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:
May. 14, 1991
Filed:
Jan. 08, 1990
Applicant:
Inventor:
Sterling J Anderson, Maple Grove, MN (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
E21C / ;
U.S. Cl.
CPC ...
299 22 ; 299 23 ;
Abstract
An apparatus (10) for placing a hard compact material such as rock surrounding a drill hole into axial tension for the purpose of breaking and excavating the material by virtue of a dual piston (23) and (25) arrangement disposed within a fluid cylinder (16) wherein the first piston (23) is attached to a thrust rod member (28) the second piston is attached to a wedge member (30) having an outwardly tapered conical end (34) and a feather member (40) surrounding the wedge (30) and thrust (28) members; wherein the feather segments (43) have a conical profile on both their internal and external peripheries.