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).
Explaining the cause of sticking top gear cones and a temporary solution.
| Identifier | ExFiles\Box 15\5\ Scan267 | |
| Date | 25th April 1932 | |
| To C.W.Hancock, Hotel de France, Chateauroux, Indre, FRANCE. V-7310 67941 From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}7/MJ.25.4.32. SELECTOR ROD IN TOP GEAR WITH GEAR LEVER IN NEUTRAL. We think we have discovered the reason why this phenomenon can occur. We think that after a long run the temperature of the oil rises and the top gear cones stick. On pulling the gear lever into central position after this, the cones remain stuck together but the driving dogs come out. Now the plungers in the synchro-mesh sleeve are trying to pull the cones out and they are pulling against the selector rod, the resistance of the selector rod being controlled by the small plunger at its end. If the six springs and plungers in the selector sleeve can exert a greater force than the plunger in the selector rod, the selector rod moves towards top gear without any assistance from the gear lever. To prove out the point you can observe if the cones are stuck next time the trouble happens, and cure it temporarily by putting up the load of the selector plunger spring on the top and third speed selector rod until it can hold against the plunger centralising the cones. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||