur F. Sidgreaves - MD} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} c. By.{R.W. Bailey - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. Da{Bernard Day - Chassis Design}/Hdy.{William Hardy} B.V. GEARBOX. We have now tested in 9.B.V. the first of the up-to-date overdrive gearboxes having helical first and reverse gears. When in June last year the first rationalised gearbox was made there were four major problems to overcome. These were jumping out of gear, synchromesh troubles, noisy overdrive and an intolerable noise from the first speed straight spur gear. A dynamometer run showed the box to be adequately strong, as has the 50,000 miles run in 8.B.V. By incorporating a helical first speed (necessitating also a helical reverse) this gear is now sufficiently quiet although the pinion is unground. On the latest box in 9.B.V. which has been tried by By.{R.W. Bailey - Chief Engineer} and Rm.{William Robotham - Chief Engineer} we are satisfied with the silence and synchromesh functioning. We took the car to Bwlch-y-Groes hill in North Wales and did ten climbs and descents to check that no gear would come out of mesh and that the lubrication functioned on a severe gradient. This included reversing both up and down the hill. We therefore consider the universal gearbox suitable for all cars in the rationalised range with an overdrive for B.V. and standard ratios for the other cars. To achieve sufficient silence on first speed we have had to make reverse more complicated by the addition of two helical gears, one integral with the layshaft and one at the front end of the reverse shaft. The first speed wheel now slides on a helically splined sleeve as in Wraith. We probably pay 30/- for this refinement. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||