Telescopic universal joint pin universal coupling

The utility model discloses a telescopic cross shaft universal coupling which comprises an adjusting cylinder, the two ends of the adjusting cylinder are respectively connected with a sleeve rod in a sliding mode, a plurality of limiting grooves are evenly formed in the inner side of the adjusting cylinder, and a plurality of strip-shaped protrusions matched with the limiting grooves are evenly distributed on the side faces of the sleeve rods. When the length of the coupler needs to be adjusted, a knob is rotated, a second transmission rod drives a worm to rotate, the worm drives a worm gear to rotate, the worm gear drives a first transmission rod to rotate, the first transmission rod drives two sleeve rods to get close to each other or be separated from each other through a first thread and a second thread on the first transmission rod, and therefore the length of the coupler is changed; compared with the traditional sliding connection between the loop bar and the sleeve, the coupling has the advantages that