next referring to fig3 main lock 6 is rotated under unlocked position of auxiliary lock 7 if auxiliary lock 7 is rotated main cam disc 62 will also be rotated but said disc 62 does not come in contact with linking plate 2 until said disc 62 has rotated to its end point so said disc 62 never directly move linking plate 2 referring to fig4 if auxiliary lock 7 is rotated for 90 u00b0 shaft 71 activates the dead bolt to extend out to lock said lock 7 and then auxiliary cam disc 72 is also rotated as shown by the arrow head actually said disc 72 can also turn counter clockwise linking plate being moved up by said disc 72 so that lower hooks 22 come to touch with two protrusions of main cam disc 62 and linking plate 2 cannot fall down of itself because of the structure of the dead bolt of auxiliary lock 7 therefore this position constitutes united opening function of the main and the auxiliary locks shaft 61 can drive main cam disc to rotate either clockwise or counter clockwise linking plate being pushed down with lower hooks 22 pushed down by two protrusions of main cam disc 62 when linking plate 2 falls down upper hooks 21 push the protrusions of auxiliary cam disc 72 which then rotates to the position shown in fig2 and 3 that is the dead bolt can be pulled in in short according to this invention linking plate 2 is in the lower.