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).
Modifications to the Synchromesh Cones for the Phantom III Gearbox.
| Identifier | ExFiles\Box 94\1\ scan0273 | |
| Date | 18th December 1935 | |
| LE Smith +326 BY.{R.W. Bailey - Chief Engineer} c. H.{Arthur M. Hanbury - Head Complaints} Hs.{Lord Ernest Hives - Chair} Mx.{John H Maddocks - Chief Proving Officer} RHD. Da.{Bernard Day - Chassis Design} HDY.{William Hardy}1/HP.18.12.35. Synchromesh Cones - T. 3rd and 2nd. Phantom 3 Gearbox. With a view to overcoming the inconsistency of operation of the cones of this box, which it is thought must be due to variation of the bedding due to a cause as yet unknown, 'E' has suggested that the bronze cones should be crowned to the extent of .001 in the width of the cone. That is, if the ends are unaltered in diameter, the middle will be .002 greater than now. The radius of the surface with a cone width of .650 (as for the T and 3rd) will be 53". The same radius may be used for the 2nd speed cone which is .700" wide. Screw threads on the cone surfaces are not to be provided at first at all events, in order to confine the experiment to one feature. The cones are not to be lapped as we consider that the bedding obtained on the lapping rig is not necessarily given by the pieces as assembled in the box. We imagine that the crowned surface will enable a sufficient width of bedding to be obtained by rubbing the cones together in the box on the road. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} has reported that lapping is condemned by General Motors on account of inconsistency. Presumably the screw thread enables a good bed to be obtained without the use of a lapping paste. Will you kindly instruct the above modifications for trial at the earliest possible moment. HDY.{William Hardy} | ||