Such cutting devices are used on ploughs for instance for working of roadways and are known in the market. The known devices, however, are connected with some problems regarding the result when ploughing. Firstly, the ability of turning away for an obstacle has the consequence that the fastening of the cutting device to the appliance becomes complicated. Secondly, known devices have a bad flexibility towards the ground.

The purpose of this invention is to remove the problems with known technique and offer a device which has an uncomplica¬ ted construction, relatively spoken, and which is so made the cutting device has a very good flexibility towards the ground, for instance a roadway. This purpose has been achieved by the fact that the cutting device has the characterizing features mentioned in the claims.

A preferred embodiment of the invention shall be described more closely with reference to the accompanying drawings, where Fig. 1 shows a perspective view of a device according to the invention, where the cutting device according to invention in a working position is fastened to an appliance, Fiσ. 2 shows the device according to Fig. 1 but where a section of the cutting device has been taken a position which is turned away, i.e. a position which is taken when the cutting section comes into contact with an obstacle, Fig. 3 shows a cross-section through the cutting device and its fastening device in the appliance, and Fig. 4 shows a detailed construction of the device making the revolution of the sections of the cutting device possible. Referring to Figs. 1 and 2 is shown there the cutting device l and the appliance 2 on which the cutting device is fastened. According to the invention the cutting device comprises a plurality of sections 3, 4, 5, each section comprising a

cutting blade 6, 7, 8. Each cutting blade is detachably fastened on a cutting blade holder 9, 10, 11 comprising a plate with a length, which essentially corresponds to the length of the cutting blade. On the rear side of the plate 9 there are arranged two projections 12, 13, which are directed rearwards and placed at a distance from each other. These two projections 12 , 13 are intended to be stationarily mounted to the ends of an essentially horizontal bar 14, the longitudinal direction of which is essentially parallel with the longitudinal direction of the cutting device 1 in such a way that the cutting blade holder 9 with the cutting blade 6 can be pivoted from a position, where they are directed obliquely forwards (see Fig. 1) to a position where they are directed obliquely backwards (see Fig. 2) . The bar 14 connects the fore ends of two parallel arms 15, 16,. which in normal position are essentially horizontal. In this connection the distance between the arms are essentially the same as the length of the bar 14, and this distance is less than the length of the cutting blade 6 and the plate 9.

The rear ends of the arms 15, 16 are articulately fastened to a bridge 17, the arms 15, 16 being able to be pivoted about an essentially horizontal axis X, the direction of which is essen¬ tially parallel with the longitudinal direction of the bar 14.

The bridge 17 comprises two side portions 18, 19, which at the front/at the top are connected by an angle-ironlike bar 20, the length of which is larger than the distance between the side portions 18, 19 and corresponds essentially to the length of the cutting blade 6 and the cutting blade holder 9. In this connec¬ tion the bar 20 is so arranged that the point of the angle is directed forwards. The side portions 18, 19 are at the front/at the bottom connected by a plate-like bar 21. At the middle portion of the bridge 17 there is fastened an essentially horizontal sleeve-formed dowel 22 between the bars 20, 21. In this connection the dowel 22 extends backwards and is intended to be inserted into an essentially horizontal sleeve-formed means 23, in relation to which the dowel 22 and by that the bridge 17 shall be able to be pivoted about an imaginary, essentially horizontal axis Z. The means 23, which in a suitable way is fastened to the appliance 1 has at the front a rectangle-like,

essentially vertical plate 24. In this plate on each side at the bottom are made recesses 25, 26, which give space for the side portions 18, 19 of the bridge. This space is so large that the bridge 17 can be pivoted in a counter-clockwise direction and in a clockwise direction ca. 3,5°. Due to the fact that the cutting blade 6 and the cutting blade holder 9 are arranged on the means comprising the bar 14 and the arms 15, 16 which arms as has been mentioned above are articulately fastened on the bridge 17, also the cutting blade/cutting blade holder will be able to pivot about the imaginary horizontal axis Z. When pivoting the cutting blade 6/cutting blade holder 9 about the axis Z there is a slide against the bar 20 of the bridge 17. This means that the diffe¬ rent cutting sections 3, 4, 5 can be pivoted in relation to each other which gives the cutting device an essentially increased flexibility towards the roadway. This is of course of extremely great value when planing uneven and humped-backed roads.

As has been previously mentioned the cutting blade 6 and the cutting blade holder 9 can be pivoted from a normal position, where they are directed obliquely backwards. This has been made possible partly by the fact that the cutting blade/cutting blade holder are pivotally arranged on the bar 14 in the means which besides this one also comprises the arms 15, 16, and partly by the fact that the mentioned arms 15, 16 are pivotally fastened on the bridge 17. Of course there is a requirement on such devices like this invention that the cutting device automatically shall be able to return to the obliquely downwards/forwards directed normal position after having passed the obstacle.

According to this invention this has been made possible by a spring means 27 (see Fig. 3) , which is arranged behind the sleeve-formed means 23. In this connection the spring means 27 comprises a plastic or rubber element which is arranged on a bolt-like means 28, the head 29 of which is intended to cooperate with a insert means 30, which is displaceably arranged forwards and backwards inside the sleeve-formed means 23. The bolt means 28 penetrates a first washer 31 which is stationarily fastened in the rear portion of the means 23.

Furthermore, a second washer is stationarily fastened at

the rear portion of the bolt means 28. Between the washers 31, 32 is the spring element 27 arranged and is accordingly intended to be compressed during the motion forwards of the insert means 30 and the bolt means 28. This motion is brought about according to 5. this embodiment by means of a steel chain 33, the one end 34 of which is fastened in a groove 38 on the top side of the dowel 22 inside the sleeve-formed means 23. The steel chain 33 which suitably is centrally arranged within the sleeve 23 goes round a first gear wheel 35 which is rotatably fastened to the insert 0 means 30 in the rear part of the sleeve 23. The chain 33 further goes via a second gear wheel 36 which is rotatably fastened in the fore portion of the sleeve 23, through the dowel 22 and out via this one to the upper portion of the cutting blade holder 9, where the second end 37 of the chain is fastened. Of course, the steel chain can be exchanged with a band, wire or another chain. The device functions in the following way: During work the cutting device normally takes the position shown in Fig. 1. When running into an obstacle, the cutting blade 6 and the cutting blade holder 9 begin to pivot about the shaft 14 in order at last to take the position shown in Fig. 2. At the same time as the pivoting movement about the essentially horizon¬ tal shaft 14 is begins, the arms 15, 16 essentially horizontal in normal position begin to pivot about the imaginary, essentially horizontal axis X which extends essentially perpendicular to the longitudinal direction of the arms 15, 16. When the cutting blade 6 and the cutting blade holder 9 begin to pivot about the shaft 14, the steel chain 33 begins to be pulled out of the sleeve- formed means 23, the first gear wheel 35 and the insert means 30 being pulled forwards towards the second gear wheel 36. This movement is made against the action of the spring means 27, where the resilience element is compressed more and more the longer forwards the insert means 30 is forced. When the cutting device and the appliance have passed the obstacle, there is a return to the normal position. This is made possible by the fact that the spring means 27 pulls the insert means 30 and the first gear wheel 35 backwards, whereby the chain 33 is pulled into the sleeve-formed means 23. In this connection the upper part of the cutting blade/cutting blade holder is forced backwards, whereas

the lower portion of these ones has been forced forwards until the normal position has been taken. In the text the expression appliance has been used. With appliance is ment for instance ploughs and the like which can be provided with the cutting de- vice according to the invention.

The invention is of course not limited to the mentioned embodiment but can be modified within the scope of the following claims. Thus, for instance a spring means may comprise a screw spring or a gas spring. Furthermore, the number of sections of the cutting device can of course be more than the three ones which have been shown in accordance to this embodiment.