Cylinder lock with a lock picking impediment

Abstract

An improved cylinder lock which is very difficult to pick has at least one cylinder pin into which a set of shallow grooves has been cut as well as a deeper notch at one end of the pin. A boring is made in the cylinder at an angle to the boring of the cylinder pin and into which is placed an appropriately sized obstructing pin. The obstructing pin is free to drop into a recess made in the lock housing when the cylinder is locked. The process of attempting to pick the lock by rotating the cylinder slightly results in the obstructing pin sliding along the side of the V-shaped recess in the housing and thereby moving toward and engaging the notches in the body of the cylinder pin preventing unauthorized movement of the cylinder pin which would render the associated locking pin inoperative. When a legitimate key has been inserted into the cylinder, the cylinder pin moves to its fully unlocked position before the cylinder rotation is initiated. Upon initiation of the cylinder rotation, the obstructing pin slides up the V-shaped recess in the cylinder lock and the end thereof moves into a deeper V-shaped groove at one end of the cylinder pin, which has already achieved its unlocked position, thereby permitting the cylinder lock to freely rotate. Since the notches in the cylinder pin disengage the obstructing pin when the attempted illegitimate rotation has been ceased, the lock may then be unlocked in a normal fashion using a proper key.