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Crankshaft modifications for a supercharged Bentley engine, specifically the reduction of bearings.


Identifier  ExFiles\Box 3\6\  06-page202
Date  16th June 1934
  
X453

To Sg. {Arthur F. Sidgreaves - MD} and WOF. from E. {Mr Elliott - Chief Engineer}

c. Hs. {Lord Ernest Hives - Chair} By. {R.W. Bailey - Chief Engineer}

E.3/HP.16.6.34.

re Bentley.

In connection with the scheme for adding the centrifugal supercharger to the Bentley engine, we are also proposing to alter the crankshaft from 7 to 4 bearings, as we feel that the increase of boost should raise the speed on which the power curve peaks and this will call for a higher major critical speed on the crankshaft if we are to take full advantage of this improvement.

It has usually been held in the past that a supercharged engine should have a main bearing on both sides of each cylinder, but we find that the Graham Paige are only using a 5 bearing shaft on their 8 cylinder engine and also we feel that the additional roughness which we expect may be introduced by leaving out bearings can be dealt with by using a sufficiently flexible engine mounting, and that the passengers will be unaware of it as far as the chassis and body phenomena are concerned.

E. {Mr Elliott - Chief Engineer}
  
  
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).


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