Patent ID: 7798738

Claim:
A swivel joint for a construction machine comprising a lower travel structure and an upper swing structure mounted on said lower travel structure, hydraulic equipment disposed on said lower travel structure and including travel motors and a blade cylinder and hydraulic equipment disposed on said upper swing structure and including valve apparatuses for control of said travel motors and said blade cylinder, said swivel joint comprising a body rotating together with said upper swing structure, and a spindle mounted to said lower travel structure and rotatably inserted in said body, said spindle being fixedly mounted to said lower travel structure when said body rotates together with said upper swing structure, a plurality of first tubes which extend to said hydraulic equipment disposed on said upper swing structure and including said valve apparatuses for control of said travel motors and said blade cylinder being connected to said body and a plurality of second tubes which extend to said hydraulic equipment disposed on said lower travel structure and including said travel motors and said blade cylinder being connected to said spindle, said plurality of first tubes and said plurality of second tubes being communicated with each other through a plurality of circumferential grooves formed in an inner peripheral surface of said body and an outer peripheral surface of said spindle and through a plurality of axial passages formed inside said spindle such that said plurality of first tubes and said plurality of second tubes are coupled to each other in a relatively rotatable manner, wherein said body has first opposed sidewall portions positioned in opposed relationship to each other and second sidewall portions positioned between said first opposed sidewall portions, said first opposed sidewall portions having wall portions respectively thicker than said second sidewall portions and formed to extend axially from an upper end surface of said body, and wherein said thicker wall portions are formed with a plurality of axial passages communicating with said plurality of circumferential grooves in a row respectively within said thicker wall portions, said plurality of axial passages being open at said upper end surface of said body to provide a plurality of ports and said plurality of first tubes being connected to said plurality of ports whereby said plurality of first tubes are connected to said upper end surface of said body in concentrated layout.