Lost key lock-out cylinder

A method for rekeying a cylinder lock having a shell with at least one pin tumbler receiving chamber and a plug mounted in the shell for rotation about an axis, the plug having a longitudinally extending keyway formed therein, a shear line being defined between the shell and the plug, the keyway communicating with the shear line so as to be registerable with the pin tumbler receiving chamber, a pin tumbler reciprocally mounted in said one receiving chamber of the shell, the pin tumbler comprising at least a bottom pin, a driver pin and a first master pin, the first master pin being located intermediate and in contact with the bottom and driver pins, the pins having a length in the direction of reciprocal motion thereof, the lock also having a spring for biasing the pin tumbler generally in the direction of the axis of rotation of the plug to a position where one of the pins extends across the shear line when a properly bitted key is not present in the keyway, said method comprising the steps of:

• inserting the blade of a first change-code key into the keyway, the blade having first and second surfaces, the first surface of the first change code key being provided with surface irregularities which define the key bitting, the second surface of the first change code key having an open-sided cut-out with a depth substantially equal to the length of the first master pin, the bitting of the first change code key displacing the pin tumbler against the urging of the spring whereby the interface between the bottom pin and the first master pin is located on the shear line;
• rotating the plug with first change code key from an initial key insertion position where the first change code key is inserted in the plug to a second position where the cut-out in the second surface of the first change code key blade is aligned with the pin tumbler receiving chamber in the shell, the bottom pin rotating with the plug, said establishment of alignment between the cut-out and the chamber thus resulting in displacement of the first master pin into the cut-out under the influence of the spring, such displacement placing the interface between the driver pin and the first master pin on the shear line;
• rotating the plug and first change code key to return the plug to the initial position;
• simultaneously withdrawing the first change code key and the first master pin from the plug;
• placing a second master pin in an open-sided cut-out in a second surface of the blade of a second change code key, the length of the second master pin being different than the length of the first master pin, the cut-out of the second change code key blade having a depth substantially equal to the length of the second master pin, the second change code key having a longitudinal slot which is parallel to the axis of plug rotation and which intersects the cut-out, the second change code key having a first surface provided with surface irregularities which define the key bitting, the bitting of the second change code key displacing the pin tumbler against the urging of the spring to position the interface between the driver pin and the bottom pin on the shear line;
• inserting the second change code key with the second master pin in the keyway with the plug in the initial position;
• rotating the plug with the second change code key from the initial position until the first cut-out in the blade of the second change code key is aligned with the pin tumbler receiving chamber, such alignment establishing an interface between the second master pin and the driver pin;
• inserting a control slide into the longitudinal slot in the second change code key until a first end of the slide contacts the second master pin;
• applying a longitudinally directed force to the control slide after contact between the first end thereof and the second master pin has been established, said longitudinal force being translated into radial motion of the second master pin against the bias of the spring, the radial pin motion placing the interface between the control slide and the second master pin at the shear line;
• rotating the plug and second change code key with the inserted control slide to the initial position to establish an interface between the bottom pin and the second master pin at the shear line;
• and
• withdrawing the control slide and second change code key from the keyway.

A method for rekeying a cylinder lock having a shell with at least one pin tumbler receiving chamber and a plug mounted in the shell for rotation about an axis, the plug having a longitudinally extending keyway formed therein, a shear line being defined between the shell and the plug, the keyway communicating with the shear line so as to be registrable with the pin tumbler receiving chamber, a pin tumbler reciprocally mounted in the said one receiving chamber of the shell, the pin tumbler comprising at least a bottom pin and a driver pin, the pins having a length in the direction of reciprocal motion thereof, the lock also having a spring for biasing the pin tumbler generally in the direction of the axis of rotation of the plug to a position where one of the pins extends across the shear line when a properly bitted key is not present in the keyway, said method comprising the steps of:

• placing a master pin in a first open-sided cut-out in a first surface of the linearly elongated blade of a change-code key, the blade of the change code key also having a second surface characterized by a pattern of surface irregularities which define the key bitting, the depth of the cut-out being substantially equal to the length of the master pin, the cut-out constraining movement of the master pin to a direction generally transverse to the length dimension of the blade, the blade of the change code key further having a longitudinal slot which intersects the first surface of the blade, the longitudinal slot also extending along the length of the blade to intersect the cut-out, the bitting on the second surface of the blade of the change code key having a contour which will cause displacement of the pin tumbler against the urging of the spring whereby the interface between the bottom pin and the driver pin is located on the shear line;
• inserting the change code key with the master pin carried thereby into the keyway, the master pin being rotationally displaced from the pin tumbler receiving chamber at the initial insertion position of the change code key into the keyway;
• rotating the plug by means of the inserted change code key from the initial position to a second position where the cut-out in the blade of the change code key is aligned with the pin tumbler receiving chamber, the rotation establishing an interface between the master pin and the driver pin at the shear line;
• causing a control slide to enter the longitudinal slot in the change code key and to move linearly along the slot until contract between a first end of the slide and the master pin is established;
• applying a longitudinally directed force to the control slide, the longitudinally directed force causing the master pin to generate a radial force which is directed generally transversely to the applied longitudinal force, the radial force being sufficient to overcome the force of the spring and displace the master pin out of the cut-out of the change code key blade whereby the interface between the master pin and the control slide will be located on the shear line;
• rotating the plug with the change code key and control slide as a unit to the initial position of the plug;
• and
• withdrawing the change code key and control slide from the plug.

A changeable code cylinder lock system comprising:

• a shell, said shell having a longitudinal axis and an inner diameter, said shell further having at least one pin tumbler stack receiving chamber which communicates with said inner diameter;
• a plug rotatably disposed in said shell, said plug having an outer diameter and having a longitudinally extending keyway formed therein, a shear line being defined between said shell inner diameter and said plug outer diameter, said keyway extending to said shear line;
• a pin tumbler stack reciprocally mounted in said receiving chamber of said shell, said pin tumbler stack comprising at least a bottom pin and a driver pin, said pins being axially aligned and having preselected axial lengths in the direction of motion thereof, said pin tumbler stack further including resilient biasing means in contact with said driver pin for urging said axially aligned pins to a position where one of said pins extends across said shear line when a key having a properly bitted blade is not present in said keyway, insertion of a properly bitted key into said keyway causing displacement of said axially aligned pins against the urging of said biasing means whereby the interface between an adjacent pair of said pins is located on said shear line and rotation of said plug relative to said shell is permitted;
• a master pin, said master pin having a cross-section commensurate with that of said driver and bottom pins, said master pin having a preselected axial length;
• a change code key, said change code key having a bow and blade which extends longitudinally from said bow, said blade having a cross-section which permits insertion thereof into said keyway, said blade being provided with irregularities in a first surface thereof commensurate with a bitting which will place the interface between an adjacent pair of said pins at said shear line, said change code key blade further having at least a first open-sided cut-out in a second surface thereof and a longitudinally extending open-sided slot, said slot intersecting and being in fixed relation to said cut-out, said cut-out having a depth commensurate with the length of said first master pin, said slot extending from said blade second surface for a distance which is at least as great as the depth of said cut-out;
• and
• a control slide, said control slide having a cross-section which permits reception thereof in said longitudinal slot of said change code key after insertion of said change code key in said keyway, said control slide having sufficient length to be at least in part in registration with said cut-out when said slide is received in said slot whereby said control slide may be employed to deliver a longitudinal force against a master pin disposed in said cut-out;
• rotation of said plug by means of said change code key with said master pin carried thereby aligning said master pin with said pin tumbler stack receiving chamber and establishing an interface between said master and driver pins, insertion of said slide into said slot in said change code key applying a longitudinal force to said master pin which is translated into a radial force sufficient to overcome the force of said biasing means and cause said master pin to move from said cut-out and into said pin tumbler chamber whereby the interface between said control slide and first master pin will be positioned on the shear line, said master pin being retained in said chamber and inserted into the pin tumbler upon subsequent rotation of said plug back to the initial position and withdrawal of said change code key from said keyway.