Patent ID: 6675679
Filing Date: 2004-01-13
Classification: B25B

Abstract:
A wrench for engaging an internal surface of a pipe and turning said pipe in either direction comprising;a shaft that rotates around a center axis, said shaft having at least two cam driving surfaces that are spaced substantially equally from said center axis for transmitting torque applied to said shaft; at least two gripping shells having external convex gripping surfaces that are cylindrically shaped to substantially match a cylindrically shaped concave internal surface of said pipe and slidingly engage said cylindrically shaped concave internal surface of said pipe, said gripping shells further including internal cam follower surfaces that are designed to be engaged by at least two cam driving surfaces on said shaft so that said torque applied to said shaft is substantially symmetrically transmitted to said at least two gripping shells from said center axis in a direction that is transverse to said center axis so that said gripping shells apply substantially equal force to said cylindrically shaped concave internal surface of said pipe and said center axis of said shaft is substantially aligned with a center axis of said pipe, a retainer that engages said gripping shells to retain said gripping shells on said wrench adjacent said shaft and allows said shells to freely move, without being biased in a direction that is transverse to said center axis to automatically open and engage said internal surface of said pipe.