Main runner coupling

Claim 1

IN A RUNNER CONSTRUCTED FOR CONNECTION TAO THE ABUTTING END OF AN ALIGNED LIKE RUNNER OF A SUSPENDED CEILING STRUCTURE, SAID RUNNER BEING OF GENERALLY INVERTED T-SHAPED HAVING A CENTRAL NORMALLY VERTICAL BODY MEMBER AND A NORMALLY HORIZONTAL FLANGE PORTION, THE COMBINATION OF AN EXTENSION MEMBER FORMED ON THE RUNNER END, AND EXTENDING LONGITUDINALLY OUTWARDLY FROM THE BODY MEMBER, SUCH EXTENSION MEMBER LYING IN A PLANE EXTENDING PARALLEL TO THE LONGITUDINAL AXIS OF THE BODY MEMBER PORTION WITH WHICH IT IS TO BE ENGAGED, MEANS FOR INTERLOCKING WITH LIKE MEANS ON ANOTHER RUNNER COMPRISING A TONGUE FORMED ON ONE OF SAID MEMBERS AND A SLOT FORMED ON THE OTHER OF SAID MEMBERS, SAID TONGUE INITIALLY EXTENDING AT SUBSTANTIALLY RIGHT ANGLES TO SAID PLANE, SAID SLOT OF A SIZE TO RECEIVE A LIKE TONGUE ON SUCH OTHER RUNNER WHEN SUCH RUNNERS ARE IN ALIGNED ABUTTING RELATION, SAID EXTENSION MEMBER BEING LATERALLY OFFSET THE THICKNESS OF THE METAL FORMING THE INTERLOCKING PORTION OF THE BODY MEMBER WHEREBY THE LATTER MEMBER OF EACH RUNNER MAY BE DISPOSED IN SIDE-BY-SIDE RELATION WITH THE EXTENSION MEMBER OF THE OTHER RUNNER WHEN THE RUNNER ENDS ARE IN ALIGNED ABUTTING RELATION, THE INTERLOCKING MEANS CARRIED BY SAID EXTENSION BEING SPACED FROM THE FREE END THEREOF WITH THE PORTION OF THE EXTENSION MEMBER THEREBETWEEN FORMIN REINFORCING MEANS OPPOSING BENDING ACTION BETWEEN A PAIR OF ASSEMBLED RUNNERS.