the sides of a doorway d1 d2 installation is accomplished by moving the handle 18 to its intermediate state again as illustrated in fig3 and 6 in this state the sections 12 14 can be moved apart relative to one another when the bumpers 30 engage the side walls d1 d2 the handle 18 is pivoted toward the upper rail 14a to cause the two sections 12 14 first to lock together and then to be forced apart thereupon compressing bumpers 30 and generating forces substantially normal to the surfaces d1 d2 these normal forces in turn produce frictional forces which prevent the gate from being dislodged from the opening the process of rotating the handle 18 downwardly toward the upper rail 14a causes the two part linkage 20 to move downwardly illustrated in fig5 linkage section 20a is vertically movable and carries section 20b section 20b carries the ratchet elements 28a 28b when section 20a moves downwardly due to handle 18 moving from its extended position fig7 to its intermediate position fig4 section 20b also moves downwardly permitting the ratchet elements to engage the rack elements 28a 28b in this state the sections 12 14 are loaded together as the handle 18 rotates toward the locked position adjacent to section 14a section 20a which carries cams 20 1 20 2 moves vertically the cams 20 1 20 2 slidably engage cam surfaces 20 3 and 20 4 on linkage element 20b the downward movement of the mechanism 20 along with the interaction between the cam elements 20 1 20 2 and the cam surfaces 20 3 and 20 4 forces the two linkage elements.