Note: Descriptions are shown in the official language in which they were submitted.
CA 02498865 2005-02-28
5'TRtX.'T~3R"E MR PUSH BACK PALLET STORAGE SYSTEMS
-1-
The present invention relates to a structure for
push back pallet storage systems which novel manufacturing,
conformation and design features fulfil the purpose to
which it has been specifically conceived, with a maximum
safety and effectiveness and providing many advantages as
it will be detailed in the present specification.
More particularly, the invention refers to an
improvement in depth pallet storage systems referred to as
push back that allow a fast operation speed and high
storage density. In these storage systems, pallets are
stored placed.on a slightly inclined plane so that the last
one that was introduced is the first one that is extracted.
Several levels may be arranged in height with which a
simple selectivity of the stock is obtained in contrast
with block stacking conventional procedures.
In conventional push back systems, a forklift
truck places the pallet loads in the system on a platform
that may be moved lengthwise so that each platform is
pushed back by the next loadedpallet. For unloading, each
platform slips forward in the rack as the previous pallet
is extracted with the help of the slightly inclined plane
on which said platforms are arranged. Loading and unloading
of the pallets is carried out through a central passageway
wherein the forklift truck moves.
The movable platforms in the conventional push
back systems basically comprise a metallic frame provided
with wheels or rollers. One of these structures is
described in the US patent 5,312,004 which refers to a
slidable platform for a push back system. The platform
comprises two rails acting as a guide for rollers fitted in
frames running above the rails.
Although this structure is effective, it suffers
from several disadvantages such as a great constructive
complexity causing, among other things, that the necessary
inclination for unloading the pallets by gravity must be
CA 02498865 2008-10-16
2
high.
The main object of the present invention is to provide an alternative to
this type of pallet storage systems through which it is possible to overcome
the
above disadvantages further providing many advantages regarding them, as it
will
be detailed hereinafter.
According to the present invention, there is provided a structure for
push back pallet storage systems comprising a set of side members and cross
members arranged in several levels inside of which pallets may be fed in depth
resting on carriages that can be moved lengthways relative to longitudinal
beams
fixed to said structure, in that said movable carriages are formed from a
substantially inverted U-shaped section member provided with wings inside of
which respective rotatable bearings are fitted, said section member being
adapted
to be arranged surrounding said longitudinal beams outwardly so that the
bearings
run inwardly along the lower portion of a flange of said beams, characterized
in that
each movable carriage is provided, at the end thereof, with a rotatable pawl
having
a first end extending upward and which may protrude from the upper portion of
the
carriage through an opening formed therein and a second, opposed end extending
downward and which may be received into an opening formed in the fixed rail,
and
a shaft being provided transversely fitted inside the movable carriage passing
through said pawl at a point of said first end nearer than said second end of
the
pawl, so that if no pallet is present on a pair of movable carriages, the
second end
of the pawl remains inserted into said opening of the fixed rail by the own
weight of
the pawl preventing the carriage from being moved relative to the
corresponding
rail, the carriage being released when a pallet rests on the first end of the
pawl
protruding from said upper portion of the carriage through the opening
thereof.
Preferably, this structure has the feature that the rails are formed by
an open, substantially inverted U-shaped section member. Respective bearings
are
rotatably fitted at the lower portion of the wings of the section member. It
should be
kept especially in mind the fact that the bearings are fitted on aligned
shafts housed
CA 02498865 2008-10-16
3
into shaped portions projecting inwardly of each wing of the U-shaped section
member of the rails, so that said bearings do not project from the entire
width of
said section. This advantageously allows reducing the distance between the
rails.
. Preferably, the open cross section of said movable carriages is
properly adapted to be arranged for surrounding the longitudinal beams. These
longitudinal beams have a substantially I-shaped cross section, so that said
bearings run through the inside of the flange of said beams.
Preferably, with a structure such as that herein described a very
reliable and effective pallet storage means is achieved by means of the so
called
push back systems. The fact of providing movable carriages obtained from a
section member having a configuration "embracing" the beam involves an
assurance that the rail will not work their way out of its path during. the
forklift truck
operation. Furthermore, since two rollers are provided for each rail, guiding
is more
accurate as there is less freedom of lateral movement.
Preferably, the beams of the structure are formed by an open section
member obtained from a single metal sheet bent for forming said section
member.
The construction of the structure of the invention is extraordinarily
simplified by
making this type of section members, thus reducing the costs of the assembly.
Preferably, in one embodiment, three pairs of carriages that can be
moved relative to the corresponding fixed longitudinal beams are provided.
Each
pair of rails is provided in such a way that the rail of each pair is arranged
at a
different level in height regarding the adjoining one, the pair of rails in
the outer
portion of the structure having the shortest height and the pair of rails in
the inner
portion thereof having the highest height. According to this embodiment, a
structure
having this *configuration allows a pallet to be stored for each pair of rails
plus an
additional pallet (if any) that would be placed in the last place resting on
the rails.
Preferably, the invention further provides a mechanism that
guarantees the locking of the assembly when there is no load on the movable
carriages. In this way, each movable carriage is provided, at the end thereof,
with a
CA 02498865 2008-10-16
4
rotatable pawl having a first end projecting upward and which may protrude
from
the upper portion of the carriage through an opening formed therein. The
rotatable
pawl has a second, opposed end projecting downward and which may be housed
into an opening formed in the corresponding fixed rail. There is also provided
a
transverse shaft inside the movable carriage passing through said rotatable
pawl.
The transverse shaft passes through the pawl at a point in the first end
thereof
nearer than the second end thereof.
Preferably, according to the previously defined structure of the pawl,
when no pallet is present on a pair of movable carriages, the second end of
the
pawl remains inserted into the opening of the fixed rail due to the own weight
of the
pawl. Displacement of the carriage regarding the corresponding rail is
therefore
prevented, locking the assembly when there. is no load.
Preferably, when a pallet rests on the pair of carriages, the pallet is
arranged on the first end of the pawl that projects from of the upper portion
of the
carriage through said opening thereof, pushing out the second end of the pawl
from
the opening of the fixed rail and thus releasing the assembly so that the
carriages
may be moved.
Preferably, the pawl in each carriage is provided at the initial end
thereof through which the pallets are fed into the structure.
Due to the provision of the rotatable pawl mechanism the pairs of
movable carriages are only moved when necessary and in a synchronized way, two
by two. A maximum optimisation in the load and unload process in the storage
system is achieved since the proper positioning of the carriages is thus
always
guaranteed.
The features and the advantages of the structure for push back pallet
storage systems of the present invention will be apparent from the detailed
description of a preferred embodiment thereof which will be given hereinafter
by
way of a non limitative example, with reference to the drawings that are
herein
accompanied.
CA 02498865 2008-10-16
4a
In the drawings:
Fig. 1 is a front elevational view of one level of the structure of the
invention;
Fig. 2 is a side elevational view of three structures as that shown in
Fig. 1, forming a push back load unit for four pallets;
Fig. 3 is a fully enlarged View of one of the rails of the structure of the
invention as seen from an
CA 02498865 2005-02-28
= ~
4
-5-
elevational view;
Fig. 4 is a fragmentary ei.ev-ational view of a
movable carriage fitted on the corresponding fixed rail,
said movable carriage being provided with a rotatable pawl
in a locked position;
Fig. 5 is _a front elevational view of the movable
carriage and the fixed rail in Fig. 4 in which the pawl is
in the locked position;
Fig. 6 is a fragmentary elevational view of a
movable carriage fitted on the corresponding fixed rail,
showing the rotatable pawl in the unlocked position;
Fig. 7 is aÃront elevational view of the movable
carriage and the fixed rail in Fig. 6 in which the pawl is
in the unlocked position;
Fig. 8 is a fragmentary plan view showing a
movable carriage fitted on the respective fixed rail of the
structure of each of the three pairs forming the assembly
of the embodiment shown; and
Fig. 9 is a front elevational view of one level
of the structure of the invention:
A detailed list of the various parts cited in
the present invention is given below.
(1) side members ;
(2) cross members;
(3) upri.ght posts;
(4, 5, 6) pallets;
(7, 8, 9) movable cartiages;
(10) direction of movement of the pallets;
(11) longitudinal beams fixed to the structure;
(12, 13) wings of the section of the rails;
(14', 15) shaped portions of the section of the
rails;
(16, 17) aligned transverse shafts;
(18, 19) washers;
(20, 21) bearings;
CA 02498865 2005-02-28
=
_ 6 ..
(22) lower portion of the web of the longitudinal
beam septi.on;
(23, 24, 25) raoks of the structure;
(26) load and unload area;
(100) initial end of the carriage;
(101) initial side member;
(102) intezmediate side members;
(103) diagonal members;
(200) pawl;
(201) first end of tho pawl;
(202) second end of the pawl;
(203) transverse shaft of the pawl;
(204) upper portion of the carriage;
(205) opening of the upper portion of the
carriage;
(206) head of the fixed r-ail; and
(207) opening in the head Qf the fixed rail.
The invention shown by way of an example in the
figures of the drawings that are herein attached in the
present specification is intended to be used to the variant
of the known compact palletisation referred to as push
back. The structure comprises a set of side members (1),
cross members (2) and upright posts (3).
In the figures only one load level has been
depicted defined by the plane of the cross members (2) but
it will be understood that there may exist as many levels
as required by the storage.
The pallets (4, 5, 6) are fed in depth resting on
corresponding pairs of movable carriages (7, 8, 9) as shown
in the elevational view in fig. 1. The pairs of movable
carriages (7, 8, 9) may be moved in the load and unload
direction as shown by the arrow (10) in Fig. 2 relative to
longitudinal beams =(11) fixedly fitted in the structure and
which may be seen in Fig. 1. The longitudinal beams (11)
rest by their own weight on the cross members (2) of the
CA 02498865 2008-10-16
-7-
structure and their ends are fixed thereto by means of
screws or any appropriate means.
As it can be seen from the view in Fig. 2, the
pairs of movable carriages (7, 8, 9) are provided in such a
way that they are slightly inclined lengthwise (of the
order of 10) for promoting unloading operations with a
forklift truck.
The movable carriages (7, 8, 9) are formed from a
open, substantially inverted U-shaped section member. Each
of the wings (12, 13) of the section member has a shaped
portion (14, 15) projecting inwardly of the U-shaped
section member. A transverse shaft (16, 17) is provided in
each shaped portion (14, 15) . Each shaft (16, 17) holds, by
means of washers (18, 19) fitted therein, respective
15. bearings (20, 21) which may be rotated freely during the
rail displacement (7, 8, 9) . Therefore, said bearings (20,
21) rest on the lower portion (22) of the web of the beam
section (11) . In said Fig. 3, it may be appreciated how a
washer (18, 19) is provided inside the section member and
another one in the outer portion thereof to retain the
bearing (20, 21) axially. The assembly of the bearings (20,
21) is such that these and the corresponding shaft (16, 17)
do not protrude from the entire width of the section member
of the rail (7, 8, 9) due to the shaped portions (14, 15),
and therefore the distance between the rails (7, 8, 9) is
notably decreased. It should be pointed out that, although
in the embodiment of the figures axialretention means of
the bearings comprising washers (18, 19) fitted in the
shafts (16, 17) have been used, other alternative means
such as threaded shaft and nut by the outer portion would
be also possible.
The open section member of the rails (7, 8, 9)
surrounds the longitudinal beam outwardly (11) of the
structure and therefore a perfect guiding of the assembly
is achieved as well as a remarkable movement accuracy. This
CA 02498865 2005-02-28
-8~
is achieved by folding said section member until conferring
it a substantially I-shaped section member, as it may be
seen from Fig. 3.
Side members (1), cross members (2) and upright
posts (3) of the structure of the push back system of the
present invention define sets of racks (23, 24, 25) forming
inner load passageways with several levels, according to
the necessities and the height of the premises. In each
level of the structure a product reference may be provided
as they are each independent since it is not necessary to
drive the f orkl i f t truck into the passageways.
The forklift trucks run along the approach
passageway perpendicular to the load passageways (not
shown). In order to be positioned, the forklift trucks are
guided toward the passageway and to the given height
required by the product in the pallet (4, 5, 6) to be
placed at every time.
In the embodiment shown in the figures, the
pallet (4) rests on the pair of rails (9) whereas, in a
similar way, the second pallet (5) rests on the
intermediate pair of rails (8) and the third pallet (6) do
it on the pair of rails (7). A fourth pallet could be
placed resting on the rails of the structure.
The longitudinal beams (11) provided on the cross
members (2) of the structure are separated according to the
width required by each pallet (4, 5, 6) for ,achieving a
stable support. The length of each rail (7, 8, 9) running
along the corresponding beam (11) is the same as the depth
of the pallet (4, 5, 6).
:.Along each rail (7, 8, 9) there are provided as
many bearings (20, 21) as necessary, generally one at each
side in the two ends of each rail (7, 8, 9) If more
bearings ,(20, 21) are requir:ed depending on the load to be
supported, more bearings may be provided, these being
perfectly guided in their path.
CA 02498865 2005-02-28
-9-
With a structure as the one herein described it
is not necessary the forklift truck to be driven inside the
passageway as it is always placed at the beginning of the
passageway above its corresponding level.
In use, the operator feeds the first pallet (6)
on the pair of rails (9) as it is at a level slightly
higher than the next one, as it can be seen from Fig. 1.
The pallet (6) only rests on said pair of rails (9). Once
the pallet (6) has been placed, the operator places the
second pallet (5) displacing with this the first pallet (6)
inward of the structure in the direction of the arrow (10)
in Fig. 2 of the drawings. The pallet (6) is moved sl ight ly
raised so that it does not touch the parts of the structure
due to the level of the rails (9). When the first pallet
(6) hasbeen travelled a distance equal to the space that
it takes up [which is occupied by the second pallet (5)),
it is lowered until resting on the immed%ately shorter
height rails (8). The third pallet (4) is moved and it is
positioned in the same way as the second pallet (5) and
2.0 since the first pallet (6) and. the second pallet (5) have
been moved inward of the structure, the third pallet (4) is
lowered and rests on the pair of shorter height rails (7).
As it has been previously noted, a fourth pallet (not
shown) may be provided resting on all of the rails (7, 8,
9).
To extract the three pallets (4, 5, 6) shown plus
the fourth pallet of the structure, not shown, the operator
first extracts the last pallet which was fed, the three
remaining pallets (4, 5, 6) being inside the passageway,
returning back to the load and unload area (26) tnoving
above the rails (7, 8, 9) due to the longitudinal
inclination, thereof that makes them to be returned back to
said load and unload area (26) of the pallets.
The movable carriages (7, 8, 9) are always braked
since the cross member (2) provi+ded at the beginning of the
CA 02498865 . 2005-02-28
-10-
passageway acts as a etop member. When removing the second
pallet (4) the process is repeated by lowering other two
pallets (5, 6) and so forth. In the loading operation, the
movement of the pallets is carried out by pushing inward of
the passageway and upwards, while in the unloading
operation this is performed outward of the passageway and
downwards slipping the pallets by gravity.
A further embodiment of the invention is now
disclosed with reference to Figs. 4 to 9. In this
embodiment, the push back cc-mpact palletisation system
comprises the already, ddisclosed structure, formed by a
frame including upright posts or props (3), an initial side
member (101) and intermediate side members (102), as shown
in Fig. 9, The frame of the structure is further provided
with diagonal rtnembers (103).
The loaded pallets (4, 5, 6) are fe:d in depth
supported on pairs of movable carriages (7). The movable
carriages (7) may be moved in the loading and unloading
direction relative to the longitudinal rails (11) fixedly
fitted in the structure. The longitudinal rails (11) rest
by their own weight on the side members (101, 102) of the
structure and their ends are fixed thereto by means of
screws or any appropriate means.
As it can be seen from the view in Fig. 9, the
rails. (11) have a small longitudinal inclination (of the
order of 4%) for promoting unloading operations with the
forklift truck.
Each of the movable carriages (7) of the
structure has, in the initial end (100) therecif, that is,
in the end corresponding to the load and unload area, a
rotatable pawl (200) . Said rotatable pawl (20Q) is a flat
metal piece having a first end (201) extending upwards and
a second end (202) extending downwards, as it can be seen
from Figs. 4 and 5 of the drawings attached iri the present
specification.
CA 02498865 2005-02-28
-11-
The rotatable pawl (200) is rotatably pivoted by
means of a transverse shaft (203) placed inside the movable
carriage (7), as shown in Figs. 6 and 7.
In the upper portion (204) of the movable
carriage (7) where the load pallet (4, 5, 6) rests an
opening (205) is formed wherein said first end (201) of the
rotatable pawl (200) projects.
In the head (206) of the fixed rail (11) an
opening (207) is provided for receiving the second end
(202) of the rotatable pawl (200).
As it can be seen from Figs. 4 and 7, the
transverse shaft (203) passes through the pawl (200) at a
point of the first end (201) nearer than the second end
(202) of the pawl (200). Therefore, when no pallet (4, 5,
6) is on the upper part (204) of a pair of movable
carriages (7), the locked position shown in Figs. 4 and 5
occurs. In this locked position, the movable carriage (7)
can not be moved relative to the fixed rail (11) as the
second end (202) of the rotatable pawl (200) remains
inserted into the opening (207) of the head (207) of the
fixed rail (11) due to the own weight of that part of the
pawl (200).
When a pallet (4, 5, 6) is placed on the. upper
portion (204) of a pair of carriages (7), the lower portion
of the pallet (4, 5, 6) rests on said first end (201) of
the pawl (200) that projected therefrom through the opening
(205) . As the pallet (4, 5, 6) rests on the first end (201)
of the pawl (200) rotation thereof around the shaft (203)
takes place as well as the subsequent releasing of the
second end (202) of the opening (207) of the rail (11) , so
that the carriage (7) may be already.moved freely relative
to the rail (11).
With this pawl mechanism unwanted advance of the
carriages (7) is avoided, thua assuring the locking of the
assembly when no load is present on said movable carriages
CA 02498865 2005-02-28
-12-
(7).
Therefore, it is started from an unloaded, locked
position as shown in Fig. 4 in which the operator may load
a first pallet (6) on a pair of carriages (7) located at a
slightly upper level than the next one. The pallet (6),
resting only on a pair of carriages (7), is placed on.said
carriage (7) unlocking the assembly according to Figs. 6
and 7 of the drawings. The operator carries out the same
operation with the other pallets, that is, a second pallet
(5) is placed moving with this the first.pallet (6) inward
of the structure as shown in Fig. 9 of the drawings. The
pallet (6) is moved slightly raised so that it does not
touch the parts of the structure due to the level of the
carriages (7). When the first pallet (6) has travelled a
distance equal to the space taken up [which is occupied by
the second pallet (5)], it is lowered until resting on the
immediately shorter height carriages (7). The third pallet
(4) is moved and it is positioned in the same way as the
second pallet (5) and, as the first pallet (6) and the
second pallet (5) have been moved inward of the structure,
said third pallet (4) is lowered and rests on the pair of
shorter height carriages (7). As it has been previously
noted, a fourth pallet (not shown) may be provided resting
on all of the rails (11Y.
To extract the three pallets shown (4, 5, 6) plus
a fourth additional pallet, not shown, from the structure,
the operator first extracts the last pallet which was fed,
the three remaining pallets (4, 5, 6) being inside the
passageway, returning back to the load and unload area
moving above the rails (11) thanks to the longitudinal
inclination thereof that makes them to be returned back to
said load and unload area of the pallets.
The movable carriages (7) are always braked since
the side member (101) provided in the initial part of the
passageway acts as a stop member. When removing the second
CA 02498865 2005-02-28
-13-
pallet (4) the process is repeated lowering the other two
pallets (5, 6) and so forth. In the loading operation, the
movement of the pallets is carried out by pushing inward of
the passageway and upward, whereas in the unloading
operation it is performed, outward of the passageway and
downward slipping the pallets by gravity.
Once having been sufficiently described what the
structure for push back pallet storage systems of the
present invention consists according to the enclosed
drawings, it is understood that any detail modification
can be introduced as appropriate, unless variations may
alter the essence of the invention as summarised in the
appended c 1 aimas .
