A Bicycle Ergometer

Aug 5, 2012 by

Everything you could possibly want to know about A BICYCLE ERGOMETER, WITH AN ELECTRIC BRAKE by Francis Benedict, originally published in 1912.  Most of this book flew right over my little head, but hopefully if you’re into ergometers….this book will be honey to your eyes.  Here’s a few lines to give you an idea what awaits you…:

With ergometer I the magnetizing current ranged from 0.70 ampere to 1.25 amperes, but inasmuch as the winding of the magnet in ergometer II was somewhat different, the current ranged from 0.95 ampere to 1.50 amperes in the calibration tests of this ergometer. It was planned to secure calibrations of the ergometer at each current with variations in speed ranging from approximately 50 to 120 revolutions of the pedals per minute. For a given speed, the highest values of heat per revolution were obviously found with the largest magnetizing current, namely, 1.50 amperes. As a matter of fact, however, the experiments of November 4 and 6 show that with less current (1.35 amperes) through the field- coils but with a low speed, the heat per revolution was exactly the same as with a current of 1.50 amperes and with twice the number of revolutions, namely, 118 revolutions per minute. It is impossible, however, to analyze satisfactorily the varying conditions without recourse to a series of curves plotted for each intensity of magnetizing current.” 

“With a magnetizing current of 1.10 amperes, we have two series of observations that are by no means concordant (fig. 10), and yet both indicate a noticeable falling off in the heat per revolution at high speed. We are unable at this time to account for the marked discrepancy be- tween these two sets of observations, but since this current is not used at present in actual experimentation with man and since the curve agrees with the others in its general form, it is deemed inadvisable at this time to repeat the calibration test. The calibrations made with a current of 1.35 amperes lie for the most part on a very definite curve (fig. 11). In one single observation at 80 revolutions per minute, it is approximately 5 per cent too high. The general form of curve noted for the other calibrations is here markedly shown, namely, a low heat per revolution with a low speed, a fairly constant heat per revolution between 60 and 80 revolutions per minute, and then a falling off in the heat per revolution as the speed is increased. ” Enjoy!

 

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