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:
Dec. 12, 1995
Filed:
Feb. 28, 1994
Roy T Abner, Lexington, KY (US);
Brian D Costley, Nicholasville, KY (US);
Sargent & Greenleaf, Inc., Nicholasville, KY (US);
Abstract
A manipulation resistant combination lock is shown which has a housing, a drive shaft, a cam driver attached to the drive shaft, a bolt slidable into and out of the housing, a fence lever, a fence attached to the fence lever, and a set of tumbler wheels. A first end of the fence lever is pivotally attached to the bolt, and a second end of the fence lever has a dog which is engagable with a slot in the outer periphery of the cam driver. The cam driver is keyed to the drive shaft and holds two circumferentially spaced permanent magnets, one on each side of the slot. The dog portion of the fence lever also has a permanent magnet mounted thereon. The permanent magnets mounted on the cam driver and on the dog portion of the fence lever are arranged such that opposing magnetic poles generate a repulsive force as the fence lever approaches both sides of the slot in the cam driver. This feature prevents a lock manipulator from detecting the precise location of the cam driver slot and therefore precludes the possibility of detecting the location of gates in the tumbler wheels that would line up with the fence at the point where the cam driver slot lines up with the dog on the fence lever.