In a magnetic coupler, a pair of magnet rotors is slidably mounted on rods. Ferrous material on the conductor rotors attracts the permanent magnets in the magnet rotors. Under static or relative static conditions, the attractive force urges the magnet rotors toward the conductor rotors to create a minimum, operational air gap therebetween. When there is a significant relative rotational velocity between the magnet rotors and the conductor rotors, a repulsion force urges the rotors apart. During start-up, latch arms retain the magnet rotors apart from the conductor rotors by a larger, soft-start air gap. During operation, centrifugal force moves the latch arms out of their active position. If the rotational speed of the load shaft decreases rapidly during operation, the magnet rotors move apart from the conductor rotors by a still larger, fully disengaged air gap.