Abstract: A jet mixer having a hub arrangement for facilitating the rotation of an impeller mounted to the hub. The hub receives fluid from a hollow conduit to provide a liquid bearing. The hub includes a sleeve member that is axially self-centering and rotatable on a body portion of the hub.

Abstract: A mixing blade assembly including a hub, a set of impeller blades having air foil configurations and flat end portions for attachment to corresponding flat surfaces of mounting members which attach the blades to the hub. The flat attachment surfaces avoid stresses tending to distort the blades. The hub is a hollow member made from a set of plates. The leading edges of the blades are generally straight, and the trailing edges are inclined rearwardly from the tips towards the roots of the blades.

Abstract: A spindle assembly of a type adapted to receive a readily removable disc for rotation senses the thickness of the disc with respect to a predetermined thickness and in response to so sensing the thickness of the disc an indication is provided as to whether the thickness of the disc varies from the predetermined thickness. The disc is clamped by movement of a clamping body while a portion of the spindle assembly serves to insure that the clamping body moves into and out of engagement with the disc surface in a direction substantially normal to the disc under control of the spindle assembly. In addition, the force with which the clamping body acts is modulated selectively as desired to accommodate the need for greater forces when mounting larger discs.