Patent ID: 8647083

Claim:
An improved plunger for a pumping apparatus comprising, in combination: a threaded north end configured to connect with a pump rod; a threaded south end; a center region between the threaded north end and the threaded south end; an interior channel extending through the threaded north end, the threaded south end, and the center region; a first shoulder located below and extending from the threaded north end capable of connecting with a pump rod, the first shoulder having a right triangular cross section wherein a height of the right triangular cross section is on an outer diameter of the first shoulder; and one or more shoulders located below the first shoulder, the one or more shoulders having a right triangular cross section wherein a height of the right triangular cross section is on an outer diameter of the one or more shoulders; wherein the first shoulder and the one or more shoulders located below the first shoulder are angled upwardly towards the north end; and wherein the outer diameter of the first shoulder is less than that of the center region in order to prevent contact between the first shoulder and a surrounding barrel.