Patent ID: 7976069

Claim:
A rotary joint comprising: a substantially cylindrical shaft; a shaft communicating hole formed in the shaft and having an opening in a side surface thereof; a housing having an insertion hole where the shaft is inserted so as to be capable of relative rotation; a plurality of housing segments formed by dividing the housing and arranged in a central-axis direction of the shaft; a housing communicating hole formed in at least one housing segment among the plurality of housing segments, so that the shaft communicating hole communicates with the outside of the housing via the housing communicating hole in the at least one housing segment; an annular groove formed in at least one of the side surface of the shaft and an inner circumferential surface of the insertion hole so that the shaft communicating hole communicates with the housing communicating hole via the annular groove; and an annular leakage-preventing member disposed between the shaft and the housing to block fluid movement in the central-axis direction wherein the shaft includes a substantially cylindrical shaft portion, and a small-diameter portion formed at one end of the shaft and having a smaller diameter than the shaft portion; at least one pair of rotating supports supporting the shaft and the housing in such a manner as to be capable of relative rotation about the central axis, being provided on the shaft; one of the rotating supports being disposed at the small-diameter portion; and wherein an outside diameter of the one of the rotating supports is smaller than an outside diameter of the shaft and is smaller than inside diameters of the plurality of housing segments.