Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
This invention relates to knock-down storage rack and more particularly to a
locking
connector for preventing the separation of the uprights from the shelves of a
knock-down
storage rack after they are interconnected.
Knock-down storage racks are well known and are in common use for storage in
such
places as warehouses, garages and basements. The racks are composed of columns
or
uprights and horizontal shelf-supporting beams. Usually the uprights have a
number of
spaced apart slots and the beams have teeth or studs. The beams are connected
to the uprights
by insertion of the teeth or studs into the slots of the uprights. The beams
can be set at a
desired level by appropriate choice of slots in which the teeth or studs are
inserted.
Once the teeth or studs of the shelf-supporting beams are in,the slots, the
beams will
remain secure so long as there is a downward force on the beams. Thus if the
beams are
loaded, the storage rack will remain intact. If however an upward force is
applied to the
beams, the beams will separate from the uprights and the storage rack will
come apart. It may
also come apart when the beams are not loaded and a sideways force is applied
to the rack.
Fork lift trucks are commonly used to load and unload heavy items on storage
racks.
Such items are usually placed on pallets so that there is space beneath them
for the prongs
of the fork lift. In unloading an item from the shelf-supporting beam, the
operator of the truck
may accidentally insert the prongs beneath the beam where the item is located
and not into
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the pallet. When the operator lifts the prongs, the beam will rise with the
load and the storage
rack may come apart. When this happens, heavy items on the beams may fall onto
the
operator of the truck or any bystanders in the vicinity of the rack with
resulting injury or, in
extreme instances, death. Items on the rack may be also damaged in the fall.
It is known to provide locks for preventing the shelves from separating from
the
uprights once the storage rack is assembled. Examples of such locks are
described in U.S.
patents no. 5,938,367 and no. 6,155,441. Such locks frequently have a plunger
which when
activated, is within the same slot as a tooth or stud of a shelf where the
plunger prevents the
tooth or stud from withdrawing from the slot in the upright. The plunger is
deactivated by
withdrawing it from the slot so that the shelf may be separated from the
upright.
A shortcoming of many such locks is that they are susceptible to accidental
deactivation. Some, for example, become deactivated when they are rotated one
quarter or
one half turn. When such locks are accidentally struck, they may turn
incrementally. If they
are struck repeatedly, eventually they will rotate sufficiently to deactivate.
Other locks are
spring-loaded and activate and deactivate when they are pressed. They too can
deactivate
when accidentally struck.
Another shortcoming of such locks is that are susceptible to breakage if they
are
accidentally struck. In some cases, for example, the locks are held in
position by tabs or ears
which are riveted or welded in position. If such locks are accidentally struck
by the prongs
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of a fork lift truck, the tabs may break off.
The locking connector of the subject invention resists deactivation when
accidentally
struck. The locking connector can only be opened or deactivated by means of a
relatively
large force. Preferably a tool such as a screw driver is required to apply
such a force and in
that case, the locking connector will not open unless an operator has such a
tool and he uses
it deliberately to open the connector. Accordingly a storage rack equipped
with such a
locking connector will not come apart should it be accidentally struck or
should its shelf-
supporting beams be accidentally raised when items are being unloaded from
them.
The locking connector of the invention also resists breakage when struck. The
locking
connector, according to one embodiment, is contained within a housing which
protects the
locking connector. Hard blows may damage the housing but are unlikely to
damage the lock.
SUMMARY OF THE INVENTION
Briefly, the locking connector ofmy invention interconnects a shelf-supporting
beam
and an upright of a knock-down storage rack. The locking connector is fixed to
the beam and
is removably connected to the upright. The locking connector has a plunger
which is slidable
between locking and unlocking positions. The plunger has a shank in which a
recess is
formed and which, when in the locking position, is within one of a number of
openings
formed in the upright with resulting locking of the upright to the connector.
When the
plunger is in the unlocking position, the shank is outside the opening thus
allowing the
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upright to be separated from the connector. The lock includes a retainer which
is biased by
resilient means into the recess when the plunger is in the locking position
and prevents the
plunger from moving from the locking position unless a force, opposed to the
bias of the
retainer, is applied to the plunger to cause the retainer to withdraw from the
recess.
A second embodiment of the locking connector has an outer wall having
oppositely
facing inner and outer surfaces and an aperture which is defined by an edge of
the front wall.
A casing extends outwardly from the front wall and has an inner end in which a
groove is
formed for receipt of the edge such that the margin of the front wall adjacent
to the edge are
within the groove. A plunger is confined within the casing and is slidable
between a locking
position in which the plunger extends though the aperture and one of the
openings in the
upright with resulting locking of the locking connector to the upright and an
unlocking
position in which the plunger is outside the opening. The locking connector
has resilient
means which biases the plunger into the locking position and which opposes
movement of
the plunger from the locking position unless a force, opposed to the bias of
the resilient
means, is applied to the plunger to cause the plunger to withdraw from the
opening
DESCRIPTION OF THE DRAWINGS
Three embodiments of the locking connector of the invention are described with
reference to the accompanying drawings in which:
Figure 1 is a perspective view of the locking connector, a shelf-supporting
beam and
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an upright of a knock-down storage rack;
Figure 2 is a perspective view of the locking connector and an upright;
Figure 3 is a perspective view of the locking connector from the side opposite
that
shown in Figures 1 and 2;
Figure 4 is a perspective view of the locking connector and upright from the
side
opposite that shown in Figure 2;
Figure 5 is a perspective view, partly in section and in enlarged scale, of
the plunger
of the locking connector in a deactivated or unlocked position;
Figure 6 is another perspective view of the plunger in a locked position;
Figures 7 and 8 are perspective views of portions of the plunger. In Figure 7
the
plunger is in the locked position and in Figure 8 the plunger is in the
unlocked position.
Figure 9 is a perspective view, partly in section, of the plunger of a second
embodiment of the locking connector in a activated or locked position;
Figure 10 is another perspective view of the plunger illustrated in Figure 9
in an
unlocked or deactivated position;
Figure 11 is a perspective view of the locking connector of Figure 9 in
conjunction
with an upright;
Figure 12 is a perspective view of the locking connector of Figure 9 in
conjunction
with an upright and a beam;
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Figure 13 is a perspective view of the locking connector of Figure 9 and an
upright from
the rear;
Figure 14 is a perspective view of the plunger of a third embodiment of the
locking
connector, in a locked position; and
Figure 15 is a perspective view of the plunger of Figure 14 in an unlocked
position.
Like reference characters refer to like parts throughout the description of
the drawings.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
With reference to Figure 1, the locking connector of the invention, generally
10, is shown
in conjunction with an upright 12 of a conventional knock-down storage rack,
generally 14. The
locking connector serves to connect the upright to a shelf-supporting beam 16.
The locking
connector is permanently connected to the beam by such means as welding while
the locking
connector is removably connected to the upright in the manner described below.
With reference to Figures 2 and 3, the locking connector has inner and outer
side walls
17, 18 spaced apart by a front wall 20. The outer side wall has an opening 22
for receipt of a bolt
for interconnecting the locking connector to the upright. The bolt adds
rigidity to the storage
rack, when assembled, should that be desirable.
The inner side wall of the locking connector has a number of teeth or hooks 25
spaced
along its inside edge. The inner wall is received in a groove or channel 26
that divides
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the upright into two parts, one for connection to beam 16 and the other to a
like beam that
extends outwardly from the opposite side of the upright.
The locking connector has a number of generally rectangular openings 28 on its
front or outer wall 20. Above each opening is a smaller aperture 29, the
uppermost 29a
of which receives plunger 30. On the inside surface of the front wall, tabs 32
extend hor-
izontally outwardly at 32a from the upper edge of each opening 28, then
downwardly.
With reference to Figures 2 and 4, vertically spaced openings 34 are formed in
the
front faces 36 of the upright. Openings 38 are also formed in the channel for
receipt of teeth
25 of the locating connector.
With reference to Figures 5 and 6, plunger 30 has a head 42 at the outer end
of a
shank 43. The shank is slidingly mounted in a bushing 44 which consists of
inner and outer
concentric cylinders 46, 48. The outer cylinder has an outer wall which is
stepped cross-
axially inward at 48a. The stepped-in area 48b is received in aperture 29a of
the locking
connector and is secured therein by means of a pressure fit. The two cylinders
which make
up the bushing are held together by a pressure fit and remain together by
friction.
With reference to Figures 7 and 8, the inner cylinder has an annular cavity 50
in
which a rod or retainer 52 is received. The rod is confined in the cavity by
means of a raised
portion 54 of the inner cylinder. The upper surface 56 of the raised portion
contacts the cross-
axially extending lower surface 58 of the outer cylinder 48 so that the rod is
confined within
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the cavity. The rod is normally straight but resiliently deforms to a curved
shape when it is
within the groove.
With reference again to Figure 5, the outer wall of shank 43 has a pair of
spaced annular
outer and inner recesses or grooves 60, 62. The rod is received in inner
groove 62 when the
plunger is in the unlocking position as illustrated in Figure 5 and in outer
groove 60 when the
plunger is in the locking position as illustrated in Figure 6.
With reference to Figure 6, the plunger is in the locking position when the
shank
projects through opening 34 of the upright and its head contacts the outer
wall 44a of the
bushing. Rod 52 is within outer groove 60 and prevents the plunger from being
withdrawn
from the bushing in the direction of arrow 65 unless an outward force is
applied to the head
of the plunger. The inner side wall or cross-axially extending wall 60a of the
groove is
bevelled or chamfered as illustrated in Figure 5 so that outward force applied
to the head will
cause the rod to rise in the groove and withdraw from it. When it does so, the
plunger can
be drawn outwardly in the direction of the arrow.
When the plunger reaches the point illustrated in Figure 5, the rod will enter
inner
groove 62. That groove serves as a stop point and prevents further outward
movement of the
plunger. That is because the groove has an inner side wall or cross-axially
extending wall 62a
which is flat and unbevelled as illustrated in Figure 6. That wall prevents
the rod from
withdrawing from the groove when further outward force is applied to the
plunger.
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The side wall 62b of the inner groove opposite that of wall 62a is bevelled so
that if
the plunger is pushed inward from the position illustrated in Figure 5, the
rod will withdraw
from the groove and allow the plunger to slide to the locking position
illustrated in Figure
6.
The means by which the plunger serves to lock the connector to the upright is
best
seen in Figure 4. In that Figure, tabs 32 and teeth 25 are in openings 34 and
38 respectively
of the upright and serve to prevent the connector from separating from the
upright unless the
connector is lifted. Lifting is resisted since there is little if any space
between the shank of
the plunger and the upper edge of opening 34. Figures 4 and 6 illustrate this.
Only when the
plunger is removed from opening 34 can the locking connector be lifted and
separated from
the upright.
The rod is composed of resilient material such as spring steel so that it will
yield to
allow the rod to withdraw from the grooves. However the material of the rod is
chosen such
that the rod does not yield in this manner unless a comparatively large
outward force is
applied to the plunger.
Preferably, the force sufficient for this purpose can only be applied by means
of a
prying tool such as a screw driver. With reference to Figure 6, to apply such
force, the prying
edge of the tool must be inserted in the space 70 between the head and the
facing wall of the
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outer cylinder of the bushing. The tool must be moved back and forth to pry
the head
outward. The rod should preferably be sufficiently stiff or inflexible that it
does not allow
the head to be removed by means of a force that is normally possible by a
human hand
unaided by a tool. As a result, the plunger cannot be accidentally removed.
Accordingly, the plunger can only be removed by means of a screw driver or
other
prying tool intentionally inserted in space 70 and deliberately moved in a way
that will cause
the plunger to move outward.
With reference to Figure 9, plunger 74 has a head or cap 76 at the outer end
of a
shank 78. The shank is slidingly mounted in a hollow cylindrical casing 80.
The casing has an outer end defined by a cross-axially inwardly extending neck
82
and an inner end in which a groove 84 is formed. The groove is defined by two
annular
ridges 85, 86 on the outer wall of the casing. The innermost ridge 86 is
formed by bending
the inner end of the casing wall outward. until it is within an annular recess
88 in the front
wall 92 of the locking connector.
Recess 88 is provided so that the innermost surface of the casing is flush
with the
inner surface of the front wall of the casing. The connector will accordingly
contact the
upright squarely and will not wobble when it is attached to the upright.
As illustrated in Figure 9, groove 84 receives the margin 92a of the front
wall
adjacent to the aperture. The two ridges of the casing press firmly against
the margin so that
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the casing is securely connected to the front wall.
Shank 78 is stepped cross-axially outward approximately midway of its ends by
an
annular wall 96. Resilient means in the form of a coil spring 98 is received
in space 100
defined, at its ends, by neck 82 and by wall 96, and by the inner wall of the
casing and the
outer wall of the shank. The spring biases the plunger to the activated or
locked position
illustrated in Figure 9. In that position the inner end of the shank projects
through the
opening in the upright.
With reference to Figure 10, the plunger is de-activated or unlocked by
grasping head
76 and pulling it outward to the position illustrated in that Figure. The
inner end of the shank
is then fully withdrawn from the opening in the upright.
In some cases, it may not be desirable that the plunger be unlocked or
deactivated
simply by pulling its head outward. In such cases, the coil spring should be
sufficiently strong
to resist such pulling but not strong enough to resist prying. To facilitate
prying, the head has
a somewhat hollow hemispheric cross-section. The central portion 76a is
generally flat while
the peripheral portion 76b extends radially outward and toward the locking
connector. As
illustrated in Figure 9, there is no space between the central portion 76a of
the head and the
neck since the two are in contact with each other. There is however a space
between the
peripheral portion and the casing. That space is sufficient large to receive a
prying instrument
such as a screw driver so that the plunger can be pried open by this means.
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With reference to Figures 11 to13, a rivet 112 is beneath the plunger and
extends
through an opening in the locking connector and terminates at a cylindrical
head 114 located
on the inner surface of the locking connector as illustrated in Figure 13. The
rivet head serves
the same purpose as tab 32 illustrated in Figure 3.
The second embodiment of the locking connector has a number of significant
advantages: first the plunger can be retracted by hand and can, as a result,
be connected and
disconnected quickly. This is to be contrasted with plungers where special
tools or a
significant force is required to open them. Secondly the plunger can be
constructed of
materials of sufficient strength that it will not break when struck violently.
When the plunger
is struck by a fork lift truck, for example, the plunger will not open.
With reference to Figures 14 and 15, plunger 120 has the same construction as
the
plunger illustrated in Figures 9 and 10 except that it lacks a head. Instead,
a hollow
cylindrical guard 122 surrounds casing 124 when the plunger is in the locking
position
illustrated in Figure 14. The guard serves both as a handle for opening and
closing the
plunger and as protection for the plunger should it be accidentally struck.
The guard is concentrically disposed about the casing and the plunger. The
outer end
of the guard is received in an annular groove 126 in the plunger. The inner
end of the guard
contacts ridge 128 of the casing.
Figure 15 illustrates the plunger when it is in an unlocking position. In that
position
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the lower portion of the casing is exposed and not protected by the guard.
However the casing
should not require protection at that time because it is only unlocked when it
is being manually
opened. Accidental impact of the plunger is unlikely to occur a such time.
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