The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 28, 2016
Filed:
Dec. 22, 2012
Kenneth B. Madgwick, Garden City, KS (US);
Kenneth B. Madgwick, Garden City, KS (US);
Other;
Abstract
A hydraulic pump jack cylinder is coupled with a closed loop hydraulic circuit, which includes a hydrostatic pump that delivers hydraulic fluid under pressure to the pump jack cylinder. The pump jack cylinder includes an inner extension piston area and an outer retraction piston area which are configured to have substantially the same area to establish a cylinder ration at 1:1. The hydrostatic pump drives the cylinder rod connected to the oil well sucker rod at a constant velocity in both the extension and retraction strokes with a quick sinusoidal turn-around at the ends of the strokes to provide a change in stroke direction. The swash plate in the hydrostatic pump brake the flow of fluid from the pump jack cylinder during retraction to prevent free-fall. A programmable logic controller controls the swash plate angles to switch stroke direction before the cylinder rod bottoms out.