Abstract: Improvement to lathes with central headstock used for machining internally and/or externally a workpiece, and comprising a bed supporting a headstock on which two workpiece-clamping chucks are mounted for pivoting on the same spindle, said chucks being fitted symmetrically on two opposite faces of the headstock.The means for transferring the workpieces from one chuck to the other are pivotally mounted on said headstock, said means being used in combination with workpiece- injecting and ejecting means situated coaxially to the spindle and opposite the two chucks of the headstock, respectively.The invention finds an application in lathes with central headstock used for machining short workpieces.

Abstract: A clamping device for simultaneously machining, internally and/or externally, the two ends of a workpiece, comprising a headstock housing in which a tubular spindle is mounted to rotate, said spindle being internally provided with two annular pistons sliding axially and acting respectively on two collets for clamping the workpiece.The two clamping collets 23, 24 mounted respectively in the two pistons 12, 13 are provided with a cone-shaped portion 21, 22 cooperating with a corresponding cone-shaped portion in the pistons and a cylindrical part 25, 26 centered in the boring of the said pistons, the said collets 23, 24 resting on the side opposite their cylindrical part against the covers 27, 28 fast with the spindle 8 by a cone-shaped face extending radially in order to allow the radial tightening of the collets on the workpiece.The invention is used in lathes with central headstock.

Abstract: The specification discloses a lathe incorporating automatic feed at fast and slow speeds for driving (a) a tool holder carriage rapidly in leftward and rightward directions along the lathe bed and slowly in a leftward direction for automatic feed, and also (b) for rapid movement of the lathe cross-slide forwardly and rearwardly across the bed and slow movement of said cross-slide in the forward direction. In order to minimize the time taken for transition from slow to rapid speed in the automatic feed mechanisms, two parallel drive trains (one fast and one slow) are arranged to be selectively clutched to a main drive means for driving the tool holder carriage along the bed and for driving the cross-slide across the bed relative to the carriage.