Pin tumbler lock

Claim 1

A key-removable pin tumbler lock core comprising core body having an axial bore, a sleeve mounted for limited rotation in said bore and carrying a lug movable therewith between a retracted position and an advanced position for retaining the core in a housing, a key plug having an axial keyway, rotatably mounted in the sleeve, a plurality of pin bores extending from said core body through the wall of said sleeve and into the key plug for receiving pin columns to be acted on by a key in said keyway, the interface between said sleeve and core body defining a control shear line at which such pins may block lug-retracting rotation of said sleeve, the interface at the periphery of said key plug defining an operating shear line at which such pins may be block rotation of said key plug, said control shear line and operating shear line being spaced from each other by a distance of 0.125 inches, said pin bores being constructed and arranged to receive columns of pin segments, each of said columns includes a lower segment having tapered lower end of arbitrary length forming a keyengaging end for engagement with cut faces on a key inserted in said keyway and is otherwise composed of segments which have lengths in whole numbers of 0.0125-inch increments, with each column axially movable in its bore to 10 combinating positions therealong spaced from each other by whole 0.0125inch increments, the key-engaging ends of said pin columns having corresponding predetermined combinating positions spaced from each other by whole 0.0125-inch increments over a predetermined key-cut range within said keyway, and with each column extending upward from said tapered lower ends a distance in whole 0.0125-inch increments such as to extend across both shear lines and into the core body in all said positions of the column and to dispose the top of the column in positions within a predetermined top-end range corresponding to the key-cut range, said pin extending upward beyond such column to receive springs for urging such column toward the keyway and operative over said predetermined top-end range, 10 of said whole increments being equal in length to the 0.125inch spacing between said shear lines, the core being thereby operable with a control key for shear separation at said control shear line and witH an operating shear line, with columns of pin segments which have lengths, excluding the arbitrary length of said tapered end, in whole numbers of said 0.0125-inch increments, to dispose shear faces therebetween at either of said shear lines with keys having key cuts in the same predetermined combinating positions for both operating and control actuation, wherein the improvement comprises said lock core being provided in each pin bore with a column of base-7 pin segments including a lower segment having a tapered lower end of arbitrary length forming a key-engaging end for engagement with cut faces on a key inserted in said keyway and being otherwise composed of segments which have lengths in whole numbers of 0.018-inch increments, each column of said base-7 segments being axially movable in its bore to seven combinating positions therealong spaced from each other by whole 0.018-inch increments, the key-engaging ends of said pin columns having seven corresponding combinating positions spaced from each other by whole 0.018-inch increments in the same said predetermined key-cut range, each column extending upward from said tapered lower end a distance in whole 0.018-inch increments such as to extend across both shear lines and into the core body in all positions of the column and to dispose the top of the column substantially within the same said predetermined top-end range, springs in said pin bores for urging said base-7 columns toward the keyway and operative over the top end range of said base-7 columns, seven of said whole 0.018-inch increments being equal in length to a distance which is operably equivalent to the 0.125-inch spacing between the said shear lines, the core being thereby made operable with control and operating keys for shear separation at each of said shear lines with keys cut to support said base-7 segment columns in said seven combinating positions spaced from each other by such 0.018-inch increments in said same predetermined key cut range, whereby the lock core is provided with wider separations between shear face positions in its pin columns than with said 0.0125inch increment pins and the number of useable combinations therein is increased.