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FIELD OF THE INVENTION 
       [0001]    This invention relates to latches, and, more particularly, to a latch mechanism for containers such as tool boxes mounted to the bed of a pickup truck. 
       BACKGROUND OF THE INVENTION 
       [0002]    Latches are routinely used on doors, chests, cabinets and other containers where a lid or door must be retained in a closed and locked position. Typically, latches include a latch plate moveable between a latched position and an unlatched position. When unlatched, the latch plate may receive a striker pin mounted to the lid of a toolbox, for example, as the lid is moved to a closed position. Once the lid is closed, the latch plate moves to the latched position to capture the striker pin and retain the lid in the closed position. The latch may be provided with a lock to prevent the latch plate from releasing the striker pin except when unlocked. 
         [0003]    A number of designs have been proposed in the prior art to move the latch plate from its latched position to the unlatched position wherein the striker pin may be released. One approach is disclosed in U.S. Pat. No. 6,973,810 in which a handle mounted to the housing of a latch is pivoted to set in motion a series of components that cooperate to move the latch plate to an unlatched position. In this and similar designs, a first end of the handle is pivotally mounted to the latch housing and its opposite, second end connects to one of the components that function to open the latch plate. The latch plate is opened by moving the second end of the handle to an unlatched position thus pivoting the handle about its first end. A substantial amount of force is required to pivot the latch handle because, as noted above, its second end is directly connected to the series of components that cooperate to open the latch plate. 
       SUMMARY OF THE INVENTION 
       [0004]    This invention is directed to a latch mechanism for use in a container such as a truck box in which a latch rail mounted to the truck box houses components that facilitate latching and unlatching of a latch plate with much less force than is required in prior art designs of the type described above. 
         [0005]    In one presently preferred embodiment, the latch mechanism of this invention comprises a latch rail which pivotally mounts a latch plate adapted to engage a striker pin when in a latched position, and a pawl lever which is pivotally mounted to the latch rail and operative to engage and retain the latch plate in the latched position except when acted upon by an actuator assembly. The actuator assembly comprises first and second slide blocks which are laterally movable within a cavity formed in the latch rail, first and second carriages each laterally movable within a separate opening in the latch rail which are located on either side of the cavity, and, a first actuator rod connected between the first carriage and the first slide block and a second actuator rod connected between the second carriage and the second slide block. 
         [0006]    In response to lateral movement of the first carriage in a first direction, the first actuator rod and the first slide block move in the same first direction therewith. A first actuator arm carried by the first slide block is positioned to engage the pawl lever, and, in response to lateral movement of the first slide block, the first actuator arm pivots the pawl lever out of engagement with the latch plate allowing it to move to an unlatched position. Similarly, in response to lateral movement of the second carriage in a second direction, opposite to the first direction, the second actuator rod and the second slide block move in the same second direction therewith. A second actuator arm carried by the second slide block is positioned to engage the pawl lever, and, in response to lateral movement of the second slide block, the second actuator arm pivots the pawl lever thus allowing the latch plate to move to an unlatched position. 
         [0007]    The first and second carriages may be positioned on opposite sides of the front wall of a truck box, for example, so that the latch mechanism may be moved to the unlatched position from either side of the box. Operation of the actuator assembly requires minimal force since the slide blocks and carriages readily slide in a lateral direction within the cavity and the openings, respectively, formed in the latch rail. Such components may be made of plastic or other smooth, low friction material to facilitate such movement. Each carriage may be provided with a finger tab, which is easily grasped by a user of the box, to effect lateral movement of the actuator assembly. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]    The structure, operation and advantages of the presently preferred embodiment of this invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a perspective view of a truck box incorporating the latch mechanism of this invention; 
           [0010]      FIG. 2  is a perspective view of a portion of the latch mechanism depicting one of the carriages, the actuator rods and the slide blocks employed in the actuator assembly of this invention; 
           [0011]      FIG. 3A  is a rear elevational view of the latch mechanism in the latched position; 
           [0012]      FIG. 3B  is a view similar to  FIG. 3A  except with the latch mechanism in the unlatched position; and 
           [0013]      FIG. 4  is an exploded perspective view of a portion of the latch mechanism herein. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    Referring initially to  FIG. 1 , a truck box  10  is shown which comprises a front wall  12 , a bottom wall  14 , opposed end walls  16 ,  18 , a top wall or lid  20  and a back wall  22 . Each of the walls  12 - 22  is preferably formed of aluminum tread plate and they are interconnected by welding to foam a hollow interior  24 . For purposes of illustration and the present discussion, a single lid, cross-over box is depicted in the Figs. but it is contemplated that other types of truck boxes may be employed with the lid of this invention, discussed below, including side-mount boxes, chest boxes, top mount boxes, trailer boxes, RV boxes and others. 
         [0015]    The interior  24  of the truck box  10  may include a pair of plates  28 ,  30  located near respective end walls  16 ,  18 . Each of the plates  28 ,  30  supports one end of a gas spring  32  which is mounted at its opposite end to the top wall  20 . The top wall  20  also mounts a pair of spaced striker bars  34 ,  36 . 
         [0016]    Referring now to  FIGS. 2-4 , the latch mechanism  42  of this invention is illustrated. The primary components of the latch mechanism  42  include a latch plate  46  and a pawl lever  86  both pivotally mounted to a rail  44  which is secured to the inner surface of the front wall  12  of the truck box  10  by tabs  45  in position for the latch plate  46  to align with one of the striker bars  34  or  36  carried by the box lid  20 . For ease of illustration, only a portion of the latch rail  44  is illustrated in  FIGS. 2-4 , it being understood that the latch rail  44  extends substantially along the entire length of the front wall  12  of the truck box  10 . As discussed below, structure for moving the latch plate  46  between an unlatched and latched position is provided along the front wall  12  near each of the box end walls  16 ,  18  for convenience and ease of operation. Additionally, for purposes of discussion, the terms “upper,” “lower,” “top,” “bottom,” “inner,” “outer,” “vertical” and “lateral” refer to the orientation of the truck box  10 , and its walls  12 - 22 , as viewed in the Figs. The term “lateral direction” refers to a direction generally between the end walls  16 ,  18  of the truck box  10 . 
         [0017]    As best seen in  FIG. 4 , the latch plate  46  is located within a latch housing  48  having a back cover  50  and a front compartment  52 . The front compartment  52  includes mounting posts  54 ,  55 ,  56  and  57 , and, a pair of spaced sleeves  60 ,  62 . The sleeves  60 ,  62  align with spacers  64 ,  66  and return springs  68 ,  70 , respectively. Preferably, the latch plate  46  is formed with a notch  72  for receiving a striker bar  34  or  36 , a pass through bore  74  and an aperture  76  which mounts a spring retainer pin  78 . The pass through bore  74  of the latch plate  46  aligns with sleeve  62 , spacer  66 , return spring  70  and a mount  80  carried by the back cover  50  of latch housing  48 . The latch plate  46  is also formed with one or more gear teeth  82  which engage the locking pawl  84  of a pawl lever  86 . The pawl lever  86  further includes a pass through bore  88 , a first aperture  90  which mounts a spring retainer pin  92  and a second aperture  94  in which an actuator pin  96  is mounted. The pass through bore  88  of pawl lever  86  aligns with the sleeve  60  in the front compartment  52  of the latch housing  48 , the spacer  64 , return spring  68  and a mount  98  carried by the back cover  50  of latch housing  48 . 
         [0018]    The latch housing  48  and the components it contains are mounted to the latch rail  44  by first and second support rods  100  and  102 . The support rod  100  extends through the sleeve  60  in front compartment  52 , the spacer  64 , the return spring  68  and the pass through bore  88  in pawl lever  86  into the mount  98  in the back cover  50  where it is secured in place. A finger  104  of the return spring  68  bears against the spring retainer pin  92  mounted to the pawl lever  86  urging it in a clockwise direction as viewed in the Figs., so as to retain the latch plate  46  in the latched position, as described below in connection with a discussion of the operation of latch mechanism  42 . The support rod  102  extends through the sleeve  62  in the front compartment  52 , the spacer  66 , the return spring  70  and the pass through bore  74  in the latch plate  46  into the mount  80  in the back cover  50  where it is secured in place. A finger  106  of the return spring  70  bears against the spring retainer pin  78  mounted to the latch plate  46  urging it in a counterclockwise direction as view in the Figs. to the unlatched position. Fasteners (not shown) are extended through bores  108 ,  109 ,  110  and  111  formed in the back cover  50 , and into aligning posts  54 - 57  in the front compartment  52 , in order to connect the back cover  50  and front compartment  52  together along the latch rail  44 . 
         [0019]    Referring to  FIGS. 2-4 , the latch rail  44  is formed with a central cavity  114  which receives a first slide block  116  and a second slide block  118 . A pair of stepped openings  120  are located on either side of the cavity  48 , one of which is shown in the drawings. Each stepped opening  120  receives a carriage  126 , which are preferably located near respective end walls  16 ,  18  of the truck box  10  for ease of access. See  FIG. 1 . 
         [0020]    In the presently preferred embodiment, the first slide block  116  mounts an actuator arm  128  in position to engage the actuator pin  96  carried by the pawl lever  86 . The first slide block  116  is formed with an upper bore  130  and a lower bore  132 . Similarly, the second slide block  118  mounts an actuator arm  134  in position to engage the actuator pin  96 . The second slide block  118  is formed with an upper bore  136  and a lower bore  138 . A first actuator rod  140  is mounted to the carriage  126 , and fixed within the lower bore  132  of first slide block  116 , but it is slidable within the lower bore  138  in second slide block  118 . A second actuator rod  142  is mounted to the carriage (not shown) on the opposite end of the truck box  10 , and fixed within the upper bore  136  of second slide block  118 , but is free to slide within the upper bore  130  of first slide block  116 . The first and second slide blocks  116 ,  118  may be fixed to respective first and second actuator rods  140 ,  142  by any suitable means, including an E-clip secured within a groove formed in such rods  140 ,  142  (not shown). In the presently preferred embodiment, a return spring  145  is positioned in between the first and second slide blocks  116 ,  118  for purposes to become apparent below. 
         [0021]    Each carriage  126  is laterally movable within the stepped opening  120  from a locked position depicted in  FIG. 3A  to an unlocked and open position shown in  FIG. 3B  where it engages an end cap  143  located at one end of the latch rail  44 , The carriage  126  mounts a finger tab  144  which extends outwardly from the front wall  12  of the truck box  10 , and a key cylinder  146  which extends into the stepped opening  120 . The inner end of key cylinder  146  mounts a locking cap  148  which is rotatable between a locked and unlocked position. 
         [0022]    The latch mechanism  42  operates as follows. Referring to  FIG. 3A , the latch plate  46  is illustrated in the latched position wherein its notch  72  is oriented generally horizontally relative to the latch rail  44  and front wall  12  of the truck box  10  so that one of the striker bars  34  and  36  may be captured an retained within the notch  72  with the lid  20  closed. Although the return spring  70  acting on the latch plate  46  urges it in a counterclockwise direction, toward the unlatched position shown in  FIG. 3B , the locking pawl  84  of the pawl lever  86  engages one of the gear teeth  82  on the latch plate  46  to retain it in the latched position since the pawl lever  86  is biased in the opposite direction by the return spring  68 . 
         [0023]    In order to allow the latch plate  46  to move to the unlatched position shown in  FIG. 3B , several components interact with one another. Initially, the latch plate  46  may be in a locked position shown in  FIG. 3A  in which the locking cap  148  connected to the key cylinder  146  is oriented generally horizontally within the stepped opening  120 . When locked, the locking cap  148  contacts an edge of the stepped opening  120  within which prevents the carriage  126  from moving to the left as viewed in the Figs. A key (not shown) may be inserted into the key cylinder  146  to rotate it, and the locking cap  148 , in a clockwise direction as viewed in  FIG. 3B  so that the locking cap  148  is oriented vertically relative to the latch rail  44  and disengages the end of the stepped opening  120 . With the locking cap  148  unlocked, the finger tab  144  of the carriage  126  may be grasped by a user and moved laterally to the left as viewed in the Figs. until it engages the end cap  143 . Because the first actuator rod  140  is fixed to the carriage  126 , it moves in the same lateral direction therewith. In turn, since the first slide block  116  is fixed to the first actuator rod  140  it too moves in the lateral direction within the cavity  114 . Although the first actuator rod  140  enters the lower bore  138  of the second slide block  118 , it is free to slide therein and therefore the second slide block  118  remains in position when the carriage  126  depicted in the Figs. is moved. In the course of movement of the first slide block  116 , the force applied to the carriage  126  though the finger tab  144  overcomes the spring force exerted by the return spring  145  positioned between the slide blocks  116 ,  118  and compresses such spring  145  against the second slide block  118 . 
         [0024]    As shown in  FIG. 3A , a side edge  129  of the first actuator arm  128  mounted to the first slide block  118  rests against the actuator pin  96  on the pawl lever  86 . In response to movement of the first slide block  116  laterally to the left as viewed in  FIGS. 3A and 3B , the side edge  129  of first actuator arm  128  bears against the actuator pin  96  forcing it in a generally downward direction. See  FIG. 3B . The pawl lever  86  rotates in a counterclockwise direction about the support rod  100  as its actuator pin  96  moves downwardly, which causes the locking pawl  84  of the pawl lever  86  to disengage one of the gear teeth  82  in the latch plate  46 . Under the influence of return spring  70 , once disengaged by the locking pawl  84  of the pawl lever  86  the latch plate  46  rotates on support rod  102  in a counterclockwise direction to the unlatched position shown in  FIG. 3B . This releases the striker bar  34  or  36  allowing the top wall  20  to be opened. Upon movement of the latch plate  46  to the unlatched position, the return spring  145  is allowed to uncoil and return the slide blocks  116 ,  118  to their original, spaced apart position shown in  FIGS. 2 and 3A . 
         [0025]    When the top wall  20  is closed, one of the striker bars  34  or  36  enters the notch  72  in the latch plate  46  rotating it in the clockwise direction and into a latched position wherein the locking pawl  84  of the pawl lever  86  engages one of the gear teeth  82  of the latch plate  46 . See  FIG. 3A . The pawl lever  86  retains the latch plate  46  in such latched position under the influence of return spring  68 . 
         [0026]    As noted above, only a portion of the latch mechanism  42  of this invention is illustrated in the drawings. It should be understood that a second carriage  126  is located on the opposite end of the truck box  10  which is fixed to the second actuator rod  142 . In response to lateral movement of such second carriage  126 , the actuator arm  134  of the second slide block  118  causes the pawl lever  86  to disengage the latch plate  46  in the same manner described above. 
         [0027]    While the invention has been described with reference to a preferred embodiment, it should be understood by those skilled in the art that various changes may be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. 
         [0028]    For example, in the embodiment of this invention described above the first and second actuator rods  140  and  142  are connected to respective first and second slide blocks  116 ,  118  such that the slide blocks  116 ,  118  are pulled with a carriage  126  toward one of the end walls  16 ,  18 . Alternatively, the first and second actuator rods  140 ,  142  and first and second slide blocks  116 ,  118  could be attached in such a way that the carriage  126  would be moved in the opposite direction so as to “push” the slide blocks  116 ,  118  instead of “pull” them relative to the actuator pin  96  mounted to the pawl lever  86 . 
         [0029]    Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Summary:
A latch mechanism is provided for securing the lid of a container in a closed position having actuator components that facilitate latching and unlatching of a latch plate of the latch mechanism.