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 faults and operational issues with a gearbox synchromesh system.
| Identifier | ExFiles\Box 91\4\ scan0131 | |
| Date | 24th July 1935 | |
| HOTEL DE FRANCE. CHATEAUROUX. Indre. France. GWH{George W. Hancock - Head Chateauroux}/2/JAB. 24th July 1935. To. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} From. G.W.H. 3. S. I. SPECTRECodename for Phantom III. We have received your memo. of the 22nd inst. You will have recieved our information re the Gear Box. With regard to the Gear Box design, in our opinion it will be a difficult design to produce, to get the third & top Synchromesh to work smoothly. It should be in two halves lengthways, not as it is now cross wise. The correct setting of the Gears, Synchromesh, and cones, could then be obtained without much difficulty. With the present design, the fault lies in more or less guess work of the position of the cones of the third and top. This is the cause of our third & top Synchromesh not working, which I hope, I can make clear enough to you. The barrel or sleeves of the two Synchromeshes are located by the selector sleeve and lever. The movement each way, is checked by the location of the plungers and the movement of the leverage of the change speed lever. The top direct gear and the cone, are located by the relative position of the ball race in the end of the case, supposing the ball race is .050 or .060 further in the case towards the front. That moves the outer cone that much further away from the engaging cone, and as in our case, the engaging cone does not come sufficiently in contact to obtain the Clutch or drive effect. Supposing its the reverse way, the cones will engage with such force, that they will not slip and you get that lumpy change. The same applies to the third Gear. It was lumpy before the box was dismantled and again after the first re assembly. Upon the second dismantling of the box and re-assembling, the position of the engaging cone must have been knocked further in on the diaphram, as now, that cone does not engage sufficiently to get the spinning effect, and neither does the top. The whole of the mechanism except the direct drive and continuous gears, have to be mounted on the Diaphram, then the end boxes wringled on. It is almost impossible to obtain a lining up figure when it is assembled. ......... | ||