Abstract: A machine tool such as a lathe having an automatically changeable tool turret and a turret changer, carried on the bed of the machine, that dismounts a turret from a spindle of a turret index unit and mounts a replacement turret thereon. Transfer of a turret between the changer and the spindle is accomplished by axial and rotary movements produced by components that are associated with the index unit and that provide other functions during regular turret indexing and machining operations. The turret mounts on the spindle with a bayonet-type connection. The changer includes a pair of opposed arms that each carry a turret and that alternately swing into alignment with the spindle.