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).
Sticking and concentricity of cones in a synchro-mesh gearbox, referencing Buick's lapping instructions.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan425 | |
| Date | 19th September 1931 | |
| MEMO. FROM DA{Bernard Day - Chassis Design}/HDY.{William Hardy} C. to HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} DA.{Bernard Day - Chassis Design} SYNCHRO MESH GEARBOX. STICKING OF CONES. We telegraphed to you yesterday to the effect that Buicks lay much stress on the bedding of the cones, and we give below the words of their instructions: (We are not sending the book in case R.{Sir Henry Royce} wishes to see it.) "Assemble "special" pilot bushing to pilot end of "splined shaft to guide the cam sleeve during lapping process. "Lap tapered portions of bronze cone and second speed "gear cone with fine grinding compound. These parts should "be lapped together by turning the second speed gear while it "supports the weight of the cam sleeve assembly only. Lapping "should be done with extreme care, frequently checking with ""Prussian Blue" to determine contact. Full contact between "cones is necessary. "Remove "special pilot bushing" and substitute therefor "the clutch gear and lap with cam sleeve, as outlined above, "raising cam sleeve assembly during process." It does not expressly state that this lapping is to avoid sticking. As no doubt the Buick cones do not stick in practice it would appear that we can come to no harm by lapping our cones. We have checked the Buick cone angle and find that as nearly as we can measure it is 6°. The Cadillac full size drawing also measures 6°, and so it would appear that we might make a success of 6°, or at least something more near it than 10° that we are going to try when we have had a little more experience with the box. CONCENTRICITY OF CONES. It appears to us that we can regard the cones in much the same way as we used to have to think of cone clutches. We know that the cone clutch will not function nicely unless the cones are truly aligned, and the drivingcone at least must be concentric. We think that for the present, and while we are having trouble with sticking, that we should true up the cones after assembly on their respective pieces by grinding. We mention this as we remember that you were hoping that grinding after assembly would not be necessary. Later on it may be shewn that this is not essential. It will be seen that the inner sleeve with the teeth at each end must also be true on its outside dia. The alignment of the 1st. motion shaft will clearly have some effect on the functioning of the top gear cone, but can hardly affect the action of the 3rd. speed cone. (1) | ||