A chuck assembly for high speed operations is provided. The workpiece gripping and releasing functions of the chuck are carried out pneumatically by a nonrotating air tube assembly extending through a bore in a machine tool to which the rotating chuck is mounted. The chuck is mounted to a portion of a machine tool for rotation therewith and is rotatably disposed over an air journal rigidly mounted to the nonrotating air tube assembly. Selective direction of compressed air causes relative movement between a piston mounted in a cylindrical work chamber of a chuck body. Relative movement between the piston and chuck body causes movement of an actuator having a wedge which is engages a generally annular clamping assembly.
