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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).
Correcting out-of-balance masses and the effects of running-balance, detailing an experiment with a brake drum.

Identifier  ExFiles\Box 25\3\  Scan043
Date  25th February 1912 guessed
  
(2)

In the sketch the out-of balance mass (A) is corrected for standing balance by drilling at the point (B). This of course puts the system out of running-balance as regards the constant angular velocity, the out-of balance couple being the centrifugal force (C) multiplied by the radius (D) and acts in the direction of the arrow (E) i.e. a clock-wise couple in the plane of the paper.

The suggestion put forward in Mr Nadin's sheet is, that in accelerating this out-of balance part (A) by rotating the shaft in the direction of the arrow (F) a couple is introduced in the plane which is at right angles to the paper and enveloping the axis of the shaft, tending to force bearing (G) downwards and bearing (H) upwards, this couple always being at right angles to the ordinary out of running-balance couple and equal to the force required to accelerate Mass A multiplied by radius D.{John DeLooze - Company Secretary} We wish to be quite clear on this point, because sometime ago we made the following experiment in order to prove whether or no the fact that the brake drum being perhaps out-of running-balance (as regards constant velocity) was of any importance from the point of view of the magnitude of the vibrations coming from this source. We removed the brake drum and bolted in its place a very narrow cast iron disc of the same inertia. The disc was carefully turned all over and was found to be in true standing balance without requiring any drilling.
  
  


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