A number of said stakes are intended to be attached to the frame with space therebetween, so that these stakes together delimit an area above a bed to counteract undesired exit of objects located in the area from this area, which objects for example are logs. The stakes are preferably arranged along the sides of railway trucks or other vehicles.

According to prior art the stakes have a hollow shape. The stakes may for example be constituted by bent plates welded to- gether or by profile plates (sections) welded together.

A fork truck is often used when removing objects from the area above the bed of for example a railway truck. When operating the fork of the fork truck the fork may be brought in contact to one or more stakes in an undesired way. Such a contact may cause an inward bend, buckle or fracture of the stake, since this has a relatively low resistance against load at isolated points.

Such an inward bend weakens the stake and such a inward bend or a number of such inward bends may cause a collapse of the stake.

A further disadvantage of the stakes according to prior art is a problem to repair of them. When repairing the stakes according to the prior art it is required that these are straightened in any way and/or that a further plate portion is welded to the stake and covers the weakened portion of the stake. However, such a repair result in a stake weakened in relation to a stake not de- formed.

SUMMARY OF THE INVENTION The object of the present invention is to provide a device at a stake, which eliminates the disadvantages mentioned above in such stakes already known, and which moreover has a weight substantially equal to or less than the weight of these.

This object is obtained according to the invention by that a spacer material is arranged between at least two stiff layers of the stake, said layers being arranged substantially opposite to each other, and that the spacer material has a lower density than the stiff layers.

A preferred embodiment of the invention, in which the spacer material is firmly connected to the surface of the respective stiff layers directed towards the spacer material by means of an ad- hesive joint means that respective layer is firmly connected to the spacer material and thereby an inward bend of the stake, during an external force applied thereupon, is prevented.

Another preferred embodiment of the invention, in which the stiff layers are arranged on both sides of the spacer material in two directions substantially perpendicular to each other, and sub- stantially perpendicular to the longitudinal direction of the stake, leads to that the spacer material is substantially enclosed by the stiff layers and that the spacer material not directly is exposed to external loading or other effect.

Another preferred embodiment of the invention, in which at least one of stiff layers has a thickness decreasing from the first end towards the second end thereof, leads to an optimal utilisation of layer material with the object to keep the weight of a stake low while maintaining a flexural resistance of the stake sufficient to prevent bending thereof when a force arising from the load is applied.

Another preferred embodiment of the invention, in which the spacer material is substantially hyrdophobic, at least at surfaces exposed to water, leads to that the density of the spacer mate- rial after a period of use will not increase and thereby the weight of the stake is maintained.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings below follows a de- tailed description of preferred embodiments of the invention cited as examples.

In the drawings: Figure 1 shows a perspective view of a first preferred embodi- ment of the device according to the invention, and a frame, to which the device is intended to be attached by means of a holder.

Figure 2 shows a cross section of the first preferred embodi- ment, in which stiff layers are arranged on both sides of the spacer material in two directions substantially perpendicular to each other.

Figure 3 shows a cross section of a second preferred embodi- ment of a device according to the invention, in which the spacer material is arranged between two stiff lay-

ers, said layers being arranged substantially opposite to each other.

Figure 4 shows a front view of the first preferred embodiment of the device according to the invention.

Figure 5 shows a partially sectioned side-elevation of the first preferred embodiment of the device according to the invention.

Figure 6 shows a front view of a third preferred embodiment of the device according to the invention.

Figure 7 shows a partially sectioned side-elevation of the third preferred embodiment of the device according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Figure 1 illustrates a first preferred embodiment of the device at a stake according to the invention, said stake comprising a first 1 and a second 2 end, said first end 1 being intended to be at- tached to a frame 13 by means of a holder 3 arranged on the frame 13. A spacer material 4 is arranged between two pair of stiff layers 5,6,7,8, said layers of each pair being located sub- stantially opposite to each other. The spacer material 4 has a lower density than the stiff layers 5-8. The spacer material 4 should have a high compression strength with the purpose to withstand high local compression loads and impacts on the stiff layers. With the purpose of providing a stake with a comparative low weight as well, the spacer material 4 should have a density of <2000 kg/m3, suitably <1000 kg/m3, preferably <500 kg/m3 and in particular <250 kg/m3. The compression strength of the spacer material 4 should be >2 MPa, suitably >4 MPa, prefera- bly >6 MPa and in particular >8 MPa.

The holder 3 in Figure 1 is shown for the sake of illustration only and the device according to the invention may be applied to a number of holders different from each other in shape.

A bottom plate 9 covering the spacer material 4 at the first end 1 of the device is preferably arranged.

The stake according to the invention should have a flexural re- sistance sufficient to prevent that the stake gives away when a force, arising from objects located within the area delimited by a number of stakes, is applied. If the objects are constituted by logs piled on each other, and lying close to the stake, a force spread is applied on the stake. It is even possible that the ob- jects introduce a force in one point on the stake. The stake, however, would have a flexural resistance sufficient to prevent that the stake is bent, or in any other way is deformed when a force is applied. The flexural resistance of the stake required is highest in the lower portion of the stake and decreases up to- wards the second 2 end thereof. The stiff layers arranged at the stake according to the first preferred embodiment of the device according to the invention have a thickness decreasing from the first end 1 of the stake towards the second end 2 thereof. In ad- dition, a cross section of the device, substantially perpendicular to the longitudinal direction of the stake, has an area decreasing from the first end 1 of the stake towards the second end 2 thereof. By this shaping a stake is accomplished, that on one hand has a high flexural resistance when so is necessary and on the other has a suitable shaping with regard to the weight of the stake with the purpose to keep the weight low.

Figure 2 illustrates in a schematic way a cross section through the first preferred embodiment of the device according to the in- vention, said cross section being substantially perpendicular to the longitudinal direction of the stake, in a upper portion of the stake. The device has two plate-like stiff layers 5,6 arranged

substantially opposite to each other, and two plate-like stiff lay- ers 7,8, arranged substantially opposite to each other and sub- stantially perpendicular to the stiff layers 5,6. The four stiff lay- ers 5-8 enclose the spacer material 4. The spacer material 4 is firmly connected to a surface of the respective stiff layers 5-8 directed towards the spacer material 4. This firm connection between the spacer material 4 and respective stiff layers is preferably constituted by an adhesive joint.

Figure 3 illustrates schematically a cross section, similar to that in Figure 2, through a second preferred embodiment of the de- vice according to the invention, in which the spacer material 4 is arranged between two stiff layers 5,6 arranged substantially opposite to each other, while the side surfaces 10,11 of the spacer material are exposed to influence from the exterior. Be- cause the side surfaces 10,11 of the spacer material 4 are not covered by any stiff layers a reducing of the weight is achieved in relation to the first preferred embodiment of the device illu- strated in Figure 2. It is important that the spacer material has a very low tendency to absorb water. The spacer material 4, for this reason, may for example be constituted by a cellular plastic with closed cell structure. With the purpose to increase the ca- pability of the spacer material 4 to withstand penetration of moisture and water the surfaces thereof exposed may be treated.

Figure 4 illustrates a front view of the first preferred embodiment of the device according to the invention. The thickness of the front side of the device decreases gradually from the first end 1 of the stake towards the second end 2 thereof. The gradual de- creasing of the thickness of the layer is achieved by forming the stiff layer by a number of sub-layers, each having a constant thickness and arranged outside each other, said number of sub- layers decreasing from the first end 1 towards the second end 2 of the stake. In the first preferred embodiment three sub-layers are arranged at the first end 1, and one sub-layer is arranged at

the second end 2. The sub-layer located at the second end 2 extends along the full length of the stake, and by connecting a second sub-layer extending from the first end 1 to a position between the two ends 1,2, and by connecting a third sub-layer extending from the first end 1 to a position between the first end 1 and the position of the second sub-layer, the gradual change of layer thickness from the first end 1 towards the second end 2 of the stake is achieved. Two adjacent sub-layers are firmly connected to each other by means of a welded joint 14.

However, within the scope of the claims according to the invention, it is possible that adjacent layers are connected to each other in a different way, for example by means of a rivet joint or an adhesive joint. The second and third sub-layers have a pointed end, said end pointing against the second end 2.

However, within the scope of the claims according the invention, it is possible that said end of respective sub-layer has a non- pointed shape, for example a rectilinear shape substantially diagonal to the extension direction of the stake, or a rectilinear shape substantially perpendicular to the extension direction of the stake.

Figure 5 illustrates a partially sectioned side-elevation of the first preferred embodiment. Here is clearly illustrated how the layer thickness decreases gradually from the first end 1 towards the second end 2 of the stake.

The side layers 7,8 according to the first preferred embodiment have a constant thickness. However, within the scope of the claims according to the invention, it is possible that also these layers have a thickness decreasing from the first end 1 of the stake towards the second end 2 thereof.

Figure 6 illustrates a front view of a third preferred embodiment of the device according to the invention. The third preferred em- bodiment is an alternative embodiment in relation to the first and the second preferred embodiments, with the difference that at

least one of the stiff layers 5-8, preferably the layer 5 and/or layer 6, consists of a number of sub-layers arranged after each other in the longitudinal direction of the stake, that respective sub-layers has a constant thickness, and that the sub-layers have, in relation to each other, a thickness decreasing from the first end 1 towards the second end 2 of the stake. A first one of two adjacent sub-layers has at one end thereof a portion 12 protruding in the longitudinal direction of the stake and overlap- ping the other adjacent sub-layer. This protruding portion 12 is arranged for connecting the two adjacent sub-layers. The con- necting is performed according to the third preferred embodi- ment by means of a rivet joint 15. However, within the frame of the claims according to the invention, it is possible that adjacent sub-layers are firmly connected to each other by means of a welded joint or an adhesive joint or by means of a combination of two or three of the joints.

Figure 7 illustrates a partially sectioned side-elevation of the third preferred embodiment according to the invention. The pro- truding portions 12 and the thickness decreasing from the first end 1 towards the second end 2 of the sub-layers in relation to each other is clearly illustrated.

According to a further development of the third preferred em- bodiment not illustrated, an upper portion of respective lower sub-layer as seen in the longitudinal direction of the stake and a lower portion of respective upper sub-layer, being adjacent as seen in the longitudinal direction of the stake, overlap each other. Furthermore, the upper portion is connected to the lower sub-layer by means of an angled portion, which in particular is suitable when objects, for example logs, which are lifted out substantially in vertical direction from an area delimited by a number of stakes by means of for example a fork truck, since the risk that the objects would hook on and in the worst case cause disengaging of a stake from a holder arranged for a stake is reduced.

In Figure 2 the layers 5-8 are arranged in form of a square pro- file. With the purpose to accomplis an easy assembling of the stake a plate-like part may be bent so that it constitutes two portions substantially perpendicular to each other, for example corresponding to the layers 5 and 7, and another corresponding plate-like part is bent so that it has two substantially perpen- dicular portions, for example corresponding to the layers 6,8.

The bent units 5,7 and 6,8 are arranged to be glued on the spacer material 4.

Furthermore, the bottom 9 may be constituted by an extension of any of the layers 5-8, said layer being bent at the first end 1.

Furthermore, also a cover may be arranged at the second 2 end of the stake, said cover protecting the spacer material against influences from the exterior.

The stiff layers 5-8 are preferably constituted by plates. This means that the respective layer is constituted by a plate. How- ever, the stiff layers 5-8 may be constituted by a non-metallic material as well, for example reinforced plastics. In this case, the sub-layers are constituted by plate-like parts of reinforced plastics. The reinforcing material is preferably constituted by glass fibre. With the object to protect the reinforced plastics against moisture a coating in form of for example"gel coat"may be applied on the same. With the aim to improve the abrasion resistance of the stake against the holder 13 plate strips of steel may be arranged around the first end 1 of the stake when the sub-layers are constituted by reinforced plastics.

In manufacturing stakes according to the present invention a rolling machine is preferably used, said layers 5-8, or the inside sub-layers when there, being pressed against the spacer mate- rial while glue is present between these. It is also possible to fill a prefabricated profile of stiff layers with floating spacer material and then let the spacer material solidify inside the profile.

Above the layers 5-8 and the sub-layers have been described to have a plate-like shape. However, within the scope of the claims according to the invention, it is possible that one or more of these has a profile shape.

By the device according to the invention with a spacer material arranged between at least two stiff layers 5,6,7,8, arranged opposite to each other, said spacer material having very low density, it is possible to reduce the plate thickness in relation to the art already known and thereby reduce the total weight of a stake while the flexural resistance of the stake is increased.

It is stressed that the embodiments described above and illu- strated in the drawing should be considered as exemples only. Thus the invention may be realised in different ways without de- parting from the basic idea of the invention. In particular, it is pointed out that a man skilled in the art is capable to make vari- ous modifications of the exemplary embodiments, after receiving the solution of the invention, without departing from the frame of the claims.