Self-returning ball coupling

The utility model provides a self-returning ball coupling. A spline shaft is sleeved with a sleeve shaft; the shaft sleeve portion, making contact with the spline shaft, of the sleeve shaft is provided with more than one key groove hole; the spline shaft is provided with key grooves corresponding to the key groove holes; irregular keys are arranged in the key grooves in a clamped mode through the key groove holes; the irregular keys are connected with pressing plates through springs, and the pressing plates are fixed to the shaft sleeve portion of the sleeve shaft; the outer end of the sleeve shaft and the outer end of the spline shaft are respectively provided with a connection assembly. The self-returning ball coupling is easy to align and install, smooth in transmission, and long in service life; sealing glands, sealing elements and sealing linings are combined to seal products very well and meanwhile respectively support the sleeve shaft and the spline shaft in the horizontal state, and therefore the prod