Field of the invention The solution to be presented relates to a boom equipped with guide tracks. The solution to be presented relates to a boom to be fastened to a work machine, whereby implements, such as earth drilling equipment and hammering devices for piles, pipes or profiles, can be fastened and supported to the guide tracks, to be movable on the guide tracks.

Background of the invention

A boom according to the preamble above is known from patent publication GB 2133821 . This document discloses a mast connected to an excavator and equipped with guide tracks, controlling auger-type earth drilling equipment for performing substantially vertical earth drilling. During the boring, the drill is driven into the soil by its own weight and by the rotation of the spiral of the drill, the rotation tending to drive the drilling device deeper into the hole. For hoisting and also supporting the drilling device under the control of the mast, a steel cable conveyed via the top of the mast is applied, which is released according to the need to allow the drilling device to go down under the control of the mast; and in a corresponding way, the steel cable is wound up to withdraw the drilling device. The arrangement used for moving a drilling device of the above described type has the disadvantage of the single action of the hoisting device. The drilling device can only be hoisted or supported, and its going down and the progress of the drilling is effected by its own weight. In transport position and during installation of the implements, when the mast is in the horizontal posi- tion, the drilling device can be moved by its own hoisting device in one direction only.

Brief summary of the invention For eliminating these drawbacks, a solution has been developed for a boom equipped with guide tracks, by which the above presented problems are solved and a substantial improvement is achieved in working with earth drilling equipment and hammering devices.

The boom equipped with guide tracks according to the solution is presented in claim 1 .

In the boom according to the solution, a fastening element for said implements is provided, which is movable on said guide tracks by means of a pulling member, e.g. a steel cable, in such a way that a rope drum rotatable by a motor is provided at the first end of the boom, and an idler is provided at the second end of the boom, the pulling member extending via them both, whereby by selecting the direction of rotation of said rope drum, the fastening element can be moved in either direction, and that the rope drum is mounted as an extension to the boom at the first end of the boom.

The advantage of the solution is that the fastening element, to which the movable implements are connected, can be moved in either direction by a power unit, whereby the movement of driving the implement is controlled under all circumstances. The length of the driving movement may be almost equal to the length of the boom, which is difficult to achieve by means of hydraulic cylinders. When a rope drum and an assembly of steel cables are used for implementing the movements, these increase the total weight of the structure very little. In an example of the solution, two pulling members are provided, one end of each being connected to the rope drum and the other end being connected to the fastening element, while one of the pulling members is guided via an idler. In an example of the solution, at least one end of the pulling member is connected to the fastening element by a spring so that the spring causes a tension in the pulling member.

In an example of the solution, the incoming position of the pulling member on the surface of the rope drum is configured to be shifted in a direction that reduces the angle error of the pulling member when the rope drum is rotated in such a way that the fastening element approaches the rope drum.

Brief description of the drawings

In the following, the solution will be described in more detail with reference to the appended drawings, in which

Fig. 1 shows a boom equipped with guide tracks according to an example of the solution, to be connected to a work machine, seen in a side view.

Fig. 2 shows the boom of Fig. 1 in a diagonal front view.

Fig. 3 shows the boom of Fig. 1 in a diagonal rear view.

Fig. 4 shows a section of Fig. 2 in an enlarged view. Fig. 5 shows another section of Fig. 2 in an enlarged view. Fig. 6 shows the lower part of the boom in a front view. Detailed description of embodiments of the invention

Figure 1 shows a boom 2 according to an example of the solution, mounted on an excavator 1 by a mounting piece 3 and shown in a vertical position.

The boom 2 comprises guide tracks for moving the mounting piece 3 to different locations on the boom 2 in a controlled manner. At the lower end of the boom 2, an auxiliary frame 5 is provided for supporting a rope drum 6 placed at the lower end of the boom 2 and a leg 1 1 supported to the ground. On the opposite side of the boom 2, guide tracks are also provided, on which a fastening element 4 for implements is movable in a controlled manner. For moving the fastening element 4, pulling members are used, such as steel ropes 8, whose ends are brought to the fastening element 4 directly from the rope drum 6 as well as via an idler 7. Figures 2 and 3 show the boom 2 in diagonal views. The rope drum 6 and a hydraulic motor 10 for rotating the same are fitted in the auxiliary frame 5 arranged as an extension to the boom 2 at its lower end. The mounting piece 3 for mounting on the work machine 1 is provided with lateral turning implemented by hydraulic cylinders 15. The position of the mounting piece on the boom 2 can be shifted, as said piece is also supported on guide tracks 9 which are thus provided on both the front and the rear sides of the boom. The pulling member, such as the steel rope 8' between the idler 7 and the rope drum 6 in Fig. 3, extends outside the boom profile.

Figures 4 and 5 show the fastening of the pulling members, in this case the steel ropes 8, 8', to the fastening element 4 in more detail. The ends of the steel ropes 8, 8' are fixed in a wedge clamp 13, from which a force is transmitted via a threaded metal rod 16 to the fastening element 4.

A nut on said threaded rod is used to adjust the tension of the pulling member as needed. A spring 14 is placed between the nut and a counter-flange of the fastening element 4, and tightened to be short when installed, in order to maintain a sufficient tension in the pulling member even if the pulling member yielded to some extent. Said springs 14 are also needed because the initial points of the steel ropes 8, 8' on the surface of the drum are shifted as the drum rotates, and the directions of the steel ropes are then slightly changed, causing changes in the rope lengths needed. Figure 5 shows a more detailed view of the arrangement of the rope drum 6 as an extension to the boom 2. The end of the steel rope 8 is fixed inside the rope drum 6, approximately at the mid-point of the drum, for example by inserting it in the drum through an opening in the surface of the drum and by locking this end inside the drum to rotate with the drum. The same is done to the end of the steel rope 8' extending from the rope drum 6 to the idler 7, by locking it to the rope drum 6. Running grooves are provided for the steel rope 8 on the right half of the surface of the rope drum 6, and for the steel rope 8' on the left half of the surface of the rope drum 6. When the fastening element 4 is pulled closer to the rope drum 6 by the steel rope 8, the steel rope 8 moves to the right on the surface of the drum, whereby the direction of the steel rope 8 is changed and the angle error of the pulling line is decreased with respect to the fastening point in the fastening element 4 shown in Fig. 4. This is particularly important when the fastening element 4 comes close to the rope drum 6.

When the steel rope 8' is guided from the rope drum 6 to the idler 7 and further to the fastening element 4, hardly any angle errors occur in the pulling line. Figure 6 illustrates the diagonal direction of the steel rope 8 in this position of the fastening element 4. The angle error decreases when the fastening element 4 is pulled closer to the rope drum 6. A pipe 12 is a pressure line connected to a hydraulic motor 10 provided for rotating the rope drum 6. The invention is not limited solely to the above presented embodiments, examples or variants of the boom according to the solution, but it can be modified within the scope defined in the appended claims.