Ogura has created a new animation showing how permanent magnet/hysteresis slip clutch/brakes work. The animation covers both construction styles. The first one is the low cost OPL series which uses a combination of permanent magnets and magnetic particle powder to create a fixed drag torque. These units are primarily used as paper feed separators in copy machines and printers. They are also used for other paper feed devices like ATM’s, card readers and mailing machines or other low torque limiting requirements.
The animation also shows the PHT series which uses opposing magnetic fields acting on a hysteresis disc to create torque magnetically or to create a non-frictional magnetic torque. The animation shows how by changing the position of the magnets, flux either increases or decreases on the hysteresis disc rotating in the internal magnetic fields which allows the user to vary the drag torque. See the animation below: