Releasable locking coupling or support device

A releasable locking, coupling or support device, comprising first and second cooperating parts which are positionable into a slidable disposition relative to each other, and interengageable latching means on said first and second parts characterised in that said latching means are engageable automatically when said first and second parts are in said disposition and the second of said parts is moved in a first direction relative to the first part by a predetermined amount so as to restrict subsequent movement of said second part relative to said first part, and are disengageable automatically upon a predetermined movement of said second part relative to said first part, from the latched position thereof, followed by movement in said first direction in an opposite direction;

• at least one abutment being provided on the first one of said cooperating parts;
• at least one rotary pawl being mounted on the second of said parts for cooperation with the abutment and being freely rotatable through complete revolutions about its axis of rotation;
• said pawl having a peripheral portion of generally parallelogram shape;
• a pair of notches formed in a pair of opposite side edges of the pawl for receiving an edge portion of the abutment in a locking position of the device;
• and control means including resilient means positioned on said second part for engaging in succession each side of the parallelogram-shaped peripheral portion associated with the pawl, as the pawl is rotated by engagement and disengagement from the abutment so as to rotate and then locate the pawl in the required angular position thereof for the next step in a locking and release sequence.