Latch and lock assemblies with spring-biased slide bolts
The present application is a continuation-in-part of a co-pending application entitled CABINET LOCK WITH RECESSED HANDLE, Ser. No. 859,194 filed Apr. 28, 1986 by Lee S. Weinerman et al as a continuation-in-part of application Ser. No. 601,648 filed Apr. 18, 1984 (now abandoned), which applications are referred to hereinafter as the &#34;Parent Cases,&#34; the disclosures of which are incorporated herein by reference Application Ser. No. 859,194 issued Aug. 4, 1987 as U.S. Pat. No. 4,683,736. 
    
    
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     Reference is made to the following related, concurrently-filed applications, the disclosures of which are incorporated herein by reference: 
     LATCH AND LOCK HOUSINGS, HANDLES AND MOUNTING BRACKETS, Ser. No. 072,176, filed July 10, 1987 by Lee S. Weinerman, Steven A. Mayo, Joel T. Vargus, Frank R. Albris, Richard H. Russell, Thomas V. McLinden, Richard M. O&#39;Grady and Timothy H. Wentzell, hereinafter referred to as the &#34;Utility Case I;&#34; 
     LATCH AND LOCK ASSEMBLIES WITH SPRING-BIASED PIVOT BOLTS, Ser. No. 072,174, filed July 10, 1987 by Lee S. Weinerman, Steven A. Mayo, Thomas V. McLinden and Timothy H. Wentzell, hereinafter referred to as the &#34;Utility Case III;&#34; 
     LATCH AND LOCK ASSEMBLIES WITH LIFT AND TURN HANDLES, Ser. No. 072,175, filed July 10, 1987 by Lee S. Weinerman, Frank R. Albris, Thomas V. McLinden and Timothy H. Wentzell, hereinafter referred to as the &#34;Utility Case IV;&#34; 
     LATCH AND LOCK ASSEMBLIES WITH EXPANSIBLE LATCH ELEMENTS, Ser. No. 072,250, filed July 10, 1987 by Lee S. Weinerman, Steven A. Mayo, Thomas V. McLinden and Timothy H. Wentzell, hereinafter referred to as the &#34;Utility Case V;&#34; 
     HOUSINGS FOR LATCHES AND LOCKS, Ser. No. 072,282, filed July 10, 1987 by Richard H. Russell, David W. Kaiser and Richard M. O&#39;Grady, hereinafter referred to as the &#34;Design Case I;&#34; 
     COMBINED HOUSINGS AND HANDLES FOR LATCHES AND LOCKS, Ser. No. 072,283, filed July 10, 1987 by Richard H. Russell, David W. Kaiser and Richard M. O&#39;Grady, hereinafter referred to as the &#34;Design Case II;&#34; 
     COMBINED HOUSINGS AND HANDLES FOR LATCHES AND LOCKS, Ser. No. 072,285, filed July 10, 1987 by Richard H. Russell and David W. Kaiser, hereinafter referred to as the &#34;Design Case III;&#34; 
     COMBINED HOUSINGS AND HANDLES FOR LATCHES AND LOCKS, Ser. No. 072,284, filed July 10, 1987 by Richard H. Russell and David W. Kaiser, hereinafter referred to as the &#34;Design Case IV;&#34; 
     COMBINED HOUSINGS AND HANDLES FOR LATCHES AND LOCKS, Ser. No. 072,276, filed July 10, 1987 by Richard H. Russell and David W. Kaiser, hereinafter referred to as the &#34;Design Case V;&#34; 
     COMBINED HOUSINGS AND HANDLES FOR LATCHES AND LOCKS, Ser. No. 072,573, filed July 10, 1987 by Richard H. Russell and David W. Kaiser, hereinafter referred to as the &#34;Design Case VI;&#34; COMBINED HOUSINGS AND HANDLES FOR LATCHES AND LOCKS, Ser. No. 072,277, filed July 10, 1987 by Richard H. Russell and David W. Kaiser, hereinafter referred to as the &#34;Design Case VII;&#34; 
     MOUNTING BRACKETS FOR LATCHES AND LOCKS, Ser. No. 072,278, filed July 10, 1987 by Richard H. Russell and Thomas V. McLinden, hereinafter referred to as the &#34;Design Case VIII;&#34; 
     MOUNTING BRACKETS FOR LATCHES AND LOCKS, Ser. No. 072,280, filed July 10, 1987 by Richard H. Russell and Thomas V. McLinden, hereinafter referred to as the &#34;Design Case IX;&#34; 
     STRIKERS FOR USE WITH LATCHES AND LOCKS, Ser. No. 072,279, filed July 10, 1987 by Lee S. Weinerman and Steven A. Mayo, hereinafter referred to as the &#34;Design Case X;&#34; and, 
     STRIKERS FOR USE WITH LATCHES AND LOCKS, Ser. No. 072,281, filed July 10, 1987 by Lee S. Weinerman and Steven A. Mayo, hereinafter referred to as the &#34;Design Case XI.&#34; 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to flush mounted latches and locks of the type used with closures for industrial cabinets, tool carts, electrical equipment enclosures and the like. More particularly, the present invention relates to novel and improved latches and locks that utilize a highly versatile housing together with other interactive components of novel form to provide desired types of latching and locking actions. 
     2. Prior Art 
     Flush mounted latches and locks including a body, a latch bolt movably carried on the body, and an operating handle that is nested by the body are well known. Normally the handle is in a flush or nested position when the bolt is in a latched position; and, unlatching movement of the bolt is effected by moving the handle to an operating position. Latches and locks of this type are well suited for use on industrial cabinets, tool carts, electrical equipment enclosures and the like. 
     Flush-mounted latches and locks having pan-shaped housings that nest paddle-shaped operating handles, and that have spring-projected slide bolts are disclosed in such U.S. Pats. Nos. as 4,335,595, 4,321,812, 4,320,642, 4,312,205, 4,312,204, 4,312,203, 4,312,202, 4,309,884, 4,231,597, 4,138,869, 3,707,862, 3,668,907, 3,449,005, 3,389,932, 3,357,734, 3,209,564, 3,209,563, 3,055,204, 2,987,908, 2,900,204 and 2,642,300, all of which are assigned to the Eastern Company, a corporation of Connecticut. 
     Flush mounted latches and locks having latch bolts of other than the spring-projected, slide-mounted type are disclosed in such U.S. Pats. Nos. as 4,413,849, 4,320,642, 4,312,203, 4,134,281, 3,857,594, 3,338,610, 3,044,814, 3,044,287 and 2,735,706, which are assigned to the Eastern Company. 
     A cabinet latch having a housing that is usable with a variety of pivotally mounted latch bolts, and with a variety of latching mechanisms is disclosed in U.S. Pat. No. 4,177,656, also assigned to the Eastern Company. 
     3. The Cross-Referenced Utility and Design Cases 
     The present invention, and the inventions described in the several referenced Utility and Design Cases, represent the work products of a long term and continuing development program. 
     The several functional features that form the subjects matter of the referenced Utility Cases, and the several appearance features that form the subjects matter of the referenced Design Cases, were developed by various co-workers, as is reflected in the listing of inventors in these cases. Many of the functional and appearance features that are claimed in separate ones of the referenced Utility and Design Cases were developed substantially concurrently. 
     If an invention feature that is disclosed in one of the referenced Utility and Design Cases constitutes a species of a development concept that is utilized in another of these related cases, it will be understood that care has been taken to present a generic claim in the case that describes the earliest development of a species that will support the generic claim. In this manner, a careful effort has been made to establish clear lines of demarcation among the claimed subjects matter of this and the several referenced Utility and Design Cases. No two of these cases include claims of identical scope. 
     4. The Referenced Parent Cases 
     The referenced Parent Cases discloses a simple means for retaining a key cylinder assembly in a lock housing. The lock housing has a generally cylindrical opening formed therethrough that extends along an axis for mounting a key cylinder assembly for rotation about the axis. Axially extending grooves are formed in an internal wall that defines the cylindrical opening. One of the grooves (referred to as an &#34;installation groove&#34;) extends rearwardly and opens through such rear wall portions of the housing as surround the cylindrical opening. The grooves serve the function of cooperating with key operated tumblers of the key cylinder assembly that project radially from opposed sides of the key cylinder assembly to selectively permit and prevent rotation of the key cylinder assembly relative to the housing. The installation groove serves the function of permitting an offset projection that is carried on the back of the key cylinder assembly to be inserted completely through the cylindrical opening of the housing as the key cylinder assembly is installed in the cylindrical opening. Once the key cylinder assembly is installed, it is rotated to position the offset projection out of alignment with the installation groove so that the offset projection extends in overlying relationship with such rear wall portions of the housing as surround the cylindrical opening in which the key cylinder assembly is installed. By this arrangement, so long as the key cylinder is prevented from rotating relative to the housing to a position where the offset projection aligns with the installation groove, the offset projection serves to retain the key cylinder assembly in place on the housing. 
     As will be explained in greater detail, the type of housing features that are described above, and that are also disclosed in the referenced Parent Cases, are utilized in the preferred practice of the present invention. For this reason, the present application is being filed as a continuation-in-part case, with the benefits of the filing dates of the referenced Parent Cases being claimed. 
     SUMMARY OF THE INVENTION 
     The present invention provides novel and improved flush mountable latches and locks for industrial cabinets, tool carts, electrical equipment enclosures and the like, with the latches and locks utilizing a highly versatile housing together with other interactive components of novel form to provide desired types of latching and locking actions. 
     A latch or lock embodying the preferred practice of the present invention includes a one-piece housing on which are mounted other interactive components that provide a variety of desired features. As will become apparent from the description that follows, the versatile housing that is used with latches and locks that embody the preferred practice of the present invention provides a rigid, sturdy base structure for securely supporting a variety of latch and lock components. Latches and locks that embody the preferred practice of the present invention advantageously employ small numbers of relatively movable parts that can be assembled and serviced with ease. 
     The versatile housing on which other operating components are mounted preferably is formed from a suitable thermoplastics material such as a glass reinforced polycarbonate based polymer blend, which provides a dimensionally stable, impact resistant structure that is rigid, strong and can be readily machined as may be needed to provide mounting formations for movably mounting operating handles of a wide variety of types. The molded housing defines a pan-shaped structure that has a forwardly facing recess for nesting an operating handle. A pair of threaded mounting studs have enlarged head portions that are embedded in the molded material of the housing so that the threaded studs project rearwardly from a back wall of the housing for receiving mounted posts that are threaded onto the studs for mounting latch and lock operating components, and for establishing connections with a mounting bracket. 
     While latch and lock structures that embody the preferred practice of the present invention have latch bolts of the spring-projected slide-mounted type, not all of the features of the invention are limited to use with spring-projected latch bolts, as will be apparent to those skilled in the art from the description and claims that follow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, and a fuller understanding of the invention may be had by referring to the description and claims that follow, taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an exploded perspective view of one form of lock assembly that embodies features of the preferred practice of the present invention, illustrating how the lock assembly is mounted on a closure, and showing two types of strikers that may be used with the lock assembly; 
     FIG. 2 is an exploded perspective view of components of the lock assembly of FIG. 1; 
     FIG. 3 is a right side elevational view thereof, with the handle in its normally nested position, with the latch bolt projected to its latched position, and with locking components locked; 
     FIG. 4 is a rear elevational view thereof; 
     FIG. 5 is a bottom plan view thereof; 
     FIG. 6 is a rear elevational view similar to FIG. 4, but with the locking components unlocked; 
     FIG. 7 is a rear elevational view similar to FIG. 6, but with the handle operated and with the latch bolt retracted to its unlatched position; 
     FIG. 8 is a sectional view, on an enlarged scale, as seen from a plane indicated by a line 6--6 in FIG. 2; 
     FIG. 9 is a perspective view of selected portions of the handle and the housing of the lock assembly of FIGS. 1-7, with the view showing principally rear portions of the handle, and with portions of the housing broken away; 
     FIG. 10 is a perspective view similar to FIG. 1, but showing only selected portions of the housing and other parts of the lock assembly, with the handle shown in its operated position whereby an operating arm that pivots with the handle also is moved to its operating position; 
     FIG. 11 is a perspective view of another form of lock that embodies features of the preferred practice of the present invention illustrating how the lock assembly is mounted on a closure, and showing two types of strikers that may be used with the lock assembly; 
     FIG. 12 is an exploded perspective view of components of the lock assembly of FIG. 11; 
     FIG. 13 is a right side elevational view thereof, with the handle in its normally nested position, with the latch bolt projected to its latched position, and with locking components locked; 
     FIG. 14 is a rear elevational view thereof; 
     FIG. 15 is a bottom plan view thereof; 
     FIG. 16 is a rear elevational view similar to FIG. 14, but with the locking components unlocked; 
     FIG. 17 is a rear elevational view similar to FIG. 16, but with the handle operated and with the latch bolt retracted to its unlatched position; 
     FIG. 18 is a sectional view as seen from a plane indicated by a line 18--18 in FIG. 12; 
     FIG. 19 is a perspective view of selected portions of the handle and the housing of the lock assembly of FIGS. 11-17, with the view showing principally rear portions of the handle, and with portions of the housing broken away; 
     FIG. 20 is a perspective view similar to FIG. 11, but showing only selected portions of the housing and other parts of the lock assembly, with the handle shown in its operated position whereby an operating arm that pivots with the handle also is moved to its operating position; 
     FIG. 21 is a perspective view of another form of lock that embodies feature of the preferred practice of the present invention illustrating how the lock assembly is mounted on a closure, and showing two types of strikers that may be used with the lock assembly; 
     FIG. 22 is an exploded perspective view of components of the lock assembly of FIG. 21; 
     FIG. 23 is a right side elevational view thereof, with the handle in its normally nested position, with the latch bolt projected to its latched position, and with locking components locked; 
     FIG. 24 is a rear elevational view thereof; 
     FIG. 25 is a bottom plan view thereof; 
     FIG. 26 is a rear elevational view similar to FIG. 24, but with the locking components unlocked; 
     FIG. 27 is a rear elevational view similar to FIG. 26, but with the handle operated and with the latch bolt retracted to its unlatched position; 
     FIG. 28 is a sectional view as seen from a plane indicated by a line 28--28 in FIG. 22; 
     FIG. 29 is a perspective view of selected portions of the handle and the housing of the lock assembly of FIGS. 21-27, with the view showing principally rear portions of the handle, and with portions of the housing broken away; 
     FIG. 30 is a perspective view similar to FIG. 21, but showing only selected portions of the housing and other parts of the lock assembly, with the handle shown in its operated position whereby an operating arm that pivots with the handle also is moved to its operating position; 
     FIG. 31 is a perspective view of another form of lock that embodies feature of the preferred practice of the present invention illustrating how the lock assembly is mounted on a closure, and showing two types of strikers that may be used with the lock assembly; 
     FIG. 32 is an exploded perspective view of components of the lock assembly of FIG. 31; 
     FIG. 33 is a right side elevational view thereof, with the handle in its normally nested position, with the latch bolt projected to its latched position, and with locking components locked; 
     FIG. 34 is a rear elevational view thereof; 
     FIG. 35 is a bottom plan view thereof; 
     FIG. 36 is a rear elevational view similar to FIG. 34 but with the locking components unlocked; 
     FIG. 37 is a rear elevational view similar to FIG. 36 but with the handle operated and with the latch bolt retracted to its unlatched position; 
     FIG. 38 is a sectional view as seen from a plane indicated by a line 38--38 in FIG. 32; 
     FIG. 39 is a perspective view of selected portions of the handle and the housing of the lock assembly of FIGS. 31-37, with the view showing principally rear portions of the handle, and with portions of the housing broken away; 
     FIG. 40 is a perspective view similar to FIG. 31 but showing only selected portions thereof, with the handle in its operated position; 
     FIG. 41 is an exploded perspective view, on an enlarged scale, of selected portions of the lock assembly of FIGS. 1-7, with the view showing alternate tool-operated plugs that can be installed in the lock housing, and with the view showing locked and unlocked positions of selected components of the locking mechanism of the lock assembly of FIGS. 1-7, it being understood that what is depicted in FIG. 41 is equally applicable to the lock assemblies of FIGS. 10-17, 20-27 and 30-37; and, 
     FIG. 42 is a perspective view of rear portions of the housing that is shown in FIG. 41. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, one form of a lock assembly that embodies features of the preferred practice of the present invention is indicated generally by the numeral 100. The lock assembly 100 has a housing 200 that mounts a plurality of interactive components that provide latching and locking functions. In preferred practice, latch and lock components that are described below are formed either from a durable thermoplastics material that will be described, or from stainless steel, whereby the resulting latch and lock units can be utilized in most normal environments without concern about deterioration from causes such as corrosion. 
     In overview, and as will be explained in greater detail, the interactive components that are carried on the housing 200 principally include a handle 300 that is mounted on the housing 200 for movement between normal and operating positions; a spring-projected latch bolt 400 that is mounted on the housing 200 for movement between latched and unlatched positions; an operating linkage 500 that drivingly interconnects the handle 300 and the latch bolt 400 for moving the latch bolt 400 to its unlatched position in response to movement of the handle 300 to its operating position; and, a locking mechanism 600 for selectively permitting and preventing movement of the latch bolt 400 by the handle 300. If the locking mechanism 600 is omitted, the lock assembly 100 is thereby transformed into a latch assembly, i.e., a unit which has a handle 300 that always can be operated to retract the latch bolt 400. 
     Appearance features of the combined housing and handle (i.e., the housing 200 and the handle 300) are shown in greater detail in the referenced Design Case II. Appearance features of the housing 200 as used with other handles are disclosed in the referenced Design Cases IV, VI and VII. 
     Referring to FIG. 1, it will be seen that the latch bolt 400 projects relatively sidewardly with respect to the housing 200 for engaging a suitably configured keeper or other structure that is located adjacent the lock assembly 100 when a closure 110 (on which the lock assembly 100 is mounted) is &#34;closed.&#34; Examples of suitably configured bolt-engaging keeper structures include strikers 180, 190 that are depicted in FIG. 1; however, those skilled in the art will understand that other types of strikers, as well as keeper formations of conventional, commercially available configurations, also may be used to engage and releasably retain the latch bolt 400. 
     The strikers 180, 190 have body structures 182, 192 that surround and define bolt-receiving chambers 184, 194, respectively. Openings 186, 196 are formed in the body structures 182, 192 and communicate with the chambers 184, 194, respectively. The openings 186, 196 are of adequate size to receive and releasably retain a tip portion of the latch bolt 400. Inclined surfaces 188, 198 are provided on the strikers 180, 190 to enable a tapered tip portion of the latch bolt 400 to be &#34;slammed&#34; into engagement with the strikers 180, 190, whereby the engagement of the latch bolt 400 with the inclined surfaces 188, 198 of the strikers 180, 190 will cause the latch bolt 400 to retract and pass by the surfaces 188, 198 on the way toward entering the openings 186, 196. Appearance features of the striker 180 are disclosed in greater detail in the referenced Design Case X. Appearance features of the striker 190 are disclosed in greater detail in the referenced Design Case XI. 
     Before turning to a more detailed description of the components of the lock assembly 100, the preferred manner in which the lock assembly 100 can be mounted on a closure 110 will be described. The portion of the closure 110 that is shown in FIG. 1 is a plate-like structure that has a mounting opening 112 formed therethrough. The closure portion 110 has a front surface 114 and a rear surface 116 that extend about the perimeter of the opening 112. The opening 112 has top and bottom boundaries 122, 124, and left and right side boundaries 126, 128. 
     In order to mount the lock assembly 100 on the closure 110, the lock assembly 100 has a pair of mounting posts 700 that project rearwardly for connection to a mounting bracket 750. The mounting bracket 750 is of generally U-shaped configuration, having a back wall 760 that connects at opposite ends with legs 762, 764. The legs 762, 764 extend forwardly from the plane of the back wall 760 toward the mounting flange 202, and cooperate with the housing 200 for clampingly mounting the lock assembly 100 on the closure 110. Appearance features of the mounting bracket 750 are disclosed in greater detail in the referenced Design Case VIII, as are other forms of mounting brackets that also may be used. 
     When the lock assembly 100 is to be installed on the closure 110, a gasket 270 is positioned to engage the mounting flange 202, and portions of the lock assembly 100 are installed through the closure opening 112 to position the gasket 270 adjacent the opening 112 in clamped engagement between the rear face 206 of the mounting flange 202 and the front surface 114 of the closure 110. The mounting bracket 750 is positioned to overlie the lock assembly 100, with the legs 762, 764 of the mounting bracket 750 extending into engagement with the rear surface 116 of the closure 110. Threaded fasteners 702 are installed to extend through holes 752 that are formed through the back wall 760 of the bracket 750. The fasteners 702 are threaded into the mounting posts 700 of the lock assembly 100 to clamp the mounting flange 202 into engagement with the gasket 720, to clamp the gasket 720 into engagement with the front surface 114, and to clamp the legs 762, 764 into engagement with the rear surface 116. 
     To facilitate an understanding of the various relative positions of the principal relatively movable components of the lock assembly 100, reference is made to FIGS. 1 and 3-6 wherein the handle 300 is in its &#34;normal&#34; or &#34;nested&#34; position; the latch bolt 400 is in its &#34;latched&#34; or &#34;projected&#34; position; and the lock mechanism 600 is &#34;locked&#34; so as to prevent unlatching movement of the latch bolt 400 in response to attempted operation of the handle 300. In FIG. 6, the mechanism of the lock 600 is shown &#34;unlocked&#34; so as to permit unlatching movement of the latch bolt 400 by operation of the handle 300. In FIGS. 7 and 10, the handle 300 is shown in its &#34;operating&#34; position wherein the handle 300 functions (in conjunction with the operation of other components, as will be described) to retract the latch bolt 400 to its &#34;unlatched&#34; position. 
     In the detailed description that follows, the lock assembly 100 and three alternate lock assembly embodiments 1100, 2100, 3100 will be described. Features of the lock assembly 100 are depicted in FIGS. 1-10. Features of the alternate lock assembly embodiments 1100, 2100, 3100 are depicted in FIGS. 11-20, FIGS. 21-30 and FIGS. 31-40, respectively. To the extent that the lock assemblies 100, 1100, 2100, 3100 use identical parts, identical reference numerals are used to designate the identical parts. To the extent that the lock assemblies 100, 1100, 2100, 3100 use slightly differently configured parts that function substantially identically, reference numerals that differ by magnitudes of 1000, 2000 and 3000 are used to identify these components--whereby many of the features that are designated by four-digit reference numerals need not be described inasmuch as the character of these features will be apparent from the discussion that is presented of features that are designated by three digit reference numerals. 
     The lock assemblies 100, 1100, 2100 and 3100 share a general layout of operating components, with many of the operating components being interchangeable from lock to lock. Features shared by all four of these lock embodiments include spring-projected latch bolts 400 of identical construction; the use of latch bolt slide housings 430 of identical construction; the use of pivotally mounted L-shaped operating arms 510, 2510 of basically similar character which drivingly connect the slide bolts 400 with their associated operating handles 300, 1300, 2300, 3300; and the identical manner in which secure locking connections are established between each of the pivotally mounted operating arms 510, 2510 and its associated key cylinder assembly 610 to selectively permit and prevent handle movement to retract an associated one of the latch bolts 400. 
     Principal areas of difference among the lock embodiments 100, 1100, 2100, 3100 reside in the configuration of their handles 300, 1300, 2300, 3300; the movements that are executed by the handles 300, 1300, 2300, 3300 to effect latch bolt retraction; the mountings of the handles on their associated housings 200, 1200, 2200, 3200; and the character of such handles extensions as project through a back wall or side wall opening(s) of the pan-shaped part 220, 1220, 2220, 3220 of the housings for engaging operating arms 510, 2510. 
     Turning now to a more detailed description of features of the components of the lock assembly 100, the housing 200 is preferably formed as a molded, one piece structure; thus it will be understood that the mounting flange 202 together with the walls that form an essentially pan-shaped housing portion 220 (i.e., the walls that define the width, length and depth of the recess 210) are integrally-formed parts of the same one-piece structure. The fabrication of the housing 200 as a one-piece member molded from thermoplastic, material such as a glass reinforced polycarbonate based polymer blend helps to provide a strong, rigid, impact resistant structure, whereby the housing 200 is capable of providing a versatile mounting platform for supporting the various relatively movable components of the lock assembly 100. 
     A preferred material from which the housing 200 is formed is a thermoplastic that is a glass reinforced polycarbonate based polymer blend, typically of the type sold by General Electric Company, Pittsfield, MA 01201 under the registered trademark XENOY. The most preferred resin blend is about 10 percent glass reinforced, and is selected from the &#34;6000 Series&#34; of the XENOY products sold by General Electric, with XENOY 6240 being preferred. While many other commercially available moldable plastics materials can be used to form the housing 200, as will be apparent to those skilled in the art, the preferred material helps to provide a high strength housing that is light in weight, resists crazing and hardening, is heat and chemical resistant, is resistant to impact, and can be machined as needed to provide suitable mounting holes and the like for movably mounting a wide variety of handles within the confines of the recess 210, as will be explained. 
     The mounting flange 202 has a front face 204 that defines the front of the housing 200. The mounting flange 202 has a rear face 206 that is substantially flat, i.e., all portions of the rear face 206 extend substantially in a single plane. The mounting flange 202 is bordered by a perimetrically extending edge surface 208 that joins the front and rear surfaces 204, 206 at their peripheries. While all portions of the mounting flange 202 are formed integrally and therefore serve to define elements of a one-piece structure, for purposes of reference, the mounting flange 202 can be thought of as having a top portion 212 that extends across the top of the recess 210, a bottom portion 214 that extends across the bottom of the recess 210, and opposed side portions 216, 218 that extend along left and right sides of the recess 210. Likewise, the edge surface 208 can be thought of as having a top portion 222, a bottom portion 224, and opposed side portions 226, 228. The flange portions 212, 214, 216, 218 and their associated edge portions 222, 224, 226, 228 cooperate to define a mounting flange 202 that has a generally rectangular configuration, with corner regions where adjacent ones of the edge portions 222, 224, 226, 228 join preferably being gently rounded to give an enhanced appearance. 
     The pan-shaped portion 220 of the housing 200 (i.e., the portion of the housing 200 that defines the forwardly facing recess 210) includes a top wall 232, a bottom wall 234, a pair of opposed side walls 236, 238, and a back wall 242. The back wall 242 is arranged so that it extends substantially parallel to the rear face 206 of the mounting flange 202. Stated in another way, the back wall 242 has a front face 244 and a rear face 246 that extend in planes that substantially parallel the plane of the rear face 206. Particular attention is paid to the molding of the rear face 246 of the back wall 242 so that the rear face 246 provides a smooth, planar back wall surface that can be utilized for the important functions of mounting and guiding the movement of other components of the lock assembly 100, as will be explained. 
     For the purpose of providing an enhanced appearance, it is preferred that front face 204 of the housing 200 be of curved, slightly convex configuration. Stated in another way, the front face 204 is convexly curved such that the thicknesses of the mounting flange portions 212, 214, 216, 218 increase progressively the closer these formations extend toward an imaginary center point of the front face 204. Likewise, the thicknesses of the mounting flange portions 212, 214, 216, 218 decreases progressively as these formations extend toward the edge surface portions 222, 224, 226, 228. Preferably, the thicknesses of the mounting flange portions 212, 214, 216, 218 as measured at locations that are adjacent to the edge portions 222, 224, 226, 228, are substantially uniform all along the edge surface 208--which is to say that the edge surface 208 has a width that is substantially constant as the edge surface 208 extends about the housing 200. Appearance features of the front face 204 of the housing 200 are within the purview of the referenced Design Case I. 
     For the purpose of providing an enhanced appearance, the positioning of the top and bottom walls 232, 234 of the pan-shaped housing portion 220 that defines the recess 210 preferably is asymmetrical relative to top and bottom edges 222, 224 of the mounting flange 202. Likewise, for purposes of enhanced appearance, the positioning of the left and right side walls 236, 238 of the pan-shaped housing portion 220 preferably is asymmetrical relative to the left and right opposed side edges 226, 228 of the mounting flange 202. This absence of symmetry in locating the recess 210 relative to opposed top and side edge portions 222, 224 and 226, 228 of the mounting flange 202 results in the top wall portion 212 being relatively short in height in comparison with the relatively tall height of the bottom wall portion 214 that depends beneath the recess 210, and results in the left sidewall portion 216 being relatively wide, while the right side wall portion 218 is a relatively narrow. 
     A feature of the present invention resides in the provision of compact, simply configured locks and latches having spring projected latch bolts, with the functional, operating components thereof being arranged substantially symmetrically about an imaginary, vertically extending center plane, designated by the numeral 201 in FIG. 4. In this regard, it will be understood that several functional features of the housing 200 are arranged substantially symmetrically about the center plane 201, including the side walls 236, 238 of the housing portion 220, and a sleeve-like housing formation 280, which will be described. 
     With respect to the side-to-side positioning of the recess 210 relative to features of the mounting flange 202, however, it will be understood that this is a feature dictated solely by appearance considerations, and not by functional considerations. Indeed, functional features of the lock assembly 100 would not be affected if the narrow flange portions 212, 218 were enlarged to give the flange portions 212, 218 widths that are equivalent to the relatively wider flange portions 214, 216, respectively. Likewise the styling of the front face 204 of the mounting flange 202 is dictated entirely by appearance considerations. 
     Threaded studs 250 project rearwardly from the rear face 246 of the back wall 242 for mounting various latch and lock components, as will be explained. Referring to FIG. X, the threaded studs 250 have enlarged head portions 252 with radially outwardly extending projections 254 that have somewhat of a toothed washer appearance and that are located adjacent the head portions 252. The head portions 252 and the projections 254 are embedded within the molded material of the back wall 242 of the housing 200 to provide structures that are anchored securely to the material of the plastic and will not rotate with request thereto. The studs 250 have elongate threaded shank portions 256 that project rearwardly from the head portions 252. The threaded shank portions 256 extend along spaced imaginary axes 251 that intersect the plane of the back wall 242 at right angles thereto. The axes 251 extend coaxially through the holes 752 that are formed in the back wall 760 of the mounting bracket 750. The axes 251 of the studs 250 are located equidistantly from the center plane 201, and are positioned on opposite sides of the center plane 201. 
     In preferred practice, the threaded studs 250 are commercially available fasteners that are sold by Penn Engineering and Mfg. Corp. of Danboro, PA, under the trademark PEM. The preferred part is model number CHN-832-4, is formed from stainless steel, has a tapered head 252 with a maximum diameter of about 0.289 inch, has radially extending projections portions 254 with a maximum outer diameter of about 0.328 inch, and has a shank length of about 0.250 inch that is threaded with a standard thread such as 8-32 NC. While these commercially available fasteners are intended for use with sheet metal, not plastic, they have been found to be quite suitable for use in the application described here. 
     Locator projections 260 are provided at spaced locations along the side walls 236, 238 at junctures of the side walls 236, 238 with the rear face 206 of the mounting flange 202. As will be seen in FIG. 4, the locator projections 260 are arranged symmetrically in pairs on opposite sides of the center plane 201. The locator projections 260 are intended to directly engage opposite sides 126, 128 of the opening 112 to orient the lock assembly 100 properly on the closure 110; however, if the opening 112 has been formed so as to be slightly &#34;oversized,&#34; the locator projections 260 may be utilized during installation of the lock assembly on the closure 110 as &#34;guides&#34; to visually aid in properly positioning the housing 200 with respect to the closure opening 112, preferably with the locator projections 260 being arranged to be spaced substantially equidistantly from opposite side portions 126, 128 of the opening 112. 
     While the gasket 270 is not essential in many applications where the lock assembly 100 can be used, the gasket 270 preferably is used in applications that present a possibility that moisture may penetrate the opening 112 as by passing between the back face 206 of the mounting flange 202 and the front face 114 of the closure 110. To aid in properly positioning the gasket 270 about the lock assembly 100, the gasket 270 has an asymmetrical configuration that causes the gasket 270 to extend in an obviously skew, out-of-alignment relationship with respect to the edge portions 226, 228 of the mounting flange 202 if the gasket 270 is installed incorrectly, e.g., in an &#34;inside-out&#34; manner. Specifically, the gasket 270 has a relatively wide left side portion 276 that underlies the relatively wide left side wall 236; similarly, the gasket 270 has a relatively narrow right side portion 278 that underlies the relatively narrow right side wall 238. Further, the gasket 270 has a relatively large, generally triangular-shaped corner region 272 that is configured to underlie a correspondingly large corner portion of the bottom wall 214 of the mounting flange 202, and a relatively smaller, generally triangular shaped corner region 274 that is configured to underlie a correspondingly smaller corner portion of the bottom wall 214 of the mounting flange. 
     The sleeve-like formation 280 of the housing 200 is located below the recess 210 and extends rearwardly from the rear face 206 of the mounting flange 202 along the bottom wall 234 of the housing portion 220. In preferred practice, the sleeve formation 280 is provided on the housing 200 regardless of whether the sleeve formation 280 is to be utilized to house operating components of a latch or lock. 
     If the sleeve formation 280 is to be utilized to house latch or lock components, an opening 282 is formed through the front wall 204 to communicate with a passage 284 that extends through the sleeve formation 280. The opening 282 and the passage 284 extend coaxially along an imaginary axis 281 (see FIG. 2) that lies within the imaginary center plane 201 and that extends substantially perpendicular to the planes of the rear face 206 and the back wall 246. If the sleeve formation 280 is not to be utilized to house latch or lock components, either no opening 282 is formed through the front wall 204, or a suitably configured plug (not shown) is installed in the opening 282 to close the opening 282. 
     Referring to FIG. 41, a shoulder 286 extends substantially radially with respect to the axis 281 to form a transition between the relatively large diameter of the opening 282 and the relatively smaller diameter of the passage 284. Axially extending top and bottom grooves 288 are formed in opposed upper and lower portions of the passage 284. Referring to FIG. 42, the grooves 288 extend axially rearwardly from the shoulder 286 and have bottom walls 289 that are curved and represent continuations of a cylindrical surface 290 of enlarged diameter that is formed in the rearward end region of the sleeve 280. A radially extending shoulder 292 forms a transition between the passage diameter that is designated by the numeral 284, and the enlarged diameter end region 290. A rounded groove 294 of shallower depth than the grooves 288 is formed in a side of the passage portion 284. The rounded groove 294 extends from the shoulder 286 to the shoulder 292. 
     Two opposed portions 296, 298 of the shoulder 292 extend radially outwardly and interrupt opposed side portions of the sleeve formation 280 to provide radially extending, rearwardly opening notches that are designated by the numerals 296, 298. 
     In preferred practice, the housing 2800 is formed without any openings, holes, slots or the like extending through the walls that define the recess 210, i.e., the top, bottom, and side walls 232, 234, 236, 238, and the back wall 242 are smooth and have no openings formed therethrough. Depending on the type of handle that is to be used with the housing 200, and on the type of latch or lock operating mechanism that is to be mounted on the housing 200, one or more suitable passages through the housing 200 are machined in the form of openings, holes, slots and the like which formed as by drilling, milling or other conventional machining techniques. 
     The handles 300, 1300, 2300 and 3300 that are used in the housings 200, 1200, 2200 and 3200 are formed from molded plastics material, preferably of the same thermoplastics material from which the housings 200, 1200, 2200 and 3200 are formed. The handles 300, 1300, 2300, 3300 have front surface portions 304, 1304, 2304, 3304 that are of complexly curved, generally convex shape, and are configured to extend in a flush, substantially contiguous manner to smoothly continue the curvature of the complexly curved, convex front surfaces 204, 1204, 2204, 3204 of the mounting flange 202, 1202, 2202, 3202 when the handles 300, 1300, 2300, 3300 are in their normal or nested position. The handle 300 is mounted on the housing 200 for movement between a normally nested position that is, shown in FIGS. 1 and 3-5, and an operating position that is depicted in FIG. 10. The handle 1300 is mounted on the housing 200 for movement between a normally nested position that is, shown in FIGS. 11 and 13-15, and an operating position that is depicted in FIG. 20. The handle 2300 is mounted on the housing 200 for movement between a normally nested position that is, shown in FIGS. 21 and 23-25, and an operating position that is depicted in FIGS. 30. The handle 3300 is mounted on the housing 200 for movement between a normally nested position that is, shown in FIGS. 31 and 33-35, and an operating position that is depicted in FIGS. 40. 
     The handles 300, 1300, 2300 and 3300 have shapes that let them nest and move with ease within he confines of their respective recesses 210, 1210, 2210, 3210. Referring to FIGS. 9, 19, and 29 the handles 300, 1300, 2300 have pivoted mounting portions 310, 1310, 2310 that extend transversely across the recesses 210, 1210, 2210 and provides through passages 312, 1312, 2312 of square cross section for receiving handle mounting shafts 350, 1350, 2350 that also is of square cross section. The opposed end regions 314, 1314, 2314 of the mounting portions 310, 1310, 2310 have cylindrical recesses 316, 1316, 2316 that surround the ends of the passages 312, 1312, 2312 for mounting O-rings 318. 
     Stop surfaces 320, 1320, 2320 are formed on depending portions of the handles 300, 1300, 2300 to engage the back walls 242, 1242, 2242 of the housings 200, 1200, 2200 when the handles 300, 1300, 2300 are nested in the recesses 210, 1210, 2210. Stop surface 322, 1322, 2322 are formed on the end regions of the handles 300 and 1300, and on the back of the handle 2300 for engaging the top walls 232, 1232 of the housing portions 220, 1220, and the back wall 2242 of the housing portions 2220 when the handles 300, 1300, 2300 are in their operating positions, as is shown in FIGS. 10, 20 and 30. 
     The handles 300, 1300, 2300, 3300 have operator engagement formations 310, 1310, 2310, 3310 that can be engaged by an operator&#39;s hand (preferably by one or more fingers thereof) for moving the handles 300, 1300, 2300, 3300 between their normal or nested positions and their operating positions. 
     Referring to FIGS. 2, 12, and 22, aligned handle mounting holes 336, 338; 1336, 1338; and 2336, 2338 are formed through the side walls 236, 238; 1236, 1238; and 2236, 2238 on opposite sides of the recesses 210, 1210, 2210. The holes 336, 338; 1336, 1338; and 2336, 2338 are concentric about imaginary axes 331, 1331, 2331 that extend substantially parallel to the back walls 242, 1242, 2242 and that extend substantially perpendicular to the side walls 236, 238; 1236, 1238; and 2236, 2238. 
     The holes 336, 338; 1336, 1338; and 2336, 2338 are of equal diameters, and serve to journal reduced diameter end regions 346, 348 of a pair of bushings 356, 358. The bushings 356, 358 have relatively large diameter portions 366, 368 that extend alongside outer surfaces of the side walls 236, 238; 1236, 1238; and 2236, 2238. The O-rings 318 are positioned on the inside of the recess 316, 1316, 2316 to surround the holes 386, 338, 1236, 1238, 2236, 2238 to provide moisture seals that are compressed between opposite sides of the handle 300, 1300, 2300 and inner surfaces of the housing walls 236, 238; 1236, 1238; and 2236, 2238. 
     The bushings 356, 358 have square holes 376, 378 formed therethrough that extend along the imaginary axes 331, 1331, 2331. The hole 378 that is formed in the bushing 358 has an end region 379 that is widened to receive a corner bend of a handle mounting shaft 350, as will be explained. The hole 376 that is formed in the bushing 356 is narrowed on opposite sides as by inwardly extending projections that are designated by the numeral 377. The purpose of providing the projections 377 is to lock the bushing 356 in place on an associated one of the handle mountings shafts 350, 1350, 2350 that extend through the square hole 376, as will be explained. 
     The handle mounting shafts 350, 1350, 2350 are formed from stainless steel stock of square cross section, and are provided with leg portions 352, 354; 1352, 1354; and 2352, 2354 that are connected by curved, right-angle bends 356, 1356, 2356, respectively. The legs 352, 1352, 1354, extend through the bushing holes 376, 378 and the handle passages 312, 1312, 2312. Grooves 380, 1380, 2380 are formed in opposite sides of end regions 382, 1382, 2382 of the leg 352, 1352, 2352, respectively, to receive the bushing projections 377. 
     With respect to each of the lock assemblies 100, 1100, 2100, 3100, its latch bolt 400 is mounted on an associated one of the housings 200, 1200, 2200, 3200 for movement between a latched position that is extended (i.e., projected) with respect to its associated housing, as is shown in FIGS. 1, 11, 21 and 31, and an unlatched position that is withdrawn (i.e., retracted) with respect to the housing 200, as is shown in FIGS. 7, 17, 27 and 37. The latch bolt 400 is an elongate member of generally rectangular configuration having a left end region 402 that carries a rearwardly extending projection 404, and an enlarged right end region 406 that defines an inclined striker engaging surface 408. The latch bolt 400 also has an elongate central region 410 that interconnects and extends between the end regions 402, 406. An elongate slot 412 is formed in the central region 410. The slot 412 has a left end wall 414 and a right end wall 416. 
     The central region 410 is slidably received in a slide channel 420 that extends horizontally across the back wall 242 of the housing 200. The slide channel 420 is of generally rectangular cross-section and is cooperatively defined by the back wall surface 246 and by a stamped stainless steel bracket 430 that is mounted on one of the housings 200, 1200, 2200, 3200 in engagement with the rear face 246, 1246, 2246, 3246 of the back wall 242, 1242, 2242, 3242. The stamped sheet metal bracket 430 has opposed top and bottom walls 432, 434 that define opposed sides of the slide channel 420, and a back wall 436 that cooperates with the rear face 246 of the back walls 242, 1242, 2242, 3242 to define the back and front of the horizontally extending slide bolt channel 420, respectively. 
     The bracket 430 has upper and lower mounting flanges 442, 444 that border the top and bottom walls, 432, 434, respectively. The flanges 442, 444 have mounting holes 446 formed therethrough to receive the threaded mounting studs 250. The back wall 436 has a forwardly extending tab 438 that projects into the slide bolt channel 420 and into the slot 412 that is formed in the latch bolt 400. 
     A compression coil spring 440 is carried in the slot 412. The spring 440 has opposed ends that engage the tab 438 and the right end wall 416 of the slot 412, respectively, to bias the latch bolt 400 toward its projected or &#34;latched&#34; position. When the latch bolt 400 is in its latched position, the tab 438 engages the left end wall 414 of the slot 412. 
     The operating linkages 500, 2500 include L-shaped operating arms 510, 2510 that are pivotally mounted on the housings 200, 1200, 2200 and 3200, respectively, by one of the mounting posts 700. The mounting posts 700 have cylindrical portions 703 that are threaded onto the studs 250 and that extend through holes 511, 2511 that are formed in the arms 510, 2510. The mounting posts have enlarged hex formations 705 that retain the arms 510, 2510 in place on the cylindrical portions 703, and that can be engaged by a nut driver or a wrench to tighten the mounting posts 700 in place on the studs 250. 
     Because the lock assembly 3100 has an operator graspable handle 3300 that slides within the recess 3210 rather than pivots relative to its associated housing 3200 (as is the case with the handles of the lock assembles 100, 1100 and 2100), a brief discussion is in order concerning the unique character of this sliding handle embodiment. 
     Referring to FIGS. 31-39 wherein features of the lock assembly 3100 are depicted, two operator engageable structure 3900, 3910 are nested in the recess 3210. The structures 3900, 3910 are identical in many essential respects, with one principal difference residing in the fact that the structure 3900 is rigidly bonded to the housing formation that surround the recess 3210, while the structure 3910 is a handle that is movable relative to the housing 3200 along the length of the recess 3210. A slot 3912 (shown in phantom in FIG. 32 and depicted in part in FIG. 39) is formed through the housing back wall 3242 to receive a handle carried arm or projection 3350 that extends through the slot 3912 for engaging the operating arm 3510 to move the arm 3510 to unlatch the lock or latch 3100. 
     As is best seen in FIG. 39, the handle operated arm or projection 3350 has a shoulder 3930 formed thereon at a location spaced slightly below the opening in the back wall 3242 so that, when a guide member 3940 is installed on the projection 3350 in a press-fit, the guide member 3940 will rest against the shoulder 3930 and not clamp against the back wall 3242 in away that will inhibit movement of the handle relative to the housing 3200. Preferably, the connection between the handle projection 3350 and the guide member 3940 is secured as by adhesive bonding, whereby the handle operated arm 3350 is every bit as suited as the handle operated arms 350, 1350, 2350 to pivot the arms 510, 2510 in response to handle movement. 
     The operating arms 510, 2510 have leg portions 512, 2512 of that are engaged by the handle operated arms 350, 1350, 2350, 3350 and that are caused to pivot about an associated one of the mounting posts 700 in response to movement of an associated handle 300, 1300, 2300, 3300 from its normal or nested position to its operating position. 
     Referring to FIGS. 2 and 12, the leg 512 of the arm 510 features a forwardly extending projection 511 that provides a stop surface 513. The stop surface 513 is configured to engage the top side wall 432 of the latch bolt housing 430 when the operating arm 510 is in the position shown in FIGS. 7 and 17, wherein the arm 510 functions to fully retract the latch bolt 400. A further feature of the configuration of the arm 510 is that the stop surface 513 is arranged to engage the latch housing wall 432 at the same time that the handle stop projections 320, 1320 engage the housing back walls 242 1242 so that further movement of the handles 300, 1300 and of the arms 510 is positively prevented. 
     The arms 350, 1350, 2350, 3350 also have leg portions 514, 2514 that overlie the housing back walls 242, 1242, 2242, 3242, that engage the bolt projections 404, and that have hook shaped end regions 520, 2520 that overlie portions of the housing sleeve formations 280, 1280, 2280, 3280. As will be explained, the lock mechanisms 600 serve to engage the hook shaped end regions 520, 2520 to selectively permit and prevent movement of the arms 510, 2510 in response to attempted operation of the handles 300, 1300, 2300, 3300. 
     The lock mechanisms 600 include a ring-like insert 610 that is provided for positioning in the rear end regions 292, 1292, 2292, 3292 of the sleeve portions 280, 1280, 2280, 3280 of the housings 200, 1200, 2200, 3200. The insert 610 serves the function of closing rear end regions of the top and bottom grooves 288, 1288, 2288, 3288, and of defining a rearwardly extending stop projection 620 for limiting the range of rotary movement of locking members 630. 
     In order to provide an extension of the rounded installation groove 294, 1294, 2294, 3294 through the ring-like insert 610, a rounded groove 624 is formed in the insert 610 and is aligned with the rounded grooves 294, 1294, 2294, 3294 of the sleeve members 280, 1280, 2280, 3280. In order to properly position the ring-like insert 610 for mounting on the housings 200, 1200, 2200, 3200, a pair of radially extending formations 626, 628 are provided to engage the grooves 296, 298; 1296, 1298; 2296, 2298; and 3296, 3298 that are formed at the rear end of the sleeve members 280, 1280, 2280, 3280. The groove 626 and the formations 296, 1296, 2296, 3296 are of relatively small size and are configured to mate in a close slip fit. The groove 628 and the formations 298, 1298, 2298, 3298 are of relatively larger size and are configured to mate in a close slip fit. 
     Referring to FIGS. 2, 12, 22, 32, a key-receiving, tumbler-carrying plug assembly 650 is provided that has an enlarged diameter head portion 652 that has a circumferentially extending groove for carrying an O-ring 653, and a smaller diameter body 654 that is configured to be rotatably received in the openings and passages 282, 284; 1282, 1284; 2282, 2284; and 3282, 3284, respectively. Radially extensible tumblers 656 form components of the plug 650 assembly and are extensible into the top and bottom grooves 288, 1288, 2288, 3288 to selectively permit and prevent rotation of the key cylinder assembly 650 with respect to the housings 200, 1200, 2200, 3200. 
     The key cylinder assembly 650 has a rearwardly projecting square drive formation 678 that is engaged by a rotary locking member 680. The rotary locking member 680 is rigidly attached to the cylinder assembly by means of a threaded fastener 682 and a lock washer 684. The locking member 680 has a rearwardly extending projection 695 of curved shape that can be rotated by the key cylinder assembly 650 into and out of locking engagement with the hook shaped end regions 520, 2520 of associated ones of the arms 510, 2510. The rearwardly extending projection 620 of the insert ring 610 limits the range of rotary travel of the locking member 680 so as to prevent full 360 degree rotation thereof. The rearwardly extending projection 695 of the locking member 680 is rotatable (1) into locking engagement with the hook shaped end regions 520, 2520 of the operating arms 510, 2510, and (2) out of locking engagement therewith to permit pivotal movement of the arms 510, 2510 by the handles 300, 1300, 2300, 3300 to retract (i.e., &#34;unlatch&#34;) the latch bolt 400. 
     A locked orientation of the locking mechanism components as described above is presented in an exploded display in FIG. 41 and is designated by the numeral 790. An unlocked orientation of these components is designated by the numeral 792. 
     If desired, the key locking cylinder assembly 650 can be replaced by tool operated plugs, as designated by numerals 800, 810 in FIG. 41. Detent devices 802, 812 are preferably provided in the plugs 800, 810 as by forming radially extending bores 804, 814 that house springs 806, 816 and balls 808, 818 which cooperate with such interior sleeve formations as the grooves 788 that are shown in FIG. 41 to releasably retain the plugs 800, 810 in position to prevent undesired rotation thereof. 
     The plugs 800, 810 carry tool receiving formations, typically a hex 820 recess for receiving an Allen wrench, or a narrow, shallow slot 822 for receiving a screwdriver. 
     Operation of the locks 100, 1100, 2100, 3100 described herein to retract their slide bolts 400 will be understood by those skilled in the art to involve a simple movement of their operating handles 300, 1300, 2300, 3300 when their locking mechanisms 600 are unlocked, whereby their operating arms 510, 2510 will pivot to effect latch bolt retraction. And, because latch bolt movement is not directly tied to operating arm movement, the described locks and latches have a &#34;slam&#34; capability that enables the latch bolts 400 to be moved into latching engagement with strikers 180, 190 without causing corresponding handle movements. 
     To the extent that orientation terms such as &#34;frontwardly,&#34; &#34;rearwardly,&#34; &#34;upwardly,&#34; &#34;downwardly&#34; and the like have been used in this document, it will be understood that such terms have been used simply for convenience and to facilitate understanding of the features that have been described, whereby the use of such orientation term should not be deemed to limit the scope of the claims that follow. 
     Although the invention has been described in its preferred form with a certain degree of particularity, it will be understood that the present disclosure of the preferred form has been made only by way of example, and that numerous changes in the details of construction and the combination and arrangements of parts and the like may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed. It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty exist in the invention disclosed.