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).
Technical memorandum discussing seizing bushes and gear creep in the 'China' Easy Change Gearbox.
| Identifier | ExFiles\Box 179\1\ img052 | |
| Date | 27th October 1931 | |
| HS{Lord Ernest Hives - Chair}/GRY.{Shadwell Grylls} FROM R.{Sir Henry Royce} C. to SO. WOR.{Arthur Wormald - General Works Manager} C. to BY.{R.W. Bailey - Chief Engineer} DA.{Bernard Day - Chassis Design} 'CHINA' - EASY CHANGE GEARBOX. The engagement of the reverse was shewn on the WW. drawing to have .100" lead between the moving wheel and the resting reverse gear. This was foreseen 25 yrs. ago and is so well known that Mr. Hardy did not call attention to it by special note - "inexcusable waste of time." The seizing bush is evidently due to lubrication not being replaced as it is squeezed out. We do not practice oil grooves at that part of the bearing carrying the load, but holes and grooves where there is no load. When the load is not relieved generally a floating bush is good, which should be bronze (bearing) preferably with some lead in the alloy as used in early RR. cars, now called 'Kelmit'. The reason for the gear creeping out, I think is because the two shafts are not absolutely parallel, the more heavily loaded smaller pinion taking charge. If the shafts were out of parallel slightly so that the creep was the same way as the engagement no one would know of this phenomenon. There is only one way that I know of to cure it - i.e. arrange the shaft not to slice, and make the gears bind themselves upon it as in our 1st. and 2nd. pinions - (RR. patent.) This is a trouble which occurs in many gearboxes, especially when small dia. wheels slide, as we were forced to do by our servo drive. We did not think our special scheme would be needed on this reverse, which we left as simple as possible. [Signature] R.{Sir Henry Royce} [Diagram] Smaller wheel driving will creep to left. Shaft shewn on left & shaft deflecting. | ||