Patent ID: 12241278

DETAILED DESCRIPTION FOR CARRYING OUT THE INVENTION

There have been many attempts over the last century to make pin tumbler locks unpickable. As used herein, the term “picking” refers to manipulation of pins in a lock assembly to actuate the lock assembly without using its matched key (or true key). Some locks remained unpicked for a period of time, but eventually, every design has been picked. Almost every “high security” or “pick-resistant” lock designer has increased the security of locks by adding more and more complicated elements (such as such as sidebars, security pins, and pins in different orientations) to their locks increasing the cost of production and difficulty in servicing these locks by trade professionals, even requiring locksmiths to purchase specialized equipment and parts to be able to service the locks. With the addition of more security features, complications are introduced which add to the number of elements that need to be manipulated in order to operate the locks and adding extra costs to the end user.

In one prior art example described in U.S. Pat. No. 5,964,111 (incorporated herein by reference in its entirety), there is a conventional pick-resistant lock assembly with an intermediary cylinder between the cylinder of the lock, which is in direct contact with the key, and the outer housing of the lock to provide a shield to separate the rotating function of the first cylinder from the “picking” or pin stack manipulation process. This lock assembly is shown inFIG.1, where it is seen that upon inserting a key4into the keyway18of the inner cylinder1, the pin stacks either are or are not raised to the proper levels at that time, depending upon whether the correct cut depths are present on the key4. The inner cylinder1must then be rotated by an amount that allows a cam pin stack formed of pins9and10to drop down on one side or the other of the pin cam16groove, at which time the shear line between parts9and10will allow cylinder2to rotate within the housing3. The bottom cam pin9will then also become connective between the inner cylinder1and the intermediate cylinder2which then allows the key4to also rotate cylinder2as it further rotates inner cylinder1. Even if the wrong key has been inserted, the inner cylinder1will rotate to this point because of a multitude of pins (known in the trade as master pins) in each pin stack area that comprises what is known as the bottom of the pin stacks. But since it is the shear line between the intermediate pins6and the top pins7that determines whether the intermediate cylinder2can be rotated, if the wrong key has been inserted it will not be discovered until after inner cylinder1has been rotated beyond the point where any pins in any of the stacks can be further manipulated. If the correct key4is being used, then further rotating of inner cylinder1pushes upon the side of the bottom cam pin9, which itself conveys that force to rotate the intermediate cylinder2, and, since all the shear lines between the pins6and7are now properly aligned, cylinder2will rotate further. While this particular lock assembly provided additional security relative to conventional lock assemblies, shortcomings in its construction were recognized by the present inventor. For example, this lock assembly is susceptible to over-lifting during picking attempts and its construction cannot be easily scaled down to fit existing door hardware, such as key-in-knob arrangements, key-in-lever arrangements and padlocks. The present inventor has also recognized that multiple operating shearlines in one cylinder can be accidently created during the manufacturing or pinning of this lock assembly and that the shearline can still be detected by skilled lockpickers because the true shearline can be achieved with the core in its resting position.

To address these and other shortcomings of conventional pick-resistant lock assemblies, the present inventor has conceived of an alternative arrangement for increasing the number of shear lines in a lock assembly that can be achieved during manipulation of the locking elements while configuring only one operable shearline capable of operating an associated lock actuator. The provision of many “decoy” shearlines will cause an attempt at picking the lock to generate a shearline which will allow rotation of an inner core without rotating an outer sleeve which actuates the lock. In exemplary embodiments described hereinbelow, a five pin lock will provide 32,768 possible shearlines with only one being operable to rotate the outer core to actuate the lock. Therefore, while it is possible that the lock assembly of this particular embodiment may be picked, the odds of successfully doing so is 1 in 32,768 possible attempts. It would therefore require an inordinate and unreasonable number of attempts for a skilled lock picker to be successful.

Embodiments of the present lock assembly make it essentially impossible for someone attempting to pick the lock to have control over the tension on the core in order to manipulate each pin stack at a time and verify that setting. The configurations of the pin stacks make it impossible for an over-lift attack to be successful. The example embodiment described herein has minimal customized components and this will significantly simplify the re-keying processes performed by locksmiths and eliminate the chances of accidently introducing multiple operating shearlines, as well as reducing the manufacturing cost. The configurations of pin stacks will make it possible for key cutters to use their existing machines to copy/cut keys for the end user by utilizing cut depths and key codes that manufacturers are already using.

A first example embodiment will now be described with reference toFIGS.2to14. For the purposes of illustration, components depicted in the FIGS. are not necessarily drawn to scale in all cases. Emphasis is placed on highlighting the various contributions of the components to the functionality of this embodiment and alternative embodiments. Alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the present technology.

InFIGS.2to14, there is shown a first example embodiment of a pick-resistant lock assembly100developed by the present inventor.FIG.2shows the lock assembly100with a key120inserted into the core via a keyway (see inFIG.3). The core110is covered with a housing140. The housing140includes an upper chamber142for holding pin stacks160(not visible inFIG.2but seen inFIGS.4-6,9and10). A cover141is provided above the pin channels144(seeFIGS.4and5) which are located inside the chamber142. InFIG.3, the key120is removed, exposing a keyway111.

The partially exploded view shown inFIG.4has the housing140and cap130removed to expose an inner sleeve150. The cap130serves as a base for attachment of an actuator which operates a bolt or latch (not shown). During construction of the lock assembly100, the core110is inserted into the sleeve150and then the sleeve150is inserted into the main housing bore143, followed by threading the cap130onto the exposed end of the sleeve150. Then the pin stacks160are placed in the pin channels144of the chamber142. This is followed by installation of the cover141. The components and function of the pin stacks160will be described in more detail hereinbelow.

The exploded view ofFIG.5has the sleeve150separated from the core110to show that the sleeve has a bore151and a series of upper openings152of which the five-leftmost openings align with the pin channels144of the chamber when the assembly100is formed.FIG.5also indicates that the rightmost pin stack is different from the others, including only two parts which are shown in more detail inFIG.9.

Turning now toFIG.6, there is shown a top perspective exploded view of part of the lock assembly100with the sleeve150removed from the core110to show that the five leftmost sleeve openings152differ from the rightmost centralizer pin opening156, which includes a beveled edge. It is also seen inFIG.6that the sleeve152has a threaded connector153which is used to install the cap130.

FIG.7shows the core110by itself, indicating that it includes five core openings114for retaining portions of the pin stacks160(which are seen inFIG.6but omitted inFIG.7). It is to be understood that each pin stack160is placed in a corresponding channel of the pin channels144in the chamber142of the housing140. The pin channels144are aligned with the openings152in the sleeve150and the core openings114such that when the pin stacks160are dropped into the pin channels144, they will drop down into the keyway111of the core110.FIG.7also shows that core wafer receivers112in the form of laterally extending grooves are provided on each side of each of the core openings114. The functionality of the core wafer receivers112will be described in more detail hereinbelow. While this embodiment100has two opposed wafer receivers112, alternative embodiments may be constructed with only one wafer receiver112on either side of each of the openings114.

FIG.8is an end view of the sleeve150from its open end, indicating that the opposing end is closed with an end wall155. The end wall155has a shaped recess154formed therein. This recess154is provided to accept the end of an actuator shaft113which extends from an end of the core110(seeFIGS.6and7). The function of the actuator shaft113and recess154will be described in more detail hereinbelow during a description of operation of the lock assembly100.

FIG.9is a side elevation view of selected components of the lock assembly100with the key120inserted into the core110. The core110is shown as transparent in order to visualize the key shaft which has portions of different levels to elevate each of the pin stacks160to different levels. Each of the pin stacks160includes a spring161which pushes against the cover141of the housing140(the cover141is not shown inFIG.9in an effort to preserve clarity). Each of the pin stacks160includes a spring161, a driver pin166, one or more thin wafers162located above and below a thicker shear wafer163(which in this embodiment has a height dimension greater than the height of the thin wafers162), and either a tall key pin164or a short key pin165which is brought into contact with one of the levels of the shaft of the key120when the key120is inserted into the keyway111(the five different levels may be identified by the vertex of each of the five key pins164,165, which makes contact with the key shaft). The rightmost pin stack160has a top-to-bottom arrangement including a spring161, a centralizer driver167and a generally frustoconical centralizer pin168which drops into the centralizer pin opening156in the sleeve150(seeFIG.6). The centralizer pin168is held in place by a gap in a snap ring115which is held in a groove in a reduced diameter portion of the core110from which the actuator shaft113extends. The centralizer pin168therefore does not make contact with any surface of the key120and does not play a role in actuation of the lock assembly100. Instead, the centralizer pin168serves to prevent undesirable rotation of the core110away from a centralized resting position wherein the keyway111is vertically disposed.

It is to be understood fromFIG.9that the true key120is configured to actuate the lock mechanism of the lock assembly100. This is accomplished by elevating the pin stacks160to provide a true shear line which will permit actuation of the lock mechanism. The true shear line follows a gap between the bottom of each shear wafer163and the outer surface of one of the wafer receivers112formed in the outer sidewall of the core110as will be described in more detail hereinbelow. InFIG.9, it is to be noted that the bottom of each shear wafer163of each pin stack160is generally aligned with the upper outer surface of the core110.

Turning now toFIG.10, there is shown a side elevation view of five pin stacks160A-E (excluding the rightmost sixth pin stack with the centralizer pin168, which is included inFIG.9). The five pin stacks160A-E are arranged in this view with the vertices of the key pins164and165aligned in order to more clearly discern the different arrangement of thin wafers162with respect to the shear wafer163within each pin stack. It is to be understood that each pin stack includes one driver pin166, six thin wafers162, one shear wafer163and either a tall key pin164or a short key pin165. In this particular embodiment, the difference in height between the tall key pins164and short key pins165is equivalent to half of the height of one thin wafer162. In this particular embodiment, all driver pins166have a substantially identical height; all thin wafers162have a substantially identical height; and all shear wafers163have a substantially identical height. In this particular embodiment, the proportions of relevant heights of selected components of each pin stack160is as follows: proportional height difference between tall key pins164and short key pins165=1; height of thin wafers163=2; and height of shear wafers163=3. Alternative embodiments may be provided with pin stacks having wafers and/or key pins and driver pins of different dimensional proportions with more or fewer wafers.

It can be seen that each one of the pin stacks160A-E has a different vertical arrangement of thin wafers162, shear wafers163and key pins164and165(for example, pin stack160A has a top-to-bottom arrangement of four thin wafers162, one shear wafer163, two thin wafers162and one tall key pin164and the adjacent pin stack160B has a top-to-bottom arrangement of five thin wafers162, one shear wafer163, one thin wafer162and one tall key pin164—therefore the vertex of the tall key pin164of pin stack160B must be moved to a higher level than its corresponding tall key pin164of pin stack160A to align the shear wafers163of these two pin stacks160A and160B, as seen inFIG.9). These arrangements provide the ability to change the vertical level of the shear wafer163within each of the pin stacks160A-E. Therefore, only when the correct key120is inserted into the keyway111, will the pin stacks160A-E be properly elevated to align the bottom edge of each shear wafer163with the outer surface of the core110such that the shear wafer163will move into one of the wafer receivers112as the core100is rotated (seeFIG.9). It is to be understood that many different combinations of different arrangements of pin stacks is possible and these different combinations will require corresponding different true key configurations to properly actuate the lock mechanism.

FIGS.11to14illustrate transverse cross sections of the lock assembly taken across pin stack160E.FIGS.11A and11Bare provided for the purpose of labelling the main components involved in the functionality of the device in providing several decoy shear lines for pin stack160E so that they can be recognized with minimal labelling inFIGS.12to14in an effort to preserve clarity.FIGS.12to14illustrate rotation of the core110and components of the pin stack160in generation of decoy shear lines (FIGS.12and13) and the true shear line (FIG.14).

Turning now toFIG.12, the cross-section image on the left side of the arrow has the core110in the resting centralized position. The cross-section image on the right indicates the location of the core110and components of the pin stack160E after the pin stack160E is dropped and the core110is rotated clockwise in the orientation shown, while the sleeve150remains stationary. It is seen in the image on the right that the shear wafer163has dropped below the sleeve150into the keyway111and a decoy shear line is attained between the second and third uppermost thin wafers162. This causes the wafer receiver112on the left side of the core110to become occupied by the uppermost two thin wafers162. The combined height of the two thin wafers162is greater than the combined height of the leftmost side of the wafer receiver112and the thickness of the sleeve150. A potential shear line between the first and second uppermost thin wafers162is located between the outer and inner sidewalls of the sleeve150. This provides the effect of blocking further clockwise rotation of the core110and sleeve150, which is required in order to actuate the lock mechanism which requires that the core110and sleeve150rotate together to press the actuator shaft113against the sidewall of the sleeve recess154(seeFIG.8) in order to rotate the connected end cap130which is connected to an actuator of a bolt or latch mechanism (not shown).

Referring now toFIG.13, there is shown another example of a decoy shear line being attained with subsequent blockage of rotation of the sleeve150and core110. InFIG.13, the cross-section image on the left side of the arrow has the core110in the centralized position. The cross-section image on the right side of the arrow indicates the location of the core110and components of the pin stack160E after the core is rotated clockwise in the orientation shown. It is seen in the image on the right that the shear wafer163has not dropped into the keyway111and instead remains in the pin channel144E while two thin wafers162occupy the wafer receiver112to block rotation of the core110and sleeve150. This provides the effect of blocking further clockwise rotation of the core110and sleeve150as described above forFIG.12.

With two examples of decoy shear lines in pin stack160E having been described with respect toFIGS.12and13(and understanding that more decoy shear lines are possible), the operation of the lock assembly100when the true shear line is attained is now described with respect toFIG.14. While not illustrated specifically inFIG.14, it is to be understood that operation of the lock mechanism requires that all five of the pin stacks160A-E are arranged to have their corresponding shear wafer163in the same position as shown inFIG.9, with the bottom surface of each shear wafer located above the upper surface of the core110(in other words, if one of the pin stacks160is not aligned properly with the true shear line, the sleeve150will not rotate). The completely aligned true shear line position is illustrated in the leftmost cross-section image inFIG.14. In this leftmost image, the shear wafer163is initially aligned with the keyway111and the pin channel144E and located between the two wafer receivers112. With initial clockwise rotation of the core110in the middle image, it is seen that the shear wafer163has dropped into the left wafer receiver112. It is to be noted in this middle image that the top surface of the shear wafer163is aligned with the outer surface of the sleeve150and therefore, there is no blockage of rotation of the sleeve150as occurs for the decoy shear lines illustrated inFIGS.12and13. Because there is no blockage, true shear line170E is attained and both the core110and the sleeve150are permitted to rotate further clockwise to the position shown in the rightmost image, where it is seen that the shear wafer163held in the left wafer receiver112has rotated over to the right side. In attaining this position, the actuator shaft113then can press against the sidewall of the recess154of the sleeve150(seeFIG.8) to cause the sleeve150and connected cap130to rotate and actuate the locking mechanism.

The operating principle of this embodiment100of the lock mechanism requires blockage of rotation of the sleeve150when a decoy shear line is attained and allowance of rotation of the sleeve150when the true shear line is attained, and in the latter case only when the true shear line is attained for all five of the pin stacks160A-E. In this embodiment100, the true shear line170E is attained by having the height dimension of the shear wafer163substantially equivalent to the depth of the wafer receiver112plus a transverse cross-sectional width of the sleeve150, thereby providing the true shear line between an upper surface of the shear wafer163and a sidewall of the main bore143of the housing140.

Because there are seven decoy shear lines and one true shear line for each of the five pin stacks160A-E, the total number of possible shear lines in this embodiment100is 85=32,768 and therefore the odds of successfully picking this lock assembly is 1 in 32,768. These highly challenging odds are expected to immediately deter even the most skilled of lock pickers. This embodiment has one true shear line for each pin stack. Alternative embodiments may have additional true shear lines for each pin stack to provide a master keying system. However, it is recognized that provision of additional true shear lines decreases the number of decoy shear lines.

InFIGS.15to25, there is shown a second example embodiment of a pick-resistant lock assembly200developed by the present inventor. In the exploded view shown inFIG.15, it is seen that the lock assembly200has several general features which are similar to those of embodiment100, such as a key220, a core210with a keyway211, a sleeve250a housing240with a housing bore243and pin channels244in a chamber242for holding pin stacks260and a locking pin269. The core210extends through the housing210and is configured to receive an end cap230. One difference between this embodiment200and the previously described lock assembly100is that the pin channels244are covered by individual set screws261threaded upper ends of the pin channels244formed in the pin chamber242of the housing240(seeFIG.16A). The set-screws facilitate re-keying of the lock to a new true key by permitting a locksmith to reconfigure the pin stacks260individually while keeping the other pin stacks contained within the pin channels244. The pin stacks260also have springs (not shown inFIG.15) located between the set screws261and the driver pins266(illustrated best inFIG.19) in an arrangement similar to the arrangement of springs161illustrated for lock assembly100(seeFIG.9). The springs of embodiment200also provide a downward-biased force on the driver pins266which is overcome by placing the true key220(or other implement) into the keyway211.

The sleeve250is shown by itself in two different orientations inFIGS.17A and17B, indicating an arrangement of six sleeve openings252extending into the central bore251of the sleeve250. This sleeve250differs from the sleeve150of embodiment100by having an internal ridge257which plays a role in rotation of the sleeve250as described hereinbelow. The sleeve250in of this embodiment200is conveniently formed of two parts in order to conveniently form the ridge257which functions to move the sleeve250with the core210when the true shear lines are attained.

The core210is shown in three different orientations inFIGS.18A,18B and18C. Like the core110of embodiment100, a series of core openings214is provided to hold the pin stacks260. The wafer receivers212however differ from the wafer receivers112of embodiment100. The wafer receivers112of embodiment100are in the form of laterally extending grooves on each side of the core openings. In contrast, in embodiment200, the wafer receivers212formed in the core are indentations or divots which are separated in space across the outer sidewall of the core210from the core openings214and which are shaped specifically to receive and retain a complementary shaped shear wafer270, which is illustrated inFIGS.19and20. In this particular embodiment, the wafer receiver212is shaped to receive a lower conical protrusion272(seeFIG.20A) of the otherwise disk-shaped shear wafer270. However, alternative embodiments may use other shapes such as spikes, radiused protrusions, blocks or other three-dimensional polygonal shapes, provided that the indentations and the shaped shear wafers have complementary shapes permitting the shear wafers to partially fit within the indentations such that the upper surface of the shear wafer aligns with the shear line to permit rotation of the sleeve250, as described in more detail hereinbelow, to permit rotation and actuation of the lock assembly200.

The core210of embodiment200also differs from the core110of embodiment100by being provided with a lock pin groove219and a threaded connector215for connecting the core210to the cap230. The functionality of the lock pin groove219will also be described in more detail hereinbelow.FIG.18Calso shows a socket231which cooperates with a complementary protrusion in the inner sidewall of the cap230in the actuation mechanism (not shown).

In this embodiment200sleeve is not connected to the actuator. The actuator is activated by the core210turning past 45 degrees.

The socket231arrangement in this embodiment200is a conventional feature. It serves to lock the end cap230in place by having a spring pushing a pin into one of the semi-circular features in the end cap230so it cannot rotate and come off inside the lock housing240. The pin that resides in this socket231also serves to connect the core210to the actuator that is sandwiched between the core210and the end cap230.

Other arrangements of engaging structures may be provided in alternative lock actuation mechanisms.

FIG.19illustrates a representative example of an arrangement of pin stacks260for embodiment200in a manner similar to that ofFIG.10, described above. Each pin stack includes a driver pin266, six thin wafers262, a single shear wafer270and either a short key pin264or a tall key pin265. As indicted in the list of components below each one of the pin stacks260A-E, the shear wafer270of each pin stack can be provided at a different height matching its position on the true key to generate the true shear line for actuating the lock, as described above for embodiment100.

Turning now toFIG.21, there is shown a cross section of the lock assembly200taken across pin stack260A, which has a vertical arrangement from top to bottom which includes a driver pin266, four thin wafers262, a shear wafer270, two thin wafers262and a short key pin264. It can be seen that the core210is shaped differently from the core110of embodiment100. In addition to the differently shaped wafer receivers212, core210includes a longitudinal cut-out portion216defining a recess with a shoulder217at each end. The ridge257of the sleeve250is located within this cut-out216and is moveable therewithin when the sleeve250is rotated. This cross-sectional view also indicates that the wafer receivers212are conical-shaped divots. It can be seen in this view that the labeled thin wafer262has a height which blocks rotation of the sleeve250if the core210is rotated.

FIG.22shows the result of such a clockwise rotation of the core where the labelled wafer262blocks rotation of the sleeve250. In this arrangement, the shear wafer270is located further down inside the core210and incorrectly placed for lock actuation. The rotation of the core210indicated inFIG.22therefore represents a decoy shear line.

FIG.23, in contrast withFIG.22, shows the proper pin height for pin stack260A which would be provided by the true key pushing the pin stack260A to the correct height. It is seen that the shear wafer270is at the correct height to have dropped into the wafer receiver212. The result of this action is that the top surface of the shear wafer270is at the same height as the outer sidewall of the sleeve250, thereby providing the true shear line for this pin stack260A and permitting further rotation to occur. The results of this rotation are shown inFIG.24, where the arrangement ofFIG.23is copied on the left side to facilitate visualization of the movement of components in the process. The lower shoulder217of the cut-out216of the core210is pushed upward against the ridge257of the sleeve250, causing the sleeve250to rotate clockwise as well. Continued rotation to provide the arrangement on illustrated on the right side ofFIG.24indicates that the shear wafer270continues to occupy the wafer receiver212as the core210and sleeve250are rotated together. The rotation to this position will lead to actuation of the lock in a manner similar to the actuation described above for embodiment100, with a cooperative interaction between complementary engaging structures provided between the inward end surface of the core210and an inner surface of the cap230serving to actuate the lock. The socket231seen inFIG.18Bis an example of such an engaging structure which cooperates with a complementary structure (not illustrated) provided in the cap230.

Turning now toFIG.25, there is shown operation of the lock pin269and the lock pin groove219formed in the core210which is another feature of embodiment200that differs from embodiment100. The lock pin groove219is also shown inFIGS.18A to18Cwhere it is seen that it is located adjacent to the connector215. The lock pin groove219has curved inner sidewalls which provide a cam surface213(seeFIG.25) that allows the lower end of the lock pin269to ride up and out of the lock pin groove219only when the true key has activated all of the true shear lines of the pin stacks260. With reference toFIG.25, there is shown a series of core210and sleeve250positions as cross sections taken through the lock assembly at the section cutting through the locking pin269. In step A, the locking pin269is located in the middle of the lock pin groove219with the lock assembly200in the resting position (keyway211oriented vertically). Following clockwise rotation of the core210to the position shown in step B, the lock pin groove219moves to the right and the bottom of the lock pin269encounters the cam surface213of the lock pin groove219. As noted with respect toFIG.24, further rotation of the sleeve250is only permitted if the true shear line of each pin stack260is attained. In this case, further rotation to step C (lower left ofFIG.25) causes the lower end of the lock pin269to slide out to the surface of the core210. From that point, the lower end of the lock pin269can move up to the outer surface of the sleeve250, allowing rotation to the lock actuation position of step D.

It is to be understood that the lock pin269moves to the outer surface of the core210just after the pin channels244are no longer accessible via the keyway211and just before the series of shear wafers270drop into their respective wafer receivers212. Therefore, the lock pin269locks the sleeve250to the housing240until the core210is rotated to “test” the shear line. As a result, the lock pin groove219moves every time the core is rotated and not just when the true shearline is reached. The main purpose is to stop lock picking efforts which attempt to set pins above the sleeve to operate the lock. In some embodiments, the lock pin groove219may also have a slightly deeper indentation at top dead center, to help realign the core210while removing the key after lock operation. The sleeve250only serves to stop the rotation of the core after turning it about 40 degrees in either direction when a decoy shear line is selected.

The following is a summary of the order of operation of lock assembly200with the assembly200installed as a standard door lock and referring to the orientation of the cross sections ofFIGS.23to25, with the starting position of the keyway211defined as zero degrees. When the true key220(not shown inFIGS.23to25) is inserted and used to rotate the core210clockwise by about 35 degrees, the lock pin269moves out of the lock pin groove219. A further clockwise rotation to about 40 degrees causes the lower shoulder217of the core210to make contact with the ridge257of the sleeve250. This action causes sufficient rotation of the core to cause the shear wafer270to drop into the left wafer receiver212. This action provides the true shear line and permits the sleeve250to rotate together with the core210. Further rotation by about 45 degrees initiates actuation of the lock. Further rotation by about 40 degrees retains the lock in the open position and the shear wafer270is returned to the pin stack244. Subsequent counter-clockwise rotation by about 35 degrees places the lock pin269back into the lock pin groove219. Continued rotation back to zero degrees (the resting position) permits removal of the key220from the keyway211. To re-lock the assembly200, the same operations are repeated in the reverse direction.

During a lock picking attempt using any implement other than the true key220, the core210may be rotated by up to about 35 degrees causing the lock pin269to move upward. Further rotation of the core210is possible to about 40 degrees where the core210engages the sleeve250at the ridge257. However, no further rotation is possible at this stage because a wafer262other than the shear wafer270blocks the rotation of the sleeve250and the core210. Further pushing of the shoulder217of the core210against the ridge257of the sleeve250is not possible.

The functionality of lock assembly embodiment200provides the possibility of configurations having multiple true shear lines. This is useful for alternative embodiments configured as “master keyed systems” with locks configured to be operated by more than one true key. This arrangement is provided by placing two or more shear wafers in one or more pin chambers. While this does decrease the amount of decoy shearlines, it does so by an insignificant margin and the benefits to the end user outweigh the risks. Since all master key systems are slightly less secure than non-master key systems, locksmiths would be expected to generally inform customers of the risks and benefits of master-keyed systems.

It is to be understood that the foregoing description has focused on two main example embodiments. A number of variations are possible which are within the scope of the appended claims. For example, alternative embodiments may include more or fewer pin stacks held in more or fewer pin channels. Alternative embodiments may include more or fewer wafers than described for the example embodiment. While the wafers described in the example embodiments are disk-shaped, other shapes are possible, such as square, polygonal or alternative radiused shapes such as ellipses or ovals for example. If such alternative wafer shapes are incorporated, the shapes of the pin channels, sleeve openings and core openings would be altered accordingly to accommodate the alternative wafer shapes. Alternative embodiments may also include wafers having more than two different sizes, as long as the pin stacks are configured to provide at least one true shear line as a result of alignment of a shear wafer with the outer surface of the sleeve.

While the example embodiment includes core wafer receivers on either lateral side of the core openings, alternative embodiments may include only a single wafer receiver located on one side of the core openings. In such alternative embodiments, the alternative embodiment will be configured for rotational movement in only one direction.

While the example embodiment100includes an arrangement of wafers with a shear wafer having a height dimension greater than the height dimension of the remaining wafers, alternative embodiments may have the remaining wafers with a height dimension greater than the height dimension of the shear wafer. While the example embodiment200includes shear wafers with a conical protrusion272, alternative shaped protrusions such as knobs, squares, or other three dimensional polygonal shapes may be used in alternative embodiments if the wafer receiver is provided with a complementary shape to preserve the function of generating a true shear line.

Any patent, publication, internet site, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

While the lock assembly is described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the embodiments encompassed by the appended claims.

In the claims, articles such as “a,” “an,” and “the” may mean one or more than one unless indicated to the contrary or otherwise evident from the context. Claims or descriptions that include “or” between one or more members of a group are considered satisfied if one, more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process unless indicated to the contrary or otherwise evident from the context.

It is also noted that the term “comprising” is intended to be open and permits but does not require the inclusion of additional elements or steps. When the term “comprising” is used herein, the term “consisting of” is thus also encompassed and disclosed. Where ranges are given, endpoints are included. Furthermore, it is to be understood that unless otherwise indicated or otherwise evident from the context and understanding of one of ordinary skill in the art, values that are expressed as ranges can assume any specific value or subrange within the stated ranges in different embodiments, to the tenth of the unit of the lower limit of the range, unless the context clearly dictates otherwise. Where the term “about” is used, it is understood to reflect+/−10% of the recited value. In addition, it is to be understood that any particular embodiment that falls within the prior art may be explicitly excluded from any one or more of the claims. Since such embodiments are deemed to be known to one of ordinary skill in the art, they may be excluded even if the exclusion is not set forth explicitly herein.