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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).
Specifications for the Bentley V dynamo coupling and camwheel to resolve gear rattle issues.

Identifier  ExFiles\Box 97\2\  scan0029
Date  14th March 1939
  
450

To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}
c. Da.{Bernard Day - Chassis Design}
c. By/NS.{Norman Scott}
c. MX.{John H Maddocks - Chief Proving Officer}
c. By/CS.

BENTLEY V UNIT FOR PRODUCTION.

Regarding the specification for the 300 Bentley V's that are to be produced, there are several items to be cleared up and are as follows.

(1) Dynamo Coupling and Camwheel.

It will be recalled that before the Wraith came on production the 15,000 mile car 20.G.VI came back with very bad gear rattle and wear of the camwheel. This gear incidentally, was in the old Fabroil material and proved to be bad for wear in comparison with the Attwater material now used.

However, the reason for the wear was investigated and found to be oscillations of the camshaft which were improved by an increase in the inertia of the camwheel combined with more flexibility in the dynamo drive. The latter not being available, the increased inertia camwheel only was standardised, which although giving some improvement regarding high speed oscillations has definitely made worse the low speed load rattle.

Since its introduction we have continued running with the light inertia camwheel experimentally and despite the oscillations, little or no wear has taken place on 27.G.VI. which has no gear rattle after 29,000 miles; also a total of 35,000 miles has been run on 28.G.VI., 1.B.50 and 9.B.V. without complaint.

A flexible dynamo coupling has been produced to our drawing by the Metalastik Co. which appreciably reduces the amplitude of the camshaft oscillations at high speeds, but increases the low speed rattle.

Therefore, from the results obtained we consider the light camwheel (EM.1729) should be specified in conjunction with the standard dynamo coupling pending further investigation of the Metalastik couplings. In order to be common with the Bentley V, the light camwheel should be re-introduced on the Wraith III.
  
  


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