Patent ID: 7216774
Filing Date: 2007-05-15
Classification: B66C

Abstract:
1. A crane comprising: a base machine; a lower boom pivotedly attached to said base machine in such a manner that the lower boom may be raised and lowered; a tower boom for a tower crane specification attachable to said lower boom to provide a tower crane; a standard boom attachable to said lower boom to provide a standard crane having a maximum boom raising angle smaller than that of the tower crane; a spreader retainer attached on a rear surface of the lower boom; and a boom raising/lowering apparatus that raises/lowers said tower boom or said standard boom, said boom raising/lowering apparatus comprising: a gantry; a lower spreader provided on a top of said gantry; an upper spreader disposed closer to an extreme end of said tower boom or said standard boom than said lower spreader; and a boom raising/lowering rope wound between said upper spreader and said lower spreader, wherein the distance between both said spreaders is S