Abstract: A power assisted clamping and rotating apparatus for coupling two threadedly engaged members into a third, central member. The central member is held on a support in a fixed position by a clamping mechanism and the other two members are threaded into the central member with rotatable driving mechanisms on each side of central member and being moveable toward the member as they rotate. The rotating side members are in proximity to limit switches which cause rotation of the driving mechanisms to be discontinued when the members are threaded together to a predetermined degree. The limit switches may either be in the form of a laser beam which is interrupted or mechanical or electromechanical switches.