Abstract: A hydraulic jack system for operating well bottom pumping units via a sucker rod string and polish rod that comprises a jack unit that is designed for mounting by being suspended fully within a well casing with a seal being created between the periphery of the jack unit and the interior of the well casing. The jack unit has a hollow piston-cylinder unit through which a polish rod is able to be inserted and withdrawn, to the top of which a top end of the polish rod is attachable and to the bottom of which a top end of a well fluid delivery tube is connectable.

Abstract: A heat exchanger plate (2, 4, 6, 8) having undulatory pleats (12) for forming fluid flow passages (18, 20) on opposite sides of the plate (2, 4, 6 8) is disclosed. The heat exchanger plate (2, 4 6, 8) is improved by providing the side walls (38, 42, 44) of each pleat (12) with a uniform slope. By this arrangement, the plate is provided with improved distortion resistance and fluid flow capacity. Method and apparatus for forming the pleated plates are also disclosed for using a pair of non-uniform donative fluid passage forming blades (34" and 36") mounted for relative oscillatory movement with respect to a recipient fluid passage forming blade (40") wherein the clearance between each blade is uniform throughout the entire length of each blade. By making the blade clearance constant the slope of pleat sidewalls may be constant even though each pleat follows a curvilinear path in plan view.