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TECHNICAL FIELD 
     The invention relates to pin tumbler cabinet door and drawer locks. More specifically, the invention relates to self-latching locks for cabinet doors and drawers. 
     BACKGROUND OF THE INVENTION 
     There are two basic families of cabinet drawer and door locks: deadlocking and latch locking types of locks, and cam-type locks. Both families of locks are used on cabinet drawers and doors such as those found on office desks, credenzas, and interior cabinetry. In the former family, an elongated bolt moves in a reciprocating manner into and out of a bolt housing between locked and unlocked positions, respectively, upon actuation of a key. In the latter family, an elongated bolt moves along an arcuate path, between locked and unlocked positions. In the cam family of locks, an angular rotation of 90 degrees is typically sufficient to determine the locked and unlocked positions. 
     Both families of locks may have their bolts actuated by either pin tumbler cylinder and plug assemblies, or disk tumbler-type assemblies. The disk tumbler-type assemblies are the least expensive and historically have been used in the cam type of lock. A lock of this type is shown in U.S. Pat. No. 3,863,476 to Patriquin, in which a plurality of spring-loaded plates in a plug are biased to position a protrusion from the plates into an elongated trough or cavity in an externally threaded lock body. Interference between the protrusions and sidewalls of the lock body trough prevent rotation of the plug. Upon insertion of a key into a keyway of the plug, the plates retract and the protrusions are withdrawn from the trough. Thereupon, the plug can rotate within the threaded lock body. The plug is longitudinally restrained within the lock body by a spring-loaded clip. The bolt is typically journaled for rotation with and screwed onto a longitudinal extension at the rear of the plug. 
     Over the years, it has become desirable to provide cam locks with a pin tumbler rather than a disk tumbler system. In the pin tumbler system, the disk plates are replaced with a series of cylindrical pins, which reside in bores in the plug. These “bottom pins” have differing lengths corresponding to protrusions and valleys in a mating key. The lock body or cylinder is provided with a corresponding series of spring-loaded top pins that can drop down into the bores in the plug into which the lower pins reside. When a key is inserted into the plug keyway, the top pins and bottom pins form a shear line at the interface of the plug and cylinder, allowing the plug to rotate freely. A particular problem with this type of lock is that the key can be inserted or removed only when the top and bottom pins are in alignment (typically the 12 o&#39;clock position). 
     In contrast to cam type locks, deadlocking and latch locking types of locks have a bolt that reciprocates transversely with respect to a keyway of the lock. In the deadlocking type of lock, the bolt remains in an extended or retracted position and is not translatable therefrom without operation of the key. In a latch locking type of lock, the bolt has a curvature on the end thereof and is spring-biased to the extended position. Transverse pressure on the curved portion of the bolt urges the bolt against the spring bias to a retracted position so that a cabinet door or drawer can be closed without the use of a key. The latch locking type of cabinet lock can also be provided with a separate deadlocking bolt that prevents “jimmying” of the spring-biased latch bolt when the deadlocking portion of the latch bolt is depressed, such as by a strike plate. An example of a rekeyable pin tumbler type of deadlocking cabinet lock is shown in U.S. Pat. No. 4,899,563, assigned to the Frank J. Martin Company, Seattle, Wash.; an example of a deadlocking, self-latching cabinet door and drawer deadlocking latch lock is shown in U.S. Pat. No. 5,657,652, assigned to the same assignee. 
     In all of the above types of locks, either a disk tumbler type of assembly or a pin tumbler type of assembly may be used. It is known to those of ordinary skill in this art, particularly with respect to the pin tumbler type of locks, that it is desirable to maintain the orientation of the bottom pins, top pins, and springs in a vertical orientation to prevent the lock from jamming, which may occur if the pins are not maintained in a vertical position (e.g., the pins are lying on their side in a horizontal plane). For this reason, cabinet door and drawer locks are typically sold in left-hand, right-hand, vertical-hand, and inverted-hand versions in which the bolt is presented in four orthogonal directions while the keyway is always maintained in the vertical position. The assignee of the present invention and/or its predecessors in interest have sold a variety of locks in these configurations, such as the Olympus Lock Company&#39;s Models 997 and 996 door and drawer latch locks. Clearly, the maintenance of stock on hand of four different varieties of every type of lock is costly, and a clear need exists for a single type of latch lock that is field configurable to any one of the above four orthogonal positions. However, complex assemblies and parts that are difficult or expensive to manufacture are generally undesirable in the lock art. Simple assemblies generally permit reduced manufacturing costs, improved reliability, and serviceability in the field. In addition, locks that require special tools to facilitate disassembly for rekeying purposes or the like have been historically disfavored by locksmiths. As a result, the development of a commercially viable, field-reversible four-way latch lock has eluded the industry. Thus, a need exists for a low-cost, pin tumbler self-latching cabinet door and drawer lock that is field reversible by locksmiths to any one of four orthogonal positions. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a low-cost, pin tumbler self-latching cabinet door and drawer lock that is field reversible by locksmiths to any one of four orthogonal positions. 
     The invention achieves the above objects, and other objects and advantages that will become apparent from the description, which follows, by providing a four-way, field-reversible, self-latching cabinet lock. The lock includes a bolt housing cover defining a central aperture. The lock is provided with a cylinder and plug assembly shell having a rear wall defining a circular plug aperture registrable with the central aperture in the bolt housing cover. The shell is further provided with a rearwardly directed hub that extends axially through and away from the shell so that the shell is journaled for rotation with respect to the bolt housing cover. The shell is axially restrained in the bolt housing cover by a locking mechanism such as a spring clip or split ring so that shell can be rotated with respect to the bolt housing cover in one of a plurality of operating positions. The operating positions may be orthogonal with respect to one another to correspond to a vertical bolt position, an inverted bolt position, a left-hand bolt position, and a right-hand bolt position. A pin-type cylinder and plug assembly is preferably removably received in the shell. The bolt housing cover is removably received on a bolt housing, which houses a reciprocating, spring-biased latch bolt. A rotary cam is also received in the bolt housing and has a rear side adapted for operational connection with the bolt so as to retract the bolt into the bolt housing when the rotary cam is rotated. The front side of the rotary cam is adapted for receipt of a cam driver that couples the rotary cam to the plug of the cylinder and plug assembly. In this way, the shell can be repositioned (with the cylinder and plug assembly therein) to any one of the operational positions so as to maintain orientation of the pins in the cylinder and plug assembly in the desired vertical position regardless of whether the bolt is in a vertical, inverted, left, or right extending position. 
     In preferred embodiments of the invention, the lock is preferably provided with a locking mechanism for selectively rotationally retaining and releasing the shell with respect to the bolt housing cover in one of the operating positions. As stated above, the operating positions may be orthogonal. In preferred embodiments of the invention, the cylinder and plug assembly is preferably slidably and removably received in the shell, and the shell includes a selectively releasable securing mechanisms (e.g., a set screw) for axially securing the cylinder and plug assembly in the shell. The rearwardly directed hub of the cylinder and plug assembly shell may be provided with four orthogonal bores for receipt of the set screw, and the bolt housing cover may be provided with a radially directed, threaded bore that penetrates the central aperture in the bolt housing cover. Thus, the set screw may interact with the holes or detents in the hub to releasably secure the cylinder and plug assembly shell in any one of the operating positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded isometric view of a preferred embodiment of the invention. 
         FIG. 2  is an exploded isometric view of a cylinder and plug assembly, and cam driver that is receivable in the invention shown in  FIG. 1 . 
         FIG. 3  is a rear elevational view of a plug shown in  FIG. 2 . 
         FIG. 4  is a side elevational view of the cam driver shown in  FIG. 2 . 
         FIG. 5  is an isometric, top left view of the cylinder and plug assembly shell shown in  FIG. 1 , illustrating an axially and rearwardly directed hub portion thereof. 
         FIG. 6  is a left front perspective view of a rotary cam for use in an alternate embodiment of the invention, illustrating a front side of the rotary cam. 
         FIG. 7  is a rear perspective view of the rotary cam shown in  FIG. 6 . 
         FIG. 8  is a bottom, rear perspective view of a cylinder and plug assembly shell for use with an alternate embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A field-reversible cabinet lock in accordance with the principles of the invention is generally indicated at reference numeral  10  in the various Figures of the attached drawings, wherein numbered elements in the Figures correspond to like numbered elements herein. As best seen in  FIG. 1 , the lock  10  includes a conventional bolt housing  12  that receives a conventional, self-latching bolt  14  having an upper curved section  16  for operation against a conventional strike or strike plate (not shown). The bolt  14  is biased, such as by springs  18  in the conventional manner to reciprocate through a recess  20  in the bolt housing  12  between extended and retracted positions. A rotary cam  22  is journaled for rotation in a bolt housing aperture  24  by way of an axially extending arbor  26  in the conventional manner. The cam has a radially directed arm  28  on the reverse side thereof that interacts with a bolt cutout surface  30  in the conventional manner such that, when the cam  22  is rotationally driven, the arm  28  urges the bolt  14  through interaction of the arm  28  and cutout surface  30  to retract the bolt  14  against the spring pressure. In this manner, the lock  10 , when connected to a cabinet drawer, for example, by way of mounting holes  32 , allows the drawer to be opened. Conversely, the drawer can be closed by merely sliding the drawer toward the closed position whereby the curved section  16  will interact with the strike plate (not shown) urging the bolt to compress the springs  18  such that the bolt is in the retracted position and may pass the strike, allowing the drawer to close and the bolt to reextend. The cam  22  rotates about a main axis  36  shown in phantom line. A front face (or front side)  40  of the cam  22  has transverse grooves or rebates  44  for receipt of a dogleg-shaped first portion  46  of a cam driver  48 , best seen in  FIGS. 1 ,  2 , and  4 . The first portion  46  is positioned on a rear side of the cam driver so as to be received in any one of four lobes  44   a  of the rebates  44 , depending on the orthogonal, desired position of the bolt  16  (e.g., vertical, inverted, left-hand, right-hand). The cam driver  48  has a second portion  50  for interaction with a rear end  52  of a plug  54  of an axially removable cylinder and plug assembly  56 . The plug  54  is a conventional type commonly referred to as an “insert cylinder” type, such as manufactured by Schlage for use with conventional deadbolt locks, such as those used on entryways. This type of pin tumbler plug conventionally is used with an extended tailpiece, such as that shown in U.S. Pat. No. 5,657,652 to Martin, assigned to the assignee of the present invention and issued on Aug. 19, 1997, the disclosure of which is incorporated herein by reference. In the present invention, the conventional tailpiece is merely shortened to the inventive cam driver  48  so as to selectively, rotationally couple a keyway  58  in the plug  54  with the rotary cam  22 . The cylinder and plug assembly  56  is provided with a cylinder  60  adapted to slidably receive the plug  54  from a rearward, axial direction. A front face  62  of the cylinder  60  is provided with an aperture  64  for access to the keyway  58  when the plug  54  is received in the cylinder  60 . 
     The entire cylinder and plug assembly  56  is forwardly receivable in a cylinder and plug assembly annular shell  66 , as best seen in  FIGS. 1 and 5 . The shell has a forward aperture  68  for receiving the aforementioned cylinder and plug assembly  56 . The shell  66  has a rear wall  70  defining a plug aperture  72  such that the plug rear end  52  may pass therethrough. The rear wall  70  also has a rearward, axially directed hub portion  74  also having a substantially cylindrical shape defining four transverse, orthogonal and radially directed detents or holes  76  for purposes that will be described further hereinbelow. The cylinder and plug assembly  60  is provided with a radially directed threaded bore  80  that is alignable with a shell aperture  82  so that a set screw or the like (not shown) may be used to axially and rotationally retain the cylinder and plug assembly inside the shell  66 , as described in detail in U.S. Pat. No. 5,657,652, previously referenced herein, the disclosure of which is incorporated by reference. The hub portion  74  of the cylinder and plug assembly shell  66  is received in a central aperture  90  of a bolt housing cover  92  as best seen with reference to  FIG. 1 . The hub portion  74  has a length greater than a thickness of the bolt housing cover  92  such that a circumferential groove  94  (see  FIG. 5 ) on a rearward portion of the hub  74  protrudes rearwardly beyond the bolt housing cover. A spring-loaded clip  96 , circlip, split ring, or the like is applied to the circumferential groove  94  after the hub  74  has been received in the central aperture  90 , to axially restrain the shell  66  with respect to the bolt housing cover  92 , while permitting rotational movement of the shell  66  with respect thereto. It should be noted that the rotational axis of the hub  74 , plug  54 , cam driver  48 , and rotary cam  22  are coincident with the main axis  36 . However, the axis of the shell  66  is displaced therefrom in a conventional manner. Thus, the bolt housing  12 , bolt housing cover  92 , and all of the structural elements therebetween are rotatable with respect to the shell  66 , while tumbler pins (not shown) residing in the plug  54  can be maintained in a desirable, vertical position, as will be appreciated by those of ordinary skill in the relevant art. In order to maintain orientation of the shell  66 , with respect to the bolt housing  12 , bolt housing cover  92 , and all of the elements therebetween, the hub  74  is provided with the four orthogonal detents or holes  76 , which can be engaged by an elongated set screw  100  received in a radially directed threaded bore  102  in the bolt housing cover  92 . Thus, a locksmith can reorient the shell  66  with respect to the bolt housing cover  92 , bolt housing  12 , and parts therebetween into any one of the above-described four orthogonal positions such that the first portion  46  on the rear side of the cam driver  48  may engage an appropriate one of the orthogonal lobes  44   a  in the rebates  44  on the rotary cam  22 . To facilitate the structural realignment, bolt housing cover  92  may be released from the bolt housing  12 , such as by conventional screws  104 , which are received in corresponding holes  106  in the bolt housing cover  92  and cooperatively threaded holes  108  in the bolt housing  12 . 
     In an alternate embodiment of the invention, particularly for use with a small pin-type cylinder and plug assembly, which has a fixed rearward projection on the plug portion thereof (as will be well known to those of ordinary skill in the art), an alternate version of a cam driver  22 ′, as shown in  FIG. 6 , is provided having a front face  44 ′ adapted to receive the fixed driver of the small pin-type plug. The rear side of the alternate rotary cam  22 ′ is shown in  FIG. 7  and is otherwise identical to the first version of the rotary cam  22  shown in  FIG. 1 . In this alternate embodiment, the cam driver  48  is not needed. The alternate embodiment of the lock  10  is provided with a modified cylinder and plug assembly shell  66 ′, as shown in  FIG. 8 , in which the shell aperture  82 ′ is modified so as to have a figure-8 shape allowing the entire cylinder and plug assembly (not shown) to be moved forwardly so as to disengage the integral rear protrusion on the plug from the rotary cam  22 ′. In this manner, the shell  66 ′ may be rotated with respect to the bolt housing cover  92  without removing the bolt housing cover from the bolt housing  12 . 
     Those of ordinary skill in the art will conceive of other alternate embodiments of the invention upon reviewing this disclosure. Thus, the invention is not to be limited to the above description, but is to be determined in scope by the claims that follow.

Summary:
A four-way, field-reversible self-latching cabinet lock includes a cylinder and plug assembly shell that is rotatable with respect to a bolt housing cover for the lock. A locking device is provided to fix the cylinder and plug assembly shell in one of four orthogonal positions with respect to the bolt housing cover. The bolt housing cover is receivable by a bolt housing and conventional self-latching latch bolt. In this manner, pins in the cylinder and plug assembly may be retained in a desirable vertical position while a throw of the bolt can be adjusted to vertical, inverted, left-hand, and right-hand positions in the field without special tools or additional parts.