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).
Opinions and design considerations for a 'Double Top Gear' system.
| Identifier | ExFiles\Box 15\5\ Scan205 | |
| Date | 7th April 1931 | |
| DA.{Bernard Day - Chassis Design} HS.{Lord Ernest Hives - Chair} } FROM R.{Sir Henry Royce} (AT Le CANADELHenry Royce's French residence.) X7310 R1/M7.4.31. C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} C. to E.{Mr Elliott - Chief Engineer} BY.{R.W. Bailey - Chief Engineer} X.523. X.7310. DOUBLE TOP GEAR. Mr. Lidsey's opinions and criticisms are premature. Our scheme of control will be found as simple as anything and should be easier to work than Wilson because we do not have to work a heavy long stroke pedal. There should be no confusion in this. It is only like many other double tops - Maybach, Mercedes, Voisin. That the epicyclic is not silent need not worry us for the moment. It can be made so by correct teeth, by finer pitch, by making these finer pitch helical to a small degree, and if still not silent enough to an increased angle and perhaps wider. DA.{Bernard Day - Chassis Design} is quite right when he suggests much less angle down from original 6º to 2º with 3 teeth instead of 5. This should be put in hand. Clearances are usual with us seem much too small and springs unnecessarily stiff - good faults easily altered. Naturally until the control is on steering column the sch. should not be criticised for handiness. The standard type of gearbox can be made to idle satis- factorily so that the same thing belonging to this combination should not give any greater trouble. A Salerni ring might be preferable to Maybach jaws. He promised me we could use these without paying any royalty.- i.e for the reputation. I do not think Synchro-mesh suitable for anything but hand controlled gears. Our complete epicyclic gear should be quieter than any known gears because the rate of engagement is extremely low. There is one scheme which has an equivalent to synchro-mesh and is meant for side lever engagement. It may be thought that our double top might be carried out with other gears than the purely simple epicyclic, such as double balanced helical as used by some German designers on electri- cal{Mr Calvert} motor work, but so far I think what we are doing is best. When idling we ought to be quite good when we have gears which have correct teeth that are not too tight. When on top we ought to be rather better than an ordinary box with 2 single helicals because the gears in our box which are always running are large in dia. and running more slowly. We may find we have some disadvantages but as far as I know there is no sch. which should give the results arrived at with less disadvantages. | ||