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 design and control of an epicyclic gearbox, including servo-assisted shifting.
| Identifier | ExFiles\Box 15\5\ Scan124 | |
| Date | 29th April 1930 guessed | |
| -3- (6) For simplicity, and for a trial, we may obtain our neutral by letting the reverse run idle. (7) The side lever should have forward, neutral, and reverse, so that one gets a neutral in each gear by this lever, and the car will be driven forwards or backwards by whatever gear train is in, but the reverse will always be at about 2/5 of the forward speed. (8) The proportion of all the 5 epicyclic trains, including reverse, I should prefer to be - annulus 100, sun 40, planets 30 and 3 planets. The width will vary with the maximum load, and the 1st, and reverse can be loaded nearly as high as an ordinary box. The pitch could be coarse on the wide 1st. train, and finest on the 3rd speed train, which has to run backwards at rather high speed while 1st is driving the car with high engine revs. Experience would soon say if this would be noisy. It is one of the doubtful points, but we might put in freewheel connection so that the car would freewheel on 3rd, which might be preferable if we had 2nd. and 4th. no freewheel. Whatever type of gear we have, the 3rd. speed brake drum would be driven round at the same speed for the same ratio, with .70 it would be slower than with .74 (9) The best control I have so far found would be to have a shaft parallel with transmission having the necessary cams for each gear. This would be rotated by a servo to follow the control lever on the steering column. A good point of the single camshaft control of the gears is that 2 gears cannot be engaged at one time by the failure of the servo, such as might be the case with independent toggling servo controls. (10) Vacuum servo is not very good as it demands that the throttle shall be closed, and has other defects. Engine oil pressure is nearly right (gearbox driven pump will not do), and another alternative I have thought of is electro-motor say worm driven to control shaft. This should be protected (patented) if new, as it promises to be useful. In this case the steering column has a quick make and break - the switch always on one of the 4 contacts, the motor runs round and breaks the circuit, end pull of the series motor (size of a klaxon) could control brake for quick stop, armature of motor could be solid iron so as to revolve slowly. | ||