Patent ID: 7306058
Filing Date: 2007-12-11
Classification: E21B

Abstract:
1. In a drilling apparatus of the type comprising a rotatable drilling shaft and a housing for rotatably supporting a length of the drilling shaft for rotation therein, a rotation restraining device associated with the housing for restraining rotation of the housing, the rotation restraining device comprising a plurality of rotation restraining carriage assemblies spaced about a circumference of the housing, wherein each rotation restraining carriage assembly is comprised of a plurality of rollers, wherein at least two of the plurality of rollers of each rotation restraining carriage assembly are spaced side to side such that the rollers are coaxially aligned, wherein each roller has an axis of rotation substantially perpendicular to a longitudinal axis of the housing and is oriented such that it is capable of rolling about its axis of rotation in response to a force exerted on the roller substantially in the direction of the longitudinal axis of the housing, wherein each roller is comprised of a peripheral surface about its circumference, wherein the peripheral surface is comprised of an engagement surface for engaging a borehole wall to restrain rotation of the housing and wherein the engagement surface is comprised of the peripheral surface of the roller being tapered.