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. 27, 2000
Filed:
May. 12, 1998
Applicant:
Inventors:
Vern Arthur Hult, Calgary, CA;
Curtis Christopher Blundell, Calgary, CA;
Assignee:
Weatherford Holding U.S., Inc., Houston, TX (US);
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
E21B / ;
U.S. Cl.
CPC ...
166 685 ; 166 781 ; 188184 ;
Abstract
A backspin retarder for a shaft comprises a brake mechanism including a stationary brake member and opposed brake members rotatable with the shaft and movable between braking position in which the movable brake members engage the stationary brake member and a non-braking position in which the movable brake members are removed from the stationary brake member and a brake control mechanism responsive to the direction of rotation of the shaft for disabling the brake mechanism when the shaft rotates in a forward direction and for enabling the brake mechanism when the shaft rotates in a reverse direction.