a single release , multiple axis coupling device for securing and positioning patient support equipment during orthopedic surgery . the coupling device can be released from or securely locked into a rigid position by a single rotation of an actuator shaft . the released or locked configuration is achieved by a rotational movement of the actuator shaft and a reciprocal axial movement of a cylindrical piston assembly . by displacing the cylindrical piston assembly within a housing chamber , either two or three movable coupling members can be rigidly secured to or released from the support shaft upon which the coupling assembly is mounted .