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: A pair of pumps which are joined by a flexible connection passing over spaced rotatable devices positioned for rotation in a substantially vertical plane. The rotatable devices are driven alternately in clockwise and counterclockwise directions whereby the lifting of one pump occurs as the other pump is lowered. To facilitate the pumping operation, a counterweight is operatively associated with the flexible connection intermediate the pair of rotatable devices.

Abstract: A pair of pumps which are joined by a flexible connection passing over a rotatable device positioned for rotation in a substantially vertical plane. The rotatable means is driven alternately in clockwise and counterclockwise directions whereby the lifting of one pump occurs as the other pump is lowered.

Abstract: The invention concerns pumping apparatus for wells, such as oil wells, coising a framework constituted by a tubular mast, a driving plant, a linkage connectable to a force pump immersed in the well, a flexible connection between the said plant and the said linkage for transmitting and imparting a reciprocating lifting and lowering movement to the rod linkage to actuate the force pump, the tubular mast including, for the connection to the rod linkage, guide pulleys with horizontal axes of rotation, and a lockable arm for carrying the guide pulleys and mounted for pivoting on the tubular mast about a vertical axis.

Abstract: A system is provided for maintaining a permanent reciprocatory movement of a mechanical arrangement, particularly a pump unit. A main driving wheel is coupled to the mechanical arrangement and fastened on the shaft of a hydraulic motor which is supplied by a variable delivery pump provided with control means. The control means is coupled to the wheel by a drive mechanism which comprises a rocking lever coupled to the control means and a cam carrier wheel rotationally fixed to the wheel. As the mechanical arrangement moves in one direction, the rotation of the driving wheel causes the cam wheel to change the position of the rocking lever thus permitting the control means to direct the flow of fluid from the variable delivery pump to the hydraulic motor to reverse the direction of travel of the mechanical arrangement.