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).
Examination of a faulty change speed mechanism on a 12-EX car, identifying the cause and the implemented solution.
| Identifier | ExFiles\Box 15\5\ Scan008 | |
| Date | 8th July 1926 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} X7320 Hs{Lord Ernest Hives - Chair}/GWH{George W. Hancock - Head Chateauroux}1/LG8.7.26. RE. CHANGE SPEED MECHANISM ON 12-EX CAR - TO ARRGT. G.74299 We examined the change speed mechanism and found that the chief cause of the sliding shaft not working freely was due to the shaft being undercut to allow for grinding at point where bush G.73759 is in working position. The width of the undercut is too great and allows the narrow bearing surface of bush to drop into it and so becomes trapped. The cause of the sliding shaft binding in any position was found to be due to distortion of the tubular support G.74140. This starts to distort immediately a light pressure is applied to the change speed lever. To determine the amount of distortion, we mounted the complete unit on a surface bed plate and by a clock micrometer took readings in the different positions shown on the sketch. The amount of distortion shown is when a light pressure is applied to the change speed lever (as when changing gear), also when the binding effect takes place. The difficulty of engaging the gears we have proved to be the effect of the oil in the plunger sockets becoming trapped. After drilling the release holes as suggested in the sockets, there has been no further difficulty in engaging the gears. Hs{Lord Ernest Hives - Chair}/G.W.Hancock. | ||