Drawer interlock to non-interlock conversion device

A non-interlock blocking element adapted for use with a furniture unit having a plurality of drawers, a vertical guide for receiving a vertical stack of blocking elements which are slidably mountable in the guide for vertical translation therein, and a wedge element associated with each of the drawers which is reciprocable into the stack of blocking elements to effect interlocking relationships among the drawers is provided. The non-interlock blocking element allows such furniture units which are adapted for use with interlocking mechanisms, to be configured as non-interlocking furniture units, or as partially interlocking furniture units. The non-interlock blocking elements are generally similar to standard interlock blocking elements, but include a recess which allows unobstructed reciprocation of a wedge element associated with a drawer when the recess is in horizontal alignment with the wedge element, whereby the drawer can be opened irrespective of whether another drawer is already opened.

FIELD OF THE INVENTION 
This invention relates to lockable furniture units of the type having two 
or more drawers, and in particular to furniture units adapted to 
incorporate an interlock system for preventing more than one drawer from 
being open at any given time. 
BACKGROUND OF THE INVENTION 
Furniture units with drawers are generally well known in the art, and 
typically include multi-drawer vertical files, such as those used in 
freestanding file cabinets, pedestals for desks, worksurfaces, computer 
support units, and other similar furniture applications. When the drawers 
in such furniture units are to be used for relatively heavy articles, such 
as document storage, the unit is preferably provided with some type of 
drawer interlock mechanism that will permit only one of the drawers to be 
opened at any given time, so as to avoid vertical instability, tipping, 
etc. Such interlock mechanisms are normally provided as a safety feature 
in freestanding vertical files. 
Many people find the interlock system annoying and inconvenient at times, 
because it prevents more than one drawer from being opened at any given 
time, even when potential tipping hazards or vertical stability problems 
are non-existent. For example, a furniture unit, such as a desk pedestal, 
having a lower 12" file drawer and one or two upper 3" personal drawers, 
is not likely to tip if one of the upper 3" drawers is open when the file 
drawer is already open. The user of a furniture unit of this type may 
desire access to the contents of one of the 3" personal drawers while the 
file drawer is already opened, such as to get a pen to make a notation in 
the file before returning it to the file drawer. With a conventional 
interlock system, the file drawer must be closed before the personal 
drawer can be opened to obtain access to the contents thereof, and the 
personal drawer must be closed before the file drawer can be reopened. In 
many cases, it would be much more convenient to be able to simply open the 
personal drawer, such as to remove a pen, without having to first close 
the file drawer. 
One way in which a furniture unit could be provided with a plurality of 
drawers which can be opened at the same time would be to simple eliminate 
the interlock mechanism. However, because the drawer interlock mechanism 
of conventional lockable furniture units generally cooperates with, and is 
integrated to, the interlock mechanism, it would be necessary to provide 
alternative locking means if it is desired to convert an existing 
furniture unit having lockable, interlocked drawers, into a furniture unit 
having lockable, non-interlocked drawers (i.e., drawers which can be 
opened irrespective of whether or not another drawer is already open). The 
use of alternative locking means would be particularly undesirable in 
situations where a manufacturer intends to manufacture both an 
interlocking version, and a non-interlocking version of a lockable 
furniture unit at the same manufacturing plant or production line, because 
excessive alternative manufacturing equipment, manufacturing processes, 
and inventory of parts would be required for the alternative locking 
means. Accordingly, it would be desirable to provide a means or device 
which is capable of converting a lockable furniture unit having an 
interlocking mechanism (for preventing a second drawer from being opened 
when a first drawer is already open) into a lockable furniture unit which 
allows a second drawer to be opened when a first drawer is already open, 
and which cooperatively interacts with an existing drawer locking 
mechanism, whereby the need for additional alternative locking means is 
eliminated. 
Known furniture units with a plurality of drawers have either been of the 
interlocking type, wherein only one drawer can be opened at any given 
time, or of the non-interlocking type, wherein any or all of the drawers 
can be opened at any given time. Heretofore, partially interlocking drawer 
systems wherein at least one drawer can be selectively opened irrespective 
of whether other drawers are already opened, and wherein at least one 
other selected drawer cannot be opened if at least a third drawer is 
already opened, have not been sold or otherwise disclosed, nor have 
advantages thereof been described. However, a partially interlocking 
drawer system may be advantageous for certain types of drawer 
configurations, such as where it might be undesirable to have two or more 
large file drawers of a furniture unit opened at the same time, yet 
acceptable and desirable to have a small drawer opened at the same time 
that a file drawer is open. Accordingly, it would be desirable to provide 
a means or device for providing a furniture unit having selectable 
non-interlocking drawers and selectable interlocking drawers. Further, it 
would be desirable to provide such means or device which would allow such 
furniture unit to be reconfigured as interlocking, non-interlocking, or 
partially interlocking, as desired. 
SUMMARY OF THE INVENTION 
One aspect of the present invention is to provide a non-interlock blocking 
element for a furniture unit having a plurality of drawers and which 
includes a vertical guide adapted for receiving a plurality of blocking 
elements which interact with wedge elements associated with the drawers to 
prevent multiple drawers from being open at any given time, the 
non-interlock blocking element being slidably mountable in the vertical 
guide to configure the furniture unit so that at least one of the drawers 
is non-interlocking, i.e., capable of being opened irrespective of whether 
another drawer in the unit is already open. More specifically, the 
non-interlock blocking element is adapted for use with a furniture unit 
having at least an upper drawer and a lower drawer, a vertical guide for 
receiving a vertical stack of blocking elements which are slidably 
mountable in the guide for vertical translation therein, and first and 
second wedge elements associated with the upper and lower drawers 
respectively. The wedge elements are horizontally reciprocable into the 
stack of blocking elements when the associated drawer is opened to cause 
blocking elements disposed at an elevation above the wedge element 
reciprocated into the stack of blocking elements to be shifted upwardly, 
and the wedge element is also horizontally reciprocable completely out of 
the stack of blocking elements when the associated drawer is closed to 
allow the blocking elements disposed at an elevation above the wedge 
element reciprocated completely out of the stack of blocking elements to 
be shifted downwardly. The non-interlock blocking element includes a 
vertically elongate body having a recess adjacent an upper edge thereof 
for receiving a laterally adjacent reciprocable wedge element associated 
with an upper drawer when the upper drawer is open and when the 
non-interlock blocking element is shifted upwardly by a reciprocable wedge 
element associated with a lower drawer, whereby both upper and lower 
drawers can be open at the same time. 
Another aspect of this invention is to provide a furniture unit including 
upper and lower drawers, a vertical guide, a plurality of blocking 
elements disposed directly on top of one another in a vertical stack and 
slidably mounted in the guide for vertical translation therein, and first 
and second wedge elements associated with the upper and lower drawer 
respectively. The wedge elements are horizontally reciprocable into the 
stack of blocking elements when the associated drawer is opened to cause 
the blocking elements disposed at an elevation above the wedge element 
reciprocated into the stack of blocking elements to be shifted upwardly, 
and the wedge elements are horizontally reciprocable completely out of the 
stack of blocking elements when the associated drawer is closed to allow 
the blocking elements disposed at an elevation above the wedge element 
reciprocated completely out of the stack of blocking elements to be 
shifted downwardly. The wedge element associated with the upper drawer is 
disposed along side of and in horizontal alignment with a bottom portion 
of a first one of the stacked blocking elements when the lower drawer is 
closed, and the wedge element associated with the upper drawer is disposed 
along side of and is horizontally aligned with an upper portion of a 
second one of the blocking elements disposed vertically adjacent to and 
below the first blocking element when the lower drawer is open. The second 
one of the blocking elements includes a recess at an upper portion thereof 
which allows unobstructed reciprocation of the wedge element associated 
with the upper drawer, whereby the upper drawer can be opened when the 
lower drawer is open. 
A further aspect of the invention is to provide a furniture unit with an 
upper drawer and a plurality of vertically spaced apart lower drawers, in 
which at least one of the drawers is interlocked with another of the 
drawers, and at least one of the drawers is not interlocked with any of 
the other drawers. The furniture unit includes an upper drawer, a 
plurality of vertically spaced apart lower drawers, each lower drawer 
being vertically disposed below the upper drawer, a vertical guide, a 
plurality of blocking elements disposed directly on top of one another in 
a vertical stack and slidably mounted in the guide for vertical 
translation therein, and a wedge element associated with each of the 
drawers. Each wedge element is horizontally reciprocable into the stack of 
blocking elements when the associated drawer is opened to cause blocking 
elements disposed at an elevation above the wedge element reciprocated 
into the stack of blocking elements to be shifted upwardly, and the wedge 
elements are horizontally reciprocable completely out of the stack of 
blocking elements when the associated drawer is closed to allow blocking 
elements disposed at an elevation above the wedge element reciprocated 
completely out of the stack of blocking elements to be shifted downwardly. 
Each wedge element is disposed along side of and in horizontal alignment 
with a lower portion of one of the stack blocking elements when none of 
any lower wedge elements are reciprocated into the stack of blocking 
elements, and each wedge element is disposed along side of and in 
horizontal alignment with an upper portion of another blocking element 
when at least one of any lower wedge elements is reciprocated into the 
stack of blocking elements. At least a first one of the blocking elements 
includes a recess at an upper portion thereof which is disposed along side 
of and in horizontal alignment with a first one of the wedge elements when 
at least one of any lower wedge elements is reciprocated into the stack of 
blocking elements. The recess allows unobstructed reciprocation of the 
first wedge element when the first wedge element is in horizontal 
alignment with the upper portion of the first blocking element. At least a 
second one of the blocking elements includes an upper portion which is 
disposed along side of and in horizontal alignment with a second one of 
the wedge elements when at least one of any lower wedge elements is 
reciprocated into the stack of blocking elements. The upper portion of the 
second blocking element obstructs reciprocation of the second wedge 
element when the second wedge element is in horizontal alignment with the 
upper portion of the blocking element, thereby preventing the drawer 
associated with the second blocking element from being opened when any 
other interlocked drawer is open. Thus, the non-interlock blocking element 
of this invention, when used in combination with interlock blocking 
elements, allows a furniture unit having a plurality of drawers to be 
configured so that a certain drawer or drawers cannot be opened when 
another interlocked drawer is open, while at least one other 
non-interlocked drawer can be opened irrespective of whether another 
drawer or drawers are open. 
In accordance with a further aspect of the invention, a method is provided 
for converting a furniture unit having interlocked drawers which cannot be 
open at the same time into a furniture unit having non-interlocked drawers 
which can be opened irrespective of whether another drawer or drawers are 
open. The method comprises providing a furniture unit with interlock 
drawers including a plurality of drawers, a vertical guide, a plurality of 
blocking elements disposed in a vertical stack and slidably mounted in the 
guide for vertical translation therein, and a wedge element associated 
with each of the drawers, the blocking elements obstructing reciprocation 
of any of the wedge elements into the stack of blocking elements when any 
of the other wedge elements has been reciprocated into the stack of 
blocking elements; removing at least one of the blocking elements having 
an upper portion which is in horizontal alignment with a wedge element 
associated with one of the drawers when a lower drawer is open; and 
replacing the removed blocking element with a blocking element having a 
recess at an upper portion thereof which allows unobstructed reciprocation 
of the wedge element associated with the selected drawer, whereby the 
selected drawer and another drawer can be open at the same time.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS 
For purposes of description herein, the terms "upper", "lower", "right", 
"left", "rear", "front", "vertical", "horizontal", and derivatives thereof 
shall relate to the invention as oriented in FIGS. 1-3. However, it is to 
be understood that the invention may assume various alternative 
orientations and step sequences, except where expressly specified to the 
contrary. It is also to be understood that the specific devices and 
process illustrated in the attached drawings, and described in the 
following specification are simply exemplary embodiments of the inventive 
concepts defined in the appended claims. Hence, specific dimensions and 
other physical characteristics relating to the embodiments disclosed 
herein are not to be considered as limiting, unless the claims expressly 
state otherwise. 
The reference numeral 1 (FIGS. 1-3), generally designates an interlock 
mechanism embodying the present invention. Interlock mechanism 1 is 
particularly adapted for use in conjunction with furniture units and the 
like of the type having two or more horizontally shifting drawers, such as 
the illustrated vertical file 2, having three, vertically arranged drawers 
3-5. Interlock mechanism 1 functions to permit only one of the drawers 3-5 
to be opened at any give time, so as to avoid vertical instability, 
tipping, etc. The illustrated interlock mechanism 1 includes a plurality 
of blocks 6 slidably mounted in a vertical guide 7, with three actuators 
8-10 associated with drawers 3-5, respectively. Each of the actuators 8-10 
comprises an arm 11 having an upper portion pivotally mounted to the guide 
7, and a lower portion with a notch 12 shaped to selectively engage an 
associated one of three actuator pins 13-15 on drawers 3-5, such that the 
closing and opening of drawers 3-5 rotates the associated arm 11 between 
corresponding unlocked and locked positions, as shown in FIGS. 10 and 12, 
respectively. Each of the actuators 8-10 also includes a wedge 16 
pivotally mounted on the lower portion of arm 11, and slidably supported 
on guide 7 to reciprocate inbetween adjacent blocks 6 when the associated 
one of the drawers 3-5 is opened, so as to lock closed all remaining 
drawers. Preferably, the vertical guide 7 is formed by a specially 
configured upright stiffener channel, and is positioned in the vertical 
file 2 in a manner, which maximizes the lateral space available for 
drawers 3-5. 
The illustrated vertical file 2 (FIGS. 1-3) includes a case 20 in which 
drawers 3-5 are slidably mounted to reciprocate horizontally between fully 
opened and fully closed positions. Case 20 has an exterior skin 21 formed 
from a sheet metal blank or the like, comprising opposite side walls 22 
and 23, and a rear wall 24, which are integrally interconnected in a 
fashion which imparts a rigid box-like configuration to case 20. Case 
walls 22-24 each include upper and lower flanges 25 and 26, which extend 
inwardly from the upper and lower edges thereof. Two pairs of 
substantially identical, specially configured, vertical stiffeners 27 and 
28 are fixedly attached to the interior sides of sidewalls 22 and 23, 
opposite adjacent ends thereof, by means such as spot welding, adhesives, 
or the like. Two pairs of horizontal stiffeners 31 and 32 extend laterally 
across the upper and lower portions of case 20, and are connected to the 
upper and lower ends of oppositely facing vertical stiffeners 27 and 28, 
as well as to flanges 25 and 26, which together serve to rigidify case 20. 
The forward edges of sidewalls 22 and 23 are beveled inwardly to define 
associated front flanges 33, behind which forward portions of the front 
vertical stiffeners 27 are received in the manner described below. 
Drawers 3-5 (FIGS. 2, 17 and 18) may have a conventional construction, 
comprising a rectangular, box-shape core assembly 36 (FIG. 18) on which a 
head 37 is mounted in the open forward end thereof, and includes a pull 38 
to facilitate manually shifting drawers 3-5 between their fully closed and 
fully opened positions. Lock actuator pins 13-5 are located on the 
left-hand side of each of the associated drawers 3-5, adjacent the forward 
portion thereof, and protrude laterally outwardly therefrom to engage the 
notch 12 in the associated one of the actuators 8-10. In the illustrated 
example, drawers 3-5 each have a unique modular and convertible 
construction. However, it is to be understood that the present interlock 
mechanism 1 can also be used in conjunction with other types of drawer 
constructions. 
The vertical stiffeners 27 and 28 (FIG. 3) include a series of slots 39 
through the outer flanges thereof in which drawer suspension units 40-42 
are detachably mounted to slidingly support associated drawers 3-5, 
respectively. In the illustrated example, drawer suspensions 40-42 have a 
generally conventional construction, and are located to position drawer 
actuators pin 13-15 in line with their respective actuators 8-10. 
In the example shown in FIG. 1, the left-hand, front vertical stiffener 27 
in case 20 defines guide 7, which as described in greater detail 
hereinafter, is specially configured to minimize the lateral space 
required for interlock mechanism 1, thereby maximizing the lateral space 
available for drawers 3-5 in such a manner that both 81/2.times.11 and A4 
sized drawers can be housed within the same case 20, without increasing 
the width of case 20 from its standard 81/2.times.11 size. The illustrated 
guide 7 (FIGS. 4-7) comprises a rigid, elongate channel, having a 
generally U-shaped transverse cross-sectional configuration, including a 
central web 44 (FIG. 6), front and rear flanges 45 and 46 extending 
laterally along the opposite edges of web 44, and wing flanges 47 and 48 
extending horizontally from front and rear flanges 45 and 46 in a 
fore-to-aft direction. As best illustrated in FIG. 6, wing flanges 47 and 
48 are positioned adjacent to the interior surface of the left-hand 
sidewall 22 adjacent forward flange 33, and are fixedly attached thereto 
by means such as spot welding or the like. Guide channel 7 and sidewall 22 
together define a vertically extending way or space 49 therebetween, 
having a rectangular transverse cross-sectional shape in which a vertical 
stack of blocks 6 are closely, yet slidably received. 
Guide channel 7 (FIGS. 4-7) has a plurality of sets of openings which 
define separate actuator mounting stations 50 that are spaced regularly 
along the length of guide channel 7 in accordance with the incremental 
depth of drawers 3-5, such that interlock mechanism 1 can be readily 
configured and reconfigured to accommodate different depth drawers, as 
explained in greater detail hereinafter. With reference to FIG. 5, each 
actuator mounting station 50 includes a pin slot 54, a slide window 55, 
and a rounded protrusion 56, each of which is positioned at least in part 
in the web 44 of guide 7. Pin slot 54 is vertically elongated, and 
includes semi-circular end edges 57. Pin slot 54 extends through web 44, 
and is positioned with its major axis located slightly rearwardly from the 
center line of web 44. Slide window 55 is generally key-shaped, and is 
positioned vertically below its associated pin slot 54. The illustrated 
slide window 55 is defined by generally parallel upper and lower edges 58 
and 59, and a forward end edge 60. End edge 60 is positioned slightly 
rearwardly from the front flange 45 of guide channel 7, while upper and 
lower edges 58 and 59 merge into an enlarged guide portion 61 of slide 
window 55, which extends laterally outwardly into the rear flange 46 of 
guide 7, as defined by associated edges 63-64 (FIG. 7). As described in 
greater detail hereinafter, the guide portion 61 of slide window 55 is 
shaped to laterally receive an associated wedge 16 therein. Rounded 
protrusion 56 extends laterally outwardly from the exterior side of web 
44, has a generally semi-spherical shape, and is positioned horizontally 
on web 44 slightly rearwardly from the center line of pin slot 54. In the 
illustrated example, actuator mounting stations 50 are located 
approximately six inches apart along the length of guide 7. 
Guide channel 7 has upper and lower ends 66 and 67 received within 
horizontal stiffeners 31 and 32 and extends continuously therebetween. The 
upper end 66 (FIGS. 3-5) of guide channel 7 includes a 
rectangularly-shaped window 65 through web portion 44 into which a sliding 
lock actuator 130 (FIGS. 14-16) is received in the manner described in 
greater detail hereinafter. 
The illustrated blocks 6 (FIG. 4) have an incremental length corresponding 
to the incremental depth of drawers 3-5, which in one working embodiment 
of the present invention is approximately three inches. Each block 6 has 
an irregular hexagonal side elevational shape, comprising a front edge 70, 
top and bottom edges 71 and 72, inclined ramp edges 73 and 74, and a rear 
edge 75. A pair of fingers 76 and 77 extend rearwardly from rear edge 75, 
and serve to expand the effective width of block 6, so as to be closely, 
yet slidably received within guide 7. The provision of fingers 76 and 77 
permits the mounting of drawer suspension units 40-42 in the slots 39 in 
web 44 of guide 7, without interfering with the vertical sliding motion of 
blocks 6. 
As best illustrated in FIGS. 4 and 5, blocks 6 are arranged in a 
vertically, stacked arrangement, retained within the interior way 49 of 
guide 7. Blocks 6 and guide 7 are mutually sized so that when the bottom 
edge 72 of the lowermost block 6 is flush with the lower end 67 edge of 
guide 7, the top edge 71 of the uppermost block 6 is spaced apart from the 
upper end 66 of guide channel 7 to define a locking space 84 therebetween 
for purposes to be described in greater detail hereinafter. 
With reference to FIGS. 8-13, interlock actuators 8-10 have a substantially 
identical construction, and can be located in any one of the actuator 
mounting stations 50. Hence, for ease of description herein, reference 
shall be had only to actuator 8, it being understood that all other 
actuators, including actuators 9 and 10 are substantially identical. The 
arm portion 11 of actuator 8 is in the nature of a cam, having a generally 
triangular side elevational configuration defined by a rear edge 88, a 
front edge 89, a rounded upper edge 90, and a notched lower edge 91. The 
notch 12 in actuator 8 extends in a generally parallel fashion with rear 
edge 88, and is defined by parallel side edges 92 and 93, and arcuate end 
edge 94. 
A mounting pin 98 protrudes from the rear surface of actuator cam 11, and 
is shaped to be received within an associated one of the pin slots 54 in 
guide 7. The illustrated mounting pin 98 includes a generally 
cylindrically shaped shank 99 having a diameter slightly smaller than the 
width of pin slot 54, and an enlarged oblong head 100, which is shaped 
slightly smaller than the plan configuration of pin slot 54, so as to be 
closely received therein. The central axis of head 100, is positioned 
eccentrically with respect to the central axis of shank 99, such that when 
mounting pin 98 is inserted into an associated pin slot 54, the cam 11 is 
shifted downwardly within pin slot 54, and the outwardly protruding head 
100 on mounting pin 98 extends over the interior side of guide web 44 to 
detachably lock cam 11 on guide 7 in a manner which permits cam 7 to 
smoothly pivot about shank 99 in a fore-to-aft direction. 
Cam 11 (FIGS. 8-13) also includes a resilient positioner element in the 
form of a wing 104, which projects rearwardly from the rear edge 88 
thereof. Wing 104 has a generally rectangular plan configuration, with its 
longitudinal axis oriented generally vertically, and includes beveled 
leading and trailing edges 105 and 106, respectively. Wing 104 has a 
relatively narrow neck 107 which connects the same with the rear edge 88 
of cam 11, and is preferably integrally formed with cam 11 from a 
resilient material, such as plastic or the like, such that wing 104 is 
resiliently, laterally flexible with respect to cam 11, in the nature of a 
leaf spring or the like. Cam wing 104 is positioned to abuttingly engage 
an associated one of the rounded protrusions 56 on guide 7 in a manner 
which serves to retain the cam 11 in its set locked and unlocked 
positions, as described in greater detail hereinafter. A depression or 
recess 108 is provided on the rear surface of cam 11, and is shaped to 
receive rounded protrusion 56 therein when cam 11 is in the unlocked 
position, as illustrated in FIG. 10. 
The lower portion of cam 11 (FIGS. 8-13) includes a longitudinally 
elongated aperture 112 therethrough in which an associated wedge 16 is 
rotatably mounted. The illustrated wedge 16 has a primary body portion 109 
with upper and lower grooves 110 and 111 formed therein into which the 
upper and lower edges 58 and 59 of an associated slide window 55 are 
closely received to slidably mount wedge 16 for horizontal reciprocation 
therein. A block separator 116 extends rearwardly from the body portion 
109 of wedge 16, and includes upper and lower edges 117 and 118, and 
angled forward edges 119 and 120, arranged in a dihedral configuration 
intersecting along a parting edge 121. The angled forward edges 119 and 
120 of block separator 116 are shaped similar to the ramp edges 73 and 74 
of blocks 6 for sliding engagement therebetween. A mounting pin 122 
extends forwardly from block separator 116, and includes an enlarged head 
123 sized to be closely received through the aperture 112 in cam 11 with a 
snap lock type of action. When block separator 116 is oriented in its 
horizontal operational position, the head 123 of mounting pin 122 is 
pivoted ninety degrees from its insertion position, so as to positively, 
yet pivotally interconnect block separator 116 with cam 11, without 
requiring any separate fasteners. 
In operation, an actuator 8 is installed in each of the actuator mounting 
stations 50 associated with an associated drawer. In the illustrated 
example, actuators 8-10 are mounted adjacent drawers 3-5 respectively. 
Each actuator is installed in its associated mounting station 50 in the 
following manner. The block separator 116 (FIGS. 8-13) is connected with 
the lower portion of cam 11 by inserting mounting pin 122 through aperture 
112, and rotating block separator 116 ninety degrees in the fashion 
described hereinabove. Block separator 116 is then inserted into the 
enlarged guide portion 61 of slide window 55, between window edges 63-65. 
The grooves 110 and 111 on wedge body 109 are aligned with the upper and 
lower edges 58 and 59 of slide window 55, and wedge 16 is shifted 
forwardly to achieve sliding engagement therebetween, such that block 
separator 116 is captured within slide window 55, and can slidingly 
reciprocate in a horizontal direction freely therein. 
Next, the mounting pin 98 at the upper portion of cam 11 is mounted in pin 
slot 54, by inserting head 100 therethrough, and shifting cam 11 slightly 
downwardly, so that the shank portion 99 of mounting pin 98 rests against 
the lower edge 57 of pin slot 54, as illustrated in FIG. 10. Both of the 
remaining actuators 9 and 10 are similarly mounted in their associated 
actuator mounting station 50 to correspond with center drawer 4 and bottom 
drawer 5, respectively. 
When one of the drawers 3-5 is opened, the block separator 116 on the 
associated one of the actuators 8-10 is inserted into the vertical string 
of block 6. When all of the blocking elements are of the type shown in 
FIG. 4, wherein the upper portion of the blocking element 6 is configured 
to obstruct reciprocation of the wedge elements 16 when the blocks are 
shifted upwardly so that the wedge element is in alignment with the upper 
portion of a blocking element 6, then the remaining drawers are locked 
closed. For example, when the center drawer 4 is open, as shown 
schematically in FIGS. 17 and 18, actuator pin 14 moves horizontally 
forwardly, thereby rotating the cam 11 of actuator 9 forwardly. The 
rotation of cam 11 causes block separator 116 to slide forwardly within 
slide window 55, such that the angled forward edges 119 and 120 of block 
separator 116 engage the adjacent ramp edges 73 and 74 of vertically 
adjacent block 6 to thereby vertically separate the same, and insert block 
separator 116 squarely inbetween the bottom edge 71 of the upper block 6, 
and the upper edge 72 of the lower block 6. In this locked position, the 
block separator 116 positively prevents vertical movement of each of the 
blocks 6 positioned below the block separator 116. Furthermore, the block 
6 positioned above block separator 116 are shifted vertically so that 
their ramp surfaces 73 and 74 are out of horizontal alignment with 
separator blocks 116, such that the block separator 116 on the uppermost 
actuator 8 will engage the rear edge 75 of the associated block 6 in the 
event someone attempts to open top drawer 3. Hence, the insertion of block 
separator 116 into the vertical string of block 6 effectively locks closed 
all of the other drawers. 
When center drawer 4 (FIGS. 4 and 5) is closed, actuator pin 14 engages the 
rearward edge 93 of notch 12, thereby pivoting the cam 11 of actuator 9 
rearwardly to withdraw the block separator 116 from the vertical string of 
blocks 6, thereby permitting another one of the drawers to be opened. 
As best illustrated in FIGS. 8-13 selective resilient engagement between 
cam wing 104 and rounded protrusion 56 serves to help ensure that cam 11 
will not be inadvertently moved from is set locked and unlocked positions. 
When cam 11 is in the unlocked position, as shown in FIG. 10, rounded 
protrusion 56 is located within the recess 108 on the rear side of cam 11, 
such that there is no engagement therebetween, and cam 11 can pivot 
forwardly freely. As cam 11 is rotated forwardly, when the associated 
drawer is opened, the leading edge 105 of cam wing 104 engages rounded 
protrusion 56, and establishes resilient contact therebetween. When cam 11 
is shifted to is fully locked position, as shown in FIG. 12, the trailing 
edge 106 of cam wing 104 passes over rounded protrusion 56 with a slight 
snapping type of action, and abuts the same, so as to prevent inadvertent 
movement of cam 11 back to the unlocked position. When the associated 
drawer is returned to its closed position, cam wing 104 again passes over 
rounded protrusion 56, as shown in FIG. 13. The contact between cam wing 
104 and rounded protrusion 56, in conjunction with the geometry of 
actuator 8 causes arm 11 to shift upwardly, with mounting pin raising in 
pin slot 54. When the drawer is fully closed, cam wing 104 snaps over 
rounded protrusion 56, and cam 11 drops back down into its normal 
position, with shank 99 resting against the lower end edge 57 of pin slot 
54, so as to assume the position illustrated in FIG. 10. This selected 
contact between cam wing 104 and rounded protrusion 56, and vertical 
shifting motion of cam 11, combine to help prevent cam 11 from pivoting 
inadvertently from either its locked or unlocked positions. 
With reference to FIGS. 14-16, a lock actuator 130 is illustrated, which is 
particularly adapted for use in conjunction with interlock mechanism 1. 
Lock actuator 130 functions to simultaneously lock all drawers 3-5 in 
their fully closed position for security. 
The illustrated lock actuator 130 comprises a slide 131 that is slidably 
supported in the forward, upper, horizontal case stiffener 31 for 
generally horizontal motion therein. Slide 131 has a generally U-shape 
transverse, cross-sectional shape, comprising a central web 132, with a 
pair of upstanding L-shaped sides, comprising flanges 135 and 136 shaped 
to snap within the interior of channel-shaped case stiffener 31. Slide 131 
includes a finger 140 extending longitudinally from an outside end 
thereof, which is shaped to be closely received through the mating window 
65 in guide 7, so as to substantially fill locking space 84. When finger 
140 is inserted into locking space 84, engagement between the uppermost 
block 6 and slide finger 140 prevents any of the blocks 6 from being 
separated from one another a distant sufficient to permit a block 
separator 116 from being inserted between vertically adjacent blocks 6, so 
as to positively lock each of the drawers 3-5 in their fully closed 
position. Slide 131 includes two vertically oriented actuator windows 141 
and 142 spaced longitudinally apart therein, which are shaped to receive 
therein an associated strike plate portion 139 (FIG. 16) of a key lock 
143, as described in greater detail hereinafter. Slide 131 also includes a 
bracket portion 144 disposed along the rear edge of slide 141, and has one 
end of a leaf spring 145 attached thereto. Bracket 144 includes vertically 
extending control rod aperture 146 therein into which a control rod 147 
from a center lock system (FIG. 1) can be inserted. The free end 148 of 
leaf spring 145 is formed to be closely received and detachably retained 
within an associated slot 149 in the rear flange of horizontal stiffener 
31, as shown at FIG. 14. Leaf spring 145 is configured to resiliently urge 
slide 131 toward its normal unlocked position. 
Lock actuator 130 is designed to be used in conjunction with either a 
center lock arrangement 154, as shown by the broken lines in FIG. 2, or in 
a drawer front configuration 155, as shown by the solid lines in FIG. 2. 
When a drawer front configuration 155 is desired, key lock 143 is mounted 
in the head 37 of top drawer 3, such that associated strike arm 139 (FIG. 
16) is received within one of the actuator windows 141 and 142 of slide 
131, depending upon whether the lock is positioned in either a center or 
left side location on the drawer front. Rotation of the tumbler portion of 
key lock 143 rotates strike arm 139, thereby shifting slide 131 laterally 
to selectively position finger 140 within the locking space 84 of guide 7 
to lock all drawers 3-5 closed. 
In the event a center lock arrangement 154 is desired, the actuator rod 147 
associated with the center key lock is inserted into aperture 146 of 
bracket 144, which serves to selectively shift slide 131 laterally between 
the locked and unlocked positions. 
The illustrated vertical file 2 is extremely versatile, and can be used in 
many different environments. For example, vertical file 2 can be used 
either as a freestanding filing unit, or as a pedestal for a worksurface 
160, as shown by the broken lines in FIG. 2. The compact construction of 
case 20, vertical stiffeners 27 and 28, and incorporation of interlock 
mechanism 1 therein, permits a standard sized case to accept either 
81/2.times.11 or A4 size file drawers therein. Interlock mechanism 1 can 
be snap locked into case 20 at several different locations to accommodate 
various drawer configurations. The lock mechanism 130 can be easily 
snapped into place, or removed completely as desired, and can accommodate 
either a center lock configuration 154, or a drawer front configuration 
155. 
Drawer interlock 1 is extremely reliable, and is also flexible to readily 
adapt the same for use in conjunction with many different drawer 
configurations. The cam 11 and sliding block separator 116 of interlock 
mechanism 1 positively prevent more than one drawer from being opened at a 
time. The snap positioning feature achieved by engagement between cam wing 
104 and rounded protrusion 56, as well as the vertical shifting motion of 
cam 11, assists in retaining each cam 11 in its set locked and unlocked 
positions, and thereby helps to prevent inadvertent movement therefrom. By 
positioning blocks 6 in a specially designed vertical stiffener 27, the 
available lateral space within case 20 is maximized for greater storage 
capacity. 
Having thoroughly described the known furniture units and interlock 
mechanisms in which the non-interlock blocking elements of this invention 
may be utilized, the non-interlock blocking elements and furniture units 
incorporating the non-interlock blocking elements will now be described. 
In FIGS. 19 and 20, there is shown a non-interlock blocking element 200 in 
accordance with this invention. The non-interlock blocking element 200 is 
generally similar in size and shape to the interlock blocking element 6 
previously described. As with block element 6, non-interlock blocking 
elements 200 has an irregular polygonal side elevational shape, comprising 
a front edge 202, top and bottom edges 204 and 206, an inclined ramp edge 
208, and a rear edge 212. A pair of fingers 214 and 216 extend rearwardly 
from rear edge 212, and serve to expand the effective width of block 200, 
so as to be closely, yet slidably received within guide 7. The provision 
of fingers 214 and 216 permits the mounting of drawer suspension units 
40-42 in the slots 39 in web 44 of guide 7, without interfering with the 
vertical sliding motion of block 6. The fundamental difference between the 
non-interlock blocking elements 200 and the interlock blocking elements 
2006, is that the non-interlock blocking elements each include a recess 
220 at an upper portion thereof which allows unobstructed reciprocation of 
wedge elements 16 when a wedge element 16 is in horizontal alignment with 
the upper portion of a non-interlock blocking element 200, whereas the 
interlock blocking elements 6 do not include a recess, but instead are 
solid, i.e., configured to obstruct reciprocation of the wedge elements 16 
when the upper portion of an interlock blocking element 6 is in horizontal 
alignment with a reciprocating wedge element 16. Recess 220 may be 
described as a cut-out defined by an upwardly facing horizontal wall 222 
and a pair of connected upright walls 224 and 226 which are arranged in an 
L-shape. However, it is to be understood that the cut-out or recess 220 
could be defined by any generally upwardly facing surface 222 and any wall 
which projects upwardly therefrom to engage the bottom edge of an adjacent 
blocking element 6 or 200. For example, wall 226, or wall 224, or any 
portion or combination thereof, could be used to provide the necessary 
spacing between adjacent lower and upper blocking elements, and the 
necessary clearance to allow unobstructed reciprocation of a wedge element 
16 when the upper portion (i.e., recess 220) of a non-interlock blocking 
element is in alignment with the wedge element. However, the combination 
of connected walls 224 and 226 arranged in an L-shape has been found to 
eliminate any tendency of non-interlock blocking elements to become 
misaligned or jammed. 
In FIG. 21, there is illustrated a furniture unit 230 having a plurality of 
drawers 231, 232, 233 and 234. Each drawer includes an associated actuator 
having a wedge element 16. A plurality of non-interlock blocking elements 
200 and conventional blocking elements 6 are arranged in a vertical stack 
within a vertical guide 7 to provide a non-interlocked drawer system 
wherein any or all of the drawers may be open at the same time. In FIG. 
21, bottom drawer 234 has been opened causing the wedge element 16 
associated with the bottom drawer to engage the ramp edge 208 of the 
non-interlock blocking element 200 positioned immediately above the 
lowermost conventional blocking element 6, and reciprocate into the stack, 
thereby vertically separating the two lowest blocking elements 6 and 200. 
Separation of the lowermost blocking elements 6 and 200 causes all of the 
blocking elements disposed above the lowermost blocking element 6 to be 
shifted upwardly so that the remaining wedge element 16 associated with 
drawers 231, 232 and 233 are in horizontal alignment with recesses 220 in 
non-interlock blocking elements 200, thus allowing unobstructed 
reciprocation of the wedge elements into the recesses 220 of the 
non-interlock blocking elements, whereby any or all of the drawers 231, 
232 and 233 can be opened even though drawer 234 is already open. The 
uppermost and lowermost blocking elements of furniture unit 230 are shown 
as conventional interlock blocking elements 6 and the remaining blocking 
elements disposed between convention blocking elements 6 are shown as 
non-interlock blocking elements 200. However, it should be understood that 
only the second, third, fourth and seventh blocking elements from the top 
need be non-interlock blocking elements in order to allow the drawers of 
furniture unit 230 to be all open at the same time. The remaining blocking 
elements can be either non-interlock blocking elements 200 or conventional 
interlock blocking elements 6. 
As illustrated in FIG. 22, the non-interlock blocking elements 200 can be 
used in combination with interlock blocking elements 6 to provide a 
furniture unit 240 having a plurality of drawers 241-244, in which at 
least one of the drawers cannot be opened if any other interlocked drawer 
is open, and at least one other non-interlocked drawer which can be opened 
irrespective of whether other drawers are open, thus providing a partially 
interlocked system. For example, in FIG. 22, only the second and third 
blocking elements from the top are non-interlock blocking elements 200. 
The remaining blocking elements are standard interlock blocking elements 
6. This particular arrangement allows drawers 241 and 242 to be open 
irrespective of whether drawer 243 or drawer 244 is already open. However, 
the arrangement prevents drawers 243 and 244 from being open at the same 
time. 
A conventional interlocking furniture unit having drawers which can only be 
opened one at a time, can be converted to a non-interlocking furniture 
unit, or to a partially interlocking furniture unit by removing selected 
standard interlock blocking elements 6 and replacing them with the 
non-interlock blocking elements 200. The procedure generally involves 
removing the pedestal from any associated worksurface, removing the 
actuators 8, dumping or otherwise removing the blocking elements 6, and 
replacing the removed blocking elements with non-interlock blocking 
elements 200 to provide a non-interlocking furniture unit, or replacing 
the removed blocking elements with a combination of non-interlock blocking 
elements 200 and standard interlock blocking element 6 to provide a 
partially interlocking furniture unit. 
It will be apparent to those skilled in the art that various modifications 
to the preferred embodiment of the invention as described herein can be 
made without departing from the spirit or scope of the invention as 
defined by the appended claims.