Abstract:
Methods, systems and apparatus for converting locks between key-retaining and non-key-retaining functions by means of a function-determinative lock actuator are disclosed. The disclosure teaches lock sub-assemblies that utilize a function-determinative actuator and a cooperating rotator bolt to transfer motion from a lock cylinder to a lock release mechanism. The function-determinative actuators can include movable portions that selectively determine the lock function by adjustment of the movable portion. Alternatively, changing the structure of, selectively adding portions to and/or removing portions from the actuator can determine the lock function. The disclosure also teaches dual-function locks that incorporate the above-noted lock sub-assemblies. Methods of converting lock functions using a function-determinative actuator are also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to systems, methods, apparatus and related sub-assemblies for converting locks between key-retaining and non-key-retaining functions. More particularly, the invention relates to conversion of locks between key-retaining and non-key-retaining functions by means of a function-determinative lock actuator. Accordingly, the general objects of the invention are to provide novel systems, methods, apparatus and sub-assemblies of such character. 
     2. Description of the Related Art 
     Key operated locks are broadly classified into two mutually exclusive lock types. Locks of the first type are known as key-retaining locks because in such locks the lock mechanism prevents the key from being removed from the lock while the lock is in an unlocked condition. Locks of the second type are known as non-key-retaining locks because in such locks the lock mechanism permits the key to be removed from the lock while the lock is in an unlocked condition. Most conventional locks only offer one of these lock functions and, hence, are known as single-function locks. 
     One prior art single-function padlock  10  is shown in FIG.  1  and preferably comprises a padlock body  12 , a lock cylinder  13  with a blade-like actuator  15  extending therefrom, at least one locking ball  16 , a shackle  14  with a one or more recesses  17  for selectively receiving ball(s)  16 , a rotational stop member  18  with an affixation screw and a rotator bolt  19 . In particular, lock  10  of FIG. 1 is a key-retaining lock. As shown, padlock  10  is of a generally conventional configuration and employs locking ball(s)  16  (that cooperate with rotator bolt  19 ) that function as a release/locking mechanism to selectively release/retain shackle  14  in a locked or unlocked condition. A well-known variation of conventional lock cylinder  13 , is the BEST-type (also known as the small format interchangeable-core) cylinder shown in FIG.  2 . As depicted therein, cylinder  13 ′ includes an end face  11  with a pair of apertures  11 ′ for receiving corresponding legs of an actuator. A well-known variation of conventional rotator bolt  19 , is depicted in FIG.  4 . As shown therein, rotator bolt  19 ′ includes a release-mechanism engaging portion  24  and an actuator-engaging end-portion  25  with wedge-shaped posts  27  and space therebetween. 
     Those of ordinary skill will readily appreciate that the particular configuration of the conventional lock/components noted-above can assume a wide variety of well-known and equivalent sizes and configurations. Thus, for example, padlock body  12 , cylinders  13  and  13 ′, actuator (or tailpiece)  15 , shackle  14 , ball(s)  16  and rotator bolts  19  and  19 ′ can assume a wide variety of well-known and equivalent sizes and configurations. A mere sampling of such configurations of the related art is provided in the Information Disclosure Statement (with the associated Form PTO-1449) attached to this application. Further references to such conventional components should be understood to encompass these and other configurations known in the art. 
     There are practical, functional and security advantages to both key-retaining and non-key-retaining single-function locks. Since most manufacturers produce single-function locks discussed above, lock purchasers normally need to first determine which lock function meets their particular requirements, and then purchase the single-function lock of the appropriate type. Therefore, locksmiths and other lock suppliers are typically required to stock inventories of both key-retaining and non-key-retaining locks in order to satisfy the needs of all potential lock purchasers. 
     In order to eliminate the need for locksmiths and other lock suppliers to stock unnecessarily large inventories of both key-retaining locks and non-key-retaining locks, dual-function locks have been developed. Some exceptionally innovative dual-function padlocks are shown and described in U.S. Pat. No. 5,174,136 granted on Dec. 29, 1992 and entitled “Dual Function Padlock With Removable Cylinder Mechanism”; and in U.S. Pat. No. 6,145,356 granted on Nov. 14, 2000 and entitled “Dual-Function Locks And Sub-Assemblies Therefor”; which Patents are hereby incorporated by reference. Other highly similar dual-function padlocks are shown and described in U.S. Pat. No. 5,363,678. 
     U.S. Pat. No. 5,174,136 and U.S. Pat. No. 5,363,678 constitute examples of padlocks which can be readily converted between key-retaining and non-key-retaining functions by the introduction and/or disposal of components between the rotator bolt and the actuator of a lock cylinder. Thus, each of these locks offer the option of selecting one of two possible lock functions at the time of installation or later. However, in the case of each of these locks, components must be introduced into or removed from between the actuator and rotator bolt in order to achieve conversion of the lock function. 
     U.S. Pat. No. 6,145,356 represents an advance over the two aforementioned designs in that the locks shown and described therein can be readily converted between key-retaining and non-key-retaining functions without the introduction and/or disposal of components. The lock designs disclosed therein rely on either of at least two primary principles of operation. In the first, the rotator bolt of the lock is manipulated to achieve lock conversion (no change in the lock actuator is necessary for conversion to occur). This may occur, for example, by manipulation of and/or reorientation of a multi-component rotator bolt. In the second principle of operation, the rotator bolt and the actuator are reoriented relative to one another to achieve lock conversion. Thus, these locks also offer the ability to select the desired lock function at the time of installation or later. Neither of the aforementioned designs shown in U.S. Pat. No. 6,145,356, however, utilize manipulation and/or modification of the actuator structure to achieve lock conversion. It would be desirable to convert locks solely by manipulation and/or modification of the lock actuator because the actuator (along with the lock cylinder) is a readily accessible component of most locks. By contrast, lock rotator bolts are typically more difficult to access since they are often located deep within a cavity of the lock body. 
     There is, accordingly, a need in the art for novel methods, systems and apparatus that offer the ability to achieve inter-function conversion solely by manipulation and/or modification of a function-determinative lock actuator. Such methods and apparatus should enable a user to conveniently select the desired lock function without the use of additional components between the rotator bolt and the actuator. Additionally, such methods and apparatus should enable a user to conveniently select the desired lock function by manipulating/modifying a dual-function actuator thereby avoiding the need to access the rotator bolt deep within a cavity of the lock body. 
     SUMMARY OF THE INVENTION 
     The present invention satisfies the above-stated needs and overcomes the above-stated and other deficiencies of the related art by providing methods, systems and apparatus for converting locks between key-retaining and non-key-retaining functions by means of a function-determinative lock actuator. In one form, the invention can be a dual-function padlock capable of conversion between key-retaining and non-key-retaining lock functions. The inventive lock includes a number of conventional components such as a body, a shackle which is at least partially disposed within the padlock body, a shackle-release-mechanism for selectively releasing/retaining the shackle, and a rotatable cylinder at least partially mounted within the body. Additionally, the inventive lock includes an axis-defining rotator bolt, which is mounted within the padlock body for rotation about the axis, with a release-mechanism-engaging portion for controlling movement of the shackle-release-mechanism and an actuator-receiving portion. The inventive lock further includes a function-determinative actuator that rotates about the rotation axis in response to cylinder rotation, the actuator cooperating with the rotator bolt such that the lock can be converted between key-retaining and non-key-retaining functions by physically modifying the actuator. 
     The invention can also take the form of a dual-function lock sub-assembly for a lock of the type having a release-mechanism and an axis-defining lock-cylinder capable of transferring rotational motion to an actuator. In this form the invention includes a rotator bolt having a release-mechanism-engaging portion at one end thereof for controlling movement of the release-mechanism and an actuator-engaging portion for mechanically engaging at least a portion of the actuator. The invention also includes a dual-function actuator responsive to movement of the lock-cylinder for axial rotation therewith, the actuator having a free end extending from the cylinder, a first section which permits limited lost-motion between the free end of the actuator and the rotator bolt, and a second section for preventing lost-motion between the free end of the actuator and the rotator bolt. With this configuration, the lock function can be selectively determined by changing the second section of the actuator. 
     Still another form of the invention includes a method of converting a dual-function lock from a key-retaining mode to a non-key-retaining mode. The inventive method can be used with a lock of the type having a body, a rotatable lock cylinder at least partially mounted within the body and defining a rotation axis, a rotator bolt within the body for rotation about the axis, and an actuator extending from the cylinder and having a selective-engagement portion cooperating with the rotator bolt such that the actuator and the rotator bolt may remain generally stationary relative to one another. The inventive method comprises the steps of (a) taking the cylinder and actuator out of the lock body while leaving the rotator bolt within the body; (b) changing the selective-engagement portion of the actuator to thereby permit limited lost motion between the actuator and the rotator bolt when the cylinder and actuator are replaced into the body; and (c) replacing the cylinder and actuator into the body. 
     Naturally, the above-described methods of the invention are particularly well adapted for use with the above-described apparatus of the invention. Similarly, the apparatus of the invention are well suited to perform the inventive methods described above. 
     Numerous other advantages and features of the present invention will become apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiments, from the claims and from the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of the present invention will be described below with reference to the accompanying drawings where like numerals represent like steps and/or structures and wherein: 
     FIG. 1 is an exploded and partially cut-away perspective illustration of a conventional single-function padlock of the prior art; 
     FIG. 2 illustrates a BEST-type lock cylinder of the prior art; 
     FIG. 3 a  shows dual-function lock sub-assembly in accordance with one preferred embodiment of the present invention; 
     FIG. 3 b  shows a function-determinative actuator in accordance with another preferred embodiment of the present invention; 
     FIG. 3 c  shows a reversible tenon pin for use in a function-determinative actuator in accordance with some embodiments of the present invention; 
     FIG. 4 depicts a conventional rotator bolt of the prior art; 
     FIG. 5 a  shows a conventional lock cylinder with a function-determinative actuator, in accordance with one preferred embodiment of the present invention, extending therefrom; 
     FIG. 5 b  depicts the actuator of FIG. 5 a  in operative engagement with the rotator bolt of FIG. 4; 
     FIG. 6 a  shows the conventional lock cylinder of FIG. 5 a  with a function-determinative actuator, in accordance with another preferred embodiment of the present invention, extending therefrom; 
     FIG. 6 b  depicts the actuator of FIG. 6 a  in operative engagement with the rotator bolt of FIG. 4; 
     FIG. 6 c  depicts a variant of the sub-assemblies of FIGS. 5 and 6 in which the actuator has been bent to select the lock function; 
     FIG. 7 a  shows the conventional lock cylinder of FIG. 5 a  with a function-determinative actuator, in accordance with another preferred embodiment of the present invention, extending therefrom; 
     FIG. 7 b  shows an inventive rotator bolt for use in a lock sub-assembly in accordance with another preferred embodiment of the present invention; 
     FIG. 7 c  depicts another inventive lock sub-assembly, the sub-assembly being shown with the actuator of FIG. 7 a  in operative engagement with the inventive rotator bolt of FIG. 7 b;    
     FIG. 7 d  depicts variant of the lock sub-assembly of FIG. 7 c  in which the actuator of FIG. 7 a  has been bent to select the lock function; 
     FIG. 8 a  depicts another inventive lock sub-assembly with an inventive actuator in operative engagement with an inventive rotator bolt; 
     FIG. 8 b  depicts the inventive lock sub-assembly of FIG. 8 a , the sub-assembly being shown in cross-section with the actuator being in operative engagement with the inventive rotator bolt; and 
     FIG. 8 c  shows a reversible tenon pin for use in the function-determinative actuator in accordance with the embodiment FIGS. 8 a  and  8   b.   
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Dual-function locks, and lock sub-assemblies therefor, in accordance with the preferred embodiments of the present invention will be described with joint reference to the Figures. Throughout this description, however, it is to be understood that, to facilitate understanding of the drawings, only enough structure of the apparatus has been illustrated to enable one skilled in the art to readily understand the underlying principles and concepts of the invention. Additionally, the present invention (although mostly illustrated herein in the context of padlocks) enjoys applicability in any lock that employs a rotatable cylinder, a lock release mechanism and structure for controlling the release mechanism in response to rotation of the cylinder. Such locks include padlocks, door locks and all other types of locks and security devices. 
     With joint reference now to FIGS. 3 a - 3   c  there is shown a number of preferred dual-function lock sub-assemblies and actuators in accordance with the present invention. The sub-assemblies and components shown in FIGS. 3 a - 3   c  are particularly well suited for use with the conventional lock cylinder of FIG.  2 . Additionally, these sub-assemblies (together with cylinder  13 ′ of FIG. 2) are well suited for use in locks of the general type shown in FIG.  1 . 
     With primary reference now to FIG. 3 a , there is shown therein an inventive subassembly  20  that includes a rotator bolt  22  and an actuator  30 . Rotator bolt  22  preferably defines an axis A and includes a release-mechanism-engaging portion  24  at one end thereof and an actuator-engaging portion  25  at an opposite end thereof. Rotator bolt  22  is designed for rotation about axis A in response to rotational motion initiated by cylinder  13 ′ and transferred to rotator bolt  22  via actuator  30 . Rotator bolt  22  preferably includes a radially-offset and arcuate slot having a lost-motion region  26  and an anchoring recess  28  at one end thereof. 
     Also shown in FIG. 3 a  is an actuator  30  in accordance with one preferred embodiment of the present invention. As shown, actuator  30  preferably includes a substantially circular plate  34  with tailpiece legs  36  and  38  affixed thereto. In use, actuator  30  is partially received within conventional cylinder  13 ′ such that legs  38  and  36  extend into apertures  11 ′ of cylinder  13 ′ and permit the free end of leg  36  to be received within slot  26 . The free end of leg  36  also preferably includes a movable member  37  which, in this embodiment, takes the form of a threaded screw that can be adjusted to reduce or increase the distance that leg  36  extends beyond the lock cylinder. When movable member  37  is in a retracted position (to thereby shorten the length of leg  36 ), it is received within lost-motion recess  26  such that limited lost motion is permitted to occur between rotator bolt  22  and actuator  30 . Hence, in the retracted position, no part of movable member  37  is in anchoring recess  28 . When movable member  37  is placed in an extended position, at least a portion of it will be trapped within anchoring recess  28  so that rotator bolt  22  remains generally stationary relative to actuator  30 . By moving member  37  between the retracted and extended positions, sub-assembly  20  can be used to selectively convert the lock function between non-key-retaining and key-retaining modes respectively. In a variation of this embodiment the threaded member  37  takes the form of a set-screw extending through the side of plate  34  in order to selectively secure a longitudinally movable leg  36  at the desired distance beyond plate  34 . 
     Turning now to FIG. 3 b , this figure shows a function-determinative actuator  30 ′ in accordance with another preferred embodiment of the present invention and can be used as an alternative to function-determinative actuator  30  in sub-assembly  20 . While actuator  30 ′ is substantially similar to, and operates in the same general manner as, actuator  30 , there are a number of differences between these actuators. First, actuator  30 ′ includes a threaded member  36 ′ in lieu of leg  36  (which is preferably snugly fit into plate  34 ) of actuator  30 . Second, plate  34 ′ includes a threaded aperture to receive threaded member  36 ′ such that threaded member  36 ′ may be adjusted to selectively determine the function (key-retaining or non-key-retaining) specified by actuator  30 ′. In particular, with threaded member  36 ′ adjusted to a retracted position in which no part of the threaded member extends into anchoring recess  28 , lost-motion may occur and a non-key-retaining function is specified. With threaded member  36 ′ adjusted to an extended position wherein at least a portion of member  36 ′ extends into and is trapped by anchoring recess  28 , a key-retaining function is specified. Naturally, as with the embodiment of FIG. 3 a , the desired lock function can be repeatedly selected and unselected without adding or taking away lock components. 
     FIG. 3 c  shows a reversible tenon pin  36 ″ for use in a function-determinative actuator in accordance with yet another preferred embodiment of the present invention. In particular, an actuator utilizing reversible tenon pin  36 ″ is substantially similar to, and operates in the same general manner as, actuator  30 ′, there are a number of differences between these actuators. First, reversible tenon pin  36 ″ is generally designed to substitute for threaded member  36 ′ in actuator  30 ′. Pin  36 ″ preferably includes a threaded first end  39  at one end thereof and an opposite end  39 ′ having both a threaded region and a non-threaded tenon extending therefrom. In a retracted position, threaded first end  39  of tenon pin  36 ″ is threaded into plate  34 ′ such that the end thereof does not extend substantially beyond plate  34 ′. In an extended position, the opposite end  39 ′ is threaded into plate  34 ′ such that the non-threaded tenon extends into and is trapped by anchoring recess  28  of rotator bolt  22 . By longitudinally reversing tenon pin  36 ″ in this way, actuator  30 ′ can be configured to determine the desired lock function. Alternatively, actuator  30 ′ can be configured to determine the desired lock function by breaking off the tenon of tenon pin  36 ″ to thereby change the distance by which pin  36 ″ extends beyond plate  34 ′. 
     Only a few simple steps are necessary to change the lock function of a dual-function lock using the inventive lock sub-assemblies described above and throughout the remainder of this specification. In particular, a user merely needs to take the cylinder  13  and actuator (e.g., 30) out of the lock body  12  while leaving the rotator bolt (e.g., 22) within the body. Then the dual-function actuator is changed such that limited lost-motion may occur between the actuator and the rotator bolt when the cylinder and actuator are replaced into the body. Finally, the cylinder and the (now modified) actuator are replaced into the lock body. While other steps can be added to this procedure, the three steps listed above are all that is necessary. 
     A number of variations of the lock sub-assemblies described above are within the skill of the ordinary artisan based on the disclosure contained herein. For example, while each of actuator  30  and  30 ′ are shown as having two legs that can be received within apertures  11 ′ of cylinder  13 ′, only one leg is necessary for functionality. Additionally, the inventive concepts represented by the embodiments of FIGS. 3 a - 3   c  can be readily adapted to any of the many well-known lock cylinders that will readily occur to those one or skilled in the art. Thus, the size, structure and configuration of legs  36  and  38  may be readily adapted for use with any given companion lock cylinder desired. Alternatively, legless actuator structures may be utilized with any given lock cylinder as appropriate. 
     With joint reference now to FIGS. 5 a - 6   b  there is shown a number of other preferred dual-function lock sub-assemblies and actuators in accordance with the present invention. The sub-assemblies and components shown in FIGS. 5 a - 6   b  are particularly well suited for use with the conventional rotator bolt  19 ′ of FIG.  4  and in locks of the general type shown in FIG.  1 . With primary reference now to FIGS. 5 a  and  5   b , there is shown therein an inventive lock sub-assembly that includes function-determinative actuator  42  and rotator bolt  19 ′. Actuator  42  preferably includes a generally blade-shaped portion  44  with a selective-engagement tab  46  extending laterally therefrom. In a particularly preferred embodiment, tab  46  is connected to portion  44  with a break-joint to assist in clean removal of tab  46  from actuator portion  44 . With selective-engagement tab  46  connected to actuator portion  44  as shown herein, actuator  42  is trapped between posts  27  in an actuator engaging portion  25 ′ of rotator bolt  19 ′ such that actuator  42  remains generally stationary relative to rotator bolt  19 ′. Hence, this configuration yields a key-retaining lock. Lock sub-assembly  40  can be selectively converted into a non-key-retaining mode by removal of tab  46  at the break-joint to thereby permit limited lost-motion between actuator  42  and rotator bolt  19 ′. 
     Turning primarily to FIGS. 6 a  and  6   b , there is shown therein an alternative variation of the dual-function lock sub-assembly described above with respect to FIGS. 5 a  and  5   b . This embodiment of the present invention includes an actuator  47  with a blade-like actuator member  44 ′ and another member  48  extending generally transverse thereto. As shown in FIG. 6 a  and FIG. 6 b , transverse member  48  can be a pin press it into an aperture of blade-like member  44 ′. Alternatively, member  48  can be a screw which is threadedly received within a threaded aperture of blade-like member  44 ′. Additionally, if member  48  is of sufficient length, it will be trapped within the lock. Thus, member  48  does not need to be press fit within blade like member  44 ′ since it may ride loosely within the rotator bolt. With transverse member  48  connected to actuator portion  44  as shown herein, actuator  47  is trapped between posts  27  in an actuator-engaging portion  25 ′ of rotator bolt  19 ′ such that actuator  47  remains stationary relative to rotator bolt  19 ′. Lock sub-assembly  40  can, thus, be configured for a key-retaining mode. Sub-assembly  40  can be selectively converted into a non-key-retaining mode by removal of member  48  to thereby permit limited lost-motion between actuator  47  and rotator bolt  19 ′. 
     In one variation of the embodiments of FIGS. 5 and 6, a portion of blade-like actuator  44 ″ can be bent to one side (e.g., by about 90 degrees) such that one of posts  27  is captured on two sides thereof (see FIG. 6 c ). By bending the actuator in this way, the sub-assembly can be converted from a non-key-retaining function to a key-retaining function and back again. 
     With joint reference now to FIGS. 7 a - 7   c  there is shown a number of preferred dual-function lock sub-assemblies and actuators in accordance with still another embodiment of the present invention. The subassemblies and components shown in FIGS. 7 a - 7   c  are particularly well suited for use with the conventional lock cylinder  13  of FIG.  1 . Additionally, these sub-assemblies (together with cylinder  13  of FIG. 1) are well suited for use in locks of the general type shown in FIG.  1 . 
     With continuing joint reference to FIGS. 7 a - 7   c , there is shown therein an inventive sub-assembly  50  that includes an inventive rotator bolt  58  and an inventive actuator  54 . Rotator bolt  58  preferably defines an axis A and includes a release-mechanism engaging portion at one end thereof and an actuator-engaging recess  62  at an opposite end thereof. Rotator bolt  58  is designed for rotation about axis A in response to rotational motion initiated by cylinder  13  and transferred to rotator bolt  58  via actuator  52 . As shown, one end of rotator bolt  58  preferably includes at least one recess, with both a lost-motion region  64  and an anchoring region  66 , for receiving actuator  52 . 
     Function-determinative actuator  52  in accordance with another preferred embodiment of the present invention is shown in perspective view in FIG. 7 a . As shown, actuator  52  preferably includes a generally blade-shaped portion  54  with a removable tab  56  extending therefrom and a junction (such as a break-joint) therebetween. In use, function-determinative actuator  52  is partially received within conventional cylinder  13  such that the free end of actuator  52  extends away from cylinder  13  and may be received within actuator-engaging recess  62 . When removable member  56  is trapped within anchoring recess  66  of recess  62 , rotator bolt  58  remains generally stationary relative to actuator  52  and the key-retaining function is selected. When removable member  56  is removed from actuator  52 , no portion of the actuator is received within anchoring recess  66  and limited lost-motion is permitted to occur between rotator bolt  58  and actuator  52 . In this state, the non-key-retaining function is selected. Thus, by removing portion  56  from actuator  52 , sub-assembly  50  can be used to convert the lock function from the key-retaining mode to the non-key-retaining mode. As shown in FIG. 7 d , one alternative to changing the lock function by removing tab  56  altogether is to bend tab  56  to one side until it can no longer reach anchoring recess  66 . Tab  56  could also be bent back to the original position to again select the key-retaining function. Those of ordinary skill will recognize other variations in light of the disclosure contained herein. 
     Another preferred dual-function lock sub-assembly in accordance with the present invention is illustrated in FIGS. 8 a - 8   c . As shown therein, sub-assembly  70  preferably includes a function-determinative actuator  72  with a substantially circular plate  77 , with reversible tenon pin  74  (see especially FIG. 8 c ) with a fixed actuator leg  74 ′ and with a raised lost-motion driver region  76 . Sub-assembly  70  also includes a rotator bolt  80  which defines an axis A and includes a release-mechanism-engaging portion  82  and an actuator-engaging portion  84  at an opposite end thereof. Rotator bolt  80  is designed for rotation about axis A in response to rotational motion initiated by a conventional cylinder  13 ′ (e.g., cylinder  13 ′ of FIG. 4) and transferred to rotator bolt  80  via actuator  72 . Rotator bolt  80  preferably includes a lost-motion region  86  and radially-offset anchoring recess  88  at actuator-engaging portion  84 . 
     In use, dual-function actuator  70  is partially received within a cylinder such that pin  74  and leg  74 ′ extend into apertures of the cylinder. Plate  77  includes a threaded aperture to receive threaded portions  75  and  75 ′ of tenon pin  74  such that one or the other of the threaded ends may be threadedy secured to selectively determine the function (key-retaining or non-key-retaining). In particular, with tenon pin  74  oriented in the extended position shown in FIG. 8 a , wherein at least a portion of end  75 ′ extends into and is trapped by anchoring recess  88  of rotator bolt  80 , a key-retaining function is specified (see especially FIG. 8 b ). With tenon pin  74  longitudinally reversed into the retracted position in which threaded end  75  is received in the threaded aperture of plate  77 , but no part of threaded end  75  extends into anchoring recess  88 , lost-motion may occur and a non-key-retaining function is specified. By longitudinally reversing tenon pin  74  in this way, actuator  72  can be configured to determine the desired lock function and the desired lock function can be repeatedly selected and unselected without adding or taking away lock components. In one variation of this embodiment, tenon pin  74  is snugly fit, but nonetheless longitudinally movable, within an aperture of plate  77  in lieu of utilizing threaded regions. 
     In an alternative variation, tenon pin  74  is a movable member that includes an elongated threaded region at free end  75 ′ (instead of the tenon shown in FIGS. 8 a  and  8   c ) that can be adjusted to reduce or increase the distance that tenon  75 ′ extends beyond the surface of plate  77  (the threads of end  75  are optional in this embodiment). When this variant movable member is in a retracted position (wherein end  75 ′ is substantially flush with the surface of plate  77 ), lost-motion driver region  76  cooperates with rotator bolt  80  such that limited lost-motion is permitted to occur between rotator bolt  80  and actuator  72 . Hence, in the retracted position, no part of the variant movable member is in anchoring recess  88  of rotator bolt  80 . When the movable member is placed in an extended position, at least a portion of it will extend substantially beyond the surface of plate  77  and be trapped within anchoring recess  88  so that rotator bolt  80  remains generally stationary relative to actuator  72  (see especially FIG. 8 b ). Thus, by moving the variant movable member between the retracted and extended positions, sub-assembly  70  can be used to selectively (and repeatedly) convert the lock function between non-key-retaining and key-retaining modes respectively. In another variation of this alternative embodiment, the movable member is threaded along the entire length thereof. In a variation of this embodiment a threaded member may be used as a set-screw extending through the side of plate  77  in order to selectively secure a longitudinally movable leg (tenon pin  74  or some variation thereof) at the desired distance beyond plate  77 . 
     While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to encompass the various modifications and equivalent arrangements included within the spirit and scope of the appended claims. With respect to the above description, for example, it is to be realized that the optimum dimensional relationships for the parts of the invention, including variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the appended claims. Therefore, the foregoing is considered to be an illustrative, not exhaustive, description of the principles of the present invention.