Abstract: A device is provided for facilitating the emptying of a container e.g. on a truck loaded with bulk material, which has a tendency of being packed together during the transport. The first and second side walls of the container are pivotally mounted at their upper edges for inward and outward swinging respectively. A movable bottom plate is hingedly connected to the first side wall. The swinging movement is caused by a jack comprising two members, e.g. a cylinder and a piston rod. The first member of the jack is at its end pivotally attached to the bottom of the container at the side thereof and the second member is pivotally attached to the lower edge of the first side wall in such a way that during the out-swinging movement of the side walls the second member of the jack makes an obtuse angle with the first side wall.