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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).
The necessity of a press fit for spring cups in the Phantom III clutch, suggesting a design change to eliminate reaming.

Identifier  ExFiles\Box 93\3\  scan0445
Date  30th June 1938
  
3/2

To RHC{R. H. Coverley - Production Engineer}/SB.{Mr Bull/Mr Bannister} from Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}
c. By.{R.W. Bailey - Chief Engineer}
c. By/NS.{Norman Scott}

Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}5/MH.{M. Huckerby}30.6.38.

P.III CLUTCH.

The question has been raised as to whether or not it is necessary to make the spring cups 0.84969 a press fit in the flywheel cover 0.84908, as this necessitates fine limits and reaming the 1.025 holes.

We find that the spring pressure is more than sufficient to prevent the cup from tipping under centrifugal force, even at 5000 r.p.m., we have, of course, considered part of the weight of part of the spring as well as part of the cup.

[Diagram of a clutch spring cup assembly with labels 'CF', 'COVER', 'SPRING THRUST', and dimension '0.84969'.]

We therefore see no reason why the cup should be a press fit in the cover, and suggest making the hole 1.025 and the land of the cup 1.0225, thus would eliminate reaming.

Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}
  
  


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