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SCOPE OF THE INVENTION  
       [0001]     This invention relates to a filing cabinet, and in particular, to a filing cabinet with a locking system.  
       BACKGROUND OF THE INVENTION  
       [0002]     Filing cabinets are known having drawers that open forwardly to provide access to paper files and the like inside. One example of a filing cabinet structure is shown in U.S. Pat. No. 4,480,883 to Edwards issued Nov. 6, 1984 which is directed to an internal anti-tip blocking device that permits only one drawer of a stacked column of drawers to be opened at any one time.  
         [0003]     Filing cabinets are known to have internal lock structures which are internal of the cabinet and prevents any of the drawers from being opened. For added security, it is also known to provide external locking devices with a metal bar which extends vertically across the height of a column of drawers and is secured at the top and bottom of the cabinet to prevent opening of any drawers. Such external bar has the disadvantage that it must be removed and stored when not in use.  
       SUMMARY OF THE INVENTION  
       [0004]     To at least partially overcome the disadvantages of previously known devices, the present invention provides an external locking mechanism for a filing cabinet incorporating two hinged blocking plates at each side of the cabinet and a locking bar which is movable without removal from attachment to the cabinet to positions such that the blocking plates can be selectively prevented from being moved to unblocked positions or permitted to be moved to unblocked positions.  
         [0005]     An object of the present invention is to provide an improved external locking system for a filing cabinet.  
         [0006]     Another object of the present invention is to provide a filing cabinet with a locking system which is very simple to use, and also relatively easy and inexpensive to manufacture.  
         [0007]     In one aspect, the present invention provides a filing cabinet having a compartment with at least one drawer slidably mounted in the compartment between retracted and withdrawn positions. Blocking plates are hinged to each opposite side of the compartment rotatable on a vertical axis between: (i) a blocked position in the path of the drawer to prevent the drawer from withdrawal from the retracted position; and (ii) an unblocked position out of the path of the drawer to permit withdrawal to the withdrawn position. A locking bar is mounted to the cabinet movable between: (i) a locked position where at least a portion of the locking bar is in the path of both of the blocking plates and prevents each of the blocking plates from movement from the blocked position to the unblocked position; and (ii) unlocked positions where the locking bar is out of the path of the blocking plates and does not prevent the blocking plates from movement from the blocked position to the unblocked position.  
         [0008]     In a preferred embodiment, the cabinet has a framework comprising by two opposite sidewalls, a back wall, a top wall, and a bottom wall which define a compartment therein containing sliding drawers and with an opening from the compartment from which the drawers are slidable through the opening.  
         [0009]     The framework preferably includes a crossbeam which has ends that are secured to the opposite side walls of the framework preferably to extend horizontally between two drawers and with the locking bar mounted to the crossbeam, preferably for sliding or pivotal movement thereto.  
         [0010]     The crossbeam preferably has a forward facing surface and the locking bar is mounted to the forward facing surface of the crossbeam.  
         [0011]     In one preferred embodiment, the two opposite side walls each have a forward facing surface. A continuous hinge is mounted to the forward facing surface of the side wall with one hinge plate of the continuous hinge forming or carrying blocking plate.  
         [0012]     In another preferred embodiment, the two opposite side walls each have a forward facing gable surface and a continuous hinge is mounted to the gable panel with one hinge plate mounted flush with the gable surface and the other hinge plate of the piano hinge pivotable relative the fixed hinge plate and forming a blocking plate which extends inwardly in front of the drawers.  
         [0013]     Preferably, the length of the locking bar is such that it does not extend past the two opposite side walls, regardless of the position of the locking bar.  
         [0014]     In an alternative embodiment, the filing cabinet comprises two locking bars mounted at opposite sides of the compartment. Each of the two locking bars is movable between: (i) a locked position where at least a portion of the locking bar is in the path of one of the blocking plates and prevents the blocking plate from movement from the blocked position to the unblocked position; and (ii) an unlocked position where the locking bar is out of the path of the blocking plate and does not prevent the blocking plate from movement from the blocked position to the unblocked position. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     Further aspects and advantages will become apparent from the following description taken together with the accompanying drawings in which:  
         [0016]      FIG. 1  is a front pictorial view of a filing cabinet in accordance with a first embodiment of the present invention showing the drawers closed and locked;  
         [0017]     FIGS.  2  to  5  are front pictorial views of a filing cabinet in accordance with the first embodiment of the present invention, wherein the drawers and associated slides have been removed;  
         [0018]      FIGS. 6, 8 ,  10  and  12  are partially cut-away top views of FIGS.  2  to  5 , respectively;  
         [0019]      FIGS. 7, 9 ,  11 , and  13  are partially cut-away front perspective views of FIGS.  2  to  5 , respectively;  
         [0020]     FIGS.  14  to  17  are front pictorial views of a filing cabinet in accordance with a second embodiment of the present invention, wherein the drawers and associated slides have been removed;  
         [0021]      FIGS. 18 and 20  are partially cut-away top views of  FIGS. 14 and 17 , respectively;  
         [0022]      FIGS. 19 and 21  are partially cut-away front perspective views of  FIGS. 14 and 17 , respectively;  
         [0023]      FIG. 22  is a partially cut-away top view of  FIG. 14 ;  
         [0024]      FIG. 23  is a cross-sectional view along section line A-A of  FIG. 22 ;  
         [0025]      FIG. 24  is a cross-sectional view along section line B-B of  FIG. 22 ;  
         [0026]     FIGS.  25  to  28  are front pictorial views of a filing cabinet in accordance with a third embodiment of the present invention, wherein the drawers and associated slides have been removed;  
         [0027]      FIG. 29  is a front view similar to  FIG. 1  but unlocked and with one drawer open;  
         [0028]      FIG. 30  and  31  are cross-sectional plan views along section lines D-D′ and E-E′ in  FIG. 2 ;  
         [0029]      FIGS. 32 and 33  are partially cut-away top views of a fourth embodiment of the present invention;  
         [0030]      FIG. 34  is a front pictorial view of a left locking bar in accordance with the fourth embodiment illustrated in  FIGS. 32 and 33 ; and  
         [0031]      FIG. 35  is a front pictorial view of a right locking bar in accordance with the fourth embodiment illustrated in  FIGS. 32 and 33 . 
     
    
       [0032]     Throughout all the drawings and the disclosure, similar parts are indicated by the same reference numerals.  
       DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     First Preferred Embodiment  
       [0033]     Reference is made to FIGS.  1  to  13  and  29  which illustrate a first embodiment of a filing cabinet in accordance with the present invention.  
         [0034]     As seen in FIGS.  1  to  13  and  29  the cabinet  10  has a framework comprising opposite side walls  12  and  13 , a back wall  52 , a top wall  54  and a bottom wall  56 . The framework defines a compartment therein. As seen in  FIGS. 1 and 29  three drawers  60  are mounted in the compartment for horizontal sliding between closed, retracted positions shown in  FIG. 1  and open, extended positions.  FIG. 29  shows a middle of the three vertically stacked drawers in an open, extended position. The drawers  60  are slidable on associated slides (not shown) mounted to the interior of the side walls  12  and  13  on each side of each drawer  60 . The framework of the filing cabinet  10  includes a horizontal crossbeam  20 . The crossbeam  20  has both of its ends permanently secured to the opposite side walls  12  and  13 . The crossbeam  20  extends horizontally between the sidewalls  12  and  13  vertically between two of the drawers  60  and presents a forward facing surface  62  best seen in  FIG. 24 . Each of sidewalls  12  and  13  carry a forward facing gable surface  14  and  15  effectively forming a gable or post extending vertically beside each drawer  60  throughout the height of the cabinet.  
         [0035]     FIGS.  2  to  13  illustrate the filing cabinet  10  of  FIGS. 1 and 29  from which the drawers  60  and associated slides have been removed.  
         [0036]     As seen in  FIG. 30  and  31  two continuous hinges  80  and  81  also known as piano hinges are mounted to the forward facing gable surface  14  and  15  of each side wall  12  and  13 . Each hinge  80  and  81  has two hinge plates namely a base plate  82 ,  83 , a blocking plate  16 ,  17  joined by a hinge pin  84 ,  85  with the base plate  82 ,  83  and blocking plate  16 ,  17  pivotable relative each other about the pin  84 ,  85 . The base plate  82 ,  83  is fixedly secured to the respective gable surface  14  and  15  of the side walls as by screws, nuts, welding or the like with the hinge pin  84  disposed to not extend laterally beyond the respective side wall  12  and  13 . Each blocking plate  16 ,  17  is thus hinged to its relative side wall  12 ,  13  for pivoting about the vertical hinge pin  84 ,  85 .  
         [0037]     The blocking plates  16 ,  17  are adapted to be rotatable from: (i) a blocked position, as shown in  FIG. 2, 6  and  7 , in which the blocking plates  16 ,  17  lie forward of the drawers  60  in the front plane of the front face of the cabinet  10  to (ii) an unblocked position, as shown in  FIG. 5, 12  and  13 , in which the blocking plates  16 ,  17  are rotated to extend forwardly preferably perpendicular to the front face of the cabinet  10  and thus parallel to side walls  12  and  13 .  FIGS. 30 and 31  show the blocking plates  16 ,  17  in solid lines in an unblocked position and in dashed lines in a blocked position.  
         [0038]     A locking bar  22  is slidably mounted to the forward facing surface  62  of the crossbeam  20  for sliding in the horizontal direction relative the crossbeam  20 .  FIGS. 2, 6  and  7  show a middle locked position in which the locking bar  22  overlaps both of the blocking plates  16 ,  17  and prevents opening of the drawers. As seen in  FIG. 6  which is a top view of  FIG. 2 , the left end  30  of the locking bar  22  is forward of the left blocking plate  16  and prevents its movement from the blocked position shown and the right end  31  of the locking bar  22  is forward of the right blocking plate  17  and prevents its movement from the blocked position.  
         [0039]     The locking bar  22  is slidable from the position shown in  FIG. 2t o the right to the position shown in  FIGS. 3, 8  and  9  such as to be clear of the blocking plate  16  thus allowing the blocking plate  16  to be rotated between the blocked and the unblocked position.  FIGS. 4, 10  and  11  show a position which after the locking bar  16  has been rotated to the unblocked position, the locking bar  22  has been slid to the left to a position shown in  FIG. 4  such as to be clear of blocking plate  17  thus allowing the blocking plate  17  to be rotated between the unblocked position and a blocked position.  FIGS. 5, 12 ,  13  and  14  show a condition which from the position of  FIG. 4 , the blocking plate  17  is pivoted to the unblocked position and the locking bar  22  is slid back to the middle position. As seen in  FIG. 12  in a top view the hinged blocking plates  16 ,  17  are in a position where they are out of the path of the drawers  60  and therefore, do not prevent the opening of the drawers  60 , as shown in  FIG. 29  with one drawer open.  
         [0040]     The length of locking bar  22  is such that when it is slid to the right, as shown in  FIG. 3 , the left end  30  of the locking bar  22  is clear of the blocking plate  16  on the left side of the filing cabinet  10 , and the right end  31  of the locking bar  22  does not extend past the edge of side wall  13 . Similarly, when the locking bar  22  is slid to the left, as shown in  FIG. 4 , the right end  31  of the locking bar  22  is clear of the blocking plate  17  on the right side of the filing cabinet  10 , and the left end  30  of the locking bar  22  does not extend past the edge of side wall  12 . Therefore, the locking bar  22  is designed such that it does not extend laterally past vertical planes of the side walls  12  and  13  of the filing cabinet  10 , and does not move into, for example, a wall adjacent the filing cabinet  10  or into the path of the drawers of any other filing cabinets which are adjacent to filing cabinet  10 .  
         [0041]     In the middle locked position of  FIGS. 2, 6  and  7 , the locking bar  22  is adapted to be fixed in the position to prevent movement of the locking bar  22 . In this regard as best seen in  FIG. 6  and  7 , a lock bracket  36  is secured to a central portion of the crossbeam  20  providing a horizontally extending flange with a vertical opening therethrough which is to align with vertical opening in the lock bar  22  such that a locking device such as a padlock may lock the locking bar  22  to the crossbeam  20  against movement. The locking bar  22  shown in FIGS.  1  to  13  has a L-shaped in cross-section with one flange vertical and the other flange horizontal. The horizontal flange carries the vertical opening to receive a padlock.  
         [0042]     As seen, for example, in  FIG. 29 , the locking bar  22  has a vertical extent which is not greater than the vertical extent of the crossbeam  20  such that with the locking bar  22  itself doe not interfere with movement of the drawers  60  on either side of the crossbeam  20  to an open extended position.  
       Second Preferred Embodiment  
       [0043]     FIGS.  14  to  24  illustrate a second embodiment of the filing cabinet  10  of the present invention in which the drawers and associated slides have been removed.  
         [0044]     In this embodiment, the locking bar  22  is pivotally mounted to the crossbeam  20  for pivoting about an axis or pivot indicated generally as  26 . This configuration allows for pivoting of the locking bar  22  between: (i) a horizontal position in which it overlies the crossbeam  20 , as seen in  FIGS. 14 and 17 ; and (ii) a vertical position parallel to side wall  13 , as seen in  FIGS. 15 and 16 . The locking bar  22  is spaced forwardly from the crossbeam  20  such that each blocking plate  16 ,  17  may be received in a space between the locking bar  22  and the crossbeam  20 .  
         [0045]     In the locked position illustrated in  FIGS. 14, 18 ,  19  and  22 , the blocking plates  16  and  17  are in a blocked position forward of the drawers and extending in the front plane of the front face of the cabinet  10 . Referring first to the left side, the locking bar  22  is in a horizontal position in which the end  30  of the locking bar  22  is forward of and overlaps the blocking plate  16  on the left side of the cabinet  10 . Thus the locking bar  22  prevents the blocking plate  16  from being moved from the blocked position to the unblocked position. The locking bar  22  does not extend laterally past the side wall  12  of the filing cabinet.  
         [0046]     Referring to the right side, the length of the locking bar  22  is such that in the position shown in  FIG. 14 , the left end  31  of the locking bar  22  is forward of and overlaps the blocking plate  17  on the right side of the filing cabinet  10 . Thus the locking bar  22  prevents blocking plate  17  from being moved from the blocked position to the unblocked position. The locking bar  22  does not extend laterally past side wall  13  of the filing cabinet  10 .  
         [0047]     From the position of  FIG. 14 , the locking bar  22  has been pivoted about pivot pin  26  to a vertical position parallel to sidewall  14  as shown in  FIG. 15 . In this vertical position, the locking bar  22  does not prevent the blocking plates  16  and  17  on either side of the cabinet  10  from being moved from the blocked position to the unblocked position, and the blocking plates  16  and  17  are each able to be moved between the blocked and unblocked positions.  FIG. 16  shows a condition in which from the position of  FIG. 15 , the blocking plates  16  and  17  have been moved to the unblocked position shown in  FIG. 16  with the locking bar maintained vertical. The locking bar  22  is pivotally connected to the crossbeam  20  at pivot axis  26  with the pivot pin  26  is spaced inwardly from an end  30  of the locking bar  22  sufficiently that when the locking bar  22  is in the vertical position shown in  FIGS. 15 and 16  the locking bar  22  is spaced laterally inwardly from the blocking plate  16  as in necessary that the blocking plate  16  be free to pivot between the blocked and unblocked positions. From the position of  FIG. 16  the locking bar  22  can be pivoted about the pivot pin  26  to assume the horizontal position shown in  FIGS. 17, 20  and  21  with the blocking plates  16 ,  17  in the unblocked position and extending forwardly parallel to the side walls  12  and  13  of the cabinet. In the position of  FIGS. 17, 20  and  21 , the blocking plates  16 ,  17  are out of the path of the drawers and do not prevent the drawers from being withdrawn and retracted.  
         [0048]      FIG. 23  is a cross-sectional view along section line A-A of  FIG. 22  showing a preferred configuration by which the locking bar  22  is pivotally mounted to the crossbeam  20  for pivoting about pivot axis  26 . The locking bar  22  is L-shaped is cross-section having vertical leg  40  and horizontal leg  41 . The crossbeam  20  has a vertical portion  61  presenting a forward face  62 . A top flange  63  and a bottom flange  64  extending rearwardly from the vertical portion  61 . At the location of pivot axis  26 , a strengthening plate  66  is secured to the rear of the vertical portion  61 . A screw  65  carrying washers  67  and  68  extends through an aperture the plate  66  and the vertical portion  61  and into a threaded nut  69  welded to a rear of the vertical leg  40  of the locking bar  22 .  
         [0049]      FIG. 24  is a cross-sectional view along section line B-B of  FIG. 22  illustrating a lock bracket  36  which is fixedly secured to the crossbeam  20  by reason of a vertical leg  37  being welded to the vertical portion  61  of the crossbeam  20  to present a horizontal leg  38  projecting forwardly. The locking bar  22  is shown with its horizontal leg  42  resting on the horizontal leg  38  of the lock bracket  36 . Vertical openings  90  and  91  in through the horizontal leg  30  of the lock bracket  36  and the horizontal leg  42  of the locking bar  22  align to receive a padlock  93  or other locking mechanism to lock the locking bar  22  against movement relative to the crossbeam  20  and, therefore, to secure the hinged blocking plates  16  in the closed position shown in  FIGS. 14, 18 ,  19 ,  22  and  24 .  FIG. 24  shows the blocking plate  17  as disposed in a blocked position rearward of the locking bar  22 .  
         [0050]     In  FIG. 14  to  24  the pivot axis  26  is show as located proximate to one side of the cabinet  10 . This is preferred but not necessary and the pivot axis  26  could be in the centre middle of the crossbeam between two sides.  
       Third Preferred Embodiment  
       [0051]     FIGS.  25  to  28  illustrate a third embodiment of the filing cabinet  10  of the present invention. The drawers and associated slides have been removed.  
         [0052]     The third preferred embodiment is a variation of the second embodiment illustrated in FIGS.  14  to  24 . In the third embodiment, however, there are two separate locking bars  22  and  23 . Each locking bar  22 ,  23  is pivotally mounted opposite ends of the crossbeam  20  by a pivot mechanism for pivoting about pivot axis  26  and  27 .  
         [0053]     In a horizontal position, as shown in  FIG. 25 , both locking bars  22 ,  23  overlie the crossbeam  20 . The ends  32 ,  33  of the locking bars  22 ,  23  which are farthest away from the pivot axes  26 ,  27  overlap in the middle of the cabinet where they can be secured, as preferably to the crossbeam  20  for locking as with a padlock and locking bracket, not shown, but similar to that in  FIG. 24 . In  FIG. 25 , the blocking plates  16 ,  17  are in a blocked position extending in the front plane of the front face of the cabinet  10  and each locking bar  22 ,  23  is in a horizontal position with the end  30 ,  31  of the locking bar  22  that is nearer to pivot axes  26 ,  27  in front of one of the blocking plates  16 ,  17  to prevent the blocking plate  16 ,  17  from being moved from a blocked position to an unblocked position.  
         [0054]     The length of each of the locking bars  22 ,  23  is such that when the locking bars  22  are in the horizontal position shown in  FIG. 25 , the near ends  30 ,  31  overlap the blocking plates  16 ,  17  but do not extend past either of the side walls  12  and  13 .  
         [0055]     In  FIGS. 26 and 27 , both of the locking bars  22 ,  23  have been pivoted about their pivot axes  26 ,  27  to a vertical position parallel to side walls  12  and  13 . In this vertical position, neither of the locking bars  22 ,  23  prevent the blocking plates  16 ,  17  from being moved from the blocked position to the unblocked position.  FIG. 28  illustrates a position in which from the position of  FIG. 27 , the locking bars  22 ,  23  are pivoted to a horizontal position. In the position of  FIG. 28  the drawers  60  may be opened.  
         [0056]     In the third embodiment, when the locking bars  22 ,  23  are in the vertical position shown in  FIGS. 26 and 27 , the length of the locking bars  22 ,  23  are limited such that the far ends  32 ,  33  of the locking bars  22  do not extend upwardly past top wall  54 .  
         [0057]     While the second and third embodiments have been illustrated with the locking bars  22 ,  23  moved to a vertical position extending upwardly from the pivot axis  26 ,  27  to permit the blocking plates  26 ,  27  to be moved between the blocked and unblocked positions, the locking bars  22 ,  23  could be moved to vertical position with the locking bars  22 ,  23  extending downwardly from the pivot axis  26 ,  27  provided sufficient vertical spacing is available above a floor on which the cabinet rests.  
       Fourth Preferred Embodiment  
       [0058]     FIGS.  32  to  35  illustrate a fourth preferred embodiment of the filing cabinet  10  of the present invention.  
         [0059]     The fourth preferred embodiment has elements of both the first preferred embodiment illustrated in FIGS.  1  to  13  and  29  and the third preferred embodiment illustrated in FIGS.  25  to  28 .  
         [0060]     Similar to the third preferred embodiment, the fourth preferred embodiment has two separate locking bars, a left locking bar  22  and a right locking bar  23 . Like the first preferred embodiment, each locking bar  22 ,  23  of the fourth preferred embodiment is slidably mounted to the forward facing surface  62  of the crossbeam  20  for sliding in the horizontal direction relative to the crossbeam  20 .  
         [0061]      FIGS. 34 and 35  provide isolated views of the left locking bar  22  and the right locking bar  23 , respectively.  
         [0062]     As shown in  FIGS. 34 and 35 , each locking bar  22 ,  23  is divided into three portions. For example, the left locking bar  22  divided into a main portion  114 , a shoulder portion  116 , and an end portion  118 . The main portion  114  is substantially parallel to the crossbeam  20  of the filing cabinet  10 . The left locking bar  22  is bent at a substantially right angle to the main portion  114  in order to form the shoulder portion  116 . Therefore, the shoulder portion  116  is substantially perpendicular to both the main portion  114  and the crossbeam  20 . The left locking bar  22  is then bent again at a substantially right angle to the shoulder portion  116  in order to form the end portion  118 . Therefore, the end portion  118  is substantially parallel to both the main portion  114  and the crossbeam  20 .  
         [0063]     The right locking bar  23  is almost a mirror image of the left locking bar  22 . The right locking bar  23  is divided into a main portion  120 , a shoulder portion  122 , and an end portion  124 . The main portion  120  is substantially parallel to the crossbeam  20  of the filing cabinet  10 . The right locking bar  23  is bent at a substantially right angle to the main portion  120  in order to form the shoulder portion  122 . Therefore, the shoulder portion  122  is substantially perpendicular to both the main portion  120  and the crossbeam  20 . The right locking bar  23  is then bent again at a substantially right angle to form to the shoulder portion  122  in order to form the end portion  124 . Therefore, the end portion  124  is substantially parallel to both the main portion  120  and the crossbeam  20 . A right reinforcement bracket  162  is placed between the main protion  120  and the shoulder portion  122 . The reinforcement bracket  162  maintains the substantially right angle between the main portion  120  and the shoulder portion  122 . Therefore, the reinforcement bracket  162  prevents the right locking bar  23  from being manually bent or pried away from its position forward of the right blocking plate  17 . A corresponding left reinforcement bracket  160  for the left locking bar  22  is shown in  FIGS. 32 and 33 .  
         [0064]      FIG. 32  shows a locked position of the fourth preferred embodiment. The left locking bar  22  is in a left most position, such that the left end  30  of left locking bar  22  is forward of the left blocking plate  16  and prevents its movement from the blocked position shown. Similarly, the right locking bar  23  is in a right most position, such that the right end  31  of the right locking bar  23  is forward of the right blocking plate  17  and prevents its movement from the blocked position shown.  
         [0065]     The left locking bar  22  is designed such that when it is in the left most position shown in  FIG. 32 , the left shoulder portion  116  abuts with a corresponding shoulder portion  110  formed in crossbeam  20 . The corresponding shoulder portion  110  of the crossbeam  20  is similar to the left shoulder portion  116  in that both of these structures are defined by two substantially right angle bends. The left locking bar  22  is prevented from sliding any further to the left. As such, the left end  30  of the left locking bar  22  does not extend past the edge of side wall  12 . Similarly, the right locking bar  23  is designed such that when it is in the right most position shown in  FIG. 32 , the right shoulder portion  122  abuts with a corresponding shoulder portion  112  formed in crossbeam  20 . The corresponding shoulder portion  112  of the crossbeam  20  is similar to the right shoulder structure  122  in that both of these structures are defined by two substantially right angle bends. The right locking bar  22  is prevented from sliding any further to the right. As such, the right end  31  of the right locking bar  23  does not extend past the edge of side wall  13 . Therefore, the locking bars  22 ,  23  are designed such that they do not extend laterally past the vertical planes of side walls  12 ,  13  of the filing cabinet  10 .  
         [0066]     Tabs  130 ,  132  are formed adjacent the far ends  32 ,  33  of each locking bar  22 ,  23 . Each tab  130 ,  132  is bent at a substantially right angle to the main portion  114 ,  120  such that the tab  130 ,  132  lies in the horizontal plane. Each tab  130 ,  132  has a top surface  134 ,  136  and a bottom surface  138 ,  140 . Vertical openings  102 ,  104  extend from the top surface  134 ,  136  of the tabs  130 ,  132  through to the bottom surface  138 ,  140  of the tabs  130 ,  132 . Preferably, the vertical opening  102  in the left locking bar  22  has the same size and shape as the vertical opening  104  in the right locking bar  23 . The size and shape of the vertical openings  102 ,  104  is not particularly limited, but should be designed such that a padlock can be received through said vertical openings  102 ,  104 .  
         [0067]     When in the locked position shown in  FIG. 32 , the vertical opening  102  of the left locking bar  22  is aligned with the vertical opening  104  of the right locking bar  23 . When desired, a locking mechanism, such as a padlock, can be inserted through both openings  102 ,  104  and secure both locking bars  22 ,  23  in the locked position.  
         [0068]     Preferably, the ends  32 ,  33  of the locking bars  22 ,  23  form finger gripping means, as shown in  FIGS. 34 and 35 . This allows a user to grasp the ends  32 ,  33  and manually slide each locking bar  22 ,  23  in the horizontal direction.  
         [0069]      FIG. 33  illustrates an unlocked position of the fourth preferred embodiment. The left locking bar  22  is slidable from the left most position shown in  FIG. 32  to a right most position shown in  FIG. 33 , such that the left end  30  of the left locking bar  22  is laterally inwardly of the left blocking plate  16  and the left blocking plate  16  is free to be rotated between the blocked and the unblocked positions. The right locking bar  23  is slidable from the right most position shown in  FIG. 32  to a left most position shown in  FIG. 33 , such that the right end  31  of the right locking bar  23  is laterally inwardly of the right blocking plate  17  and the right blocking plate  17  is free to be rotated between the blocked and the unblocked positions.  
         [0070]     Each of the embodiments show a filing cabinet with a crossbeam  20  which is preferred but not necessary. The sliding locking bar  22  of  FIG. 1  could be mounted to one or both of the gable-like crossbeams  95  and  96  forward as part of and adjacent top wall  10  and bottom wall  56 . The pivoting licking bars  22 ,  23  of FIGS.  14  to  25  could similarly be mounted to the top crossbeam  95  and possibly the bottom crossbeam  96 .  
         [0071]     The continuous hinges forming the blocking plates  16 ,  17  are shown in each embodiment to extend the entire height of the cabinet  10 . This is not necessary but preferred. The hinges need to only extend adjacent a portion of each drawer  60  whose opening is to be blocked.  
         [0072]     Although this disclosure has described and illustrated preferred embodiments of the invention, it is to be understood that the invention is not restricted to these particular embodiments. Rather, the invention includes all embodiments that are functional or mechanical equivalents of the specific embodiments and features that have been described and illustrated herein. Many modifications and variations will now occur to those skilled in the art. For a definition of the invention, reference is made to the following claims.

Summary:
An external locking mechanism for a filing cabinet incorporating two hinged blocking plates at each side of the cabinet and a locking bar which is movable without removal from attachment to the cabinet to positions such that the blocking plates can be selectively prevented from being moved to unblocked positions or permitted to be moved to unblocked positions.