Patent ID: 7278669

Claim:
A bottom opening type container composed of side plates and a pair of bottom plates, having hinges of the bottom plates attached to near bottom portions of the side plates, locking pins provided near distal ends of the bottom plates, and a pair of open/close arms which are pivotally supported around center portions thereof by fixed pins fixed to the side plates, and which interlock with each other via gear portions, and which are capable of locking the locking pins by lower end hook portions thereof, the container comprising an open/close control mechanism including: hoisting plates supported pivotally about fixed pins fixed to upper portions of the side plates and having hoisting holes at outer ends thereof for connecting a wire rope to hoist the bottom opening type container; a vertical link one end of which is connected to a hoisting plate and the other end of which is connected to an oscillating link swingably supported to a fixed pin fixed to a lower portion of a side plate; a lateral link one end of which is connected to the oscillating link; a link which is inserted into a hollowed out plate fixed to a lower portion of a side plate and one end of which is connected to the lateral link, and which is biased to one direction by a return spring; and an operation cam which has a rotating center thereof at a rear surface side of the open/close arms outside of the locking pins, and which restrains the rear surface of the open/close arms in a rise posture to maintain the open/close arms in a close state and releases the open/close arms in a down posture when the bottom plates are closed, wherein in a state that a distal end of the link or an extended portion attached to the distal end is placed on a stepped portion of the hollowed out plate or an upper end of the operation cam in a rise posture, one upper end of the open/close arms is restrained so that the open/close arms are maintained in a close state, wherein in a state that the distal end of the link or the extended portion attached to the distal end drops out of the stepped portion of the hollowed out plate or the upper end of the operation cam in the rise posture, one upper end of the open/close arms is released, and wherein the link moves to a horizontal direction interlocking with a movement of the hoisting plate, and a placed state is changed into a dropped state, so that the open/close arms are pressed to an open direction by a hoisting force.