US Patent 7567159 Energy absorbing magnetic coupling device

A non-contact apparatus removes translational energy (slows movement) of a first magnetic assembly when it is moved through the magnetic field of a second magnet. The first magnetic assembly contains a magnet that can rotate, such as a diametrically magnetized cylindrical magnet in a cylindrical cavity. Rotation of the first magnet does work against a predetermined drag. The apparatus also forms a non-contact magnetic coupling that holds a predetermined relative position. The apparatus can be used as a door catch that slows down and quietly stops a door at a predetermined position.