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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).
Design and control of an epicyclic gearbox with hydraulic friction brakes.

Identifier  ExFiles\Box 178\3\  img083
Date  26th February 1932
  
HS.{Lord Ernest Hives - Chair}
FROM R.{Sir Henry Royce}
DA{Bernard Day - Chassis Design}/HDY.{William Hardy}) (At Le CanadelHenry Royce's French residence.)

C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} RG.{Mr Rowledge}
C. to BY.{R.W. Bailey - Chief Engineer} E.{Mr Elliott - Chief Engineer}
C. to Mr. CLAREMONT.

CHANGE GEAR.
EPICYCLIC WITH FRICTION BRAKES.

R2/M24.2.32.
Sent from WW. 26.2.32.

x7310
x7360

I think the best control for the passengers would be our hydraulic, arranged in the following way:

(1) The brakes to be about 3 times more powerful driving than over-running, by self-servoing action.

(2) The brakes can be released as quickly as one likes, but to be applied slowly by withdrawing the oil through a small orifice, the excess given by the pump passing a high pressure release valve.

(3) We should only ask the driver to close the throttle when changing to a higher gear, and keep it open when changing down. (This can be tried on our double top or synchro mesh.)

(4) It is so much easier (with these schemes) to change at high speeds without accelerating the engine, and I think it will be found that jerking the passengers is caused while changing down at high speeds.

(5) I have schemed several special ports and passages in the control cylinders so as to make their action more certain, interlocked, and in sequence, which would be valuable if we adopt this scheme.

We have now covered much ground on this subject, and seem to know more about it at the moment (perhaps not much) than any other subject; we ought therefore to try to profit by it.

I hope to keep Mr. Hardy on the change gear problem for the present, and that when I return to WW. he will consent to work in my house.

R.{Sir Henry Royce}
  
  


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