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:
Apr. 11, 1978
Filed:
May. 16, 1977
Paul R Proefrock, Nicholasville, KY (US);
Sargent & Greenleaf, Inc., Nicholasville, KY (US);
Abstract
A key-operated rotary plug cylinder lock having rotary disc tumblers arranged in a stack with a concentric cylindrical boss on one face of each disc tumbler projecting axially into internesting relation into a complimental cylindrical well or recess in the confronting face of the next adjacent tumbler, and having center openings in the rotary disc tumblers shaped to receive a cylindrical guide pin along the center axis of the stack of tumblers and an arcuate substantially semi-circular cross section bit portion of a key. A set screw is threaded into the rear wall of the plug assembly to adjust the axial position of the guide pin and reduce the clearance between tumblers made to normal manufacturing tolerances to insure that the space between adjacent tumblers always assumes a labyrinth configuration resisting passing of a combination reading probe or picking tool therebetween and provides proper spacing for engagement with key bits. A frangible fence in the form of a bar having two relatively thin frangible fence portions extending into section peripheral recesses in the disc tumblers is subject to destruction upon attempts to torque the cylinder and thus render the cylinder inoperable, still in the locked condition.