Patent ID: 6024166
Filing Date: 2000-02-15
Classification: E21B

Abstract:
An apparatus for forming an elongate slot in material surrounding the apparatus, the apparatus having a longitudinal axis and comprising at least one endless cutting chain mounted on at least one cutting arm having an axis; a motor for driving the chain, the motor having an output shaft located substantially coaxially with the longitudinal axis of the apparatus; drive means connecting the motor to a drive sprocket which itself is drivingly engaged with the chain; and means for rotating the cutting arm from an initial position in which the axis of the cutting arm is substantially parallel to the longitudinal axis of the apparatus to a final position in which the axis of the cutting arm extends obliquely or perpendicularly to the longitudinal axis of the apparatus; the rotating means comprising a sleeve piston which surrounds the drive means and is located below the motor, a rack driven by the sleeve piston, and a pinion driven by the rack and connected to the chain arm.