Abstract: A table has more than three legs, two of the legs being pivotable relative to the rest of the table. The pivotable legs are selectively locked against movement by a lock device that adjustably expands into contact with opposing control surfaces. One of the control surfaces is fixedly coupled to the pivotable legs and another one of the control surfaces is fixedly coupled to the rest of the table. Pivotal movement is prevented when the lock device is wedged against the opposing control surfaces. When the lock device is pulled out from between the control surfaces, the table can stabilize on an uneven floor surface, which may cause the opposing control surfaces shift in orientation relative to each other. A biasing member urges the lock device to self-expand and to automatically move into the same or different position between the opposing control surfaces as may be required to prevent subsequent movement.