Abstract: A machining assembly includes a single machining unit, a plurality of multiple heads, a cross transfer device for changing the heads by moving them transversely relative to the machining unit, and means for recirculating the heads from the discharge end section of the cross transfer to the feed end section, the end sections being tiltable about a horizontal axis from a vertical position to a horizontal position so that the heads may be used with their spindles horizontal but are moved along the circulation conveyor with their spindles vertical, wherein each of said end sections ensures, in its vertical position, the direct cross transfer of the heads without intermediate movement from or towards the machining unit and, in its horizontal position, the horizontal transfer of the heads in the direction perpendicular to the axis of tilt.