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Continuation of a report comparing governor control sensitivity and calculations for spring requirements.


Identifier  WestWitteringFiles\M\2Jan1925-March1925\  Scan14
Date  1st January 1925 guessed
  
-4-

which in the extreme case only increases the throttle opening by 1/240 of the total range, a hardly appreciable amount. Now upon another occasion the governor is set to give a speed of 30 m.p.h. when ascending a gradient so that the cam is on the rapid portion of its movement. A variation in gradient causes a momentary drop of 100 r.p.m. whereupon the cam is rotated through the same amount, 12 1/2°, but the throttle opens through 1/8 of the total movement.

The EAC. governor control is therefore 30 times as sensitive in the latter case as the former, while the 40/50 governor would open the throttle through 1/20 of its total range in each of the cases mentioned. To expect to get the same consistency of operation out of each governor arrangement is therefore unreasonable.

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Spring required to make throttle governor more sensitive.

Governor and actuating spring in equilibrium.
Then pull from spring = x lbs.
" " governor = x lbs.

Suppose engine r.p.m. falls n. R.P.M. and in consequence that the pull of the governor falls y.lbs.
Now the governor spring rating = p lbs/1".

. . movement of the end of this spring when load is decreased by y.lbs. = y/p

Now y/p is required to be a maximum. Therefore p is required to be a minimum.

contd :-
  
  
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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