A magnetic rotor arrangement is provided, having a primary rotor including an array of magnets arranged to provide alternating polarity around the outside of the primary rotor and at least one auxiliary rotor including an array of magnets arranged to provide alternating polarity around the outside of the auxiliary rotor. The primary rotor and each auxiliary rotor are arranged such that when the primary rotor is rotated, the rotation of the primary rotor magnetically induces rotation of each auxiliary rotor.