US Patent 10563458 Mechanical disconnect for rotation drive

A horizontal directional drilling system. The system has a pilot drill and an exit side drill, with a drill string extending between them. A backreamer is positioned between the drills to enlarge a borehole. The pilot drill pulls and rotates the backreamer. The exit side drill adds segments to the product pipe and pushes the product pipe into the enlarged borehole. The exit side drill is equipped with a rotational disconnect. The disconnect is engaged to allow torque transfer between a motor and a spindle when adding segments to the product pipe. The disconnect is disengaged to prevent torque transfer between the motor and the spindle when pushing the product pipe into the enlarged borehole.