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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).
Gearbox relay and options for managing an unsynchronised first speed on the Spectre model.

Identifier  ExFiles\Box 94\1\  scan0150
Date  5th July 1935
  
X328

Er. and Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} from HDY.{William Hardy}

c.c. Er. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}

HDY.{William Hardy}1/HP.5.7.35.

Gearbox Relay.

With reference to the difficulty with the operation of the 1st speed by the relay there is a very strong case for the use of only three speeds on the SpectreCodename for Phantom III in order to simplify the relay.

The difficulty is that with an unsynchroneshed 1st speed we must not allow the relay to attempt to engage this gear except when the car is stationary as the noise and shock above a very low speed would, in our opinion, be objectionable and dangerous. We are aware that the Hudson has no safeguard against this danger but we cannot believe that it is a satisfactory arrangement. The Hudson has three unsynchroneshed speeds actuated by electro-vacuum-relay and it may be that by reason of the speed and force of the actuation there is little noise, but we think that there must be high stresses. It can be seen from the report in the Motor of the 18th June that there is much to be desired and that the saving feature is that it need not be used owing to the high performance on top gear.

If it is accepted that we cannot permit the engagement of an unsynchroneshed gear except when the car is stationary we appear to have three possible courses:-

(1) To retain four speeds and latch out the 1st speed in such a way that it cannot possibly be accidently engaged. In this case we are doubtful whether 2nd speed would not be too high for some occasions such as when climbing Porlock with a fully laden car.

There would be no difficulty, of course, unless the climb was baulked, but in this case there would be very little reserve for acceleration according to our calculations. We imagine that most drivers would change into a gear which gave them some reserve and to require the car to be stopped to engage 1st speed is hardly satisfactory in our opinion.
  
  


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