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).
Secret memo discussing the causes of 'creep' in the reverse shaft of a 4-speed gearbox for 'India'.
| Identifier | ExFiles\Box 6\4\ 04-page053 | |
| Date | 1st February 1925 | |
| X. 5310 To AJS. Hs.{Lord Ernest Hives - Chair} } FROM R.{Sir Henry Royce} c. to CJ. BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} SECRET R1/MS.2.25. INDIA. 4-SPEED BOX. X.5310 I have received Hs.{Lord Ernest Hives - Chair} report that the reverse shaft with stepped dimensions caused the reverse to work out. This bears on one of the mysteries referred to in my last memo, but even this is difficult to explain unless it would now creep into gear when it would shew that the creep had been reversed, which may be quite a harmless creep. You will remember that in my recent memo, I ask for the bare to be purposely made with extra slack at either ends in turn, to see if this had any bearing on the creep. We will say that in this case the fork had nothing to do with the fault, but that it was the epicyclic creep I feared, and which indicates probably that the sliding should be inside the running bearing - i.e. slide on a stationary shaft which cannot revolve, but this may not be good otherwise and may be inconvenient. If the shaft as at present had keys it would prevent the shaft creeping round inside the hub, but still the wheels might creep along because there is no torque to bind the keys unless each wheel referred its torque to the shaft. There are still therefore some more experiments needed before we really know what did happen. More important still is to learn what caused the 1st. and 2nd. to work out, the 1st. in one direction, the 2nd. in another, then by only altering the fork, neither. To my mind it may be any of the following :- (1) Creep by combined action of the close fitting fork with creep on keys. (2) Action of the fork plus spring of the splined shaft. It will be realised that owing to the presence of the keys epicyclic rolling cannot take place, but the wheel can move about on the shaft if the torque is insufficient to cause enough friction to bind the shaft in the bore, but if they are moving on the keys there should be signs of these biting their way in, and especially would they shew if the hub were chambered as I would recommend in some of these experiments, though if the wheels are O.K. with continuous keys it may be as well to leave them so, because they would be free from steps even if they did bite in. Naturally we shall go on with the larger parallel reverse shaft with the solid race unless more information directs otherwise. I would like to point out that we must not let any discredit fall on Mr. Stent for this trouble. I helped to produce, and thoroughly approved the features that have given trouble. contd :- | ||