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).
Progress report on gearbox development, detailing issues with gears, synchromesh, and oil leaks.
| Identifier | ExFiles\Box 112\2\ scan0093 | |
| Date | 23th August 1938 | |
| -3- Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}/H.23.8.38. We are trying a pinion with a longer hub and more teeth. If this does not work we shall use the Vauxhall lock or Reverse only. To prevent 2nd and overdrive coming out we tried several spline arrangements including FD.{Frank Dodd - Bodies}218 and GS.3907 without success. Both boxes are now satisfactory with .020 removed diametrically from the addendum of the engaging teeth, and a further .025 off the relieved side; together with selector springs of 9 lbs which are the same as H.II. It was found that when stationary on a gradient of 1 in 6 either way oil leaked past the end bearings and poured out at 1 in 4. This has been put right by an oil seal at the front and a plain parallel close clearance fit at the rear. The seal at the front is to prevent any oil ever reaching the clutch. A small leak at the rear on the rare occasions that a car is left on a gradient is not important. The synchromesh operation is good on the 12° cone box except that occasionally the engagement of 2nd requires considerable effort. We suspected drag from the other cones and removed them for experiment, the 2nd speed change becomes excellent. We are trying smaller wider top and overdrive cones to cure this trouble. We have found so far that the synchromesh balls and springs are unnecessary on any gear, the cam alone being sufficient. No gear has yet been sufficiently silent, but none has been lapped. The gears for the next box will have been passed by the Works, and we shall know whether the amount of noise is acceptable. This memo is a report on what has been done. Hdy.{William Hardy} has been "au fait" with all troubles as they arose and designs have been made to overcome them. The boxes that will go to France on B.E.V. and be made for future experimental cars are specified in Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}7/M.21.7.38. and Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}7/M.9.8.38. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||