Commonly used in paper-feeding applications like copy machines and printers to prevent paper jams and misfeeding of paper sheets, these slip clutches are actually rather simple.
Most slip clutches are mechanical, but Ogura’s OPL clutch is a unique design. It is a hybrid between a permanent magnet and a magnetic particle clutch. In this clutch, multiple-pole magnets are solidly attached to a rotor shaft. The magnet/shaft assembly turns relative to the housing, which is magnetic high carbon steel. There is an airgap between the rotor and the housing. That airgap contains magnetic particles. The magnets on the rotor create magnetic flux lines across alternating magnetic poles. The magnetic flux tries to bind the particles together. The particles form chains along these flux lines between the magnets and the housing which causes a smooth drag torque when rotated. The housing is normally connected to a gear or pulley. Either the shaft/bore of the unit or the housing (gear/pulley) can be the input or the output.
These clutches are available in bushing or ball-bearing design, with a shaft or without. For best repeatable performance, they are used in horizontal applications.
These clutches normally produce very little internal wear and will provide very stable torque and help improve the life of the machine. The units are sealed which prevents particles from getting out of the device but it also prevents contaminants from the machine environment from getting in. They are easy to install because they a preassembled to a preset torque value, so there is nothing for the user to adjust.