Pumping unit with variable work stroke and return stroke torque factor characteristics

A pumping unit for actuating a down hole pump including a walking beam pivotally connected to a post at approximately a midpoint thereof by a saddle bearing, said post fixedly secured to a base mounted on the earth's surface, said pumping unit having a sequential pumping cycles including an upward work strokes and downward return strokes, comprising:

• a prime mover connected to supply power to a gear reducer mounted on said walking beam for rotating a drive shaft extending therefrom, a crank arm connected at one end to the drive shaft, said crank arm being interconnected to one end of a pitman rod for oscillating said walking beam in said pumping cycles, a rearward end of said walking beam having mounted thereon a counterweight that combined with the weight of said gear reducer, at least in part, balances the load of sucker rods connected to a forward end of said walking beam, said sucker rods operably connected to a subsurface pump, rotational cycles of said crank arm providing coordinated movement of said pumping cycles, said crank arm unidirectionally rotating relative to said walking beam through a maximum lever arm distance from the center bearing pivotal connection between said walking beam and said post as said forward end of said walking beam moves in work strokes upwardly lifting said sucker rods, said crank arm unidirectionally rotating relative to said walking beam through a minimum lever arm distance from the center bearing pivotal connection between said walking beam and said post as said forward end of said walking beam moves downwardly in return strokes lowering said sucker rods, a second end of said pitman rod being selectably connectable with respect to said post by which torque applied by said drive shaft during said upward work strokes compared with the acceleration during said return strokes is adjustably selectable.

A pumping system unit having a base supported with respect to the earth's surface, a sampson post structure extending upwardly from the base, a walking beam pivotally supported by a saddle bearing at the upper end of the sampson post and a horsehead affixed at a forward end of the walking beam adapted to support the upper end of a downwardly extending sucker rod string by which the string is vertically reciprocated, the system including:

• a gear reducer mounted at selectable positions relative to said saddle bearing on said walking beam having a horizontally extending output drive shaft having an axis of rotation with respect to the walking beam;
• a crank arm having an inner end affixed to said output drive shaft and a crank pin bearing adjacent an outer end thereof, the crank throw achieved by the spacing between said crank arm and said crank pin bearing being adjustable;
• a selectable length pitman rod having a first end secured to said crank arm crank pin bearing and a second end having a pitman bearing that is selectably mountable to a plurality of pitman bearing locations relative to said base and sampson post structure;
• and
• a prime mover for supplying energy input to said gear reducer for the rotation of said output shaft and wherein the pumping characteristics of the pumping unit are determinable by the combination of (1) the selectable position of said gear reducer relative to said saddle bearing, (2) the selectable crank throw of said crank arm, (3) the selectable length of said pitman rod, and (4) the selectable pitman bearing location.