| 摘要 |
<p>A magnetic clutch or drag brake for a rotary shaft which is particularly adapted for use as a web or sheet tensioning control is disclosed. The device includes a first clutch element providing a selectively variable torque which is independent of shaft rotation or slip speed and a second clutch having an independently selectively variable torque which is dependent upon slip speed. The two clutch elements are associated in one housing between input and output shafts such that their clutching or braking action is cumulatively applied to the output shaft to provide an infinitely variable output from zero to maximum shaft speeds. The first clutch element utilizes the principal or magnetic hysteresis of a driven disc of high hysteresis-loss material while the second clutch element utilizes the principle of magnetic eddy current variations caused by an adjustable flux gate which varies the magnetic coupling between a driven and fixed member.</p> |
