Patent ID: 7771281

Claim:
A gear coupling comprising: a pinion provided with external gear teeth, and fixed to a first rotary shaft; a sleeve provided with internal teeth gear for meshing with the external gear teeth of the pinion, the sleeve having an opening in an end-face on each of the sides of the sleeve, through either one of which the pinion is introduced into the inside of the sleeve, and being coupled to a second rotary shaft; a first end member for closing over the opening present in one of the sleeve end-faces through which the first rotary shaft passes, for forming a rotary shaft space through which the first rotary shaft passes; and a second end member for closing off the other opening present in the other end-face of the sleeve; wherein the sleeve, the first end member, and the second end member are configured to form a space for retaining lubricant, the pinion having a portion that increases in diameter heading outward along an axis of the first rotary shaft to form a tapered surface opposed to an inner circumferential surface of the rotary shaft space, wherein the tapered surface is provided with circumferentially oriented grooves formed therein in such a manner that both side faces of each groove are inclined, from an opening thereof, heading inward along the axis of the first rotary shaft so that an outward edge portion of the bottom of each groove is positioned axially inward from an inward edge portion of the opening of each groove.