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 technical merits of using vacuum versus oil for a pre-selection gearbox system.
| Identifier | ExFiles\Box 94\1\ scan0152 | |
| Date | 5th December 1934 guessed | |
| (3) The other important point which requires a decision before we can proceed is whether we are to employ vacuum or oil. As we have remarked in our outline of the possibilities if we use vacuum we are tied to the Wilson selection which requires springs to permit of preselection and without doubt will result in a heavier control than we can secure with oil as with the latter we propose to operate small piston valves direct. We regard the latter as more reliable as there is nothing dependent for its movement on a light spring. The difficulty with oil is with what appears to be the necessity of driving the pump from the engine in order to move into neutral when a gear has been left in mesh and the oil pressure has leaked away. We should be glad to have your views as until these two major points are settled we cannot make much progress with working drawings. HDY.{William Hardy} | ||