US Patent 7278669 Bottom discharge container

A bottom opening type container bottom plates of which can be opened only by a hoisting operation using a crane by performing a simple preparing operation can be realized. A vertical link 32, a lateral link 35, and a link 45 are arranged on a middle between a hoisting plate 31 and open/close arms 43, and an operation cam 41 is provided to the outside of the open/close arms 43. The operation cam 41 is turned to a rise posture or a down posture so that the open/close arms 43 can be switched freely between an opened state or a closed state by the hoisting force, and the state can be checked externally.