Patent ID: 8438889
Filing Date: 2013-05-14
Classification: E05B,Y10T

Abstract:
1. A pin and tumbler cylinder lock which is configured to prevent opening of the lock by bumping comprising: a cylinder; a plug rotably mounted in the cylinder and having a key slot and forming a shear line between the inner surface of the cylinder and outer surface of the plug, the cylinder and plug having a plurality of registering radial pin receiving bores which have straight non-chamfered sidewalls at the shear line; spring pressed top driver pins mounted in the cylinder holes, each of the driver pins being about the same height; and tumbler pins mounted in the registered plug bores; wherein each of the top driver pins has a smaller diameter intermediate section forming at least a lower lip having an inner surface and an outer surface where the outer surface of each top driver pin lip is in contact with the upper surface of the registered tumbler pin and the inner surface of each top driver pin lip is below the shear line and the thickness of the lip of the top driver pin is less than the shear line height minus the tallest tumbler pin stack height of the lock so that if the plug is rotated during bumping the driver pins will be disposed at an angle because of the smaller diameter intermediate section of the top driver pins and the driver pins will be caught at the shear line preventing rotation of the plug and opening of the lock by the bumping.