Patent ID: 7954510

Claim:
In combination with a pump which comprises a fluid bore and a valve member which is positioned in the fluid bore, the fluid bore comprising a central axis and a pair of generally diametrically opposed, radially inwardly extending protrusions which are spaced apart a distance, the improvement comprising a retainer for the valve member which includes: a retainer head which comprises a pair of diametrically opposed grooves within which the protrusions are received to thereby secure the retainer head within the fluid bore; a retainer hub which is connected to or formed integrally with the retainer head and which is movably coupled to the valve member; each groove defining a corresponding pair of upper and lower lips, the upper lips being disposed in a first plane which is generally perpendicular to the central axis and the lower lips being disposed in a second plane which is generally perpendicular to the central axis; wherein the width of the retainer head in each of the first and second planes in a direction generally perpendicular to a line joining the grooves is less than the distance between the protrusions.