FIELD OF TECHNOLOGY

[001] The present invention relates to a wheel track to be attached to the wheels of a wheeled vehicle. In particular the invention relates to a wheel track to increase the adhesion of a vehicle’s rubber tyres. More specifically, the invention relates to a wheel track according to the preamble to Claim 1.

BACKGROUND

[002] Net-like snow chains and wheel tracks made from chains and chain loops are known from the prior art. They are fitted around the wheels of vehicles to improve the wheels’ traction. In vehicles used on roads, slats or chains are usually installed temporarily on the wheels when driving on snow or other treacherous surfaces with poor adhesion. Particularly in cars and other lighter vehicles the chains can be of a quite light construction due to their temporary and short-term use. In timber harvesters, agricultural tractors, and military vehicles the wheel tracks can be kept on the tyres for long periods of time in winter or when moving and working on boggy ground. The slats or chains are then subjected to great stress. Therefore they must be made from high-quality durable steel and be at least partly tempered. In lighter vehicles, the chains can be of composite or even plastic materials, or made of aluminium alloy, because their use is short-term and the chains need not withstand long-term stress and wear. Net-like chains or slats are made by welding chain loops together and further attaching grip spikes to them by welding. Manufacture is very laborious, which leads to high prices.

[003] Another type of wheel track consists of track slats that extend laterally over the wheel, which are attached to each other with the aid of connector loops at the sides of the wheels. Such wheel tracks are intended for long-term use by heavy vehicles and a single wheel track can weigh several tens of kilogrammes. The wheel track thus becomes quite heavy. The track slats are made by first casting a blank, in which places are machined for the brackets. The track slat can also be made by bending from metal profile. The track slat must be of a strong and wear-resistant material, and the track slats are tempered to achieve sufficient wear-resistance and strength. Due to the many manufacturing stages, such wheel tracks are expensive and the weight of the cast track slats makes them heavy. Heavy wheel tracks are difficult to handle when placing them on and taking them off the wheels.

[004] Wear and grip studs are usually attached to track slats by welding, which adds one more work stage to their manufacture.

SUMMARY

[005] The present invention is intended to create an improved wheel track for different types of vehicle. In particular the invention is intended to create a wheel track for the rubber wheels of forestry vehicles. [006] The invention is characterized by what is stated in the characterizing portion of the independent Claim.

[007] According to one embodiment of the invention, the wheel track comprises at least two track slats, in which there is an elongated body, which is dimensioned to extend across the vehicle’s tyre and at the end of which are flange branches turning away from the longitudinal direction of the body. At the end of both flange branches is a bracket and the wheel track includes at least two links, which are fitted to the brackets of the flange branches in such a way that, with the aid of the links, a chain of track slats can be formed. The track slats are made by cutting from a single piece of sheet material. [008] According to a second embodiment of the invention, the links are formed of two loop chains.

[009] According to a third embodiment of the invention, the track slats are cut from a sheet of tempered steel.

[0010] According to a fourth embodiment of the invention, the brackets at the ends of the flange branches are closed loops.

[0011] According to a fifth embodiment of the invention, the bracket at the end of at least one flange branch is a hook. [0012] According to a sixth embodiment of the invention, the bracket at the end of at least one flange branch is a slot formed of two branches.

[0013] According to a seventh embodiment of the invention, the bracket at the end of at least one flange branch comprises a pin extending in the longitudinal direction of the track slat.

[0014] According to an eighth embodiment of the invention, at least one grip stud is formed in the body of the track slat, which is of the same uniform sheet material as the track slat’s body and flange branches.

[0015] According to a ninth embodiment of the invention, the track slat is made from sheet material by cutting with some of the following methods: oxygen cutting, laser cutting, plasma cutting, water-jet cutting.

[0016] According to a tenth embodiment of the invention, the wheel track comprises at least one track slat, in which a carrier piece is attached to the track slat.

[0017] According to an eleventh embodiment of the invention, at least one carrier piece of the track slat is detachable.

[0018] According to a twelfth embodiment of the invention the track slat’s carrier piece is fixed.

[0019] According to a thirteenth embodiment of the invention, the track slat’s carrier piece is grooved on the side facing outwards relative to the track slat’s body. [0020] According to a fourteenth embodiment of the invention, in the track slat’s carrier piece there is a wear piece facing outwards relative to the track slat’s body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the following, some embodiments of the invention are described in greater detail with reference to the accompanying drawings, in which:

FIGURE 1 shows a wheel track according to at least one embodiment installed on top of a tyre and seen from the side of the tyre, FIGURE 2 shows the wheel track of Figure 1 seen towards the tyre’s wear surface,

FIGURE 3 shows a perspective view of the wheel track of Figures 1 and 2,

FIGURE 4a shows a wheel track, without tyre, according to at least one embodiment,

FIGURE 4b shows a detail of the wheel track of Figure 4a, FIGURE 5a shows a wheel track, without tyre, according to at least one embodiment,

FIGURE 5b shows a detail of the wheel track of Figure 5 a, FIGURE 6 shows the track slat used in a wheel track according to at least one embodiment,

FIGURE 7 shows the assembly of a wheel track according to at least one embodiment,

FIGURE 8 shows a track slat used in a wheel track according to at least one embodiment,

FIGURE 9 shows one embodiment of a wheel track formed of the track slats of

Figure 8,

FIGURE 10 shows a track slat used in a wheel track according to at least one embodiment of the invention, FIGURE 11 shows one embodiment of a wheel track formed the track slats of

Figure 10,

FIGURE 12 shows a track slat used in a wheel track according to at least one embodiment of the invention,

FIGURE 13 shows a wheel track formed of the track slat of Figure 8 according to at least one embodiment of the invention,

FIGURE 14 shows a track slat suitable for use in at least one embodiment of the invention, FIGURE 15 shows a side view of a track slat suitable for use in at least one embodiment of the invention,

FIGURE 16 shows an end view of the track slat of Figure 15,

FIGURE 17 shows a track slat suitable for use in at least one embodiment of the invention, and

FIGURE 18 shows a wheel track according to at least one embodiment of the invention, installed on a wheel.

EMBODIMENTS [0022] DEFINITIONS

[0023] In this context, the expression“wheel track” covers tracks, consisting of track slats set transversely to the wheel and links connecting them, fitted around a single wheel or several consecutive and/or parallel wheels of a vehicle.

[0024] The term sheet refers to a planar flat material, the thickness of which is determined by two surfaces at a distance from each other. The surfaces are essentially parallel and either smooth or patterned.

[0025] The present invention is particularly directed to wheel tracks used to increase the traction of heavy off-road vehicles. Due to the invention’s good scalability, it can also be applied to increase progression and traction ability in the wheels of many other kinds of vehicle, either temporarily or continuously. In general, the wheel track consists of several track slats extending over the width of a vehicle’s wheel, which are connected to each other with links on both sides of the wheels. The links can be chain links or the track slats can be connected in a unified chain. The track slats are made by cutting them from a flat sheet. Thus the manner of making a track slat is extremely cheap and different sizes of track slat can be made for different sizes of tyre can be made using automatic cutting machines, by altering the control of the machine. A track slat cut from sheet lies transversely around the wheel, so that it forms a paddle recalling the paddle of the paddle-wheel of a paddle steamer. The tractive ability of such a paddle-like track slat is particularly good on soft ground and snow.

[0026] FIGURES 1 - 3 show one wheel track installed around a tyre 1. The wheel track comprises of track slats 2 extending over the wear surface of the tyre 1 to its sides and chains 3 at the sides of the tyre 1 joining the track slats 2 to form the wheel track. In this example, the wheel 1 is a pneumatic rubber tyre, but the invention can also be applied to other types of wheel. Further, in Figures 1 - 3 the wheel track is fitted around one tyre. It can be envisaged that the wheel track is dimensioned to be installed around two (or more) parallel wheels, a double wheel, as a unified track, or as a continuous drive track around two or more consecutive wheels. If the same track is used as a single track around several tyres, the vehicle’s surface pressure and load-bearing capacity will be reduced, but at the same time the stresses on the wheel track and its weight will increase. It can be seen particularly from FIGURE 1, that the track slats 2 protrude like paddles from the surface of the tyre 1. The distance between the track slats 2 is also quite large and the gap between them opens in a V-shape outwards in the radial direction of the tyre 1. This is important for the operation of the wheel track on soft surfaces, such as snow, boggy ground, mud, clay, and similar conditions. The paddle-like track slat 2 protruding from the surface of the tyre 1 as a plate grips soft material and pushes it along with its movement, so that traction is good even though the surface itself gives way and slips under the tyre 1. The construction of the wheel track is open and has no narrow structures that become blocked, so that the material of the drive surface does not become packed into the wheel track, instead the wheel track cleans as it rotates and has good adhesion during the following rotation of the wheel.

[0027] FIGURE 4a shows a wheel track, which consists of track slats 1 and chain loops connecting them. A suitable track slat 2 for this embodiment is shown in Figure 6. The track slat 1 of FIGURE 6 consists of an elongated body 4 and flange branches 5 at each end of the body 4. The flange branches 5 turn away from the longitudinal direction of the body 4 at both ends of the body 4. The length of the body 4 and the length and angle of the flange branches 5 are dimensioned in such a way that the track slat 2 can be set on top of the tyre’s 1 wear surface in such a way that the flange branches 5 extend to the sides of the tyre 1. In each flange branch 5 is a guide surface 6 in the inner side of the U-shape formed by the track slat 2. The guide surface is supported on the side of the tyre 1 and holds the track slat 2 on top of the tyre 1. Grip studs 8 are formed in the body 4 on the outer side of its U-shape. These increase the adhesion of the track slat 2 laterally and in the drive direction. The number and shape of the grip studs 8 can easily vary, thanks to the track slat’s 2 manufacturing method. To attach the track slat 2 to neighbouring track slats and to assemble a wheel track, a loop 7 is attached to the track slat of Figure 6. In this example, the loop is a normal oval chain loop with a rounded eye. The loop 7 is attached to the outer ends of both flange branches 5. The loop 7 can be a single chain loop, which is welded to the end of the flange branch 5, or the ends of the flange branches 5 can be welded directly to a unified chain 3. An enlargement of such a solution is shown in Figure 4b. If track slats welded to a unified chain are used, there must be at least one openable link in the chain, so that the chain can be installed on top of a wheel and, if necessary, removed from the wheel. This is shown in FIGURES 5a and 5b, in which one of the links is a shackle 9, which can be opened and closed using a bolt 10. There can be several shackles in the wheel track and it can even be envisaged that all of the track slats are connected to each other by the loops attached to them, using openable shackles. This would permit the replacement of individual track slats.

[0028] The track slat 2 is made from sheet material by cutting. The track slat 2 itself includes a body 4 and flange branches 5, as well as optionally grip studs 8. However, grip studs 8 are nearly always needed, especially for lateral grip. In wheel tracks made for heavy vehicles, such as timber harvesters and forestry vehicles and earth-moving vehicles, the stresses acting on the wheel track are large, so that the material must be sufficiently durable. A suitable material for their track shoes is tempered sheet steel. Tempered sheet is needed to achieve sufficient strength and wear-resistance. The working of such sheet is, however, difficult, so other manufacturing methods have been used to make track slats. However, various cutting methods can be used to cut pieces from tempered sheet. For example, the track slats 2 of Figures 6, 8, 10, and 12 are made by cutting, so that the inside and outside of the track shoe’s 2 U-shape are cutting surfaces and the surfaces transverse to them, i.e. the inner surfaces of the track slat 2 are formed from the surfaces of the blank sheet. If the track slat is made by cutting from sheet, its shape and dimensions can easily be changed. To make track slats of different models and sizes, all that is needed is a design program suitable for dimensioning and drawing them, then sending the manufacturing instructions to an automatic cutting machine. This permits cheap manufacture and easy variability. Wheel tracks and their parts can be made in even very short series for different tyre sizes, without increasing manufacturing costs. Expensive manufacturing lines are not needed to achieve profitability, instead manufacture can be started using even simple devices, because the most complicated and expensive part, the track slat, is made advantageously by cutting from sheet metal.

[0029] Particularly for light vehicles and temporary use the track slats can be made from lighter and less durable materials, such as plastics, aluminium, light-metal alloys, or composites. Then too, the manufacturing method used is cutting from sheet. Suitable cutting methods for tempered steel include oxygen cutting, water-jet cutting, laser cutting, and plasma cutting. For other materials, water-jet cutting and laser cutting can be more suitable. If another material than steel is used, it can be envisaged that the other parts of the wheel track too are made from a material other than steel.

[0030] FIGURE 7 shows a wheel track, in which the number of track slats 2 can vary. In it are link track slats 11 according to Figure 6, which are joined together by a chain 3, in such a way that there are three chain links 12 between each link track slat 11. Thus the wheel track’s link track slats are farther apart. This has the advantage that the wheel track is lighter and is easier to handle, for example when installing it on a wheel 1. Because there are fewer track slats, the wheel track’s purchase price will be lower. If additional adhesion or traction is needed, the necessary number of short link tracks 13 can be installed between the track slats with the aid of shackles 9. The short link tracks 13 can be set in place while the wheel track is installed on the wheel, or they can be attached to the wheel track beforehand. In this example, one short link track 13 can be attached between every two link tracks 11. The wheel track according to this example can, of course, be dimensioned otherwise, i.e. the gaps of the link tracks 11 can be larger, when more short link tracks can be placed between them. The dimensioning and adaptability of this can be entirely decided by the designer, so that the wheel track can be tailored to the customer’s wishes.

[0031] FIGURE 8 shows an embodiment of the track slat, in which there are different brackets at the different ends of the track slat. At the first end of the track slat, the bracket at the end of the flange branch 5 is a hook 14 opening in the opposite direction to the track slat’s body 4. Thus this track slat is called a hook track slat 15. the bracket at the opposite end of the hook track slat 15 is a slot 17 formed of two branches 16. The slot 17 opens transversely to the length of the hook track slat 15 to receive a chain link and in both branches 16 are holes 18 for a locking pin or bolt 19.

[0032] The basic construction of the wheel track of FIGURE 9 is the same wheel track as in Figure 7. The hook track slats 15 are attached to the chain links 12 between the link track slats 11 by taking the hook 14 through the link and placing the slot 17 on top of the side of the chain link 12 on the opposite side to the hook 14. The bolt 19 is placed in the hole 18 and the hook track slat 15 is locked in place by the bolt. This construction too can be varied similarly to the construction described above.

[0033] In FIGURE 10, there are slots in both ends of the track slat 17, and it is installed from both ends as described above in connection with the bracket of one end. FIGURE 11 shows the slot track slat 20 of FIGURE 10 in connection with the basic construction of FIGURE 7.

[0034] In FIGURE 12, the basic construction of the hook track slat has been altered so that, in place of the slot, at the opposite end to the hook 14, there is a protrusion 21 starting from the flange-branch 5 end, in which there is a transverse bolt 22. The hook is set in the wheel track as described above. At the end on the side of the protrusion 21, the bolt 22 is fitted into a link in the chain link 12 and locked using a nut 23 according to FIGURE 13.

[0035] FIGURE 14 shows a track slat based on the basis construction of FIGURE 8. a carrier piece 24 is added to this track slat. Here the carrier piece 24 has an even surface and is attached to the body 4 of the track slat by lugs and bolts. The are holes for this purpose in the body 4 of the track slat. The carrier piece is intended to increase the load-bearing capacity of the wheel track. The carrier piece can be part of a separate load-bearing track slat, or, if there are holes in the track slat for installing carrier pieces, the carrier pieces can be installed in the wheel track whenever addition load-bearing capacity is needed. Holes for carrier pieces can be made in all the track slats used in embodiments of the invention. A sufficient number of separate carrier pieces and/or track slats with carrier pieces can be installed in a wheel track, according to the desired load-bearing capacity. The necessary load- bearing capacity can be obtained by varying the number of load-bearing track slats.

[0036] The track slat shown in FIGURES 15 and 16 too is based on the basic construction of FIGURE 8. In this construction, the carrier piece 24 is attached to the track slat by welding it onto the track slat’s body 4. The opposite surface 27 of the carrier piece 24 to the track slat’s body 4 is formed as a groove with a V-shaped cross-section. Using this groove shape, a good load-bearing capacity is achieved, along with good adhesion on soft surfaces, such as, for example, snow and boggy ground.

[0037] FIGURE 17 shows a further variation of the track slat. Its construction otherwise corresponds to the track slat of FIGURE 14, except that a wear piece 28 is attached to the surface of the carrier piece. This wear piece 28 can be of rubber or hard plastic. A wear piece made from a suitable material can reduce the stress acting on the ground, or permit driving on asphalt or other hard surfaces. Thus the vehicle can drive over a road or drive on a road or a track with similar surfaces, without damaging them. Suitable wear-piece materials are those used, for example, in tracked vehicles, such as excavators. When moving on a road, the wear pieces must be sufficiently high that the track slats possibly producing adhesion between than do not extend to the road surface or similar.

[0038] FIGURE 18 shows a wheel tracked fitted to a wheel 1. In this embodiment, adhesion-increasing track slats, which are according to Figure 6, are attached permanently to the chains 3 of the wheel track. These track slats are attached by welding them to the chain. There are three chain links 12 between each permanently attached track-slat 2 link 7. Track slats equipped with carrier pieces 24 according to FIGURES 15 and 16 are attached to the centremost of these, in the manner shown in FIGURE 9. As can be seen, the carrier pieces 24 can extend farther than the width of the wheel and thus increase the wheel’s load-bearing capacity. [0039] Plastic, rubber, or iron parts, and/or alternatively additional pieces like carrier pieces can further be separately attached to the track slats. The intention is to attach, either as additional pieces or paddle-wheel like parts or similar parts according to the purpose (e.g. in sand) or which accelerate movement in water, when the application is vehicles travelling on land and in water.

[0040] The benefits are the following:

Able to travel faster in water

- Landing is facilitated when the gripping track takes“hold” of the bank,

The breaking of the paddle-wheel construction is not necessarily important, so they can break when landing.

The rubber piece or similar wear pieces, which lift the gripping track, work by permitting travel on a sensitive surface, for example, do not damage the asphalt, as the track’s steel parts and gripping parts do not make contact with the ground, the application is, for example, road crossing, when it is possible by altering the piece to lift the machine up so that its metal parts do not make contact with the ground.

[0041] In addition to the above brackets, other methods of bracket and brackets can be used. In addition to a chain and chain links, other kind of links too can be used to combine track slats to form a wheel track, for example, a roller chain or similar parts, or special links made for the purpose. However, the advantage of an ordinary rounded-hole oval-link chain is that they are available cheaply in different sizes and different strength grades. The rounded links also do not easily jam in operation. The wheel track can, in principle, be assembled only from edge chains and detachably attached track slats, but to facilitate installation there is reason to pre- assemble at least part of the wheel track. The track slats and bracket methods described above can be freely combined with each other to form various totalities. Thus, for example, the retrofitted track slats need not be identical, instead those that are available can be used. The number of track slats is determined by the wheels’ size and the need for adhesion. The wheel track can be made, for example, densely spaced, so that every second one of the chain’s 3 links is attached by welding a track slat. Track slats cannot then be added by retrofitting, because there is no space or bracket place for them. Places for track slats and places permitting retrofitted track slats can, of course, be added with the aid of specially-made edge chains.

[0042] The shape of the track slat can be easily varied within the scope of what can be done by cutting from sheet material. For example, the number and shape of grip studs can easily be varied according to the customer’s preferences. The track slats can either be made high themselves or their height can be increased by additional pieces corresponding to the carrier pieces. Using such wheel tracks vehicles’ ability to cross watercourses can be increased. For example, the wheel tracks can be made in such a way that they have very high track slats or carrier pieces, which are not, however, dimensioned to withstand driving on ground or roads. Thus the wheel track can be attached to the vehicle when it crosses a watercourse. The high track slats act like the paddles of paddle-wheels, so that each drive wheel becomes a paddle-wheel and the vehicle can cross the watercourse. The wheel tracks can be removed after crossing the watercourse, or they can be dimensioned to disintegrate when climbing onto ground, when movement continues normally on the wheels.

INDUSTRIAL APPLICABILITY

[0043] The present invention is suitable for improving the ability of vehicles to move in various driving conditions and for manufacturing wheel tracks for vehicles.

REFERENCE-NUMBER LIST

1 wheel

2 track slat

3 chain

4 body 5 flange branch

6 guide surface

7 loop grip stud shackle bolt link track-slat chain link short link track hook hook track-slat branch slot hole bolt slot-track slat protrusion bolt nut carrier piece lug

bolt