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).
Outlining the advantages of a new synchromesh 2nd speed gearbox design, for which a provisional patent is being sought.
| Identifier | ExFiles\Box 123\3\ scan0113 | |
| Date | 24th January 1934 | |
| CRY X5310 4704 To BY/NW.{N. Walker - Patents} from HDY.{William Hardy} c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} W. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} HDY.{William Hardy}2/HP.24.1.34. Synchromesh 2nd Speed. We wish to take out a provisional patent for a combination of features which we are using on the new J.3. gearbox to obtain a synchro mesh 2nd speed, as shown on our N. Sch.3788/9. We give below the advantages which we claim for our arrangement:- (1) The S.M. clutch is placed on the layshaft. Existing schemes for a synchro mesh 2nd speed that we are aware of, have the clutch on the third motion shaft. The advantages given by the former position are:- (a) The torque that must be exerted by the clutch is less than when the clutch is on the 3rd motion shaft since in the latter position when the 2nd speed gears are of the proportions that usually obtain, the clutch will be on a large gear which is driving a small gear. (b) When the 2nd speed gears are idling the torque that is necessary to revolve them is provided by the 3rd motion shaft instead of by the 1st motion shaft as would happen if the clutch were on the 3rd motion shaft. Consequently there is no increase of the duty of the 3rd speed S.M. clutch due to the drag of the 2nd speed gears. (c) The 2nd speed gears do not rotate when the engine is idling and all gears are in neutral. There is, therefore, no increase in idling noise from the gearbox as there would be were the clutch on the 3rd motion shaft. (2) The 1st and 2nd speed gear trains are interchanged in position from what may be regarded as the usual arrangement so that the 2nd speed gears are the rearmost gears in the box. The advantages of this | ||