Furniture anti-tip and lock mechanism

An improvement in an actuator of the type having a slide plate with an L-shaped slot, guide structure for movement of the slide plate in a reciprocating path between locked and unlocked positions, structure for connecting the slide plate to a locking member so that the locking member follows reciprocating movement of the slide plate, a crank for rotation about an axis and having a pin offset from the axis, and structure mounting the crank to the channel so that the crank is rotatable back and forth about its axis through a predetermined range with the pin in the slot to thereby cause the pin to engage and shift the slide plate between its locked position and its unlocked position upon the crank being rotated. With the pin at the juncture of the two slot legs, the slide bar can be shifted to its unlocked position without rotating the crank. With the pin so situated and all drawers closed, the crank is jammed and cannot be rotated. Structure is provided to permit rotation of the crank with the pin otherwise situated in its jammed position. To accomplish this, the slide plate has a deflectable tab with transverse edges bounding a portion of the L-shaped slot. The crank can be rotated in one direction to thereby move the pin from its jammed position at the bottom of the vertical slot leg against the tab, which is thereby deformed to allow passage of the pin into the horizontal slot leg. Thereafter, the crank can be rotated opposite to the one direction to normally move the slide plate and associated locking bar to its open position.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to crank-type actuators for controlling a 
translating locking bar for drawers in furniture systems and, more 
particularly, to structure for preventing jamming of the crank. 
2. Background Art 
One type of drawer locking system is disclosed in my U.S. Pat. No. 
4,609,233. That system is designed for use with a piece of furniture 
having at least two vertically stacked drawers, each of which has a ramp 
plate defining an entry slot. A vertically reciprocating locking bar has 
associated lugs and, through a keyed operator/actuator assembly, is 
selectively positioned to situate the lugs either in a closed, blocking 
position with the ramp plates, to thereby prohibit opening of the drawers, 
or an open position, wherein the lugs each align with a slot in the ramp 
plates. In this latter position of the locking bar, opening of one of the 
drawers causes the ramp plate thereon to deflect the locking bar from its 
open to its closed position, thereby prohibiting opening of the remaining 
drawer(s). This arrangement prevents opening of more than one drawer as 
might cause the piece of furniture to tip. 
The locking bar position is controlled by a keyed operator which, through a 
rotary cable, operates a crank-type actuator that is directly attached to 
and moves the locking bar. The actuator converts rotary motion of the 
cable into translatory vertical movement of the locking bar. To accomplish 
this, the actuator has a slide plate which is guided in a channel attached 
to a frame in which the drawers are slidably mounted. The slide plate has 
an L-shaped slot with intersecting horizontal and vertical legs. The 
crank, which is driven by the cable, is journalled for rotation in the 
channel about an axis and has an eccentric pin which is guided in the 
L-shaped slot. Rotation of the crank in one direction, with the pin in the 
horizontal slot leg, causes the pin to drive the slide plate upwardly into 
the locked position. Opposite rotation of the crank causes the pin to 
drive the slide plate downwardly into its unlocked position. With the 
slide plate in its unlocked position, the pin resides at the junction of 
the horizontal and vertical legs. Thereupon, withdrawal of one of the 
drawers forces the locking plate and thereby the slide plate upwardly so 
that the pin resides at the bottom of the vertical leg. Closing of the 
open drawer slides the locking bar vertically upwardly to its unlocked 
position so that any drawer can thereafter be pulled out. 
While the above system has proven to be very effective, under normal 
operating conditions, there has been one drawback. The furniture may be 
jolted, as upon being dropped during shipping or handling, and the locking 
bar as a result may shift from its open to its closed position with all of 
the drawers closed. The crank then becomes jammed with the pin residing in 
the bottom of the vertical leg. This condition is remedied by gaining 
access to the locking bar and manually shifting it to its unlocked 
position. This is an inconvenience that may also necessitate expensive 
service calls. 
SUMMARY OF THE INVENTION 
The present invention is specifically directed to overcoming the above 
problem in a novel and simple manner. 
The present invention is an improvement in an actuator of the type having a 
slide plate with an L-shaped slot, guide structure for movement of the 
slide plate in a reciprocating path between locked and unlocked positions, 
structure for connecting the plate to a locking member so that the locking 
member follows reciprocating movement of the slide plate, a crank for 
rotation about an axis and having a pin offset from the axis, and 
structure mounting the crank to the channel so that the crank is rotatable 
back and forth about its axis through a predetermined range with the pin 
in the slot to thereby cause the pin to engage and shift the slide plate 
between its locked position and its unlocked position upon the crank being 
rotated. With the pin at the juncture of the two slot legs, the slide bar 
can be shifted to its locked position without rotating the crank. With the 
pin so situated and all drawers closed, the crank is jammed and cannot be 
rotated. 
According to the invention, structure is provided to permit rotation of the 
crank with the pin otherwise situated in its jammed position. To 
accomplish this, the slide plate has a deflectable tab with transverse 
edges bounding a portion of the L-shaped slot. The crank can be rotated in 
one direction to thereby move the pin from its jammed position at the 
bottom of the vertical slot leg against the tab, which is thereby deformed 
to allow passage of the pin into the horizontal slot leg. Thereafter, the 
crank can be rotated opposite to the one direction to normally move the 
slide plate and associated locking bar to its open position. 
In a preferred form, the tab is integrally formed with the slide plate and 
is carried in deflectable, cantilever fashion. 
The tab has a wall surface facing the crank, which is preferably ramped to 
permit progressive deflection of the tab as the pin moves thereagainst 
upon rotation of the crank in the one direction from its jammed position. 
Once the pin moves past the tab into the slot, the tab reassumes its 
undeformed state and one edge thereof can be used as a drive surface 
against which the pin can act to move the slide plate from its locked 
position to its unlocked position. 
Preferably, the slide plate is molded from plastic as a single piece, to 
include the flexible tab.

DETAILED DESCRIPTION OF THE DRAWINGS 
In FIG. 1, a conventional lateral file is shown at 10 and consists of a 
cabinet 12 with internal framework that mounts vertically spaced drawers 
14, 16 for fore and aft sliding movement relative to the cabinet 12. A 
recessed pull 18 is provided on each drawer 14, 16 to facilitate 
withdrawal of the drawers 14, 16 from the closed position, in which the 
lower drawer 16 is shown in FIG. 1, to an open position, in which the 
upper drawer 14 is shown in FIG. 1 and wherein access can be gained to the 
inside of the drawer 16. 
The drawers 14, 16 are selectively secured in their closed position by a 
locking system, shown generally at 20 in FIG. 1, and consisting of a keyed 
operator 34 for rotating a cable 36, actuators 38, 40 which are operated 
by the ends of the rotary cable 36, and locking bars 42, 44, responsive to 
movement of the actuators 38, 40, for selectively locking the drawers 14, 
16. The structure of actuators 38, 40 is wherein the present invention 
resides and this structure converts rotary motion of the cable 36 into 
vertical reciprocating movement of the locking bars 42, 44, as described 
more fully below. 
The operation of locking bar 44 will now be described with respect to one 
exemplary drawer 16, with reference specifically to FIGS. 1 and 9. The 
drawer 16 has a ramp plate 46 attached to a laterally facing surface 48 on 
the drawer 16. The ramp plate 46 cooperates with a laterally projecting 
lug 50 on the locking bar 44. More specifically, the ramp plate 46 has an 
inverted V-shaped section 52 defining sloping ramp surfaces 54, 56. A 
second section 58 has an underside surface 60 that is generally parallel 
to the ramp surface 54 and spaced slightly thereabove so as to define a 
slot 62 that has a vertical dimension substantially greater than the 
diameter of the lug 50. 
With the drawer 16 in the closed position of FIG. 1, the lug 50 resides in 
front of the ramp plate 46. The locking bar 44 is movable vertically 
between a locked position, wherein the lug 50 is in front of a vertically 
extending blocking surface 64, and an unlocked position, wherein the lug 
50 is aligned vertically with the slot 62. If one attempts to withdraw the 
drawer 16 with the locking bar 44 in its locked position, the lug 50 
interferes with the blocking surface 64, thereby prohibiting opening of 
the drawer 16. With the locking bar 44 in its unlocked position, the lug 
50 aligns with the slot 62 and upon withdrawal of the drawer 16, the lug 
rides up ramp surface 54, thereby shifting the locking bar 44 in the 
process to its locked position. The drawer 16 can be freely withdrawn, 
while the drawer 14 thereabove is locked by reason of the cooperation of a 
separate lug 66 with a second ramp plate (not shown) on the side wall 68 
of drawer 14. This arrangement prohibits withdrawal of both drawers 14, 16 
as might cause the field 10 to be unbalanced and prone to being tipped. 
Locking bar 42 on the opposite side of the file 10 operates in the same 
manner as bar 44. Upon the drawer 16 being closed, the lug 50 moves 
against ramp surface 60 and is thereby deflected with bar 44 downwardly 
into its unlocked position as the door 14 realizes its closed position, 
thereby making possible opening of either drawer 14, 16. Opening of drawer 
14 locks drawer 16 in similar fashion. 
Reference is now made to FIGS. 1-8, wherein details of the inventive 
actuators 38, 40 are shown. Each actuator 38, 40 operates in the same 
manner and thus discussion herein will be limited to exemplary actuator 
38. The actuator 38 consists of a metal channel 70 having a U-shaped seat 
72 for a generally rectangular slide plate 74. The seat 72 is bounded by a 
base 76 and spaced legs 78, 80. The slide plate 74, which is preferably 
molded from plastic, has integral rails 82, 84 for guiding vertical 
movement of the slide plate 74 relative to the channel 70. The range of 
vertical movement of the slide plate 74 is limited by a lug 86 on the 
plate 74, which is guided in an oval slot 88 in the channel base 76. The 
slide plate 74 is held captive in the seat 72 by legs 78, 80, which have 
portions 90, 92, respectively, folded laterally outwardly and portions 94, 
96 doubled back on leg sections 90, 92 respectively, so that wall surfaces 
98, 100 on leg sections 94, 96 overlie the outwardly facing wall surface 
102 of of the slide plate 74. By extending fasteners (not shown) through 
bores 104 in the leg sections 90, 92 and aligned bores 106 in the leg 
sections 94, 96, and into the frame 28, the leg sections 90, 92, 94, 96 
are held in doubled back relationship so that the slide plate 74 cannot 
escape from the channel 70 with the actuator 38 assembled to the file 10. 
A wire spring 108 is held in place on the base 76 on a rib 110 struck 
directly therefrom. The spring 108 has legs 112, 114, inwardly bent in the 
shape of a V to define apexes 116, 118 spaced less than the width of the 
slot 88. The lug 86 on the slide plate 74 is movable from the locked 
position wherein the slug 86 resides in the slot above the apexes 116, 118 
to an unlocked position wherein the lug 86 resides below the apexes 116, 
118 in the slot 88. In the transition between the locked and unlocked 
positions for the slide plate 74, the lug 86 encounters the apexes 116, 
118 and thereby deflects the spring legs 112, 114 away from each other. 
The restoring force in the legs 112, 114 tends to urge the leg 86 towards 
each of the locked and unlocked positions therefor. 
The lug 86 has a through bore 120 which accepts a lug 121 on the locking 
bar 44. The locking bar 44 thereby follows vertical movement of the slide 
plate 74. 
To convert rotary motion of the cable 36 into translatory movement of the 
slide plate 74, a crank 122 is keyed to the cable end 124 to follow 
rotation thereof and is situated between the channel base 76 and the slide 
plate 74. The crank 122 has a cylindrical body 126 guided for rotation in 
a bore 128 in the channel 70, and an integral disk 130 carrying a pin 132 
that is offset from the axis of rotation of the crank 122. The pin 132 
cooperates with an L-shaped slot 134 in the slide plate 74 having a 
horizontal leg 136 and a connecting vertical leg 137. Rotation of the 
crank 122 in a counterclockwise direction in FIG. 2 bears the pin 132 
against edge 138 bounding the horizontal leg 136 and thereby draws the 
slide plate 74 into its locked position shown in FIG. 8. Rotation of the 
crank in a clockwise direction bears the pin 132 against edge 140 to 
thereby shift the slide plate 74 downwardly into its unlocked position. 
Upon the unlocked position of FIG. 5 being realized, the pin 132 resides 
at the juncture of the horizontal slot leg 136 and vertical leg 137. With 
the slide plate 74 in the unlocked position of FIG. 5 and one of the 
drawers 14, 16 opened, the locking bar 42 is forced upwardly by the ramp 
plate 46 on the opening drawer so that the slide plate 74 is carried 
thereby upwardly to the FIG. 6 position. It is also possible for the slide 
plate 74 to be moved from the FIG. 5 position to the FIG. 6 position as by 
jolting the furniture with the drawers 24, 26 both closed, as frequently 
occurs during shipping or handling. With the actuator 38 in the FIG. 6 
position and both drawers 14, 16 closed, the crank 122 is jammed i.e. 
cannot rotate, thereby making the locking system 20 inoperable. It is this 
condition that the inventive structure is intended to overcome. 
According to the invention, a deflectable tab 144 is integrally formed with 
the slide plate 74. The tab 144 has a generally rectangular configuration 
and is integrally attached at its lower end to the slide plate 74 so that 
a cantilever-type connection is made therewith. The tab 144 has a 
wedge-shaped configuration increasing in thickness progressively laterally 
from vertical edge 146, bounding the vertical slot 137 to its opposite 
free edge 148. The tab 144 has a thickened ridge 150 defining the edge 140 
bounding the horizontal slot leg 136. 
The pin 132, upon the crank 122 being rotated counterclockwise from the 
FIG. 6 position, moves past edge 146 and against ramped surface 152 facing 
the crank 122 and progressively deflects the tab 144 away from the crank 
122. Eventually, the tab 144 is deflected sufficiently away from the crank 
that the pin 132 can move past the ridge 150 into the horizontal slot leg 
137 as shown in FIG. 8. In FIG. 7, the pin 132 is shown approximately 
midway between the FIG. 6 and FIG. 8 positions. Once the FIG. 8 position 
is realized, the crank 122 can be rotated in a clockwise direction, 
thereby bearing the pin 132 against the edge 140 so as to move the locking 
bar 44 to its open position. 
It can be seen that the inventive structure obviates the need to manually 
manipulate the locking bar 42 with the actuator in the FIG. 6 position and 
both drawers closed. Thus by simply turning a key 154 for the operator 34, 
the jammed position of FIG. 6 can be overcome and the system reset for 
normal operation.