Central rotary joint

The utility model discloses a central rotary joint, include back axle and cover return in locating epaxially and with in return axle normal running fit and return the seat in, it is equipped with annular oil groove in the pore of seat time shaft fit in with to return in, the epaxial intercommunication that is equipped with returns in the axial oil circuit of annular oil groove, the first hydraulicfluid port that is equipped with connected ring shape oil groove on the seat returns in, first hydraulic fluid port and annular oil groove adopt " eight " style of calligraphy casting runner intercommunication, go back to the epaxial radial hole that is equipped with penetrating shaft to oil circuit and annular oil groove in, radial hole diminish gradually towards axial oil circuit direction aperture. The utility model discloses a first hydraulic fluid port and annular oil groove adopt " eight " style of calligraphy casting runner to communicate, and radial hole court axial oil circuit direction aperture diminishes g