I'm planning to design two types of clutch to be used in packaging machines (capping machines to be more precisable. Until now I getting into design a slip clutch and hysteresis clutch. The slip clutch is not a problem for me. I have a good idea about the mechanism and the calculation behind this project. Although regards the hysteresis clutch I have a reasonable ideia about the concept but complete ignore the mathematical and eletrical design and calculation behind the clutch. I must understand how the magnetic field relates to the torque applied to the cap as well as how to control its torque when being apllied to the bottle through magnetic field. Does anyone know some sort of source, books, articl or something that could help to solve my questions?