The invention relates to a snow plough comprising a frame, a snow plough blade for pushing snow, a wing moving arrangement and a connecting arrangement for connecting the snow plough to a vehicle. The snow plough has a first end of the snow plough and a second end of the snow plough. The snow plough blade is located at the second end of the snow plough and the connecting arrangement is located at the first end of the snow plough. The snow plough blade has an extended position and a retracted position and a first surface and a second surface, and the second surface is a snow-pushing surface. The snow plough blade comprises three platelike parallel sections: a middle blade section, a first wing section and a second wing section, and the three blade sections each have an upper edge and a lower edge and have corresponding first and second surfaces. The lower edges are configured to be held against the ground when pushing snow. The first wing section and the second wing section have outer ends and inner ends and the inner ends face each other. The middle blade section is fixed to the frame, and the wing moving arrangement is configured to move the first wing section and the second wing section in the direction of the plane of the middle blade section between the extended and the retracted positions.

BACKGROUND

Snow removal involving small and medium-size vehicles such as the small four- wheel drive vehicles, or pickup trucks, tractors and such equipped with removable snow plough arrangements for clearing snow. The snow ploughs comprise wings or blades for pushing and loosening snow. The blades or wings are generally of a fixed length that is slightly greater than the width of the vehicle and are supported by an adjustable framework permitting the snow plough to be held against the ground or to be lifted well above the ground for transit to and from the place of use. Usually, the wings or blades of the removable snow ploughs are perpendicular to the direction of motion for pushing snow ahead to an out of the way location, but it is not uncommon for them to be at an angle for pushing the snow to one side or the other.

Such blades that are limited in length transversely of the vehicle for compliance with regulations as to overall dimensions of road vehicles and as to extent of projection beyond the vehicle structure, and to permit passage through restricted spaces such as between gateposts or trees. The consequence is that effective snow removal generally requires many more trips of the vehicle, and therefore at much greater expense than would be the case with longer snow plough blades on the same vehicle.

This problem has been dealt with in the past by equipping heavy vehicles specifically designed for snow removal with wings, blades or similar extensions which can be extended or retracted by a mechanism actuated from the driver's position, to suit the condition which may be encountered. For smaller vehicles, some use has been made of extensions, which can be bolted onto one or both ends of the snow plough blade when needed and stowed in the body of the vehicle when not needed. The former mechanized adjustment of width is quite expensive, and the latter is cumbersome and inconvenient because of the need for tools, the likelihood of loss of the nuts and bolts, and the problem of finding a satisfactory stowage location when the extensions are not being used. The consequence is that almost all snow removal is carried out with snow plough blades of a fixed length.

There are some snow ploughs that utilize blade or wing constructions that can be converted from their basic length to an extended length and vice versa. However, these snow ploughs are complicated and have additional parts compared to the traditional snow ploughs and thus the weight is increased. Also, they have hinge systems that are prone to torque power stress and thus must be enforced, which leads even more weight increase and more parts that are susceptible to damage during the snow removal process. The patent publication US7584557 discloses such a system. It presents a snow plough with scraper blades that have auxiliary wings or extensions. The snow plough is detachable and is driven by a suitable vehicle. The snow plough has hydraulically adjustable wing blades, each of which pivots under separate control around a main blade. Pins that support power cylinders between braces are arranged to enable each wing to extend through a range of motion from essentially perpendicular to and ahead of the main blade to essentially perpendicular to and behind the main blade. The pivot arrangement demands complicated hydraulic cylinder positioning. The patent publication US20040216333 discloses a snow plough comprising a pair of plough wings that are pivotally mounted at opposite ends of a center plough. Each of the plough wings may pivot between a forward-angled position and an aligned position. This is achieved with a multitude of levers and pivot arrangements. The complex structure is quite heavy and prone to malfunctions. Also, maintenance of such snow plough is slow and demands a lot of experience.

There is a clear need for a simple and reliable snow plough the width of which can be adjusted. BRIEF DESCRIPTION

The object of the invention is a solution that can significantly reduce the disadvantages and drawbacks of the prior art. In particular, the object of the invention is a solution where a width of a snow plough is adjustable.

The objects of the invention are attained with a snow plough that is characterised by what is stated in the independent patent claim. Some advantageous embodiments of the invention are disclosed in the dependent claims.

The invention is a snow plough comprising a frame, a snow plough blade and a wing moving arrangement. The snow plough blade comprises three sections: a middle blade section, a first wing section and a second wing section, and the sections have an upper edge and a lower edge. The middle blade section is fixed to the frame, and the wing moving arrangement is configured to move the first wing section and the second wing section in the direction of the plane of the middle blade section for the purpose of increasing and decreasing the width of the snow plough blade. The lower parts and upper parts are composed of different materials and the density of the material on the upper part is less than the density of the material on the lower part. At the outer ends of the first wing section and the second wing section are a first pivotal wing and a second pivotal wing.

When reference is made in the text to the upper or the lower parts or respective directions such as down or up, a situation is described in which the snow plough according to the invention is in use. Also, when reference is made to the vertical or horizontal directions or surfaces, the snow plough is placed similarly.

In one embodiment of the invention is a snow plough comprising a frame, a snow plough blade for pushing snow, a wing moving arrangement and a connecting arrangement for connecting the snow plough to a vehicle. The snow plough has a first end of the snow plough and a second end of the snow plough, and the snow plough blade is at the second end of the snow plough and the connecting arrangement is at the first end of the snow plough. The snow plough blade has an extended position and a retracted position and a first surface and a second surface. The second surface is a snow-pushing surface. The snow plough blade comprises three plate-like parallel sections: a middle blade section, a first wing section and a second wing section, and the sections have an upper edge and a lower edge and have corresponding first and second surfaces as the snow plough blade. The lower edges are configured to be held against the ground when pushing snow. The first wing section and the second wing section have outer ends and inner ends and the inner ends face each other. The middle blade section is fixed to the frame, and the wing moving arrangement is configured to move the first wing and the second wing in the direction of the plane of the middle blade section between the extended and the retracted positions. In one advantageous embodiment of the invention, the first wing and the second wing are in the retracted position at least partly behind the middle blade section, i.e. , the second surfaces of the first wing section and the second wing section face the first surface of the middle blade section. The snow plough further comprises a first pivotal wing, a second pivotal wing, and a pivotal wing moving arrangement, and the first pivotal wing is pivotally fixed to the outer end of the first wing section and the second pivotal wing is pivotally fixed to the outer end of the second wing section. The middle blade section, the first wing section and the second wing section each comprise a lower part and an upper part, and the lower edges of the sections are on the lower parts and the upper edges of the sections are on the upper parts. The lower parts and the upper parts are composed of different materials and the density of the material on the upper part is less than the density of the material on the lower part. The materials and sizes are configured in such a way that the centre of gravity of the snow plough blade is below the centreline of the snow plough blade, i.e. the centre of gravity is closer to the lower edge than to the upper edge.

In one embodiment of the snow plough, the middle blade section, the first wing section and the second wing section are flat plates. This feature makes the total length of the snow plough shorter.

In a second embodiment of the snow plough, the first wing section and the second wing section are in the same plane. This feature makes the total length of the snow plough shorter.

In a third embodiment of the snow plough, the snow plough comprises three platelike visors: a middle visor, a first visor and a second visor, and the middle visor is on the upper edge of the middle blade section, the first visor is on the upper edge of the first wing section and the second visor is on the upper edge of the second wing section, and the visors extend to the direction of the second end of the snow plough, and the first visor and the second visor are at least partly above the middle visor both in the extended position and the retracted position. The inventor has found out that these visors increase stability of the snow plough blade and at the same time prevent snow flying over the snow plough blade. In a fourth embodiment of the snow plough, the angle between the visors and the planes of the wings is between 70 and 180 degrees. The inventor has discovered that these are the most preferrable angles for stability and guiding snow and storing the snow plough. In some embodiments, the angle between the visors and the planes of the wings is between 90 and 135 degrees.

In a fifth embodiment of the snow plough, the material on the lower parts is metal and the material on the upper parts is plastic. These materials provide a good difference in density and make it easier to lower the level of the centre of gravity of the snow plough blade.

In a sixth embodiment of the snow plough, the heights of the lower parts are less than the heights of the upper parts. This feature improves the stability of the snow plough blade when using snow plough. Also, the weight of the snow plough blade is decreased, and the level of the centre of the gravity of the snow plough blade is kept below the centre line of the snow plough blade.

In a seventh embodiment of the snow plough, the first pivotal wing and the second pivotal wing comprise both a lower part of the pivotal wing and an upper part of the pivotal wing, and the lower parts of the pivotal wing and an upper parts of the pivotal wing are composed of different materials and the density of the material on the upper part of the pivotal wing is less than the density of the material on the lower part of the pivotal wing. This feature results in the same advantages to the pivotal wings as the corresponding structure in the wings.

In an eight embodiment of the snow plough, the wing moving arrangement comprises two hydraulic cylinders: a first hydraulic cylinder and a second hydraulic cylinder, and the hydraulic cylinders have a first end of hydraulic cylinder and a second end of the hydraulic cylinder, and the first ends of the hydraulic cylinders are fixed to the frame and the second ends of the hydraulic cylinders are fixed to the first wing section and the second wing section, and the longitudinal axis of the first hydraulic cylinder and the second hydraulic cylinder are parallel to the plane of the middle blade section. The inventor has discovered that this feature allows the construction of shorter snow plough structures. Also, this feature decrease torque forces between the cylinders and the wings. In a ninth embodiment of the snow plough, the second ends of the first hydraulic cylinder and the second hydraulic cylinder are fixed to the lower parts of the first wing section and the second wing section. This feature lowers the centre of gravity of the snow plough blade even further. In a tenth embodiment of the snow plough, the frame comprises a support arrangement comprising two elongated flat beams: a first beam and a second beam, and the beams have outer ends and inner ends, and the beams are positioned with their flat sides up, and longitudinal axis of the beams is parallel to the plane of the middle blade section, and the first beam is fixed to the first wing section and the second beam is fixed to the second wing section, and the beams and the first wing section and the second wing section are configured in such a way that when the first wing section and the second wing section are moving to the retracted position, one beam is sliding over the other beam, and the outer ends of the beams are fixed to the outer ends of the first wing section and the second wing section. This feature provides additional stability to the moving parts of the snow plough blade. Also, the centre of gravity of the snow plough blade is lowered even further.

In an eleventh embodiment of the snow plough, the pivotal wing moving arrangement comprises two hydraulic cylinders: a third hydraulic cylinder and a fourth hydraulic cylinder, and the third hydraulic cylinder is fixed to the first beam and the fourth hydraulic cylinder is fixed to the second beam, and the third hydraulic cylinder and the fourth hydraulic cylinder are parallel to the longitudinal axis of the beams.

In a twelfth embodiment of the snow plough, the first hydraulic cylinder and the second hydraulic cylinder are above the beams.

In a thirteenth embodiment of the snow plough, the pivotal wing moving arrangement is configured to turn the first pivotal wing and the second pivotal wing in the front of the middle blade section when the first wing section and the second wing section are in the retracted position.

In a fourteenth embodiment of the snow plough, the wing moving arrangement and the pivotal wing moving arrangement are configured in such a way that the first wing, the second wing, the first pivotal wing and the second pivotal wing are independently movable.

It is an advantage of the invention that it provides a snow plough that is easy to use and it is suited to different conditions and environments. Using the snow plough significantly improves the efficiency of removing snow. The invention also produces a snow plough that has no complex parts, so that it is easier to manufacture and maintain than snow ploughs according to known techniques.

One advantage of the invention is that it is easy to store, and it is light compared to the other snow ploughs, but still offers good stability. The lightness of the snow plough allows the use of smaller vehicles for pushing the snow plough. This saves fuel and reduces noise.

It is a further advantage of the invention that it can be easily optimized for different situations. Furthermore, scalability is good.

The invention also provides a snow plough that is wider than snow ploughs according to known techniques.

DESCRIPTIONS OF THE FIGURES

In the following, the invention is described in detail. The description refers to the accompanying drawings, in which

Figure 1 shows an example of a snow plough according to an embodiment,

Figure 2 shows the snow plough presented in Figure 1 as seen from above,

Figure 3 shows a second example of a snow plough according to an embodiment,

Figure 4 shows a third example of a snow plough according to an embodiment,

Figure 5 shows the snow plough presented in Figure 4 as seen from above,

Figure 6 shows the snow plough presented in Figure 4 as seen from behind and upwards, and

Figure 7 shows a fourth example of a snow plough according to an embodiment as cross-section.

DETAILED DESCRIPTIONS OF THE FIGURES

The embodiments in the following description are given as examples only and someone skilled in the art can carry out the basic idea of the invention also in some other way than what is described in the description. Though the description may refer to a certain embodiment or embodiments in several places, this does not mean that the reference would be directed towards only one described embodiment or that the described characteristic would be usable only in one described embodiment. The individual characteristics of two or more embodiments may be combined and new embodiments of the invention may thus be provided.

Figure 1 shows an embodiment of a snow plough 100 as seen from the front. The snow plough comprises a frame, a snow plough blade 101 , and a connecting arrangement for connecting the snow plough to a vehicle. The snow plough has a first end of the snow plough and a second end of the snow plough, and the connecting arrangement is at the first end of the snow plough. This means that the snow-pushing parts, in this case the snow plough blade, of the snow plough are at the second end of the snow plough. The width of the snow plough blade is adjustable, i.e. , the snow plough blade has an extended position and a retracted position.

The snow plough blade 101 is a flat structure and has a first surface and a second surface, and the second surface is a snow-pushing surface, i.e., the second surface is towards or on the second end of the snow plough. The snow plough blade comprises three plate-like parallel sections: a middle blade section 102, a first wing section 103 and a second wing section 104. The blade sections are flat or their vertical curvature is small, such as less than 5 degrees. The wings are configured to be movable in relation to each other by a wing moving arrangement. The wings have an upper edge 105 and a lower edge 106 and have corresponding first and second surfaces of the wings as the snow plough blade, i.e., the second surfaces of the wings are snow-pushing surfaces. The lower edges of the wings are configured to be held against or towards the ground when the snow plough 100 is used for pushing snow. The first wing section and the second wing section have outer ends and inner ends. The inner ends face each other. The middle blade section is fixed to the frame, and the wing moving arrangement is configured to move the first wing section and the second wing section in the direction of the plane of the middle blade section between the extended and the retracted positions of the snow plough blade. The middle blade section is therefore stationary and the first wing section and the second wing section are movable in relation to the middle blade section. When the first wing section and the second wing section are in the retracted position, they are at least partly behind the middle blade section, i.e., the second surfaces of the first wing section and the second wing sections face the first surface of the middle blade section. The first wing section and the second wing section do not overlap when the wing sections are in the retracted position. In the extended position, the first wing section and the second wing section are moved away as far as possible from the retracted position. The first wing section and the second wing section are in the same plane, i.e., their longitudinal axes coincide. The blade sections and the frame comprise structures to facilitate sliding, such as grooves and beam that keep the wings vertically at the same level when the first wing section and the second wing section are moved, preventing the wing sections from disengaging from each other. The first wing section and the second wing section are independently movable.

The middle blade section 102, the first wing section 103 and the second wing section 104 comprise each a lower part 110 and an upper part 111. In this embodiment, the lower parts and the upper parts are rectangular pieces that are fixed to each other in such a way that the connection line is horizontal, i.e., parallel to the upper and the lower edges. The lower edges of the blade sections are on the lower parts, and the upper edges of the wings are on the upper parts. The lower parts and the upper parts are composed of different materials and the density of the material on the upper part is less than the density of the material on the lower part, and the thicknesses of the upper parts and the lower parts are approximately same. This means that the centre of gravity is lowered below the horizontal centreline of the wings and at the same time below the centreline of the snow plough blade 101. In some embodiments, the heights of the lower parts are less than the heights of the upper parts. This lowers the centre of gravity even further. Having the centre of gravity below the centreline of the snow plough blade is beneficial because it keeps the lower edges 106 of the blade sections and the snow plough blade firmly against the ground when pushing snow. Also, it makes it possible to construct a lighter frame than the frames of usual snow ploughs, in addition to a lighter snow plough blade, because the fixing points between the frame and the snow plough blade can be positioned lower than in the known technique. In some embodiments, the fixing points between the frame and the snow plough blade is near the line of the centre of gravity, i.e., the line that is parallel to the edges of the blade sections and includes the centre of gravity. In some embodiments, the material of the lower parts is metal, and the material of the upper parts is plastic. In some embodiments, the metal is steel. In some embodiments, transparent plastic can be used at least for the upper part of the middle blade section for improving the view of the driver of the vehicle.

The snow plough 100 comprises three plate-like visors: a middle visor 112, a first visor 113 and a second visor 114, and the middle visor is at the upper edge 105 of the middle blade section 102, the first visor is on the upper edge of the first wing section 103 and the second visor is at the upper edge of the second wing section 104, and the visors extend to the direction of the second end of the snow plough, i.e., to the direction in which the snow is pushed. The first visor and the second visor are at least partly above the middle visor both in the extended position and the retracted position. The visors are both preventing snow from flying over the snow plough blade 101 and increasing the integrity of the snow plough blade. The material of the visors is advantageously the same material as that of the upper parts 1 11. Naturally, other materials can be used as long as the centre of gravity of the snow plough blade is below the centreline of the snow plough blade. In this embodiment, the visors are stationary and perpendicular to the planes of the blade sections, i.e., to the plane that is parallel to the surface of the blade section. In some embodiments, the visors are positioned at an angle that is in the range 90 to 135 degrees from the plane of the blade section. In some embodiments, the angle between the visor and the surface of the wing is adjustable by a visor moving arrangement. In some embodiments, the visor moving arrangement adjust the angle between the visor and the surface of the blade section from 70 degrees to 180 degrees.

The snow plough 100 further comprises a first pivotal wing 107, a second pivotal wing 108, and a pivotal wing moving arrangement 109. The pivotal wings have outer ends and inner ends. The inner end of the first pivotal wing is pivotally fixed to the outer end of the first wing section and the inner end of the second pivotal wing is pivotally fixed to the outer end of the second wing section. The pivot axis is parallel to the vertical level of the wing section onto which the pivotal wing is fixed. The pivotal wing moving arrangement is configured to turn the pivotal wings from 0 degrees (when the pivotal wing and the wing section onto which it is fixed are at the same level, i.e., they are parallel) to almost 180 degrees. In this case, the pivotal wing is at least folded over the wing section on which it is fixed and over the middle blade section 102, depending on the position of the wing section. In some embodiments, the construction of the pivotal wing moving arrangement may prevent 180- degree folding. The pivotal wing moving arrangement is configured to rotate the pivotal wings independently of the positions of the wing section onto which they are fixed. Also, the pivotal wings can be in different positions. Using the pivotal wings increases the maximum width of the snow plough blade when the wing sections are in the extended position. The first pivotal wing and the second pivotal wing comprise both a lower part of the pivotal wing 115 and an upper part of the pivotal wing 116. The lower parts of the pivotal wing and the upper parts of the pivotal wing are composed of different materials. The density of the material on the upper part of the pivotal wing is less than the density of the material on the lower part of the pivotal wing. Advantageously, the materials of the pivotal wings are the same materials as that of the wings, but there are embodiments where different materials may be used. For example, some lighter metal may be used. When the snow plough is used, the angle between may be vary between 0 and 90 degrees. The pivotal wings are used to further increase the width of the snow plough blade or to make sidewalls for the snow plough blade in order to gather snow in front of it. When the vehicle to which the snow plough is connected is moving to another workplace, the snow plough is moved to the retracted position and the pivotal wings are rotated in front of the middle blade section to minimize the width of the snow plough for improved safety. Also, this is the position in which to store the snow plough. In some embodiments, the pivotal wings, the first wing section and the second wing section are configured in such a way that they can be moved to a position where the outer ends of the pivotal wings make contact with each other and form a plough tip in front of the middle blade section 102. In that case, the snow plough 100 can be used as a conventional plough that has an angle in the plough blade.

Figure 1 shows the snow plough 100 in the extended position, i.e., the distance between the first wing 103 and the second wing 104 is maximised. The pivotal wings are placed in the parallel position to the wing sections. In this position the snow plough blade 101 is at its widest.

Figure 2 shows the snow plough 100 presented on Figure 1 as seen from above. The snow plough has a first end of the snow plough 217 and a second end of the snow plough 221. The snow plough comprise the frame 218 and a snow plough blade 101 , which comprises the middle blade section, the first wing section, the second wing section, the first pivotal wing 107 and the second pivotal wing 108. The pivotal wings are rotated by the pivotal wing moving arrangement 109. The snow plough further comprises three plate-like visors: the middle visor 112, the first visor 113 and the second visor 1 14, and the visors are fixed to the upper edge of the corresponding blade section.

The snow plough 100 comprises a wing moving arrangement. The wing moving arrangement comprises two hydraulic cylinders: a first hydraulic cylinder 219 and a second hydraulic cylinder 220. The hydraulic cylinders have a first end of hydraulic cylinder and a second end of the hydraulic cylinder. The first ends of the hydraulic cylinders are fixed to the frame 218 or to an extension placed on the first surface of the middle blade section. The connection point or points at the ends of the hydraulic cylinders are fixed onto the lower part of the middle blade section or onto the frame at the level of the lower part of the middle blade section. The first ends of the hydraulic cylinders are stationary in relation to the frame. The second end of the first hydraulic cylinder is fixed onto the first wing section and the second end of the second hydraulic cylinder is fixed to the second wing section. The second ends of the first hydraulic cylinder and the second hydraulic cylinder are fixed to the lower parts of the first wing section and the second wing section. The first wing section and the second wing section are moved by the first hydraulic cylinder and the second hydraulic cylinder correspondingly. The frame has some shapes, such as grooves or similar structures, to guide the movements of the first wing section and the second wing section and to keep them in the right position in relation to the middle blade section. The longitudinal axes of the first hydraulic cylinder and the second hydraulic cylinder are parallel to the plane of the middle blade section. This makes it possible to use a thinner structure for the snow plough, i.e. , the distance between the first end of the snow plough 217 and the second end of the snow plough 221 can be reduced compared to a conventional structure. Advantageously, the first hydraulic cylinder and the second hydraulic cylinder are positioned horizontally at the same level, i.e., the first ends and the second ends of the first and the second hydraulic cylinder are at the same level.

The frame 218 comprises a support arrangement comprising two elongated flat beams: a first beam 224 and a second beam 225. The beams have outer ends and inner ends, and the beams are positioned with their flat sides up. Longitudinal axis of the beams is parallel to the plane of the middle blade section. The beams are at the level of the lower parts of the blade sections. The first beam is fixed to the first wing section and the second beam is fixed to the second wing section. The beams and the first wing section and the second wing section are configured in such a way that when the first wing section and the second wing section are moving to the retracted position, one beam is sliding over another beam. The outer ends of the beams are fixed onto the outer ends of the first wing section and the second wing section or near them. In some embodiments, the first hydraulic cylinder and the second hydraulic cylinder are above the beams.

The pivotal wing moving arrangement 109 comprises two hydraulic cylinders: a third hydraulic cylinder 222 and a fourth hydraulic cylinder 223. The third hydraulic cylinder is configured to rotate the first pivotal wing 107 and the fourth hydraulic cylinder is configured to rotate the second pivotal wing 108. One end of the third hydraulic cylinder is fixed onto the first beam 224 and one end of the fourth hydraulic cylinder is fixed onto the second beam 225. Other ends of the third hydraulic cylinder and the fourth hydraulic cylinder are connected to the corresponding pivotal wings with a rotating arrangement that transforms the longitudinal movement of the hydraulic cylinder to a rotational movement of the pivotal wing. The connections of the ends of the hydraulic cylinder make it possible to move the pivotal wing to all positions of the wing section, either the first wing section or the second wing section. The rotating arrangement is configured in such a way that when the hydraulic cylinder is extended, the pivotal wing turns to the direction of the second end of the snow plough 221 , and when the hydraulic cylinder is retracted, the pivotal wing turns towards the level of the wings, i.e., the level of the snow plough blade. The third hydraulic cylinder and the fourth hydraulic cylinder are parallel to the longitudinal axes of the beams.

Figure 3 shows a second example of an embodiment of a snow plough 300. The snow plough has a first end of the snow plough and a second end of the snow plough. The snow plough comprises a frame 318 and a snow plough blade, which comprises a middle blade section 302, a first wing section, a second wing section, a first pivotal wing 307 and a second pivotal wing 308. Each said blade section has an upper edge and a lower edge. The pivotal wings are rotated by the pivotal wing moving arrangement 309. The snow plough further comprises three plate-like visors: the middle visor 312, the first visor 313 and the second visor 314, and the visors are fixed to the upper edges of the corresponding blade sections. The blade sections and the pivotal wings comprise upper parts 311 and lower parts 310 of the blade sections and upper parts 316 and lower parts 315 of the pivotal wings. The blade sections and the pivotal wings are divided horizontally into said parts, and the heights of the upper parts are higher than the heights of the lower parts. The lower parts and the upper parts are composed of different materials and the density of the material on the upper part is less than the density of the material on the lower part. In this embodiment, the snow plough further comprises an additional ploughing blade 326 for each blade section and pivot wing. The additional ploughing blades are platelike objects and are fixed to the lower parts in such a way that the lower edge of the additional ploughing blade forms at least a part of the lower edge of the snow plough blade. The additional ploughing blades are for improving the snow removal process. The lengths of the additional ploughing blades correspond to the lengths of the blade sections that they are fixed to. In some embodiments, the additional ploughing blades are used only on some blade sections. For example, in some embodiment, the snow plough comprises one additional ploughing blade that is fixed to the middle blade section.

The snow plough 300 presented in Figure 3 is in the retracted position, i.e., the first wing section and the second wing section are behind the middle blade section 302. The first pivotal wing 307 and the second pivotal wing 308 are rotated inwards from the plane that the first, the second and the middle blade section form. Figure 4 shows a third embodiment of a snow plough 400. The snow plough comprises a frame and a snow plough blade. The snow plough blade comprises a middle blade section, a first wing section, a second wing section, a first pivotal wing 407, a second pivotal wing 408 and a pivotal wing moving arrangement 409. The blade sections have upper edges and lower edges 406. The blade sections are divided into upper parts and lower parts as was described earlier. In Figure 4 the first wing section and the second wing section are in the retracted position where they are behind the middle blade section. The first pivotal wing and the second pivotal wing are folded in front of the middle blade section in such a way that the pivotal wings are overlapping. To make this possible the lengths of the pivotal wings should be shorter than the length of the middle blade section. In some embodiments, the pivotal wing moving arrangement is configured in such a way that one pivotal wing is folded first over the middle blade section and then another pivotal wing is folded over the previously folded pivotal wing. Advantageously, this is done in such a way that, when folded, both pivotal wings are at least approximately parallel to the plane of the middle blade section. By approximately it is mean that maximum deviation is 10 degrees.

Figure 5 shows the snow plough 400 in the same position as was shown in Figure 4, but it is now seen from above. The snow plough comprises a wing moving arrangement and a pivot wing moving arrangement 409.

The wing moving arrangement comprises two hydraulic cylinders: a first hydraulic cylinder 419 and a second hydraulic cylinder 420. One end of the hydraulic cylinder and another end is fixed onto the first or the second wing section. In this example, the hydraulic cylinders have pulled the first wing section and the second wing section into the retracted position, behind the middle blade section. When the hydraulic cylinders are extended, they push the first wing section and the second wing section towards the extended position and, at the same time, move the pivotal wings and pivotal wing moving arrangement together with the first wing section and the second wing section.

The pivotal wing moving arrangement 409 comprises two hydraulic cylinders: a third hydraulic cylinder 422, a fourth hydraulic cylinder 423 and a rotating arrangement. In this example, the hydraulic cylinders have pushed the rotating arrangement that have turned the pivotal wings to the front of the middle blade section.

Figure 6 shows the snow plough 400 in the same position as was shown in Figure 4, but it is now seen diagonally from behind. The frame 418 slopes towards the snow plough blade, and the frame is fixed onto the middle blade section, and more accurately, the frame is fixed onto the lower part of the middle blade section. This kind of frame structure is significantly lighter than conventional snow plough frames. Also, the centre of gravity of the frame is situated lower than in conventional snow ploughs. The inventor has discovered that contrary to common belief, lightening of the structure of the snow plough does not worsen the efficiency of the snow plough.

Figure 7 shows a fourth embodiment of a snow plough 700 as seen as a longitudinal cross-section. The snow plough comprises a frame 718 and a snow plough blade comprising a middle blade section 702. Also, the snow plough blade comprises a first wing section and a second wing section and a first pivotal wing and a second pivotal wing. The wing sections are divided into horizontally upper parts and lower parts 710. Said wing sections function as described earlier. The snow plough has a first end of snow plough 717 and a second end of snow plough 721 .

The frame 718 comprises a support arrangement comprising two elongated flat beams: a first beam 724 and a second beam 725. The beams have outer ends and inner ends, and the beams are positioned with their flat sides up. Longitudinal axes of the beams are parallel to the plane of the middle blade section. The beams are at the level of the lower parts of the blade sections, and one beam is over another beam, i.e. , they overlap. The first beam is fixed onto the first wing section and the second beam is fixed onto the second wing section, i.e., the beams support the first and the second wing section. The pivotal wing moving arrangements are fixed onto the first wing section and the second wing section in such a way that when the first wing section or the second wing section is moved, the pivotal wing moving arrangement moves together with the wing. Thus, the position of the pivotal wing in relation to the middle blade section can be changed.

The shape of the cross-section of the frame 718 roughly resembles an orthogonal triangle. The frame is highest at the first end of the snow plough 717. The frame 718 comprises a connecting arrangement 728 at the first end of the snow plough 717 for connecting the snow plough 700 to a vehicle. The frame further comprises a fixing arrangement 727. The fixing arrangement is for joining the snow plough blade and the frame together. The fixing arrangement is fixed onto the lower part 710 of the middle blade section 702. In some embodiments, the level of the fixing points is at the level of the level of the centre of gravity of the snow plough blade or near it. In the example shown in Figure 7, the fixing arrangement is a plate-like structure comprising one or more plates. The plates are positioned in such a way that they do not block the movements of the first wing section and the second wing section. In this embodiment, the plates comprise a recess or recesses for the first beam 724 and the second beam 725. The recess or recesses are open towards the first end of the snow plough.

Some advantageous embodiments of the snow plough according to the invention have been described above. The invention is however not limited to the embodiments described above, but the inventive idea can be applied in numerous ways within the scope of the claims.