Patent ID: 7237738
Filing Date: 2007-07-03
Classification: B23D,E02F,E04G

Abstract:
1. A demolition cutter comprising: a stationary bracket carrying a rotary joint and adapted to be connected to an arm of a construction machine; a movable bracket rotatably coupled to said stationary bracket and including a pair of opposed side plates; an arm pin extending between said pair of side plates; a pair of cutter arms, pivotably mounted on said arm pin so as to be pivotable between an open position and a closed position, said cutter arms having surfaces formed with cutting edges that are configured to cross each other when said arms are pivoted toward said closed position; and a pair of cylinders each connected to one cutter arm of said pair of cutter arms, said cylinders being extended and retracted by supplying pressure oil into said cylinders through said rotary joint, thereby pivoting said cutter arms between said open and closed positions, said cylinders each having a central axis; wherein at least one of said central axes of said cylinders is offset in the direction of the axis of said arm pin from a plane including said mating surfaces so that a plane including said axes of said cylinders intersects said plane including said mating surfaces; wherein each of said cylinders comprises wherein said rotary joint includes a rotary cylinder secured to said movable bracket and formed with a pair of first oil ports and a pair of second oil ports; and wherein said first oil passage and said second oil passage formed in said piston rod of each of said cylinders are connected to one of said pair of first oil ports and one of said pair of second oil ports, respectively.