| 摘要 |
PCT No. PCT/JP97/03792 Sec. 371 Date Jun. 1, 1998 Sec. 102(e) Date Jun. 1, 1998 PCT Filed Oct. 21, 1997 PCT Pub. No. WO98/17888 PCT Pub. Date Apr. 30, 1998A balancing device (11) has a first balance pulley (20) provided in a hoisting drum (3) and a second balance pulley (40) connected to a coil spring (31). These pulleys are connected through a tension wire (50). The first balance pulley has a main pulley portion (25) for taking-up the tension wire at the beginning of a feed-out process from a fully opened position, and a zero-point return pulley portion (26) for taking-up the tension wire from halfway. The zero-point return pulley portion has an outer circumferential shape in which the tension wire passes the pulley axial center at a fully shut position. The second balance pulley (40) has a cylindrical portion (46) for feeding-out the tension wire at the beginning of the feed-out process from the fully opened position, and a conical portion (47) for feeding-out the tension wire from halfway. The conical portion has a shape in which its diameter is smaller on the cylindrical portion side. There is provided an operation rope unit (11) having an operation rope (70) for operating the hoisting drum to rotate on the indoor side. Further, by decentering the rotation center of a large pulley (220), a mountain-shaped characteristic is given to balance torque every rotation.
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