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).
Suggestions to improve a vacuum-assisted gearbox mechanism based on experimental tests.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan152 | |
| Date | 24th April 1931 | |
| HS.{Lord Ernest Hives - Chair} DA.{Bernard Day - Chassis Design} ) FROM R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} BY.{R.W. Bailey - Chief Engineer} ) (At Le CanadelHenry Royce's French residence.) C. to SQ. WOR.{Arthur Wormald - General Works Manager} ORIGINAL DOUBLE TOP. R2/M24.4.31. J235. I telegraphed a suggestion to meet the imperfections found in experimental tests. I have not the drawing of the vacuum mechanism but I understand that there is some loss of time between closing the throttle and withdrawing the jaws because the piston has to travel half its stroke at least before the toggle is thrown over. If therefore we let the piston drive the rocker shaft direct the jaws should move as soon as the piston. There would be a spring drive between them so that the piston could move if the jaws were still under load, and also the piston could travel on if the jaws were not synchronised for engagement, so there would be a spring drive each way, but no slack. The toggle spring would have very little to do but just hold the piston at the ends of its stroke. Probably it would not need such a high vacuum, but to work quickly the pipes and passages should be large. I have suggested that this sch. should work with jaws which are not backed off (even 2º) so they would not need Maybach's patent. I have also suggested that the over-running faces can have a few degrees of taper to make withdrawal easier in case of some over-running load. They would not be enough for the over-run to force out or to make too much clearance when about to enter. The corners that we did not wish to engage could be rounded and those we did wish could be nearly sharp. We have many other schemes if this is not entirely satisfactory. We expect that the epicyclic unit will need to be somewhat wider in the teeth, finer in pitch, and cut helically, before it is really silent enough. The gearbox can be just an ordinary 3 speed box, but any-way I should delete the Maybach jaws and fit ordinary ones. One feels it is the best sch. we know of both for handiness and reliability, and we know it can be made to work as in the Maybach and Mercedes, but they have had trouble the same as we are finding. We ought to find out what Voisin is doing. Our scheme must be made to work without touching the clutch except for the still lower gears. R.{Sir Henry Royce} | ||