Turning head, in particular a facing head

In an apparatus for supporting a tool on a rotatable spindle of a machine tool, including a frame adapted to be secured to the spindle, a slider supported on the frame for movement radially of the axis of rotation of the spindle, having means for supporting the tool thereon and having a toothed first rack thereon extending in the direction of movement thereof, an adjusting member movably supported on said frame and having teeth thereon which operatively engage the teeth of said first rack, movement of said adjusting member effecting radial movement of said slider and said slider being urged radially outwardly by centrifugal forces generated by rotation of the spindle, and counteracting means for exerting a radially inwardly directed force on said slider to counteract centrifugal forces acting thereon, the improvement comprising wherein said counteracting means includes a toothed second rack on said slider extending in the direction of movement thereof, pinion means rotatably supported on said frame and having teeth operatively engaging the teeth of said second rack, an axially extending third rack having teeth operatively engaging teeth of said pinion means and means supporting said third rack for axial movement relative to said frame, and resilient means cooperable with said third rack and one of said frame and adjusting member for yieldably urging axial and rotational movement of said third rack and pinion means, respectively, in directions which correspond to radially inward movement of said slider.