am improved railway vehicle coupler head is provided having knuckle pin retaining element which is free to fully rotate with the knuckle pin to enable continuous rotation of the knuckle pin during use . an elastic ring located within a circumferential groove on a bottom portion of the knuckle pin precludes the knuckle pin from unintentional upward removal during use while allowing for continuous rotation therewithin . the continuous rotation of the knuckle pin allows for the distribution of stress about the circumference of a knuckle pin resulting in a longer fatigue life for the knuckle pin .