Patent ID: 8231307
Filing Date: 2012-07-31
Classification: E21B,E21D,F16L

Abstract:
1. A device for tightening string sections of a string, comprising: a traction element disposed at a rear end of the string: a linear tensioning drive constructed for detachable engagement to the traction element and application of a tension force to tighten the string sections of the string; and a sliding brake operatively connected to the linear tensioning drive and movable from an idle position to an operative position in which the sliding brake is able to engage with and disengage from the traction element, thereby allowing the tensioning drive to extract itself in increments from the string by alternately applying a tensile force and thrust force upon the sliding brake, wherein the linear tensioning drive has an adapter for placement against a rearmost one of the string sections, a locking sleeve disposed at a distance to the adapter and constructed for engagement in the traction element, and a hydraulic cylinder assembly acting between the adapter and the locking sleeve to effect a tightening, when the locking sleeve engages the traction element.