The present invention relates to a vehicle-mounted lift arm assembly according to the introduction to claim 1. The invention concerns, in particular, a lift arm assembly of the type that, in the form of an accessory through what is known as a rapid attachment, is intended to be attached to the free end of a moving arm on a vehicle such as a loader, tractor or similar.

Scrapers, excavators, buckets and similar tools mounted onto an arm that can be moved in a vertical plane on a vehicle, for example a tractor, in order to scrape snow at the edge of a carriageway have limited range due to the arm as such being able to move only in the said vertical plane. The limited range means that it is normally possible to use the tool only in a region of the carriageway that is located immediately in front of the vehicle. In order to be able to scrape snow beyond or on the opposite side of a protective rail, posts or similar obstacles, providing the mobile arm of the vehicle with an accessory of some form is known. Such an accessory is like a supplementary arm section or an extension attached to the existing mobile arm of the vehicle with the task of improving the range and manoeuvrability of the existing arm.

For scraping at the side of the carriageway, it has until now been necessary to use various types of special vehicle, whereby an arm is attached to the chassis or frame of the vehicle, which arm has been given the mobility and manoeuvrability that are required in order to carry out work at the side of the carriageway shoulder. An example of such a vehicle is known from EP 1759571 A1 , whereby an arm is mounted at the front of this vehicle, the manoeuvrability of which is so extensive that the arm can essentially be compared with a conventional crane arm. This crane arm includes principally a crane arm supported on a frame that is mounted to pivot on the vehicle. This crane arm is similar to a crane built up from a number of arm sections arranged in a jointed manner after each other, with a drop arm directed upwards first from the frame and subsequently two lift arms, whereby the outermost of these two lift arms is provided with a tool. The crane arm that is formed from the crane parts can be pivoted in the horizontal plane and the arm sections are mutually mobile in the vertical plane through the influence of piston-cylinder units that act between the arm sections. By setting the arm in a V configuration to a condition in which the drop arm points upwards from the vehicle and the two lift arms point downwards, the arm is given a swan- neck form that allows a tool attached to the end of the arm to work at the side of the road, while obstacles such as protective rails and posts can at the same time pass under the arm.

The purpose of the present invention is to achieve a lift arm assembly of the type that, in the form of an accessory, is intended through a rapid attachment to be attached to the free end of a mobile arm section of a vehicle such as a loader, tractor or similar and that significantly facilitates operations during work at the side of a carriageway, on the outside of a protective rail, that makes it easier for the driver of the vehicle to avoid collisions with obstacles along the carriageway or road.

This purpose of the invention is achieved through a lift arm assembly that has been given the distinctive features and characteristics specified in claim 1.

An embodiment of the invention will be described below in more detail with reference to the attached drawings, of which:

Figure 1 shows a side view of a lift arm assembly according to the invention, seen obliquely from behind and in a condition in which it is not attached to a loader,

Figure 2 shows a side view from behind of the lift arm assembly according to Figure

1 mounted on a mobile arm on a vehicle and in use during excavation work at the side of a carriageway,

Figure 3 shows a side view of the lift arm assembly corresponding to Figure 2, but in this case seen obliquely from the front,

Figure 4 shows a view from above of a part of an attachment means that is a component of the lift arm assembly for mounting onto the mobile arm of the vehicle,

Figure 5 shows a side view of the lift arm assembly corresponding to Figure 1 , in an alternative design.

Figure 1 shows a lift arm assembly according to the invention intended to be carried as an accessory at the free end of a mobile arm section A on a loader B or tractor. Also Figures 2 and 3 are referred to in order to illustrate this. The lift arm assembly is shown in Figure 1 for purposes of clarity in a condition in which it is not attached to the loader. The lift arm assembly comprises a support arm 1 , 2, 3 designed as one unit that is provided at one end with an attachment part 5, a rapid attachment, with the aid of which it is intended that the support arm be attached, in a manner that allows it to be removed, with the free end of the mobile arm section A of the loader B, and a second end at which it is intended that the support arm carry a tool 4. A first 6 and a second 7 pivot including power cylinders (not shown) allow the support arm and the supported tool 4, respectively, (the tool in this case being a bucket that is extended in a sideways direction, or a broad bucket) to pivot independently of each other in the horizontal plane around a first 6' and a second T axial line, respectively, relative to the mobile arm section A of the loader B. The tool 4 is attached at the free end of the support arm 1 , 2, 3. The pivots 7, 8 make it possible to turn the tool 4 around the vertical axis T and to tilt the tool upwards and downwards by pivoting it around a horizontal axis 7". The horizontal axis 7" of the tool 4 is perpendicular to the said vertical axis 7'. By tilting the tool 4 upwards and downwards, the height or the level between the forward edge of the tool relative to a support or to a ground level can be regulated. The support arm 1 , 2, 3 extends outwards from the attachment part 5 forwards in the direction of travel of the vehicle, and which support arm is formed from linear first 1 and second 3 extended sections attached to each other, which sections have the form of a V relative to each other and pass the one into the other through a relatively short horizontal transition section 2 located in an upper part of the support arm, also which transition section is linear. The first section 1 extends at an angle obliquely upwards from the horizontal plane while the second section 3 extends essentially at a right angle, down towards the horizontal plane from the transition section 2. The angles between each one of the said sections 1, 2, 3 are fixed. The second section 3 extends essentially vertically downwards from the transition section 2 and it is intended that it should be positioned to have its forward end, which supports the tool 4, just above the support. The angle between the transition section 2 and the second extended section 3 is approximately 90°, and fixed. The first section 1 extends in a horizontal plane upwards from the end of the mobile arm of the loader at an angle a, which is selected to be in the interval 30-70°, but which is preferably approximately 45°.

Figures 2 and 3 show the lift arm assembly mounted on a loader B seen from the back and from the front, respectively, during the execution of scraping with the tool 4 at the side of a carriageway C, and extending over a protective rail 9. Due to the fact that the support arm 1 , 2, 3 of the lift assembly demonstrates a swan-neck form, the loader B can be driven parallel to the barrier while at the same time the first pivot 6 and its vertical axis 6' make it possible to allow the support arm 1 , 2, 3 to extend obliquely to the side from the loader B in its forward direction of travel. The essentially swan-neck formed support arm 1 , 2, 3 thus extends over the protective rail 9, whereby the first section 1 of the lift assembly extends outwards from the mobile arm A of the loader B at an angle obliquely upwards from the horizontal plane, while the second section 3 extends at essentially a right angle downwards towards the horizontal plane from the transition section 2. Careful study of Figure 2 will show with desired clarity how the transition section 2 of the arm extends horizontally a certain distance above the protective rail 9.

A typical field of use for the lift arm assembly and its attached tool 4 is to scrape snow away from the carriageway shoulder immediately beyond the protective rail 9, seen from the carriageway C. The purpose of this is to increase visibility for drivers since high snow walls immediately adjacent to the road often limit the view at curves. It is, however, also a purpose of this operation to prepare space for further snow that is to be scraped from the carriageway. It is, therefore, important that the tool 4 obtain access immediately beyond the protective rail 9 and this is achieved through the swan-neck form of the support arm, where the third section 2 of the support arm extends straight downwards. The three sections 1 , 2, 3 of the support arm are mutually essentially V-formed and the arm has been given such dimensions that it is able to extend over the greatest height that obstacles immediately adjacent to the carriageway demonstrate, i.e. the heights of common protective rails 9 and roadsigns. The transition section 2 of the support arm 1 , 2, 3 extends horizontally and leaves space for the arrangement to pass over objects that are broader than a protective rail 9, and it allows the driver a certain degree of freedom of movement or leeway for the loader, without risking collision of any part of the support arm with the protective rail 9 or other obstacles along the carriageway C.

The attachment part 5 of the lift arm assembly is shown in Figure 4, seen from above. The attachment part 5 has a suspension arrangement 20 for the attachment of the free end of a mobile arm section A of the loader B in a manner that allows it to be released. The suspension arrangement 20 is formed as one unit and comprises in a known manner to side pieces 21 arranged at a distance from each other that have the form of hooks 22 at their upper parts. These can be lowered down into corresponding openings or recesses formed in an attachment part arranged at the free end of the mobile arm A that supports the tool (not shown). As has been mentioned above, the attachment part 5 has a first pivot 6 that allows the support arm 1 , 2, 3 of the lift arm assembly, and thus also the tool 4, to pivot in the horizontal plane around a first vertical axis line 6' relative to the mobile arm A of the loader B. The reference number 24 denotes a number of support legs that can be lowered, onto which a lift arm assembly can be placed to rest when it is unattached to the mobile arm A of the loader B. The support legs 24 are arranged in tubes and can be telescopically set at different fixed vertical positions in the tubes, such that the support legs extend a certain distance down from the lower edge of the attachment part 5. A foot 25 is located at the bottom end of each support leg 24, which foot distributes the weight over a larger area.

The lift arm assembly is shown in an alternative design in Figure 5 whereby the support arm formed from the attached sections 1, 2, 3 is designed as a single unitary swan- neck shaped form, with rounded gentle curves and lacking sharp transition radii. The risk of stress concentration between the sections 1, 2, 3 is reduced by such an arm without fixed bend points between straight sections, and loads that arise are distributed more evenly over the complete arm.