The invention relates to a machine comprising a first member, a rotatable second member rotatable relative to the first member relative to an axis, a control device, a drive connected with the control device for moving the two members relative to one another, and a first Hall sensor connected with the control device and arranged on the first member. On the second member, a first, second and third magnet are arranged next to each other on a common circular trajectory such, that during a rotation of the two members relative to one another, the first Hall sensor is located at a specific position in the detection zone of the magnets. The second magnet which is developed as the center magnet is facing towards the first Hall sensor with another magnetic pole than the first and third magnet.