Patent Publication Number: US-2023151645-A1

Title: Interchangeable Latch Assembly for an Exit Device

Description:
RELATIONSHIP TO OTHER APPLICATIONS AND PATENTS 
     This application is a continuation of U.S. Pat. Application No. 16/202,802, filed Nov. 28, 2018, now U.S. Pat. No. 11,566,449, which claims the benefit of U.S. Provisional Pat. Application No. 62/591,985, filed Nov. 29, 2017, which is hereby incorporated by referenced in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a door latch system for latching a hinged door into a frame; and more particularly, to a door latch system wherein any one of a variety of latch heads may be selectively assembled to a universal actuating assembly as required for a particular application. The door latch system includes a universal actuating assembly and an interchangeable latch assembly, wherein the interchangeable latch assembly is removably coupled to the universal actuating assembly as a unit. The interchangeable latch assembly includes a driven member commonly configured to releasably mount with a driving member of an actuating mechanism of the universal actuating assembly. Interchangeable latch assemblies having any one of a variety of latch heads, such as a Pullman style latch head, a star wheel style latch head, a mortise style latch head or a vertical rod style latch head, may then be readily and interchangeably mounted to the universal actuating assembly without requiring modification of the remainder of the latch system. The door latch system may include other features and accessories making the door latch system readily convertible to various field applications and needs. 
     BACKGROUND OF THE INVENTION 
     Existing door latch systems, such as exit devices, incorporate a locking element, such as a latch, engageable with a mating strike. In unlocking, the latch of the exit device is required to rotate or retract out of the way of the mating strike to reach a state of being unlocked. The latch is typically mounted in a door and the strike in a door frame. However, the opposite may exist to equal effect. 
     Exit devices typically employ a push bar to enable unlocking of the latch system so as to enable door opening. Push bars allow users to open the door without necessarily requiring the use of their hands. Rather, the user’s body can be used to push against the push bar until the latch is retracted from the strike. Alternatively or additionally, exit devices may also include an electrically actuable latch such that an electric current is supplied to the latch to withdraw the latch from the strike. 
     Doors associated with exit devices may be secured in the door frame through numerous possible latching heads such as, for example, a Pullman style latch head, a star wheel style latch head, a vertical rod style latch head or a mortise style latch head. In some cases, where an alternate means is used to secure the door, such as an electromagnetic lock system, a dummy “latch-less” head may be used. 
     Typically, each of these devices requires an entire, dedicated door latch system to be utilized with that particular style of latch head. As a result, numerous bulky systems must be fabricated and inventoried by a manufacturer or distributor so a desired door latch system is available when requested or needed. Further, special features, such as for example, a dogging feature to lock out the push bar, a push bar position sensor or a built in audible alarm, may be desired adding to the number of systems that must be fabricated and inventoried. In addition, if repair or reconfiguration of the door latch system in the field is required, replacement of the entire door latch system may be necessary. 
     Thus, what is needed in the art is a simplified door latch system, and especially a simplified door latch system that incorporates a universal actuating assembly configured to engage with one of a number of various interchangeable latch head assemblies such that fabrication and stocking requirements are reduced and ease of repair or reconfiguration is improved. 
     What is further needed is a door latch system with an assortment of available add-on accessories and features wherein the system is designed to readily incorporate any of the accessories/features, or not, depending on the end use needs of the system. 
     It is a principal object of the present invention to address these, as well as other, needs. 
     SUMMARY OF THE INVENTION 
     Briefly described, an exit device-type door latch system is configured for releasably securing a door in a door frame. The door latch system generally comprises an interchangeable latch assembly, a universal actuating assembly and a housing for receiving the interchangeable latch assembly and universal actuating assembly. 
     The interchangeable latch assembly comprises a latch head having a latch mounted to the latch head, the latch being selectively moveable between an extended or latched mode wherein the door is secured in the door frame and a retracted or unlatched mode wherein the door is unsecured. The interchangeable latch assembly further comprises a driven member operatively connected to the latch, the driven member moveable to extend or retract the latch. 
     The universal actuating assembly, removably couple-able with the interchangeable latch assembly, comprises an actuating mechanism. The actuating mechanism includes a mounting bracket, a driving member, at least one actuating member and a push bar operably coupled to the at least one actuating member. The interchangeable latch assembly is removably securable to the mounting bracket of the universal actuating assembly. Actuation of the driving member by depressing the push bar translates the driving member and the connected driven member to move the latch to the retracted position and place the latch assembly in the unlatched mode. 
     A first interchangeable latch assembly may be swapped with a second interchangeable latch assembly without requiring modification of the universal actuating assembly. 
     In accordance with an aspect of the present invention, the actuating mechanism comprises at least one actuating member coupled to a push bar, the actuating member including a pivoting leg coupled to the driving member of the actuating mechanism and configured to translate the driving member and the driven member to retract the latch when the push bar is in a depressed position and extend the latch when the push bar is in a released position. 
     In accordance with a further aspect of the present invention, one or the other of the driven member and the driving member includes a threaded post while the other includes a slot configured to receive the threaded post, and a corresponding threaded fastener is configured to threadably engage the threaded post to couple the driven member to the driving member. 
     In accordance with another aspect of the present invention, the interchangeable latch assembly is selected from one of the following types: a Pullman style interchangeable latch mechanism, a star wheel style interchangeable latch mechanism, a surface vertical rod style interchangeable latch mechanism, a concealed vertical rod style interchangeable latch mechanism or a mortise style interchangeable latch mechanism. 
     In accordance with another aspect of the invention, the interchangeable latch assembly may include a dummy head. 
     In accordance with the invention, to assure compatibility between a universal actuating assembly and a selected interchangeable latch assembly, x-y-z coordinates measured between: (a) an arbitrary mounting point commonly shared by the universal actuating assembly and the selected interchangeable latch assembly when the interchangeable latch assembly is secured to the universal actuating assembly and (b) a connector point of the driving member and a connector point of the driven member when the latch is in its latched position are generally equal so that connector points, when the interchangeable latch assembly and the universal actuating assembly are connected, share the same point in space. 
     In accordance with another aspect of the invention, a method of swapping a first interchangeable latch assembly with a second interchangeable latch assembly without requiring modification of the universal actuating assembly of a door latch system is provided including the steps of: 
     providing door latch system having a universal actuating assembly and a first interchangeable latch assembly, wherein the x-y-z coordinates measured between an arbitrary mounting point commonly shared by the universal actuating assembly and the first interchangeable latch assembly when the first interchangeable latch assembly is secured to universal actuating assembly, and a connector point of the driving member and a connector point of driven member when the latch is in its latched position are generally equal; (2) disconnecting and removing the first interchangeable latch assembly; (3) selecting a second interchangeable latch assembly wherein the x-y-z coordinates measured between an arbitrary mounting point commonly shared by the first universal actuating assembly and the selected second interchangeable latch assembly when the second interchangeable latch assembly is secured to the universal actuating assembly, and a connector point of the driving member and a connector point of the driven member when the latch is in its latched position are generally equal; and (4) connecting the second interchangeable latch assembly to the universal actuating assembly. 
     In a further aspect of the invention, following step (1), further steps may include: removing the end cap and removing the push bar. Following step (4), further steps may include: reconnecting the push bar and reinstalling the end cap. 
     Numerous applications, some of which are exemplarily described below, may be implemented using the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG.  1    is a perspective view of a door latch system incorporating an embodiment in accordance with the present invention; 
         FIG.  2    is an exploded view of the latch system shown in  FIG.  1   ; 
         FIG.  3    is detailed view of components of a universal actuating assembly and an interchangeable latch assembly in accordance with the present invention; 
         FIG.  3 A  is a magnified view of the interchangeable latch assembly end of  FIG.  3   , in accordance with the invention; 
         FIG.  4 A  is a perspective view of a Pullman style interchangeable latch assembly in accordance with the invention; 
         FIG.  4 B  is a perspective view of a latch head used with the Pullman style interchangeable latch assembly shown in  FIG.  4 A ; 
         FIG.  4 C  is a perspective view of the Pullman style interchangeable latch assembly shown in  FIG.  4 A  mounted within the door latch system shown in  FIG.  1   ; 
         FIG.  4 D  is a cross section view of the Pullman style interchangeable latch assembly shown in  FIG.  4 C  mounted onto a door and in engagement with a strike; 
         FIG.  4 E  is an exploded view of an end of a Pullman style door latch system configured for left-handed operation; 
         FIG.  4 F  is an exploded view of an end of a Pullman style door latch system configured for right-handed operation; 
         FIG.  4 G  is a phantom perspective view of a fire rated Pullman style interchangeable latch assembly (without its driven member) similar to that shown in  FIG.  4 A  with the fire roll pin in a non-engaged orientation; 
         FIG.  4 H  is a phantom perspective view of the Pullman style interchangeable latch assembly shown in  FIG.  4 G  with the fire roll pin in an engaged orientation such as after being exposed to a fire; 
         FIG.  5 A  is a perspective view of a star wheel style interchangeable latch assembly in accordance with the invention; 
         FIG.  5 B  is a perspective view of a latch head used with the star wheel style latch mechanism shown in  FIG.  5 A ; 
         FIG.  5 C  is a perspective view of the star wheel style interchangeable latch assembly shown in  FIG.  5 A  mounted within the door latch system shown in  FIG.  1   ; 
         FIG.  5 D  is a cross section view of the star wheel style interchangeable latch assembly shown in  FIG.  5 C  mounted onto a door and in engagement with a strike; 
         FIG.  5 E  is an exploded view of an end of a star wheel style door latch system configured for left-handed operation; 
         FIG.  5 F  is an exploded view of an end of a star wheel style door latch system configured for right-handed operation; 
         FIG.  5 G  is an exploded view of a star wheel style interchangeable latch assembly in accordance with the invention; 
         FIG.  5 H  is an exploded view of a prior art star wheel latch assembly; 
         FIG.  5 I  is an exploded view of a fire rated star wheel style interchangeable latch assembly; 
         FIG.  6 A  is a perspective view of an interchangeable dummy head in accordance with the invention; 
         FIG.  6 B  is a perspective view of the dummy head shown in  FIG.  6 A  mounted within the door latch system shown in  FIG.  1   ; 
         FIGS.  6 C and  6 D  are views of an embodiment of the door latch system shown in  FIG.  1    wherein in the push bar is disabled in its extended position; 
         FIGS.  6 E and  6 F  are views of an embodiment of the latch system shown in  FIG.  1    wherein in the push bar is disabled in its retracted position; 
         FIG.  7    is a perspective view of a lock out bracket that may be used in conjunction with disabling of the push bar shown in  FIGS.  6 C and  6 E ; 
         FIGS.  8 A and  8 B  are perspective views of a surface vertical rod style interchangeable latch assembly in accordance with the invention; 
         FIGS.  9 A through  9 C  are perspective views of a concealed vertical rod style interchangeable latch assembly; 
         FIGS.  10 A through  10 C  are perspective views of a mortise style interchangeable latch assembly; 
         FIG.  11 A  is a perspective view of a mortise style interchangeable latch assembly wherein the driven bar is oriented for right-handed operation; 
         FIG.  11 B  is a perspective view of a mortise style interchangeable latch assembly wherein the driven bar is oriented for left-handed operation; 
         FIG.  12 A  is a view of a shaft and related parts of an interchangeable latch assembly in accordance with the invention; 
         FIG.  12 B  is a view of a shaft of an interchangeable latch assembly showing how the shaft engages with an actuator; 
         FIG.  12 C  is a view of a shaft of an interchangeable latch assembly showing how the shaft engages with the shaft hub; 
         FIG.  12 D  is a view of a hub and a shaft indicating placement of a magnet in the hub to retain the shaft during assembly; 
         FIG.  12 E  is a view of a shaft of an interchangeable latch assembly showing how the shaft engages a cam plug of a mortise-style latch; 
         FIG.  13 A  is a perspective view of a latch position sensor actuator plate attached to the driving member used in conjunction with the door latch system in accordance with the invention; 
         FIGS.  13 B and  13 C  are views of a latch position sensor (latched and unlatched positions) that may be used in conjunction with the door latch system in accordance with the invention; 
         FIG.  14    is a view of an embodiment of a dogging mechanism that may be used in conjunction with the door latch system in accordance with the invention; 
         FIG.  15    is the a view of the dogging mechanism shown in  FIG.  14    with the push bar depressed; 
         FIGS.  16 ,  17 A and  17 B  are views of noise reduction devices that may be mounted within the door latch system shown in  FIG.  1   ; 
         FIGS.  18 A and  18 B  are views of a noise reduction head flange of a dogging mechanism; 
         FIG.  19 A  is a perspective view of an actuating member equipped with a noise reduction bar mount and actuating member spacer; 
         FIG.  19 B  is a side cross section view of the actuating member shown in  FIG.  19 A  with the push bar is in its depressed position; 
         FIG.  19 C  is a side cross section view of the actuating member shown in  FIG.  19 A  with the push bar in the extended position; 
         FIGS.  20 A through  20 C  are views of an embodiment of an alarm assembly that may be mounted within the door latch system shown in  FIG.  1   ; and 
         FIGS.  21 A through  21 C  are views of a wire clip that may be mounted within the door latch system shown in  FIG.  1   . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate currently preferred embodiments of the present invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     Referring to  FIGS.  1 - 3  and  3 A , door latch system  10  in accordance with the invention may include universal actuating assembly  11  and exemplary interchangeable latch assembly  12 . Door latch system  10  may be mounted on a door  18  while a mating strike may be mounted on a door frame  22 . See e.g.,  FIG.  4 D . 
     To assure compatibility between a universal actuating assembly and a selected interchangeable latch assembly, an important aspect of the invention is that, when a selected interchangeable latch assembly is connected to an associated universal actuating assembly, regardless of: (1) the type of actuator (e.g., linear movement as described in detail below, rotational movement, arcuate movement, etc.); (2) the type of latch head (e.g., Pullman style, star wheel style, vertical rod style, mortise style, etc.); (3) how the interchangeable latch assembly connects to the universal actuating assembly (e.g., pin and slot, fastener, by mating surfaces contact, etc.); or (4) whether the latch head is being exchanged for an identical latch head or for a different type of latch head or whether the universal actuating assembly is being replaced, the interchangeable latch assembly matches up with the universal actuating assembly when the two are connected so that retraction of the latch from the associated strike is accomplished when the push bar is depressed. 
     For purposes of describing the general aspects of the invention, the device as described in  FIG.  1   -3A include a Pullman style latch head interchangeable latch assembly  12  mated to a universal actuating assembly  11  with a linear-movement actuator. However, it is understood that the invention comprehends any types of movements or latches available in the art. 
     Referring further to  FIGS.  1 - 3  and  3 A , universal actuating assembly  11  includes actuating mechanism  16  which is mounted to housing  26  (a linear-movement actuating mechanism is shown). Housing  26  has a U-shaped cross section. Actuating mechanism  16  may include mounting bracket  40 , a driving member  46 , such as an actuating bar, movably connected to mounting bracket  40 , at least one actuating member  34  and push bar  24 . Actuating mechanism  16  may be actuable by push bar  24  secured within housing  26  which is mounted on door  18 . An end cap  28  may be secured to housing  26  to cover any exposed internal components and present an aesthetically pleasing lock system. Depression of push bar  24  into housing  26 , such as in an actuating direction  30 , operates to move latch  14  of an exemplary interchangeable latch assembly  12  in an unlocking direction  32  which is generally orthogonal to actuating direction  30 . Such movement causes exemplary latch  14  to disengage from corresponding strike  20  which is secured in door frame  22  ( FIG.  4 D ). 
     To facilitate depression of push bar  24  so as to direct exemplary latch  14  from the latched position to the unlatched position, push bar  24  may be coupled to at least one actuating member  34  by way of respective bar mounts  36  situated on each actuating member  34 . Each actuating member  34  may include a fixed leg  38  secured to mounting bracket  40  at a first end  38   a  and to a pivoting leg  42  at the opposing second end  38   b  via a pivot pin  44 . Pivoting leg  42  may be pivotally coupled to bar mount  36  at a first end  42   a  and to driving member  46  at a second end  42   b , wherein driving member  46  may be slidably coupled to mounting bracket  40  for linear movement. Mounting bracket  40  may be fixedly secured to door  18  such that movement of push bar  24  in the actuating direction  30  through manual depression of push bar  24  pivots pivoting leg  42  about pivot pin  44  thereby causing driving member  46  to translate in the unlocking direction  32  and thereby causing latch  14  to withdraw from strike  20 . Each actuating member  34  may further include a biasing member  48  (see for example  FIG.  19 C ) which may operate to urge driving member  46  in a locking direction  50  to reverse pivot actuating member  34  and return push bar  24  to the extended position shown in  FIG.  1    whereby latch  14  is placed in the latched position so as to engage strike  20  and secure door  18  in door frame  22 . 
     Bar mounts  36  may include opposing flanges  52  which are configured to slidably engage with a mating set of tracks  54  located along the inner surface  56  of push bar  24 . See e.g.,  FIG.  17 A . Opposing push bar ends  58 ,  60  are constrained within housing  26  so as to prevent lateral movement of push bar  24  during operation. In this manner, push bar  24  floats within housing  26  and is able to cycle between extended and depressed positions through sliding travel of flanges  52  within the mating set of tracks  54  on push bar  24 . Push bar  24  may also be selectively secured in the depressed position by way of a dogging mechanism  62  which will be discussed in greater detail below. Door latch system  10  may also include one or more bar guides  64  which will be discussed in greater detail below with regard to  FIGS.  17 A and  17 B . 
     With continued reference to  FIGS.  2 ,  3  and  3 A , regardless of the type of latch head or actuator mechanism used with the door latch system, exemplary interchangeable latch assembly  12  (shown in  FIG.  1   -3A as having a Pullman style latch head  66 ), generally comprises latch head  66  and driven member  76  (shown as a linearly moving driven member). Driven member  76  is operatively connected at one end (not shown) to latch  14  of latch head  66  and, at the opposite end  78 , connectable to a universal actuating assembly as described above. Noting the interchangeability of the design, when an interchangeable latch assembly is connected to the universal actuating assembly, regardless of the latch type, retraction of the latch from the associated strike is accomplished when the push bar is depressed. 
     Latch head  66  may include one or more lobes  68  which are adapted to be releasably secured to mounting bracket  40  via one or more head fasteners  70  through mounting holes  69 . Latch head  66  may further include a recessed ledge  72  configured to engage a forward edge  74  of mounting bracket  40  when head fasteners  70  are inserted through holes  71  in mounting bracket  40  and are secured within holes  69  of lobes  68 . Latch head  66  may further include a housing edge  73  configured to engage with housing end wall  27  (see  FIG.  2   ). The engagement of ledge  72  with edge  74 , as well as the engagement of housing edge  73  with housing end wall  27 , may operate to prevent or inhibit rotational/torsional displacement of exemplary latch head  66  in relation to strike  20  during the repeated use of door latch system  10 . 
     To assure compatibility between a universal actuating assembly and a selected interchangeable latch assembly, the three dimensional coordinates that locate the attaching features of the respective assemblies from a common mounting must be the same. Referring to  FIG.  3 A , the x-y-z coordinates measured between: (a) an arbitrary mounting point  41 , commonly shared by the universal actuating assembly and the selected interchangeable latch assembly when interchangeable latch assembly  12  is secured to universal actuating assembly  11 , and (b) connector point  82  of driving member  46  (i.e., first spatial relationship) and connector point  79  of driven member  76  (i.e., second spatial relationship) are generally equal when the latch is in its latched position. As a result, connector points  79  and  82 , when the interchangeable latch assembly and the universal actuating assembly are connected, share the same point in space. In the example shown in  FIG.  3 A , connector point  82  (shown as a post) and connector point  79  (shown as an end of a slot) share the same x-y-z coordinate position relative to common mounting point  41  when the assemblies are connected. 
     To make connection with universal actuating assembly  11 , and by way of example and by no means to be limited specifically thereto, connector point  79  of driven member  76 , located within slot  80 , may be configured to coincide with a corresponding connector point  82  of driving member  46 , shown as a post, wherein fastener  84  is removably coupled to connector point  82  to releasably secure driven member  76  to driving member  46 . In this manner, exemplary latch head  66  remains in a fixed position relative to mounting bracket  40  via head fasteners  70  while driven member  76  is coupled to driving member  46  via fastener  84 . As a result, once a particular interchangeable latch assembly  12  is connected to universal actuating assembly  11 , actuation of actuating members  34  by depressing push bar  24  may drive the coupled driving member  46  and driven member  76  in unlocking direction  32  thereby causing latch  14  to move from its extended position to its retracted position so that latch  14  is freed from strike  20  and door  18  is able to be opened. It should be noted that, while shown as a post-in-slot coupling, any suitable releasable coupling may be used, such as but not limited to clips, snaps and the like. It is also contemplated that the connector points may be coupled to each other by surface contact. 
     Driven member  76  may further include a tongue  98 . Tongue  98  may be configured to engage one end of a biasing member (not shown in  FIG.  3    but shown as feature  100  in  FIG.  4 D ) while the opposing end of the biasing member is secured to a component fixed to housing  26 , such as for example, the bar guide  64  as shown in  FIG.  17 A , such that driven member  76  is biased to place latch  14  in its extended position when exemplary interchangeable latch assembly  12  is in its locking orientation. 
     In accordance with the above description, one aspect of the present invention is to provide a door latch system configured to accommodate one of a number of interchangeable latch assemblies without requiring modification of the remainder of the door latch system. In this manner, latch assembly manufacturing and inventorying efficiencies may be improved as a single universal actuating assembly  11  may be fabricated and any desired/required interchangeable latch assembly may be connected to the universal actuating assembly  11 . Accordingly, door latch system  10  for releasably securing a door  18  to a door frame  22  is provided wherein door latch system  10  includes a first interchangeable latch assembly, having a first latch, such as latch  14 , and a first driven member, such as driven member  76 . Movement of the first driven member moves the first latch between a latched position to secure the door to the door frame and an unlatched position to release the door from the door frame. Door latch system  10  also includes a universal actuating assembly  12 . The universal actuating assembly includes driving member  46  wherein driving member  46  is movable between a first driving member position and a second driving member position by depression of push bar  24 . When driving member  46  is operatively connected to the first driven member as described above, movement of driving member  46  between its first driving member position and its second driving member position moves the first latch between its latched position and its unlatched position. 
     To facilitate readily swapping the first latch assembly with a second latch assembly without requiring modification of the remainder of the door latch system, door latch system  10  is configured so that when driving member  46  is connected to a driven member of a second interchangeable latch assembly, movement of the second driven member by driving member  46  moves said latch of the second latch assembly between a latched position to secure said door to said door frame and an unlatched position to release said door from said door frame. 
     It should be noted that universal actuating assembly  11  (and associated push bar  24  and housing  26 ) may be fabricated in various standard or custom lengths so as to accommodate doors of varying widths. 
     By way of the following examples, various latch head styles of an interchangeable latch assembly  12  may be designed to fit with an exemplar linear-movement type universal actuating assembly  11 . 
     Pullman Style Interchangeable Latch Assembly 
     As best seen in  FIGS.  4 A through  4 D , door latch system  10  may be configured having a Pullman style interchangeable latch assembly  12   a  having a latch mechanism similar to that shown and described within commonly owned U.S. Pat. No. 10,017,964, the entirety of which is incorporated herein by reference. Pullman style interchangeable latch assembly  12   a  generally comprises a latch head  66   a  with latch  14   a  pivotally connected thereto by a pivot pin  86   a  situated within a pivot hole  88   a  on latch head  66   a . Pullman style interchangeable latch assembly  12   a  may also include a deadlatch  90   a  coupled to latch  14   a  wherein deadlatch  90   a  is operable to prevent unwanted pivoting of latch  14   a  when latch  14   a  resides within strike  20 . Driven member  76   a  may be slidably constrained within a groove  92   a  defined in latch head  66   a  such that driven member  76   a  may reciprocally slide in unlocking/locking directions  32 / 50  as described above. Latch head  66   a  may also include one or more groove plates  94   a  that completely or partially overlap groove  92   a  so as to define channels  96   a  which may minimize or prevent any movement of driven member  76   a  other than in unlocking and locking directions  32 / 50 . 
     Driven member  76   a  may further include connector point  79   a  defined by second end  78   a  of the driven member. Latch head  66   a  may also include one or more lobes  68   a  which are adapted to be releasably secured to the mounting bracket (not shown) via one or more head fasteners. To assure compatibility between a universal actuating assembly and the selected Pullman style interchangeable latch assembly, and in general reference to  FIGS.  3 A and  4 A , the x-y-z coordinates measured between: (a) an arbitrary mounting point  41  commonly shared by the universal actuating assembly and the selected Pullman style interchangeable latch assembly when interchangeable latch assembly  12   a  is secured to universal actuating assembly  11 , and (b) the connector point of the driving member (not shown) and connector point  79   a  of driven member  76   a  when the latch is in its latched position are generally equal so that the two associated connector points, when the assemblies are connected, may share the same point in space. 
     Latch head  66   a  may further include a recessed ledge  72   a  configured to engage a forward edge  74  of mounting bracket  40  when head fasteners  70  are secured within lobes  68   a  as described above (see  FIG.  3 A ). Latch head  66   a  may further include a housing edge  73   a  configured to engage with housing end wall  27  (see  FIG.  4 C ). Driven member  76   a  may further include a tongue  98   a . Tongue  98   a  may be configured to engage one end of a biasing member  100  while the opposing end of the biasing member is secured to a component fixed to housing  26 , such as for example, bar guide  64  as shown in  FIG.  17 A , such that driven member  76   a  is biased to place latch  14   a  in its extended position when Pullman style interchangeable latch assembly  12   a  is in its default locking orientation. 
     Star Wheel Style Interchangeable Latch Assembly 
     Turning now to  FIGS.  5 A through  5 D , another latch configuration may be adapted to universal actuating assembly  11 . Door latch system  10  may be configured having a star wheel style interchangeable latch assembly  12   b , having a latch mechanism similar to that disclosed within commonly owned U.S. Pat. No. 4,458,928, the entirety of which is herein incorporated by reference. Star wheel style interchangeable latch assembly  12   b  generally comprises a latch head  66   b , having features similar to latch head  66   a , with latch  14   b  rotationally connected therein by spindle  86   b  situated within a spindle hole  88   b  defined within latch head  66   b . Driven member  76   b  may be slidably constrained within a groove  92   b  defined in latch head  66   b  such that driven member  76   b  may reciprocally slide in unlocking direction  32 /locking direction  50  as described above. Latch head  66   b  may also include groove plate  94   b  that completely or partially overlap groove  92   b  so as to minimize or prevent any movement of driven member  76   b  other than in unlocking direction  32  and the opposing locking direction  50 . 
     Driven member  76   b  may further include connector point  79   b  defined by second end  78   b  of the driven member. Latch head  66   b  may also include one or more lobes  68   b  which are adapted to be releasably secured to the mounting bracket (not shown) via one or more head fasteners. To assure compatibility between universal actuating assembly  11  and the selected star wheel style interchangeable latch assembly, and in general reference to  FIGS.  3 A and  4 A , the x-y-z coordinates measured between: (a) an arbitrary mounting point  41  commonly shared by the universal actuating assembly and the selected star wheel style interchangeable latch assembly when interchangeable latch assembly  12   b  is secured to universal actuating assembly  11 , and (b) the connector point of the driving member (not shown) and connector point  79   b  of driven member  76   b  when the latch is in its latched position are generally equal so that the two associated connector points, when the assemblies are connected, may share the same point in space. 
     Latch head  66   b  may further include a recessed ledge  72   b  configured to engage a forward edge  74  of mounting bracket  40  when head fasteners  70  are secured within lobes  68   b  as described above. Latch head  66   b  may further include a housing edge  73   b  configured to engage with housing end wall  27  (see  FIG.  5 C ). Driven member  76   b  may further include a tongue  98   b  configured to engage one end of a biasing member  100  while the opposing end of the biasing member is secured to a component fixed to housing  26  such that driven member  76   b  is biased to place latch  14   b  in its latching position when star wheel style latch mechanism  12   b  is in its default locking orientation. 
     Dummy Head Used With an Electromagnetic Latch 
     In reference to  FIGS.  6 A and  6 B , door latch system  10  may be configured with a dummy head  66   d  which need not be mechanically connected to a latch by way of a driven member. For example, dummy head  66   d  may be used in conjunction with an electrified locking system which incorporates an electromagnetic lock system (not shown) to secure a door in a doorframe rather than a latch such as latch  14   a  and  14   b . In this type of system, depression of the push bar may operate to sever electrical power to the electromagnet thereby unlocking the door. To that end, dummy head  66   d  may include one or more lobes  68   d  which are adapted to be releasably secured to a mounting bracket via one or more head fasteners through mounting holes in the mounting bracket as described above. Dummy head  66   d  may further include a recessed ledge  72   d  configured to engage a forward edge of mounting bracket when the head fasteners are secured within lobes  68   d  as described above. Dummy head  66   d  may further include a housing edge  73   d  configured to engage with housing end wall  27  (see  FIG.  6 B ). 
     In a door latch system described above, and in reference to  FIGS.  6 C- 6 F  and  FIG.  7   , there may be a need to disable push bar  24  in either its extended position ( FIG.  6 C ) or its depressed position ( FIG.  6 E ), using one or more lock out brackets  126  ( FIG.  7   ). Each lock out bracket  126  may include one or more lobes  128 , each lobe defining a mounting hole  130 . Lobes  128  may be positioned along the length of bar portion  127  so as to define first end  132  and second end  134 . Ends  132 ,  134  may be of differing lengths extending from lobes  128 . Mounting holes  130  may be configured to align with respective pre-formed receiving holes on housing  26  such that lock out bracket  126  is secured to housing  26 , such as through a threaded screw fastener. 
     As shown in  FIGS.  6 C and  6 D , push bar  24  may be secured in the extended position by securing bracket  126  to housing  26  so that first end  132  is adjacent to actuating mechanism  16  thereby preventing pivoting of pivoting leg  42  as described above. As a result, actuating mechanism  16 , and therefore push bar  24 , are maintained in the extended position. To accommodate stress or other forces placed upon push bar  24 , two or more lock out brackets  126  may be secured within housing  26 . Alternatively, as shown in  FIGS.  6 E and  6 F , if push bar  24  is secured in the retracted position, lock out bracket  126  may be oriented such that second end  134  lies adjacent to or abuts actuating mechanism  16  after pivoting of pivoting leg  42 . Because push bar  24  is situated within housing  26  in its depressed orientation, a single lock out bracket  126  may be used in this alternative without compromising the structural integrity or security of the door or locking system. 
     Adaptation of a Dummy Head With Other Mechanical Latches 
     By incorporating features for adaptation to other style latches, dummy head  66   d  as shown in  FIG.  6 A  may also be used as a base to form a number of alternative interchangeable latch assemblies, such as for example, a surface vertical rod (SVR) style interchangeable latch assembly  12   e  ( FIG.  8 A ), a concealed vertical rod (CVR) style interchangeable latch assembly  12   f  ( FIG.  9 A ), or a mortise style interchangeable latch assembly  12   g  ( FIG.  10 A ). Each respective interchangeable latch assembly  12   e ,  12   f ,  12   g , may be readily constructed to include dummy head  66   d  to facilitate latch actuation. 
     Referring to  FIGS.  8 A and  8 B  (SVR style interchangeable latch assembly)  9 A- 9 C (CVR style interchangeable latch assembly) and  10 A- 10 C (mortise interchangeable latch assembly), each respective driven member  138   e ,  138   f  and  138   g  comprising a driven bar  140   e ,  140   f  and  140   g  and pivoting bar  142   e ,  142   f  and  142   g  couples respective latch  14   e ,  14   f  and  14   g  to driving member  46  of the universal actuating assembly ( FIG.  3 A ). Respective first ends  140   e ′,  140   f ′ and  140   g ′ and  142   e ′,  142   f ′ and  142   g ′ of driven bar  140   e ,  140   f  and  140   g  and pivoting bar  142   e ,  142   f  and  142   g  are pivotally connected to one another at pivot  144   e ,  144   f  and  144   g . At its second end  142   e ″,  142   f ″ and  142   g ″, pivoting bar  142   e ,  142   f  and  142   g  may be operably coupled to a respective spindle  86   e ,  86   f  and  86   g  via a removable fastener  143 . Each driven bar  140   e ,  140   f  and  140   g  at its respective second end  140   e ″,  140   f ″and  140   g ″ may also include a respective slot  145   e ,  145   f  and  145   g  in which connector point  79   e ,  79   f  and  79   g  is located. In this manner, by moving driven bar  140   e ,  140   f  and  140   g  in unlocking direction  32 /locking direction  50 , respective latch  14   e ,  14   f  and  14   g  is selectively moved to its retracted/extended orientation, as described above. To assure compatibility between universal actuating assembly  11  and any of the interchangeable latch assemblies described in reference to  FIGS.  8 A,  9 A or  10 A , the x-y-z coordinates as described above measured between: (a) an arbitrary mounting point, commonly shared by the universal actuating assembly and the selected interchangeable latch assembly when interchangeable latch assembly  12   e ,  12  and  12   g  is secured to the universal actuator assembly, and (b) the connector point of the driving member and connector point  79   e ,  79   f  and  79   g  of driven member  138   e ,  138   f  and  138   g  when the latch is in its latched position are generally equal so that the two associated connector points, when the interchangeable latch assembly and the universal actuating assembly are connected, may share the same point in space. 
     Change of Handedness - Pullman, Star Wheel and Mortise Style Latches 
     In a Pullman style latch assembly, a handle or key actuator disposed on a door side opposite the push bar may be used to retract its respective latch from its mating strike. Referring specifically to  FIGS.  4 A,  4 D,  4 E and  4 F , handedness of rotation of the key or handle  110  through drive shaft  102  of Pullman style interchangeable latch assembly which acts upon driven member  76   a  may be reversed by inverting drive lever  104   a  and base plate  106  in an end-over-end fashion. That is, drive lever  104   a  engages projection  108  coupled to driven member  76   a  whereby actuation of key or opposing door handle  110  selectively causes either counter-clockwise rotation ( FIG.  4 E ) or clockwise rotation ( FIG.  4 F ) of drive lever  104   a . Drive lever  104   a  in turn drives projection  108 , and therefore driven member  76   a , so as to cause latch  14   a  to disengage from strike  20  and allow for opening of door  18 . 
     As shown in  FIGS.  5 E and  5 F , in a similar fashion, handedness of rotation of a key or handle coupled to a star wheel style interchangeable latch mechanism  12   b  may be reversed by inverting drive lever  104   b  and base plate  106  in an end-over-end fashion. 
     As shown in  FIGS.  11 A and  11 B , with respect to the mortise style latch assembly  12   g , the handedness of operation of a key or handle coupled to a mortise style interchangeable latch mechanism  12   g  may be switched from right-handed to left-handed and vice versa by flipping driven bar  140   g  and pivoting bar  142   g , as shown. 
     Shaft Orientation - Concealed Vertical Rod Style Latch Assembly 
     In some applications, such as when used with a CVR style interchangeable latch assembly as shown in  FIG.  9 A , it is important to properly index the driven member  138   f  relative to the position of the latch so that, when the push bar is depressed, the latch will properly disengage from its respective strike. Referring to  FIGS.  9 A and  12 A -  12 C , to facilitate proper indexing of shaft  102  between pivoting bar  142   f  and the position of latch  14   f  in order to achieve proper latch disengagement, shaft  102  may have a generally square-shaped cross section wherein one pair of opposing apexes  148  are truncated to form a flat face  150 , and the other opposing apexes  152  are formed without flats. In the shaft design as shown, and in further reference to hub  164  shown in  FIG.  12 C , a first end  156  of the shaft may be flattened so as to form a blade  158  extending between opposing apexes  152 . Blade  158  is configured to be received within a slot  160  defined within a first end  162  of shaft hub  164 . A second end  166  of shaft hub  164  is configured to be operably connected to pivoting bar  142   f  and may include a flat edge  167  configured to orient shaft hub  164  to pivoting bar  142   f  in only one orientation such as in one of only two axial positions 180 degrees apart. 
     A second end  168  of shaft  102 , formed as a truncated square as described above is configured to slidably reside within a corresponding, similarly configured slot  170  ( FIGS.  12 A and  12 B ) defined within an actuator  169  of latch  14   f . The orientation of the flat faces  150  within slot  170  dictate the orientation of blade  158 . In this manner, blade  158  will properly engage slot  160  only if slot  160  is in a complementary orientation. As a result, flat faces  150  prevent shaft  102  from being inserted 90 degrees from its proper orientation. Thus, door latch system  10  cannot be assembled so that, when the interchangeable latch assembly  12   f  is oriented in a locking position, the latch  14   f  is in an unlocking position. 
     In accordance with a further aspect, as shown in  FIG.  12 D , a magnet  174  may be secured within shaft hub  164 , wherein magnet  174  attracts and holds shaft  102  during installation so as to facilitate proper alignment between latch head and its associated actuator. 
     Note that, in connection with a mortise style interchangeable latch assembly as shown in  FIG.  12 E , shaft  102 , having an end formed universally as a truncated square, will nevertheless fit is a square-shaped slot  170   a  of cam plug  171  of a mortise lock since the axial presentation between the latch and latch head is not as critical. 
     Door Thickness Compensation 
     As is known in the art, doors may have different thicknesses. As a result, the latch assembly may be located a spaced distance from a latch resident within the body of the door. To accommodate doors of varying thicknesses, shaft  102  as discussed above (see  FIGS.  12 A &amp;  12 C ) may be configured to include one or more external annular grooves  146  so as to enable shortening of shaft  102 , facilitated by annular grooves  146 , so as to accommodate doors of different thickness. 
     Star Wheel Style Latch Assembly Sequence 
     In reference to  FIGS.  5 G and  5 H , additional features of star wheel style latch assembly  12   b  are shown. 
     Referring first  FIG.  5 H , a prior art star wheel latch assembly  412  is shown. Star wheel latch  414  is positioned within the latch head  466  and rotatably secured within the housing by spindle  486 . Respective balls  409  and then springs  411  are inserted within holes  408  formed in the top side of latch head  466  defined along either side of the star wheel latch such that the balls engage respective fluted sides of spindle  486  to properly position the star wheel for engagement with an associated strike. A respective set screw  470  is then secured to each hole  408  above the spring  411  so as to constrain the spring and ball within the hole and control the magnitude of the force imposed by the spring upon the ball, and thereby onto the flutes of the shaft. While this approach has proven to be effective, there exist a number of drawbacks. For instance, the set screw may unthread over time, lessen the force imposed on the flutes of the shaft and cause subsequent malfunction of the latch mechanism. 
     Returning to  FIG.  5 G , in accordance with the invention the order of assembly of star wheel latch assembly  12   b ′ is changed. Latch head  66   b ′ may be prefabricated to define a pair of blind holes  408 ′ on either side of groove  92   b ′ which may be configured to receive star wheel latch  14   b  and spindle  86   b . The depth of blinds holes  408 ′ is finely controlled during manufacture and machining so as to be consistent from latch head to latch head. With holes  408 ′ so defined, springs  411 ′ and then balls  409 ′ may be loaded within blind holes  408 ′. Star wheel latch  14   b  is then positioned within groove  92   b ′ and secured to latch head  66   b ′ by spindle  86   b  such that fluted spindle sides  86   b ′ engage with and compress a respective ball  409 ′ and spring  411 ′ within its respective blind hole  408 ′. Spindle  86   b ′ may then be secured in position by push plug  414 . Springs  411 ′ are selected such that the bias exerted upon balls  409 ′ and thus fluted spindle sides  86   b ′ properly index star wheel latch  14   b  within groove  92   b ′. Thus, proper positioning of the star wheel is maintained. In this manner, set screws are no longer required to secure the balls and springs within the latch head and no field adjustments are needed. Rather, the position and orientation of the star wheel latch  14   b  is established at the factory due to the depth of blind holes  408 ′ and the selected length, produced force and compression of springs  411 ′. 
     Fire Rated Star Wheel Style and Pullman Style Latch Assemblies 
     A star wheel style latch assembly, which may be configured as an interchangeable latch assembly, may be fire rated so as to secure latch  14   b  in a locked position, and therefore the door in a closed position, upon occurrence of a fire. To that end, star wheel style latch assembly  12   b ′ as shown in  FIG.  5 I  may further include one or more fire roll pins  116   b  configured to reside within holes  118   b  defined within latch head  66   b ′ and secured in place via set screw  120   b . Fire roll pins  116   b  may generally include a metal core portion  122   b  partially or fully encapsulated by a plastic/polymeric sleeve  124   b . Sleeve  124   b  is dimensioned such that its external diameter causes fire roll pins  116   b  to snuggly reside within hole  118   b  such that during normal operations (no fire conditions), fire roll pins  116   b  are retained in place adjacent to, but not overlapping with, groove  92   b ′. In this manner, star wheel latch  14   b  may freely rotate within groove  92   b ′. However, in the event of a fire condition wherein the heat of such fire is sufficient to melt the plastic/polymer of sleeve  124   b  but not metal core portions  122   b , metal core portions  122   b  may now translate into groove  92   b ′ and selectively engage star wheel latch  14   b  between successive extending arms  14   b ′ and  14   b ″. Further rotation of star wheel latch  14   b  is prevented as any attempts to move arms  14   b ′ or  14   b ″ will drive metal core portion  122   b  against latch head  66   b ′ thereby arresting star wheel latch  14   b . As a result, an outwardly extending arm of the star wheel remains secured within the door strike  20  and preventing the door from being opened. 
     Referring to  FIGS.  4 G and  4 H , a Pullman style latch assembly  12   a ′, which may be configured as an interchangeable latch assembly, may be fire rated so as to secure an associated latch  314  in a locked position, and therefore a door in a closed position, upon occurrence of a fire. To that end, the depicted Pullman style interchangeable latch assembly  12   a ′ (shown without its driven member) may further include fire roll pin  316  configured to reside within hole  318  defined within latch  314 . Fire roll pin  316  generally include a metal core portion partially or fully encapsulated by a plastic/polymeric sleeve, as described in detail in reference to the star wheel type interchangeable patch assembly presented above. The sleeve’s external diameter is dimensioned such that it causes fire roll pin  316  to snuggly reside within hole  318  such that during normal operations (no fire conditions), fire roll pin  316  is retained in place within latch  314  as shown in  FIG.  4 H . When the latch is in its extended, locked position, fire roll pin  316  is adjacent to, but not overlapping with, groove  392  formed in latch head  66   a ′ as shown in  FIG.  4 H . In this manner, latch  314  may freely rotate about its rotational axis. However, in the event of a fire condition wherein the heat of such fire is sufficient to melt the plastic/polymer of sleeve but not metal core portion, the metal core portion of fire roll pin  316  may now translate partially into groove  392  formed in latch head  66   a ′, locking latch  314  in its extended, locked position and preventing the door from being opened. 
     Latch Position Sensor 
     In the prior art, to sense the state of the latch (latched or unlatched), a position sensor, such as a switch, is used to sense the state of the latch by sensing the position of the push bar. When the push bar is depressed, the switch senses the depressed position of the push bar and, only indirectly, that the latch is in its unlatched state. 
     In accordance with the invention, a sensor, which may be a switch, senses a position of the driving member  46 . Generally stated, where a driving member has a first position allowing a connected latch to be in its latched position and a second position causing the connected latch to be in its unlatched position, the sensor senses when the driving member is in its second position. Thus, since the driving member is more directly connected to the latch, the sensor more precisely senses when the latch is in an unlatched state. 
     In reference to  FIG.  3   , and as described above, pivoting leg  42  of one or more actuating members  34  is connected to driving member  46  so that, when the one or more actuating members are acted upon by depressing push bar  24  ( FIG.  2   ), driving member translates in direction  32  to withdraw latch  14  from the strike, thereby placing the latch in its unlatched position. 
     As shown in  FIGS.  13 A- 13 C , in accordance with the present invention, the position of driving member  46  of door latch system  10 , is monitored using a position sensor  176  readily adaptable to the construct of universal actuating assembly  11  without further modification of its driving member  46  or mounting bracket  40 . Sensor  176 , shown as a micro-switch, may be mounted to pre-drilled holes in mounting bracket  40  of universal actuating assembly  11  by a bracket  177  and fasteners  178 , as shown, and may be hardwired to an external monitor (not shown). Actuator plate  180  may be mounted to a predrilled hole in driving member  46  by fastener  181  so that actuator plate  180  moves with driving member  46 , in direction  182 , when the driving member translates to place the latch in its unlatched position. Trigger arm  179  of sensor  176  aligns with ramp portion  184  of ramp plate  180  so that trigger arm  179  is deflected upward when the latch is in its latched position ( FIG.  13 B ) and trigger arm  179  is allowed to extend outward ( FIG.  13 C ) when the latch is placed in its unlatched position by driving member  46 . In this manner, since driving member  46  is directly connected to the latch through driven member  76  ( FIG.  3   ), the unlocked state of the latch may be more precisely monitored. 
     Instead of a mechanical switch as shown, position sensor may be configured as a magnetic Hall Effect sensor triggered by movement of a magnet attached to driving member  46 . 
     Position sensor  176  may also be configured to issue an alarm signal should the latch be in an unlatch position for a preselected length of time. This alarm signal may be an audio, visual or audiovisual alarm and/or may include an electronic signal transmitted to a remote security monitoring location. In this manner, building security may be alerted to the potential compromised security condition. 
     Push Bar Dogging Mechanism 
     There may come times when a door latching mechanism needs to have the push bar temporarily held in the retracted position thereby holding the latch in an unlatched position and rendering the door unlocked, a situation generally referred to as dogging. To facilitate dogging of an exemplary latching assembly, such as latch system  10 , the door latch system may include a dogging mechanism  62  (see  FIG.  2   ). 
     In accordance with an aspect of the present invention, and in further reference to  FIGS.  14  and  15   , an exemplary dogging mechanism  62  is readily adaptable to the construct of universal actuating assembly  11 . Dogging mechanism  62  may be a two-piece assembly comprised of a bar portion  192  configured to slidably engage within a housing portion  194 . Bar portion  192  may include a head flange  196  configured to slide within and be constrained by tracks  54  on push bar  24  (see  FIGS.  18 A and  18 B ). Head flange  196  may be mounted onto a post  198  with post  198  having a keyed opening  200  defined in a first end  202  and a second end  204  terminating in a pair of opposing outwardly extending tabs  206 . Keyed opening  200  is configured to correspond with an opening  208  in push bar  24  (see  FIG.  2   ). Housing portion  194  includes a generally tubular shaped body  210  defining a pair of grooves  212  configured to slidably receive a respective tab  206  therein. Respective bottom flanges  214  of housing portion  194  define a pair of mounting holes  216  through which housing portion  194  may be fixedly secured to housing  26  via a suitable fastener. Bottom flanges  214  may include a stepped flange portion  218  having one end  218 ′ opening on groove  212 . 
     To dog push bar  24  in the depressed position, with further reference to  FIG.  15   , push bar  24  is depressed in actuating direction  30  until latch  14  is disengaged from strike  20  as described above. With push bar  24  so depressed, bar portion  192  travels axially within housing portion  194 . While maintaining the actuating force upon push bar  24  to keep push bar  24  depressed, a key or wrench (not shown) may be then inserted though push bar opening  208  and within keyed opening  200  and rotated in the rotation direction shown as R, thereby rotating post  198  and tabs  206 . Tabs  206  then travel under stepped flange portion  218  on housing portion  194 . Removing the actuating force being applied to push bar  24  would normally permit push bar to return to its extended position. However, interference between tabs  206  on bar portion  192  and stepped flange portion  218  on housing portion  194  prevents return travel of push bar  24 . As a result, push bar  24  is dogged in the unlatched position. To alleviate the dogged condition, an operator would need to reverse rotate the key or wrench such that tabs  206  again correspond with grooves  212  whereby reverse travel of post  198  and tabs  206  is again permitted. It should be noted that housing  26  may include predrilled holes to correspond with mounting holes  216  such that keyed opening  200  aligns with hole  208  within push bar  24 . 
     Noise Dampening Features 
     In accordance with a further aspect of the present invention, door latch system  10  may include one or more of a number of noise dampening elements designed to enable quieter operation. As shown in  FIGS.  16 ,  17 A and  17 B , housing  26  may be configured to include one or more bar guides  64 . As shown in  FIG.  17 A , bar guides  64  may be placed proximate each end of push bar  24 . Each bar guide  64  may be constructed of a durable plastic configured to reduce vibration and rattling as push bar  24  travels in directions  32 / 50  as described above. Bar guide  64  may further include shock absorbing material  260 , such as Viton or other suitable elastomer/composite, which is configured to engage push bar  24  upon full depression of push bar in actuating direction  30 . In this manner, the metal portions of push bar  24  do not strike metal portions of housing  26 , including bottom edges  262  of push bar contacting back panel  264  of housing  26 . 
     With reference to  FIGS.  18 A and  18 B , for those systems employing dogging mechanism  62 , head flange  196  may be fabricated from a non-metal material as head flange  196 ′. Head flange  196 ′ may be fabricated from materials such as, but not limited to, glass-filled nylon, and more particularly Nylon 6/6 with 30% glass-fill. Head flange  196 ′ may minimize or eliminate vibration and other rattling between dogging mechanism  62  and push bar  24 . Head flange  196 ′ may also include one or more crush ribs  268  configured to press against the inner surface  56  ( FIG.  17 A ) of push bar  24  in a light interference fit to minimize clearance between the thickness of head flange  196 ′ and the width of tracks  54  ( FIG.  17 A ). Crush ribs  268  may be made of any suitable material, such as Viton or other fluoroelastomer. 
     Referring to  FIGS.  19 A- 19 C , additional noise reduction features may include non-metallic bar mounts  36 ′ fabricated from materials such as, but not limited to, glass-filled nylon, and more particularly Nylon 6/6 with 30% glass-fill, and actuating member spacers  170 . 
     Actuating member spacers  270  are mounted beneath fixed leg  38  and pivoting leg  42  of actuating member  34 . Spacers  270  are proportioned such that pivoting leg  42  lightly impacts spacer  270  upon full depression of push bar in actuating direction  30  as shown in  FIG.  19 B . In this manner, the metal components of actuating member  34  do not impact any mounting structures on housing  26  or housing  26  itself. 
     Additionally, snubber  272  may be mounted within housing  26  proximate upwardly extending portion  47  of driving member  46  so as to selectively control return of push bar  24  from its depressed orientation to its extended orientation opposite actuating direction  30 . As shown generally in  FIG.  19 B , depressing push bar  24  in actuating direction  30  pivots pivoting leg  42  as described above and driving member  46  (and upwardly extending portion  47 ) travel in unlocking direction  32 . As a result, plunger  274  is biased outward from snubber housing  276  to its extended position. When push bar  24  returns to its extended orientation ( FIG.  19 C ), which may be influenced by a restorative force exerted by biasing member  48 , upwardly extending portion  47  engages plunger  274  of snubber  272 . Plunger  270  absorbs some of the restoration force of biasing member  48  and slows the return travel of push bar  24  thereby enabling push bar to gently return to its extended orientation without forcefully (and noisily) impacting housing  26 . 
     When the snubber is used in conjunction with the position sensor described above, the sensor (such as a switch) may be mounted to the snubber. 
     Integrated Alarm System 
       FIGS.  20 A- 20 C  show an alarm assembly  280  configured to be mounted to tracks  54  on inner surface  56  of push bar  24  (see  FIG.  17 A ). Alarm assembly  280  includes a keyed cylinder  282  coupled to a switch lever assembly  284  mounted to a circuit board  286 . A speaker  288 , such as for example a piezo speaker, is connected to circuit board  286  and is configured to issue an alarm should unauthorized use of push bar  24  be detected. Alarm assembly  280  may be hard wired or may be battery powered. A battery pack  290  can be conveniently accessed and changed via removal of push bar end  58 . Speaker  288  is configured to be mounted a spaced distance from inner surface  56  so as to defeat an attempt to damage the speaker with a foreign object inserted through openings in the push bar in order to disable the alarm. 
     Wire Clips 
     Turning now to  FIGS.  21 A through  21 C , a wire clip  292  is shown releasably attached to existing track  293  formed on housing  26 . Clip  292  includes a generally C-shaped center region  294  with an outwardly extending tab  296  extending from a first side  298 . Tab  296  may aid in inserting or removing clip  292  from track  293 . Center region  294  is configured to receive an electrical wire  300  used within door latch system  10 . In accordance with one aspect of the present invention, center region  294  is proportioned to snuggly receive 0.22 inch diameter wire. Opposing second side  302  may include a pair of generally V-shaped upper and lower extensions  304  and  306  configured to be snuggly received within track  293 . Lower extension  306  may include a boss  308  configured to releasably lock within groove  310  on track  252 . In this manner, one or more clips  292  may be provided so as to securely channel wiring within housing  26  so prevent any tangling or damaging of the wiring upon repeated depression and extension of the push bar. 
     Method of Converting the Latch Head of a Door Latch System 
     In accordance with the invention, and in reference to  FIG.  1   -3A, a method of swapping a first interchangeable latch assembly with a second interchangeable latch assembly without requiring extensive modification of the actuating assembly is as follows: (1) providing door latch system  10  having a universal actuating assembly and a first interchangeable latch assembly, wherein the x-y-z coordinates measured between an arbitrary mounting point  41 , commonly shared by the universal actuating assembly and the first interchangeable latch assembly when the first interchangeable latch assembly  12  is secured to universal actuating assembly  11 , and connector point  82  of driving member  46  and connector point  79  of driven member  76  when the latch is in its latched position are generally equal; (2) disconnecting and removing the first interchangeable latch assembly; (3) selecting a second interchangeable latch assembly wherein the x-y-z coordinates measured between an arbitrary mounting point  41 , commonly shared by the first universal actuating assembly and the selected second interchangeable latch assembly when the second interchangeable latch assembly  12  is secured to universal actuating assembly  11 , and connector point  82  of driving member  46  and connector point  79  of driven member  76  are generally equal; and (4) connecting the second interchangeable latch assembly to the universal actuating assembly. 
     In a further aspect of the invention, following step (1), further steps may include: removing end cap  28  and removing push bar  18 . Following step (4), further steps may include: reconnecting the push bar and reinstalling end cap  28 . 
     It is understood that the swap can be made to replace one interchangeable latch assembly with an identically configured interchangeable latch assembly or to replace one interchangeable latch assembly with an interchangeable latch assembly of a different configuration as generally shown in  FIGS.  4 A- 10 C . Also, the swap can be made while door latch system  10  is attached to a door or while not attached to a door. 
     It is also understood that a similar process may be used to swap out a first universal actuating assembly for a second universal actuation assembly wherein the second universal actuating assembly may be the same as the first universal actuating assembly, or not. 
     Accordingly, a method of swapping a first universal actuating assembly with a second universal actuating assembly without requiring extensive modification of the actuating assembly is as follows: (1) providing door latch system  10  having a first universal actuating assembly and an interchangeable latch assembly, wherein the x-y-z coordinates measured between an arbitrary mounting point  41 , commonly shared by the first universal actuating assembly and the interchangeable latch assembly when the first interchangeable latch assembly  12  is secured to universal actuating assembly  11 , and connector point  82  of driving member  46  and connector point  79  of driven member  76  when the latch is in its latched position are generally equal; (2) disconnecting and removing the first universal actuating assembly from the interchangeable latch assembly; (3) selecting a second universal actuating assembly wherein the x-y-z coordinates measured between an arbitrary mounting point  41 , commonly shared by the selected second universal actuating assembly and the interchangeable latch assembly when the interchangeable latch assembly  12  is secured to the second universal actuating assembly  11 , and connector point  82  of driving member  46  and connector point  79  of driven member  76  when the latch is in its latched position are generally equal; and (4) connecting the interchangeable latch assembly to the second universal actuating assembly. 
     In a further aspect of the invention, following step (1), further steps may include: removing end cap  28  and removing push bar  18 . Following step (4), further steps may include: reconnecting the push bar and reinstalling end cap  28 . 
     In the descriptions above, the commonly shared arbitrary mounting point  41  is shown to be a point on lobe  68 ,  68   a ,  68   b  that touches a point on mounting bracket  40  when the interchangeable latch assembly is secured to the universal actuating assembly. However, it is understood that the “commonly share arbitrary mounting point” in accordance with the invention may be any common point shared by the interchangeable latch assembly and the associated universal actuating assembly when the two are assembled together. 
     While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.