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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).
Future gearbox design, focusing on arranging a helical second speed for quieter operation.

Identifier  ExFiles\Box 15\5\  Scan338
Date  7th September 1932
  
To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair}
c. SS.{S. Smith} WCr.
c. E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design}
c. EV.{Ivan Evernden - coachwork} Hdy.{William Hardy}

X7310.

Hs.{Lord Ernest Hives - Chair}1/AM7.9.32.

X5310.

GEAR BOXES

We have previously pointed out that we consider in the design of future gear boxes we ought to arrange for a helical second speed to give us silence.

It must be realized that the second speed on cars is now used very much more than hitherto. After a stop at a traffic signal it is necessary on all our cars to get away on second speed. In order to get away from the surrounding traffic the car is accelerated quite a good distance on this gear.

On our present cars the second speed is relatively noisy. The cars with 3-speed boxes have, of course, a quiet second, and the cars with the Wilson gear box have a more silent second speed than we have.

It was therefore agreed by Sg.{Arthur F. Sidgreaves - MD} that we should fit up one of our present gear boxes with a temporary arrangement having a helical gear second speed. One of the objects of this is to see whether there is any disadvantage in having three sets of gears in mesh.

In our design of gear box we have the advantage that as the change for the second is made on the lay shaft, when the engine is idling the second speed helical gears do not rotate and therefore we have no more gears running when the car is standing than we have at present. We had the car on the road and found, as one would expect, that the second speed is very much more silent than the present standard car. The jaw clutch engagement, instead of sliding the gear, also makes the change gear easier.

We are not convinced that it is necessary to have a synchromesh engagement for second speed. The fact of having jaw clutch engagement will make the second speed engagement definitely easier than at present and this may be all that is required.

At the present time we are changing the designs of all our gear boxes to get rid of the difficulty of engaging the first gear. We think this alteration is very much less important than the necessity of having a quiet second speed. We would recommend that when we make this change we try and incorporate both improvements at one move.

HS.{Lord Ernest Hives - Chair}
  
  


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