Abstract: A radially expandable tool is provided that includes a tool body and a radially moveable member coupled to the tool body and in force receiving relation to a constant force actuator. The radially moveable member is movable by the constant force actuator from an closed position to a plurality of radially expanded open positions, which includes a fully open position. The constant force actuator includes an opening arm having a force transmission member; and a movement control guide in force reacting engagement with the force transmission member. The tool also includes a linear force generator; which applies a linear force to the constant force actuator, which the actuator transfers to a radial force perpendicular to the linear force.

Abstract: A downhole tractor is provided that may be used in open or cased wells, and is also designed for use in open holes having a variety of soil/formation consistencies (e.g., soft, firm, rigid, etc.), varying diameters and non-uniform and irregular bore profiles. The tractor may include a track assembly including a plurality of idler wheels and a continuous track rotatably disposed around the idler wheels. A motor may be adapted to rotate the track around the idler wheels. Upper and lower arms may be pivotally connected to opposite ends of the track assembly and pivotally connected to a tractor housing. An actuator arm or link assembly may be provided to impart an outward force to the track assembly to move the track assembly outwardly into an open position and a retracting force to retract the track assembly into a closed position. A rotatable screw may be connected to a second motor, or a rod may be connected to a hydraulic system, to actuate the actuator arm or link assembly.