Valve cage for a rod drawn positive displacement pump

A cage for a reciprocating rod drawn positive displacement pump valve, comprising:

• a generally tubular side wall forming an axial bore for containing a valve ball, said side wall having upper and lower ends and forming an external thread for connection with one of the pump plunger or barrel, said side wall forming an internal annular seat shoulder adjacent its lower end, against which a seat may abut to provide an annular seating area against which the valve ball may seal;
• said external thread being located intermediate the upper and lower ends of the side wall;
• stop means, integral with the side wall and extending transversely of the bore in spaced relation above the seat shoulder, for limiting upward rise of the ball from the seat, said side wall and stop means forming a confining enclosure within which the ball may travel vertically when unseated;
• said stop means being located at the upper end of the side wall;
• said side wall diminishing progressively in thickness between the seat shoulder and the stop means so that a tapered and upwardly enlarging portion of the bore is defined, whereby the flow area around the valve ball will increase as the ball rises from the seat toward the stop means;
• and
• said side wall forming a plurality of internal, elongated, circumferentially spaced apart, inwardly projecting ball guide ribs which extend longitudinally between the seat shoulder and the stop means and progressively increase in height, as the side wall diminishes, along their lengths from the seat shoulder to the stop means, so that they form a race of substantially constant diameter for vertically guiding the valve ball.