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).
Cause and potential cure for a 'creeping out of gear' issue in a 4-speed gearbox.
| Identifier | WestWitteringFiles\M\Jan1925-March1925\ Scan23 | |
| Date | 3rd February 1925 | |
| TO HS.{Lord Ernest Hives - Chair} } FROM R.{Sir Henry Royce} ORIGINAL SECRET Copy to [overtyped text] RG.{Mr Rowledge}DA{Bernard Day - Chassis Design}-BY- U. S. A.{Mr Adams} 4 SPEED BOX. K5310 Since writing my memo. of yesterday Mr.Elliott's letter has come to hand. I am very pleased you find the creeping out of gear could be cured by altering the slider fork, but your conclusions do not agree with mine, and it is important. You say, Gear crept up to fork, which by springing tilted the wheel and made it creep more. I say, original creeping was due to the close fitting slightly out of square fork. If you are right then the wheels should still creep, you having done nothing to alter this primary creep. The force would be very great under load, and the plungers could not prevent the gears working out. This is what I feared, and would be very difficult to cure. From the evidence that the gears now stay in I say that there was no tendency for the gears to creep at all except that caused by the tilting action of the out of square smug fitting fork. There are still slight mysteries and I am not sure we are quite clear of trouble unless the fork was entirely the fault. To support our confidence we have similar pinions on the 1st. and 2nd. speeds of the 40/50, which are OK., but these may have the slight difference of relatively bigger pinions to their shaft and relatively more bind on the keys and 14° teeth, hence my suggestion of using similar gears. If the 1st. only still works out we might try using keys only under this gear and a plain bore under 2nd. speed pinion so as to get the bind under the smaller pinion. Owing to the flexibility of the 2nd. motion shaft being considerably more than the double pinion hub, one can see that the teeth can only be really tight at the forward end under the 2nd. Speed pinion, hence my suggestions to see if these two pinions could be torsionally free so that each could bind on their own keys, (assuming some trouble still exists.) Regarding the reverse, here we have no keys, and this might have been a new experience resulting in a slow epicyclic creep, but here again either we have not cured it or the fork was the cause. An idea has occurred to me (1) | ||