Abstract: A tool adapted to be mounted on an elongated fluid conductive assembly such as a drill string for performance of a predetermined work operation at a remote location, such as the directional control of drilling, the tool having a tool body borne by the fluid conductive assembly for positioning in the remote location; a work member mounted on the tool body for movement laterally thereof; and a cam member received in the tool body in engagement with the work member for movement longitudinally in the tool body to move the work member laterally of the tool body upon predetermined pressurization of the fluid conductive assembly.