Crane extension and installation device to achieve bidirectional tension control and method for achieving bidirectional tension control crane

A crane extension and installation device to achieve bidirectional tension control comprising, the extension device, the winch, the pulley and the cable, the crane is connected to the extension device in a horizontal direction through a movable joint at one end in a vertical direction, the crane is connected to a crane base through a joint at the other end of the vertical direction, and the crane base is used to fixedly support the crane, a main arm of the crane is installed with a slide rail in the vertical direction, the main arm has an inclination angle to the vertical direction, N second pulleys at different heights of the slide rail are installed in the vertical direction of the slide rail, N≥4, and the second pulleys can slide vertically along the slide rail, and can be fixed at a certain position of the slide rail, the second pulley comprises a highest position second pulley, a lowest position second pulley and a central position second pulley between the highest position pulley and the lowest position pulley, if a N−2th second pulley in the central position has a higher serial number, the lower a position at the rail thereof;

• the extension device consists of several cantilever beams connected end-to-end, a front cantilever beam of the extension device has the fixed pulley installed on its lower peripheral surface, and an end face of the front cantilever beam is installed with a lower arm in the vertical direction through a joint, a bottom end of the lower arm has a first pulley fixed by it;
• an end of the load in a horizontal direction is connected to the cable, and the cable bypasses the first pulley, the fixed pulley, and the second pulley with a highest vertical position to connect to a Nth winch, and the Nth winch is fixed on the crane base;
• an other end of the load in the horizontal direction is connected to the cable, and the cable bypasses a pulley with a lowest vertical position to connect to a first winch, the first winch is fixed on the crane base;
• the number of the cables connecting a middle part of the load in the horizontal direction is N−2, and the N−2 of cables bypass the second pulley in a middle position to connect to the second to N−1st winch, and the second to N−1stwinch are fixed on the crane base;
• the first winch and the Nth winch are located at ends of the crane base in the horizontal direction, and the second to N−1st winches are in middle positions of the crane base in the horizontal direction, and the first winch is closer to the extension device in the horizontal direction.