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).
Design considerations and comparisons for epicyclic gearboxes, brakes, and control systems.
| Identifier | ExFiles\Box 178\3\ img082 | |
| Date | 26th February 1932 guessed | |
| (2) (1) That the brakes in an epicyclic gearbox shall be arranged to be self servoing in one direction so that the braking is ample to prevent the engine running away at full throttle, but in the other direction only powerful enough to keep the engine running - i.e. equal to the over-running torque. I shall be pleased to know what this ratio is. I should estimate it at about 4 to 1. i.e. maximum engine torque. max: over-running torque. This should be given with a cold and a hot engine. (2) To make a brake for such a great difference it would be necessary, if in a well lubricated box, to have more than one complete turn, so that for simplicity one would try to get the two most used brakes - viz: 3rd. & 2nd. - in a special compartment where there need not be any oil. I did this in one design some years ago and believe it is possible in the train of epicyclic gears I have now devised. (3) I was on the point of proceeding with hydraulic control on the lines of the double top, 2 cylinders working 3 brakes and a clutch, but it has occurred to me that a good alternative would be to make the Lanchester/Wilson change by means of a vacuum cylinder which would work when the accelerator pedal was raised to close the throttle. This would avoid the long and heavy pedal work of this scheme of control, which is now long over the patentable time as it was used by Lanchester 20 years ago. (4) Wilson has schemed his own train of gears somewhat differently to Lanchester's original. They have some good and some bad points, and he may have a fairly strong patent on the self adjusting of the brakes, and for the very peculiar form he has given his brakes to avoid bearing pressure. (5) Regarding the fluid flywheel, this I know very little about, but one feels that it would lose considerable energy at slow engine revs. I shall be interested to learn more about it. I want you to try everything possible, and if there is anything we cannot equal we can ask for a licence to fit it to our car if we decide it is the best, but there is no finality, and we may hope to get on with the next move. Mr. Wilson has been on this work for 25 yrs., much the same time as F.W. Lanchester, whose scheme was the parent of the Wilson gear and its operation. R.{Sir Henry Royce} | ||