Patent ID: 7448841

Claim:
A front device including a box member formed by welding together an upper flange, a lower flange, a left web and a right web; and a boss located at least at one end of said box member and welded to the ends of said upper flange, said lower flange, said left web and said right web, characterized in that: at least one of said left web and said right web is provided with a face plate portion which is extended in the longitudinal direction of said box member and formed as at least one of the left side face and the right side face of said box member, and a bent plate portion which is bent inward and extended from the end of the longitudinal direction of said face plate portion to said boss, and welded to said boss at one end of said bent plate portion; a reinforcement plate is located outside of said bent plate portion and welded to said face plate portion of said left web or said right web and said boss respectively; and the portion of said box member to be welded to said boss forms a double structure by use of said bent plate portion and said reinforcement plate.