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).
Design options and issues for a 4-speed gearbox, with diagrams of bearing arrangements.
| Identifier | WestWitteringFiles\M\Jan1925-March1925\ Scan29 | |
| Date | 2nd February 1925 | |
| TO A.J.S. & H.S. } FROM R.{Sir Henry Royce} SECRET. R1/M13. 2. 25. Copy to - C.J. B.J. H.T. WOR.{Arthur Wormald - General Works Manager} INDIA. 4 SPEED BOX. X 5310 I understand from H.S. memo. of 4/2/25. that there is now no trouble with the reverse working out, but I am not sure if this is so, and it may be unreliable, or be creeping about on the shaft, but if it can be relied upon to stop in it may be quite satisfactory for 20 years use as it is so seldom used for even a minute at a time at the full load and engine speed. So that even though we have to spline the shaft to prevent epicyclic roll it may be thought OK. If not I think we ought to re-arrange it with the running bearing between the wheels and the sliding as suggested by telegram. The sliding surfaces would not then roll. This is plain bearing (i.e. not ball) used for both sliding and running, which, if well lubricated cannot be wrong. It is shewn out of gear, thus:- [Diagram of an axle with gears in the 'Out' position] Out. In gear would be thus:- [Diagram of an axle with gears in the 'In' position] In. The gears are solid or rigidly fastened on shaft. This scheme is simple and practical, cannot be wrong, and only has the fear of a badly lubricated bearing. (because it is a plain bearing which can be rather heavily loaded.) If one were to make the wheels fast on the shaft and slide the shaft through fixed ball bearings we still may have creeping through the rolling fit between the shaft and the bore of the bearing, but I should say that this would be found to be much less likely and less vigorous, and might be tried. However to be perfect it should be as shewn for plain bearing - i.e. carry its bearings with it, thus:- [Diagram of an alternative axle and gear arrangement] Out. Which does not seem very convenient. For the object of curing the reverse there is no advantage in altering the dia. or angle of action of the gears, but some diametral increase to the smaller pinion might have advantages. Referring to the 1st. & 2nd. speeds, these are reported to still very slowly work out in occasional specimens or cases. I am not surprised at the 1st. coming out but the 2nd. is surprising. I have already given my views but nothing has so far been done or comparisons made. The only move from my suggestion that has been tried or mentioned or even replied to is the chambering of the gears. The points yet to try are:- (1) Handwritten notes: ? ? ! V.V. | ||