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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).
Letter discussing the operation of a balancer and its effect on vibration frequency.

Identifier  ExFiles\Box 25\3\  Scan218
Date  15th December 1926
  
(3)

December 15, 1926.

We find there is practically no difference in the operation of the balancer when equipped with leaf springs or with coil springs. The beneficial action of the balancer is not through frictional dissipation of the energy. In fact, friction is a hindrance to its operation. It controls vibration effectively through superimposing upon one vibration system another system of a different frequency so there is interference.

You asked whether the balancer might not split the period, forcing one disturbance higher and another lower than the normal period of the shaft. I have observed this effect on some of the earlier experimental types when a rather heavy type of balancer was used. At certain speeds the shaft vibrated within the balancer, the springs giving an added rigidity to the shaft, imparted to it a higher frequency. At another speed the balancer mass acting with the shaft resulted in lower frequency. This does not occur however in the commercial device as it is relatively light so the tail cannot wag the dog. It does lower the fundamental period as mentioned before.

I shall be glad to discuss this matter further with you at any time. While we have a working knowledge of some of the practical aspects of the device there are many things about it which we do not know. It is more than possible that in an exchange of information I may receive more than I impart.

Yours very truly,

Sgd. C.E. Summers.

Copy to Mr. H.M. Crane.
Mr. J.{Mr Johnson W.M.} McEvoy.
  
  


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