Patent ID: 9045949
Filing Date: 2015-06-02
Classification: E21B,F04B,Y10T

Abstract:
1. A tool connectable between the last sucker rod of a sucker rod string and a downhole pump comprising: a circular cylinder having a closed upper end externally adapted for connection to the last sucker rod of the sucker rod string; and a circular cylindrical piston reciprocally slidably and rotatively disposed within said cylinder and having a lower portion extending through an opening in a lower end of said cylinder and adapted for connection to the pump; said closed upper end of said cylinder and an upper face of said piston having a cooperable tongue and groove for preventing relative rotational motion of said piston in said cylinder when said tongue is engaged in said groove, said tongue being engagable in said groove by an intentional rotation of the string at a top of a stroke of the string until said groove rotates into alignment with said tongue and an upward inertia of said tongue causes said tongue to engage in said groove and turn therewith.