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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).
Tests to show the effect of temperature on the calibration of Bentley speedometers.

Identifier  ExFiles\Box 59\2\  Scan225
Date  16th August 1933 guessed
  
BENTLEY SPEEDOMETERS.

TESTS TO SHEW TEMPERATURE EFFECT ON CALIBRATION.

A.T. INSTRUMENT NO. G.382.

Scale Reading (M.P.H.) | R.P.M. of Drive. | Temperature. | Calibration.
--- | --- | --- | ---
60 | 770 | 18°C. | 3.5% F.{Mr Friese}
60 | 774 | 25°C. | 3.0% F.{Mr Friese}
60 | 785 | 35°C. | 1.5% F.{Mr Friese}
60 | 795 | 45°C. | Correct.
60 | 810 | 55°C. | 1.5% S.
60 | 820 | 65°C. | 2.5% S.

When driven at 797 R.P.M. at 60 M.P.H. as on Bentley with 10/41 axle.

Smith "Nemag" instrument.

Scale Reading (M.P.H.) | R.P.M. of Drive. | Temperature. | Calibration.
--- | --- | --- | ---
60 | 767 | 35°C. | 4.0% F.{Mr Friese}
60 | 772 | 45°C. | 3.0% F.{Mr Friese}
60 | 780 | 55°C. | 2.0% F.{Mr Friese}
60 | 790 | 65°C. | 1.0% F.{Mr Friese}

Hs{Lord Ernest Hives - Chair}/H.E.West.
  
  


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