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).
Solutions to pinion gear creeping, slack, and binding issues.
Identifier | ExFiles\Box 6\4\ 04-page054 | |
Date | 30th January 1925 | |
-2- Also I must withdraw my inference that Mr. Hives wedging caused collar friction, but that it was the result of creeping against forks which were purposely made immovable. We must thank Mr. Hives for putting in the small parallel shaft to shew it was not simply the deflection of the thin shaft but either an unfortunate deflection, or is still some mystery of different slacks in the bore of the double pinion. (Continued after re. to Mr. Hives' memo of 30.1.25.) This confirms my fears that we are not quite yet on sure ground. Naturally the 1st. and 2nd. are the most important. (1) Given a free and relieved fork which it would be as well to adopt, (but we want other precautions). (2) The largest pinions as advised but only such as would leave the gear ratios ideal. (3) The angle of action of 14 1/2° if considered equally as good as the 20° but not if it would spoil the strength or silence of the gears. (4) Provision that each pinion shall bind itself on its keys opposite its teeth. Because it should have no movement: even, if it does not creep it may bite in which would be bad - (don't forget similar gear on 40/50 is O.K. as remarked and explained. The two ways of getting the pinions to bind are (a) to destroy the torsional rigidity between them by each having its own keys and flanging or screwing the 2 gears together, or (b) leave the 2nd. to act as at present (if O.K.) and so cut the keys away - (narrow) that when in 1st. the keys under the 2nd. pinion cannot drive. SEE ORIGINAL FOR SKETCH. As for the reverse the keys on this may not be entirely satisfactory, as the gear although not creeping may work about, but at the same time it is so little used that such movement may not do any harm. How can we most practically and quickly cure the reverse? Supposing the parallel shaft is not a reliable cure, as I fear, that with keys there is no creep and the biting in does no harm, I think we should use a splined shaft of the largest dia. with 6 shallow keys. At the same time try if a stationary shaft can be used, and if with all sorts of faults cures the creep, the shaft would be hardened. Certainly not have any keys. If not hardened it might have a bush sliding on it hardened on the outside on which the pushed pinions should run. This would not creep, but may be inconvenient because there is not sufficient dia. and difficult to get sufficiently well lubricated. I must now finish as it is mail time. R.{Sir Henry Royce} | ||