Well drilling tool

Claim 1

A drilling tool for use on a drill string, suspended in a well, to enable a driller to selectively alter a down hole drilling assembly for either straight hole drilling or deflected drilling configuration by axial manipulation of the drill string, the tool comprising: (a) a body adapted to function as a length of the drill string, with drilling fluid conducting means extending therethrough, and comprising: an upper portion and a lower portion, one of said portions, at least in part, telescopingly received within the other and secured therein for limited telescoping movement therein such that column loads through said body tend to shorten said body; hinge means arranged to secure one of said portions to the other and having a transverse axis about which the centerline of said lower portion can pivot between a first configuration generally coincident and a second configuration deflected from an extended general centerline of said upper portion; and rotational drive means comprising a non-circular surface on said upper portion coacting with a non-circular surface on said lower portion; (b) deflector means, in said body, comprising a first cam and a second cam, both carried on one of said portions, and a movable third cam carried on the other said portion, said movable third cam situated to move between a first position to engage said first cam to force said lower portion to said first configuration and a second position to engage said second cam to force said lower portion to said second configuration, said cams positioned to execute said forcing when said body is shortened by column loads greater than a preselected amount; (c) deflection selector means, in said body, comprising; said movable third cam and cooperating first and second selector cams, said first selector cam carried on said movable third cam and said second selector cam arranged to move in sympathy with said portion carrying said first and said second cams, said selector cams arranged to be actuated by said telescoping relative movement of said two portions in response to changes in said column loads to move said movable third cam to said first position on preselected instances of application of said column load, in a series of instances of application of said column load, greater than a preselected amount, and to move said movable third cam to said second position on other instances of said series.