Cabinet locking system

A combined locking and anti-tilt device (1) for a cabinet, and a cabinet including such a locking and anti-tilt device, having a plurality of drawers (3) mounted so as to be slidable out of the cabinet, comprising a guideway (G), and, slidably mounted within the guideway (G), a plurality of block units (7), a part (9) of each block unit (7) projecting to a position engageable by part (5) of an adjacent drawer (3), opening of a drawer (3) causing movement of an adjacent block unit (7) in a direction towards a first end of the guideway (G), the length of the guideway (G) within which the block units (7) may slide being limited such that the extent of movement of the block units (7) is limited, and a lock mechanism comprising a locking member (11) movable between a locked position and an unlocked position, is characterized in that the locking mechanism also comprises an elongate locking element (13) extending from the first end of the guideway (G) to at least the region of the locking member (11); the locking element (13) is secured to the first block unit (15) closest to the first end of the guideway (G) but arranged for relative movement with respect to the other block units (7); and the lock element (13) includes a lock engagement member (45) arranged such that in the locked position of the locking member (11), movement of the first block (15) towards the first end of the guideway (G) causes the lock engagement member (45) of the lock element (13) to engage against the locking member (11) thus limiting movement of the first block (15).

BACKGROUND OF THE INVENTION 
The present invention relates to a device for locking a cabinet having a 
plurality of drawers, the device also serving as an anti-tilt mechanism 
for the cabinet. The invention is applicable with particular advantage to 
tall cabinets. 
In the following specification, the term "cabinet" will be used to describe 
filing cabinets and other items of furniture within which there are 
mounted drawers for access or use. They include domestic furniture, office 
cabinets, laboratory furniture, kitchen furniture and indeed any item of 
furniture having a plurality of drawers. The furniture does not need to be 
enclosed. Open racking can be fitted with units that slide out and the 
invention can be equally applied in this case. 
The term "drawer" will be used in its broadest sense to mean a thing 
capable of being drawn out, which apart from encompassing a standard 
slidable box, also includes shelves, trays and frames from which files can 
be suspended or otherwise supported. 
Cabinets often have a plurality of drawers which are fixed to the cabinet 
and when slid out remain supported by it cantilevered out beyond the base 
of the cabinet. If several of the drawers are withdrawn simultaneously and 
are heavy or carry weight, for example, those drawers full of office 
files, there is a serious risk that the cabinet may tilt forward. A number 
of devices have been proposed which act as a safety device to limit the 
number of drawers which can be withdrawn at the same time. Indeed, in some 
countries all office filing cabinets have to include such a safety device. 
One such device is described in GB Patent 2 095 322. This patent describes 
a safety device which comprises a guide extending up a wall of the cabinet 
and blocking elements for the drawers of the cabinet. The blocking 
elements can be moved along the guide to release the drawer but limited 
free length on the guide restricts the number of drawers which can be 
released simultaneously, preferably to one only. 
In the example shown in the above patent, the blocks are movable manually 
up and down the guide which can sometimes prove cumbersome. The device 
described includes no means for locking all of the drawers in a closed 
position. A number of improvements to this design have attempted to use 
the movable blocks to lock all of the drawers closed. The majority of such 
mechanisms comprise a lock mounted at the top of the cabinet with a lock 
mechanism which blocks the top of the guide to prevent upward movement of 
any of the blocks. The disadvantage of such a system is that in a tall 
cabinet the lock can at times be inaccessible. 
SUMMARY OF THE INVENTION 
According to the invention, there is provided a combined locking and 
anti-tilt device for a cabinet having a plurality of drawers mounted so as 
to be slidable out of the cabinet, comprising a guide, and, slidably 
mounted within the guide, a plurality of block units, a part of each block 
unit projecting to a position engageable by part of an adjacent, 
operatively associated drawer, opening of a drawer causing movement of an 
adjacent block unit in a direction towards a first end of the guide, the 
length of the guide within which the block units may slide being limited 
such that the extent of movement of the block units is limited, and a lock 
mechanism comprising a locking member movable between a locked position 
and an unlocked position, characterized in that the locking mechanism also 
comprises an elongate locking element extending from the first end of the 
guide to at least the region of the locking member; the locking element 
being secured to the first block unit closest to the first end of the 
guide but arranged for relative movement with respect to the other block 
units; and the lock element includes lock engagement means arranged such 
that in the locked position of the locking member, movement of the first 
block towards the first end of the guide causes the lock engagement means 
of the lock element to engage against the locking member thus limiting 
movement of the first block. 
Thus the locking member can be mounted to any point within the cabinet 
since the locking element extends from the region of the locking member to 
the end of the guide limiting movement of the end blocking unit and thus 
all of the blocking units and therefore preventing the opening, 
withdrawal, or removal of any of the drawers. 
The cabinet may be adapted to include vertical drawers such that the guide 
is horizontally aligned with the floor of the cabinet. However, typically 
the cabinet is an upright cabinet with horizontal drawers so that the 
first end of the guide is uppermost. The cabinet may not include just 
drawers, and thus the guide only has to extend in the region of the 
drawers. However, in many cases the guide extends the full length of the 
cabinet, and thus the invention is particularly advantageous when the 
cabinet is tall, since the lock can be positioned at any conventional 
height for the user. 
Preferably the locking mechanism includes a standard locking bar known in 
the art where rotation of a key in a lock causes movement in a transverse 
direction of a horizontal bar. 
Preferably the locking member is arranged such that when in its locked 
position, it can also engage the adjacent block unit for extra security. 
For example, the adjacent block may include a bore into which the locking 
member may extend when in its locked position. 
The elongate locking element has to be such that it does not impede the 
movement of the drawer. In one embodiment, an elongate rod with a series 
of projections forming the lock engagement means can be used. Here the 
locking member comprises a locking rod extending transverse to the 
elongate rod which in its locked position engages across the locking 
element such that the projection bears against the lock mechanism to 
prevent any movement. 
In an alternative and preferred embodiment, the elongate locking element 
comprises an elongate plate which passes over the block units and includes 
at least one slot into which the lock member may extend when in its locked 
position. The edge of the slot forms the lock engagement means of the 
locking element which engages against the lock member to restrict the 
movement of the locking element with respect to the lock member. 
For ease of manufacture, the plate typically includes a plurality of such 
slots spaced along its length. In this way the same design of plate may be 
used in a variety of cabinets having locking mechanisms mounted at 
different positions. The locking element does not have to prevent movement 
of the block units, but simply to restrict the movement sufficiently to 
not allow opening of a drawer. 
A cabinet typically includes on each drawer a projecting elongate member 
with a tapered nose which engages against an adjacent block unit. 
Preferably the block units adjacent to the nose of each drawer extension 
have mounted upon them a roller which is the part engageable by part of 
the drawer such that opening of a single drawer automatically moves the 
block units above that drawer in a direction towards the first end of the 
guide in a smooth movement. In their raised position, such rollers block 
the movement of any other drawer projections. Preferably the block units 
are arranged such that rollers in adjacent pairs are positioned such that 
opening of a drawer causes engagement of part of the drawer between the 
rollers of the adjacent block units. This is especially useful when the 
part of the drawer which engages the rollers is the elongate member with a 
tapered nose. 
It will be readily appreciated by one skilled in the art that there are 
many different shapes, materials and forms of block units which could be 
used in the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A first example of a combined locking and anti-tilt device 1 for an 
exemplary multi-drawer cabinet is illustrated schematically in FIGS. 1 to 
5 of the accompanying drawings. In the figures, the structure of the 
cabinet and other selected structure is not shown for reasons of clarity. 
The cabinet has a plurality of drawers 3 that are typically fabricated as 
parallelepipeds, each represented in the drawing by their respective front 
panels, mounted so as to be slidable toward and to an open or extended 
position (i.e., to the right in FIGS. 1, 3, and 4). Each drawer 3 has a 
side rail 5 mounted or secured upon its side, typically upon a side panel 
(not shown) of each drawer 3. The device 1 includes a guideway that, in 
the embodiment illustrated, is channel-shaped, upright, elongate, and 
mounted at or defined by the side structure of the cabinet. In FIGS. 1, 3, 
and 4, the guideway is represented in generic dotted-line fashion and is 
designated generally by the reference character G. The structure of those 
surfaces (unnumbered) of the cabinet side panel that form the 
channel-shaped guideway G of the illustrated embodiment is shown in more 
detail in FIG. 2. 
A plurality of block units 7 are slidably mounted within the guideway G in 
a stacked or superposed relationship as shown. As shown in FIG. 2, the 
first or uppermost block unit is designated by the reference character 15. 
Each block unit 7,15 is hollow and of U-shaped cross-section, as can be 
seen more clearly in the perspective view of FIG. 5. Displacment of a 
block unit 7 upwardly in the guideway G will also lift the block units 7 
thereabove. As explained more fully below, each block unit 7 includes a 
component or part (i.e., part 9 in FIG. 1) that normally assumes a 
position in which it can be subject to engagement by a corresponding 
component or part (i.e., part 5) of its operatively associated drawer 3. 
In the case of the structure of FIG. 1, the opening of the mid-position 
drawer 3 intermediate the upper and lower drawers in the direction of the 
arrow causes the part 5 (mounted on the drawer) to engage the part 9 of 
its adjacent, operatively associated block unit 7 and move the so-engaged 
block unit 7 in a direction towards the first end of the guideway G, in 
this case in an upwards direction as indicated by the vertically aligned 
arrows in FIGS. 1 and 2. In addition to the movement of the block unit 7 
caused by the direct engagement of the parts 5 and 9, all block units 7 
above the so-moved block unit 7 will also be lifted upwardly towards the 
first end of the guideway G. 
As explained in more detail below, the device 1 also includes a locking 
mechanism having a locking member 11 movable from a locking position, 
shown in FIG. 4, to an unlocked position, as shown in FIG. 3, and an 
elongate locking element 13 which extends from the region of the locking 
member 11 to the first end of the guideway G and which is also secured to 
the first block unit 15 closest to the first end of the guideway G but 
arranged for relative movement with respect to the other block units 7 
below the first block unit 15. 
In the locked position of the locking member 11 (FIG. 4), movement of the 
first block 15 towards the first end of the guideway G causes the base or 
lower edge 44 of a locking slot 45 of the locking element 13 to engage 
against the end of the locking member 11 to thus limit movement of the 
first block 15. 
In the exemplary embodiment of FIGS. 1-5, the part 5 is defined by the 
drawer side rail 5 which also includes a tapered nose 17 at its 
front-facing end. Each block unit 7,15 has a roller, designated 
generically by the reference character 9, mounted thereon at each end 
thereof. The rollers 9 correspond to the part 9 that is positioned or 
projects into the path of the side rail 5 of the drawer 3 as the drawer 3 
is moved toward and to its opened position. When all the drawers 3 are in 
their respective closed positions, the rollers 9 are arranged so that 
rollers 9 of adjacent block units 7 are in contact with one another when 
the block units 7 are in contact with one another. 
The opening of a drawer 3 and the consequent movement of an operatively 
associated block unit 7 is illustrated in FIG. 1. As the drawer 3 is moved 
towards and to its opened position, the drawer side rail 5 moves forward 
in the direction of the arrow until the tapered nose 17 enters the nip 
between the subjacent roller 27 and the superjacent roller 19 of two 
contiguous block units 25,26. As the tapered nose 17 of the side rail 5 
engages the roller 19, the roller 19 and its connected block unit 7 is 
displaced upwardly. Because no other drawer 3 is in the open position, 
there is enough room within the guideway G for the block units 7 above the 
extended side rail 5 to be lifted or displaced upwardly in the guideway G 
by a distance that is determined by the vertical thickness of the side 
rail 5. The co-action of the roller 19 and the tapered nose 17 facilitates 
a smooth movement of the block units 7 above the side rail 5 in the 
guideway G as the side rail 5 of the opened drawer 3 moves or lifts the 
block units 7 above the side rail 5 upwardly in the guideway G. The 
interposition of the side rail 5 of the now-opened drawer 3 between its 
operatively associated rollers 19,27 effectively blocks or bars upward 
movement of the block units 7 associated with the closed drawers 3 below 
the opened drawer 3. Accordingly, the drawers 3 below the now-opened 
drawer 3 cannot be pulled towards their open positions because the block 
units 7 cannot be moved upwardly in the guideway G; any upward movement by 
any of the block units 7 below the opened drawer 3 is blocked by the 
engagement of the roller 27 with the underside of the side rail 5 of the 
opened drawer 3. While the side rail of any closed drawer 3 below the 
opened drawer 3 can attempt to enter the nip between its operatively 
associated rollers (e.g., the side rail 21 and the rollers 28,30 in FIG. 
1), that closed drawer 3 cannot be pulled outwards since the attempted 
upward movement of the superposed block units 23,25 is blocked by the 
roller 27 bearing against the underside of the side rail 5 of the opened 
drawer 3. This arrested mobility applies to any drawer 3 mounted below the 
open drawer 3. 
The interposition of the side rail 5 of the opened drawer 3 between the 
rollers 19,27 displaces the block units 7 in the guideway G above the 
opened drawer 3 upwardly by a distance that is a function of the vertical 
thickness of the side rail 5. The dimensions of the parts are selected so 
that the nip between any two rollers above the opened drawer 3 is 
sufficiently displaced that the operatively associated side rail cannot 
enter its nip. More specifically, the side rail 29 of the drawer 3 above 
the open drawer 3 in FIG. 1 cannot be moved towards its open position 
since its tapered nose 31 will bear against and be blocked from further 
movement by a roller 33. The side rail 29 cannot enter the nip between the 
two adjacent rollers 32,33 so that no further forward movement of the 
drawer 3 toward the open position is allowed. 
The elongate locking element 13 is defined by an elongate ladder strip 35 
coupled to projecting flanges 37 that guide and confine the ladder strip 
35. As shown in FIGS. 2 and 5, the ladder strip 35 is secured to the first 
or uppermost block unit 15 through a bolt 38 (FIG. 2) or other fastener 
passing through holes 39,41 (FIG. 5) to ensure that relative movement 
between the ladder strip 35 and the first block unit 15 is not permitted. 
The ladder strip 35 lies over the front face of the block units 7 and 
includes a plurality of elongate slots 43 (FIG. 2) through which the 
various rollers may pass. When in the position shown in FIG. 1 in which a 
drawer 3 is open, the plate-like ladder strip 35 moves upwards with the 
block units 7. 
The ladder strip 35 also includes a plurality of locking slots 45, only one 
of which is used as shown in FIGS. 3 and 4. The locking member 11 is 
coupled to a locking mechanism, such as a key-operated lock (not shown) 
which ensures that, in its locked position, the horizontally aligned, 
bar-like locking member 11 moves such that its end 47 enters into and 
engages a locking slot 45. By effecting this relative movement between the 
locking member 11 and the elongate member 13, the ladder strip 35 is 
effectively locked or secured against movement. This means that movement 
of the first block unit 15 is prevented since the lower edge 44 of the 
locking slot 45 will bear against the end of the locking member 11. Thus 
and as explained above, all of the block units 7 beneath the now-locked 
first block 15 are also locked in position. This effectively ensures that 
none of the drawers 3 can be opened. As shown in the detail of FIG. 2, the 
block units 7,15 can include apertures 50 in general registration with the 
locking slot 45 which are also intended to receive the end 47 of the 
locking member 11. 
In an alternative embodiment illustrated in FIG. 6, each of the block units 
51 is of more solid construction and has mounted upon it two rollers 
53,55. The mechanism for opening and closing the drawers however is 
similar to that described in connection with FIGS. 1 to 5 in that the 
tapered nose 57 of a drawer side rail 59 enters the nip between and 
engages two adjacent rollers 53,55 as a drawer 3 is moved toward and to 
its open position (to the left in FIG. 6). Each of the block units 51 
includes a central bore 61 into which may be engaged a locking bar 63 
which prevents movement of the engaged block unit 51 and any block units 
51 therebelow, but still allows freedom of movement of any block units 51 
above the locked-in-place block unit 51. An elongate locking element 65 is 
illustrated schematically in a dotted-line illustration. The top end 67 of 
the locking element 65 is affixed to the uppermost block unit 51 and 
projections 69 are positioned such that, on engagement of the locking bar 
63, upward movement of the uppermost block unit 51 would cause the 
projection 69 to bear against the locking bar 63 so that the upward 
movement is limited. 
It will be appreciated that the invention is applicable to systems where 
the guideway G is arranged horizontally and the blocks move horizontally. 
Such a horizontally organized system would require means to restore or 
return the block units to their original positions upon closure of a 
drawer. 
As will be apparent to those skilled in the art, various changes and 
modifications may be made to the illustrated cabinet locking device of the 
present invention without departing from the spirit and scope of the 
invention as determined in the appended claims and their legal equivalent.