Double deck elevator

A double-deck elevator capable of adjusting the spacing in the vertical direction between an upper cage and a lower cage which are provided on said cage frame in a vertically movable manner, comprising:

• right and left screw shafts rotatably supported on right and left sides of said cage frame and extending in the vertical direction, respectively;
• right and left screw shaft driving units for rotating said right and left screw shafts in the forward and reverse directions, respectively;
• controllers for individually controlling the operation of said right and left screw shaft driving units;
• an upper supporting member, which extends in the right-and-left direction above said upper cage, and is engaged with upper screw parts of said right and left screw shafts and vertically moved by said screw shafts;
• a lower supporting member, which extends in the right-and-left direction above said lower cage, and is engaged with lower screw parts which are threaded in a direction opposite to that of said upper screw parts of said right and left screw shafts and vertically moved by said screw shafts;
• right and left upper hoist-and-support parts which are disposed on the right and left sides of an upper part of said upper cage in the vicinity of said right and left screw shafts, and engaged with said upper supporting member respectively to hoist and support said upper cage;
• right and left lower hoist-and-support parts which are disposed on the right and left sides of an upper part of said lower cage in the vicinity of said right and left screw shafts, and engaged with said lower supporting member respectively to hoist and support said lower cage;
• right and left upper measuring units for measuring a load applied to said upper supporting member from said right and left upper hoist-and-support parts;
• and
• right and left lower measuring units for measuring a load applied to said lower supporting member from said right and left lower hoist-and-support parts,
• wherein said controllers control the operation of said left screw shaft driving unit based on the load value obtained from said left upper measuring unit and the load value obtained from said left lower measuring unit before adjusting the spacing in the vertical direction between said upper cage and said lower cage so that a drive torque with a direction and magnitude for canceling the rotational biasing force applied to said left screw shaft attributable to the difference between the load applied to said upper supporting member from said upper hoist-and-support part and the load applied to said lower supporting member from said left lower hoist-and-support part is output, and
• wherein said controllers control the operation of said right screw shaft driving unit based on the load value obtained from said right upper measuring unit and the load value obtained from said right lower measuring unit before adjusting the spacing in the vertical direction between said upper cage and said lower cage so that a drive torque with a direction and magnitude for canceling the rotational biasing force applied to said right screw shaft attributable to the difference between the load applied to said upper supporting member from said upper hoist-and-support part and the load applied to said lower supporting member from said right lower hoist-and-support part is output.