[0001] The invention concerns a pallet consisting of a number of parallel stringers and
a deck surface formed by deck elements fitted at right angles to the stringers at
distances one from the other.
[0002] A pallet of this kind is generally known and is described in, for example, Dutch
patent application no. 7201117. This is a pallet made entirely of aluminium, with
stringers and deck elements fastened to the latter. Versions of similar structure
but made of wood are also known. A particular type is described in Dutch patent application
no. 291343.
[0003] Efforts to design a pallet which complies simultaneously with a multiplicity of requirements
specified by users have meant that the market has been flooded in the last few decades
with a great variety of pallet versions each of which satisfies more or less of those
requirements.
[0004] Experience shows that in large sectors of the market compliance with the following
three main criteria is still insisted on. In the first place the pallet has to be
inexpensive, preferably so inexpensive that it can be used as a one-way or expendable
pallet. Secondly, the pallet has to be light with a view to ease of handling and because
of transport costs. In the third place it must have a loading capacity such that fairly
heavy loads of, for example, 1000 kg are possible without causing the deformation
of the pallet to increase beyond acceptable limits. A large number of other requirements
specified can usually also be met without much difficulty. The dimensions can be altered
as desired or measures can be taken to enable the pallet to be used for a particular
application.
[0005] The invention concerns a pallet which satisfies the three main conditions mentioned,
while at the same . time, on the basis of the original form of the pallet, the use
of present-day technical possibilities enables an entirely new and surprising pallet
design to be offered.
[0006] In accordance with the invention this is obtained by the fact that the stringers
are constructed of at least two rectangular plates arranged predominantly vertically,
which are joined to each other by transverse partitions, and have recesses at their
; top into which the deck elements fit closely .
[0007] By designing the stringers of the pallet in this way great rigidity combined with
low weight can be obtained. The stringers with the transverse partitions and recesses
will preferably be made of plastic in one piece by injection moulding. The thickness
of the material and the sizes of the plates and partitions can be adjusted as desired,
as also can the plastic to be selected. With regardto the length of the stringers
the requirement to be met can be easily satisfied by making use of an adjustable mould.
The number of stringers will depend on the size of the pallet but is usually three.
Smaller pallets can be made with only two stringers.
[0008] It is an advantage that vertically arranged transverse partitions should extend over
the whole height of the plates to ensure that the plates do not buckle under a load.
These transverse partitions will be preferably located immediately beside the recesses,
thereby making it possible to fasten the deck elements to be inserted in the recesses
to the transverse partitions and hence to the stringers with glue or staples or with
the aid of snap-in fastenings. There can be transverse partitions on either side of
the. recesses. In the case of stringers consisting of more than two plates the transverse
partitions may, with a view to saving material, but also in order to make fastening
of the deck elements on two sides possible, be fitted alternately to opposite sides
of the recesses in adjacent spaces between the plates. Greater stability of the deck
elements is thus obtained.
[0009] The deck elements may be supported by all the stringers. It is, however, also possible
for a deck element to span fewer stringers. The first version is preferable for reasons
of stability and production.
[0010] A stringer consisting of four plates with a number of alternately arranged transverse
partitions alongside the recesses is in many cases of sufficient strength to take
usual loads.
[0011] In a preferred embodiment of the invention the deck elements are of rectangular cross-section
and are arranged so that their narrow sides form the load-bearing surface of the pallet.
[0012] As already stated, the pallets with recesses in them can be made of plastic integrally
with the transverse partitions by injection moulding. The deck elements, however,
will, be preferably made of another material possessing greater rigidity. The chief
materials in mind are wood and board, of which wood deserves preference because of
its deflection properties and the fact that wood is more resistant than board to the
effects of moisture.
[0013] It is an advantage to have the deck elements project somewhat above the stringers.
In this way it is chiefly the deck elements which are subject to wear and, if necessary,
they can be replaced.
[0014] In some cases it may be advisable to fit the underside of the pallet with two or
three stacking strips perpendicular to the stringers.
[0015] To make the pallet suitable for four-way approach by a fork-lift truck holes can
be made in the long sides of the stringers in which the fork of a fork-lift truck
can be inserted. It will be clear that there is ample space between the stringers
for this purpose on the other side of the pallet.
[0016] The invention will now be further explained with reference to an example of embodiment
in the drawing. In the drawing:
Fig. 1 is a top view of a pallet according to the invention in which some deck elements
have been omitted;
Fig. 2 is a front view of the pallet in fig. 1;
Fig. 3 is a section along III-III in fig. 1;
Fig. 4 is a side view of the pallet in fig. 1; and
Fig. 5 is a detail, on a larger scale, of a stringer-with deck element as shown in
the outlined part V in fig. 1.
[0017] Fig. 1 shows stringers marked 1, 2 and 3 of a pallet and deck elements marked 4.
To bring out the recesses more clearly in the drawing some deck elements have been
omitted. Every stringer consists of four rectangular plates 6, 7, 8 and 9, arranged
predominantly vertically, with recesses 5 made in their upper sides; see figs. 1 and
4. Beside the recesses transverse partitions 10 are fitted over the full height of
the plastics plates. The ends of the stringers are fitted with end plate 11. Transverse
partitions 10 are fitted in such a way that they are located in gaps 12, 13 and 14,
alternately immediately next to one of the sides of the recesses. The deck-elements
inserted in the recesses are thus better supported on both sides.
[0018] The wooden deck elements which have a rectangular cross-section are placed so that
their narrower sides form the load-bearing surface of the pallet. This means that
the fullest possible advantage is taken of the rigidity properties of the material
of which the load-bearing (deck) elements consist. These load-bearing elements may
be completely recessed into the stringers or project slightly above them.
[0019] The load-bearing elements are fastened to the stringers by stapling them to the adjacent
transverse partitions as shown by 15 in fig. 5.
[0020] As indicated in fig. 4 the long sides of the plates have openings 16 and 17 to make
entry by the fork of the fork-lift truck possible.
[0021] It can be seen from figs. 2 and 3 that the position of plates 6, 7,8 and 9 is not
completely vertical.-That, however, is desirable in order to obtain the necessary
draft for the dies in an injection- moulding mould.
Example
[0022] In a pallet produced in accordance with the description and drawing the stringers
were made of low-density polyethylene. The plates and transverse partitions were 3
mm thick. Wooden deck elements with cross-section dimensions of 32 x 10 mm were placed
in the recesses. The dimensions of the pallet were 1200 x 800 mm. The total weight
of the pallet was 5.8 kg, of which 1.4 kg was accounted for by the wood.
[0023] The pallet was tested using a fork-lift truck for lifting and laying, with DIN 32600
as guideline, the width of the truck forks being 100 mm and the centre distance between
the forks 575 mm. The load was 600 kg, distributed evenly over the pallet. The deflection
in the middle and at the outsides of the pallet was found to be 3.5 mm.
[0024] In a load test in which the pallet, standing on a flat base, was subjected to an
evenly distributed load of 1200 kg (= 2-high stacking), a deflection of 1.5 mm was
found to have occurred in the middle between the stringers after 24 hours. The tests
were carried out at an ambient temperature between 25 and 30 °C.
1. A pallet consisting of a number of parallel stringers and a deck surface formed
by deck elements fitted at right angles to the stringers at distances one from the
other, in which the stringers are constructed of at least two rectangular, parallel
plates arranged predominantly vertically, which are joined to each other by transverse
partitions and have recesses at their top into which the deck elements fit closely.
2. A pallet as claimed in claim 1, in which the deck elements are of rectangular cross-section
and are fitted into the recesses in such a way that the narrow sides of the deck elements
form the top surface of the pallet.
3. A pallet as claimed in claim 1 or 2, in which the transverse partitions are arranged
vertically and extend over the entire height of the plates.
4. A pallet as claimed in any of claims 1 to 3, in which transverse partitions are
fitted immediately beside the recesses.
5. A pallet as claimed in any of claims 1 to 4, in which transverse partitions are
fitted on either side of the recesses.
6. A pallet as claimed in any of claims 1 to 5, in which, in the case of stringers
made'up of more than two plates, the transverse partitions are fitted alternately
on either side of the recesses, in adjacent spaces between the plates.
7. A pallet as claimed in any of claims 1 to 6, in which each deck element is supported
by all the stringers.
8. A pallet as claimed in any of claims 1 to 7, in which each stringer is made up
of four plates.
9. A pallet as claimed in any of claims 1 to 8, in which the pallet is made entirely
of plastic.
10. A pallet as claimed in any of claims 1 to 8, in which the stringers are made of
plastic and the deck elements of wood.
11. A pallet as claimed in any of claims 1 to 10, in which the deck elements project
partly above the top surface of the stringers.
12. A pallet as claimed in any of claims 1 to 11, in which the deck elements are fastened
to the stringers by stapled, glued or snap-in fastenings at the transverse partitions.
13. A pallet as claimed in any of claims 1 to 12, in which openings are provided in
the long sides of the stringers for the insertion of the forks of a fork-lift truck.
14. A pallet as claimed in any of claims 1 to 13, in which two or more stacking strips
are fitted perpendicular to the stringers on the underside of the pallet.
15. A pallet as substantially described in the description and/or drawing.