Mechanism securing lathe chuck in centred position - includes expanding pins with taper ends engaging in annular groove

The mechanism secures a chuck in a centred position on the end flange of a tubular lathe spindle, this flange bearing against the rear face of the chuck. An actuating ram is mounted at the rear spindle end, its piston being coupled to a push-and-pull rod passing through the spindle. In the forward end of the rod (24) are a number of guides (36) running in the lengthwise direction and inclined to the spindle axis, for the feet (38) of expanding pins (32) working in radial guides in the flange. The portions of these pins protruding from the flange as the result of axial movement of the rod taper towards the outside on their rear faces (34), and engaged in an annular groove (20) in a centring sleeve (16) on the chuck (14), so as to clamp the latter against the flange on extension.