Abstract: A vertically reciprocating and substantially constant power drive unit, including pumping equipment situated at the bottom of a string of drive rods is provided. The drive unit comprises a linear electric motor whose field inductor and whose armature are constituted by two coaxial cylindrical parts, one of which is coupled to the top end of the drive rods and is movable relative to a stationary structure. A balancing device exerts a force on the moving equipment constituted by the pumping equipment, the rods, and the motor coupled thereto, which force is equal and opposite to the sum of the weight of the moving equipment plus one-half the weight (H/2) of the load.

Abstract: The walking beam of a pumping unit is suspended from an oscillating hanger arm. It is pivoted at one end to a crank and to a link, the other end of the latter being pivoted to a fixed position shaft. At the other end of the walking beam is a point which follows a virtually rectilinear path between a bottom dead center position and a top dead center position. This point may therefore be coupled through a rigid member to an oil well pump sucker rod line.