Patent ID: 6880712

Claim:
A crane provided with a trolley which is supported in a horizontally movable manner, a hanging member which is hung from the trolley via a rope member and supports a cargo, and a hoisting device which raises and lowers the hanging member by winding and unwinding the rope member, said crane being used to land the cargo supported by the hanging member at a predetermined landing place, comprising: a horizontal position displacement detection unit which detects a horizontal positional displacement between at least two corners, including a first corner and a second corner, of the cargo and a position relating to the landing place of each of the first corner and the second corner; a horizontal position displacement correction unit which corrects a horizontal positional displacement between the at least two corners, the first corner and the second corner, of the cargo and the position relating to the landing place of each of the first corner and the second corner when the first corner and the second corner, respectively, land based on a detection signal from said horizontal position displacement detection unit, a horizontal position displacement determination unit which determines if the horizontal positional displacement between the first corner and the second corner is within an allowable range; a hoisted cargo lowering speed determination unit which determines a lowering speed of the cargo when the horizontal positional displacement determined by the horizontal position displacement determination unit is within the allowable range; and a hoisted cargo lowering timing determination unit which determines a timing for starting to lower the cargo at the lowering speed determined by the hoisted cargo lowering speed determination unit; wherein the first corner of the cargo lands at the landing place of the first corner, and then the second corner lands at the landing place of the second corner.