Patent ID: 8360140

Claim:
A well head lubricator assembly, comprising: an elongated rigid tubular body having an upper end and a lower end and defining an interior chamber open at said lower end to receive a plunger at a well head, with a cap for closing said interior chamber at said upper end of said tubular body; and an axially elongated one-piece thermo-plastic ether ester elastomer spring defining an elongated bore opening to opposed ends thereof and which is generally coaxially aligned with a longitudinal axis of said spring, with said bore having a closed margin about a diameter thereof, and with said spring having a plurality of axially spaced flange sections along a length thereof, with each flange section having an outer diameter which is substantially equal to an inside diameter of the tubular body such that said flange sections axially guide said spring within said tubular body, and with any two axially adjacent flange sections on said spring being axially separated by an axially elongated energy absorbing section for allowing said spring to react to energy imparted to said plunger, and with each energy absorbing section having the form of a ring whose lateral outer face is curved toward an exterior of said spring, and wherein each energy absorbing section on said spring extending between any two axially adjacent radial flanges defines a wall having a generally constant cross-section ranging between about 17.5% to about 27.6% of an axial length of the respective energy absorbing section such that, upon axial compression of said spring, said energy absorbing sections radially expand outwardly toward an inner diameter of said tubular body.