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).
Fit of gears on keys for a 40/50 gearbox and proposed solutions.
| Identifier | ExFiles\Box 75\1\ scan0171 | |
| Date | 24th January 1923 | |
| REC'd.{John DeLooze - Company Secretary} JAN 24 1923 X3426 BY18-P23.1.23. 40/50 GEARBOX. Re EP{G. Eric Platford - Chief Quality Engineer}/Mx{John H Maddocks - Chief Proving Officer}2/H8123. attached. X3426 It is not practicable to make the gears a tighter fit on these keys than they are at present as the gears have to be assembled on second motion and dismantled from same when the parts are in the gearbox itself, and therefore when gears and shafts are difficult of access so far as holding the gears and forcing shaft out of gear hubs is concerned. The question of increasing the "draw" allowance on the taper diameter represented by the internal diameter of the keys is again a matter which owing to certain peculiarities due to design we cannot help you upon, so far as obtaining a frictional grip of the shaft is concerned, and therefore the only factors remaining are;- (a) Works must keep strictly within the keyway and key limits on drawings, as well as making sure that the dividing plate used is accurate for spacing, if error exists here we must get a new dividing plate made preferably by the Gear Grinding Company who understand the class of accurate work we require. (b) The inside of each gear hub should be liberally treated with a heavy mineral oil before assembling the gears on their respective shafts (2nd and 3rd motion). (c) The nuts cramping up the string of gears must be thoroughly well tightened up to get as much end pressure on the gears as possible. The foregoing covers all the possibilities of improving our product which are at the moment practicable, as it is necessary to ensure the gears being located on their taper bores in order to keep them concentric, and to attempt to make press key fits would be to make it almost impossible to dismount the gears. The limits on the drawings are as fine as we can work to, being from "size to size" to .002" slack, which means minus 1 on the key and plus 1 on the keyway, as these limits have to cover spacing errors as well as tool wear. If SMT, will let EP{G. Eric Platford - Chief Quality Engineer}, know when boxes assembled strictly as above go on test and give him clearances between keys and keyway, EP{G. Eric Platford - Chief Quality Engineer}, will then be able to state if above proposals assist him actually or not. WWLP | ||