EP2134157A1

EP2134157A1 - Stump harvester

Info

Publication number: EP2134157A1
Application number: EP08724194A
Authority: EP
Inventors: Sven-Åke GUSTAVSSON
Original assignee: Durban AB
Current assignee: CeDe Group AB
Priority date: 2007-03-06
Filing date: 2008-03-05
Publication date: 2009-12-23
Also published as: SE531782C2; WO2008108733A1; SE0700564L

Abstract

A method of harvesting stumps by means of a stump harvester comprises the steps: that a gripping device (30) is connected to the stump harvester (20) by means of a quick coupling; that the gripping device (30) is positioned above a stump (42); that the gripping device (30) is opened by moving apart a cutting jaw (33) and a counter jaw (34) of the gripping device (30); that the gripping device (30) is rotated about an axis of rotation into an operative position; that the stump (42) is treated by the gripping device (30), the stump (42) being gripped and cut by moving the cutting jaw and counter jaw towards each other; and that the treated stump (42) is at least partially removed from the plant area.

Description

STUMP HARVESTER

Technical Field

The present invention relates to a method of harvesting stumps, and it also concerns a stump harvester and a gripping device for stump harvesting.

Background Art

There is an increasing demand for equipment intended for handling and treat- ment of stumps. Basically, there are two reasons for this: the increasing lack of fibre plant and the high content of energy in the stumps. In addition, removal of stumps also provides better conditions for planting of new trees, and the risk of rot and damages by noxious insects (for instance pine weevil) is reduced.

Methods used at present for the treatment of stumps are, for instance, cutting and reaping.

US-A-5179985 discloses a stump harvester which is mounted to a standard excavator. The stump harvester has two jaws which grip and pull out the stumps. One of the jaws serves as a knife which - when large stumps are handled - cuts these into pieces before they are pulled out of the ground. SE-B-443699 discloses another known apparatus for the treatment of stumps.

This apparatus is also mounted to an excavator.

However, both these known apparatuses have certain drawbacks. The radius within which they operate is limited, which means that the excavator has to be moved each time a stump is to be cut from a different direction. Furthermore, the apparatus disclosed in US-A-5179985 is attached to the bucket arm of the excavator in a complex manner, and it takes much time to bring the stump harvester into its operative mode.

Summary of the Invention

An object of the present invention is to improve the prior art described above.

A specific object of the present invention is to provide a method of harvesting stumps which preserves the ground from unnecessary damage and which requires less energy.

These objects are achieved by the present invention by a method of harvesting stumps by means of a stump harvester, comprising the steps: (a) that a gripping device is connected to the stump harvester by means of a quick coupling, (b) that the gripping device is positioned above a stump, (c) that the gripping device is opened by moving apart a cutting jaw and a counter jaw of the gripping device, (d) that the gripping device is rotated about an axis of rotation to an operative position, (e) that the stump is treated by the gripping device, the stump being gripped and cut by bringing the cutting jaw and the counter jaw closer together, and (f) that the treated stump is at least partially removed from the ground. Hereby the stumps can be treated efficiently in a simple and energy-saving manner.

In step (b) the gripping device may be positioned above the stump by movement of a bucket arm of the stump harvester, the gripping device being attached to an end of the bucket arm and the other end of the bucket arm being attached to the stump harvester, the movement of the bucket arm being carried out by radial movement of the same outward from the other end. This is advantageous since the gripping device is moved by means of standard equipment on the stump harvester.

The opening of the gripping device according to step (c) may be carried out by movement of the cutting jaw away from the counter jaw, the cutting jaw being articu- lated on the gripping device and the counter jaw being secured to the gripping device, which is advantageous in that only one of the jaws has to be moveable.

The steps (c)-(e) may be repeated at least one time, which has the advantage that the stump is cut into several pieces which thereby are more easy to handle.

The steps (b)-(f) may be repeated without any movement of the stump har- vester, wherein a new stump is harvested during each repeated cycle. This is advantageous in that the fuel consumption is kept low.

A gripping device for use in harvesting stumps is achieved in accordance with a second aspect of the invention. The gripping device comprises means for mounting of the gripping device to a stump harvester, a cutting jaw and a counter jaw for gripping and cutting of a stump, an intermediate member configured to connect the mounting means to the counter jaw and the cutting jaw, and means for moving the cutting jaw and the counter jaw between an open position and a closed position. The mounting means of the gripping device comprise a quick coupling, and the intermediate member comprises a rotatable turning ring. This structure is advantageous in that stumps can be cut effi- ciently and in that the gripping device can easily be attached to standard equipment.

The cutting jaw may be articulated on the gripping device, which has the advantage that the cutting effect can be achieved by a simple movement.

The counter jaw may be secured to the cutting device, which has the advantage that only one jaw is moveable. Moreover, the gripping device may include a padding portion for padding the plant area of the ground which has been digged into, which is advantageous in that the same equipment can be used for restoring the ground.

A stump harvester for use in harvesting stumps is achieved in accordance with a third aspect of the invention. The stump harvester includes a bucket arm and a ro- tatable gripping device which is mounted to the stump harvester by means of a quick coupling.

In addition, it should be mentioned that the order in which steps (c) and (d) of the method described above is carried out is optional. In step (f) the stump is suitably brought to a storing area, preferably by rotation of the bucket arm.

Furthermore, in step (f) pieces of the treated stump are left in the plant area.

It is also preferred that the plant area is padded after step (f). This padding is suitably carried out by means of a padding portion of the gripping device. Furthermore, it is preferred that the counter jaw of the gripping device is provided with two teeth which are spaced a distance, in which the cutting jaw is intended to engage.

In addition to the embodiments discussed above, further embodiments are defined in the appended claims. Brief Description of the Drawings

Further objects and advantages of the invention and its embodiments, as well as features thereof, will by understood by the following description of a number of embodiments; with reference to the accompanying drawings.

Fig. 1 illustrates the general principles of the present invention. Fig. 2 is a side view of a stump harvester with a gripping device in its open position.

Fig. 3 is a side view of the stump harvester with the gripping device in an intermediate position.

Fig. 4 is a side view of the stump harvester with the gripping device in its closed position.

Fig. 5 is a view from above of the stump harvester shown in Figs 2-4.

Fig. 6 is a side view of a gripping device of the stump harvester shown in Figs 2-5.

Fig. 7 is a side view of the gripping device of Fig. 6 rotated about its axis of ro- tation. Description of Preferred Embodiments

Fig. 1 illustrates a method according to the present invention, which uses a stump harvester and a gripping device as shown in Figs 2-7. A method 100 of harvesting stumps by means of a stump harvester 20 includes a plurality of different steps, each of which represents a box in Fig. 1. In step 110 a gripping and cutting device 30 provided with jaws is connected to the stump harvester 20. In step 120 the gripping device 30 is positioned above a stump 42, and in step 130 the gripping device 30 is opened. Then the gripping device 30 can be rotated about its axis of rotation 38 - in step 140 — and in step 150 the stump is treated. In a final step 160 of the method 100 the stump 42 is at least partially removed from the plant area.

Step 110 is performed by positioning the gripping device 30 in a raised position, and by moving the stump harvester 20 towards the gripping device 30 by a bucket arm 22. Thereafter the bucket arm 22, which is provided with a suitable type of connecting means, connects to the gripping device 30 by a quick coupling 32 provided on the gripping device 30. Such quick couplings are known per se, for instance by SE-B-

443699, and therefore no specific description thereof is required herein. Additional hydraulic, pneumatic and electrical connections may be provided between the bucket arm 22 and the gripping device 30.

In step 120 the stump harvester 20 - with its bucket arm 22 radially move able - may operate the gripping device 30 by means of the bucket arm 22, so that the gripping device 30 is vertically positioned above a stump 42. Furthermore, the bucket arm 22 is rotatable which means that the bucket arm 22 is angularly moveable as well. By rotation as well as translation in radial directions, the gripping device 30 can be positioned above stumps 42 within an annular working area 44 which is defined by the maximum and minimum range of the bucket arm 22.

In step 130 the gripping device 30 is opened by moving a cutting jaw 33, which is articulated on a counter jaw 34, in a direction away from the counter jaw 34. Preferably, this step is performed by activating a hydraulic cylinder (not shown) which is connected to the cutting jaw 33 and the counter jaw 34. In step 140 the gripping device 30 is rotated about its axis of rotation 38. Preferably, the rotation is carried out when the axis of rotation 38 and thereby the gripping device 30 are substantially vertical. Thereby, the cutting jaw 33 and the counter jaw 34, respectively, may be positioned in such a way in relation to the stump 42 that cutting effect can be provided along desired directions. The rotation of the gripping device 30 can be carried out both clockwise and counterclockwise, respectively. In step 150 the stump 42 is treated in that the cutting jaw 33 by activation of the hydraulic cylinder is moved towards the counter jaw 34 in such a manner that it grasps into the stump 42. By the movement of the cutting jaw 33 towards the counter jaw 34 the stump 42 is cut into pieces. Preferably, steps 130, 140 and 150 are repeated a number of times, so that the stump 42 is cut in several pieces from different directions. It is preferred that the gripping device 30 is rotated between some of the repeated cycles so that optimum cutting is achieved.

In step 160 at least some parts of the stump 42 are removed from the plant area whereas other - preferably small pieces of the stump - are left. The removed parts 42' of the stump are brought to a storing area 50 situated within the range of the bucket arm 22 of the stump harvester 20. Preferably, the storing area 50 forms a part of the annular working area 44 described above. Hence, there is no need to move the stump harvester 20 when it is in operation within its range. The stump harvester 20 may operate succes- sively onward from positions of operation in parallel with the storing area 50 which forms a string of stump parts 42' which easily and efficiently can be loaded on a truck (not shown). The stump parts 42' laid in the string 50 may be left to dry for some months before loading, which is advantageous with respect to later use of the same. In this way, the plant area is preserved from unnecessary damage and at the same time the fuel consumption is reduced compared to prior-art methods.

The gripping device 30 may also be used for treatment of the ground, since it is provided with an integral padding portion 39 configured to pad the ground surface which has been digged into.

Preferably, the steps 120, 130, 140, 150 and 160 are repeated several times, the gripping device 30 being moved to a new stump 42 after each cycle. Thus, a large number of stumps 42 can be harvested efficiently without any need for the stump harvester 20 to be moved from different positions of operation.

Figs 2-4 show how the stump harvester 20 is treating a stump 42 in step 150. This stump harvester may for instance be a standard excavator, to which the gripping device 30 has been connected.

Fig. 2 shows a stump harvester 20 in accordance with a preferred embodiment of the present invention, including a bucket arm 22, a housing 24 and a gripping device 30 attached to an end of the bucket arm 22. The gripping device 30 is opened and ready to grip a stump 42. Fig. 3 shows the stump harvester 20 of Fig. 2, but in a position where the cutting jaw 33 of the gripping device 30 is moved halfway in a direction towards the counter jaw 34. In this intermediate position, the cutting jaw 33 performs a certain degree of cutting since the cutting jaw 33 is pressed towards the counter jaw 34 by means of the cutting cylinder (not shown).

Fig. 4 shows the stump harvester 20 of Figs 2-3 when the cutting jaw 33 has been moved to a closed position. The stump 42 has thereby been treated in accordance with step 150.

Fig. 5 shows the stump harvester 20 from above. The housing 24 of the stump harvester 20 may be turned within its range of operation, as is indicated by arrow 26. The outer end of the bucket arm 22 is attached to a gripping device 30 and it can move the same radially from a maximum radius to a minimum radius. Since the housing 24 of the stump harvester 20 can be turned, the gripping device 30 can operate over the entire annular working surface 44. Hence, the gripping device 30 can reach and treat all stumps 42 within the working area 44 without any need for the stump harvester 20 to be moved.

Fig. 6 is a detailed view of a gripping device 30 according to a preferred embodiment of the present invention. The gripping device 30 includes attachment means 31 with a quick coupling 32. Furthermore, the gripping device 30 has an intermediate member 35 comprising bearing means with a slewing bearing or a turning ring 36. The turning ring 36 is rotatable about an axis of rotation 38. It is preferred that the turning ring 36 is rotatable at least +/- 30°, more preferred at least +/- 45° and most preferred +/- 360° with respect to a starting position. The gripping device 30 also has a cutting jaw 33 and a counter jaw 34. The cutting jaw 33 is articulated on the counter jaw 34, and actu- ating means, for instance a hydraulic cylinder (not shown), is provided in order to move the cutting jaw 33 towards the counter jaw 34. Preferably, the back side of the counter jaw 34 - in relation to the cutting knife 33 - is provided with a portion 39 by which the plant area (ground) from which a stump has been removed can be padded and repaired after the removal of the stump. Fig. 7 shows the gripping device 30 in a position where the turning ring 36 has been rotated about 30°.

It should be appreciated that several modifications of the embodiments of the invention described above are feasible within the scope of the invention, as it is defined in the appended claims.

Claims

1. A method of harvesting stumps by means of a stump harvester, comprising the steps: a) that a gripping device is connected to the stump harvester by means of a quick coupling, b) that the gripping device is positioned above a stump, c) that the gripping device is opened by moving apart a cutting jaw and a counter jaw of the gripping device, d) that the gripping device is rotated about an axis of rotation to an operative position, e) that the stump is treated by the gripping device, the stump being gripped and cut by bringing the cutting jaw and the counter jaw closer together, and f) that the treated stump is at least partially removed from the ground.

2. The method of claim 1, wherein the gripping device in said step (b) is positioned above the stump by movement of a bucket arm of the stump harvester, the gripping device being attached to an end of the bucket arm and the other end of the bucket arm being attached to the stump harvester, the movement of the bucket arm being carried out by radial movement of the bucket arm outward from said other end.

3. The method of claim 1 or 2, wherein opening of the gripping device according to said step (c) is carried out by movement of the cutting jaw away from the counter jaw, the cutting jaw being articulated on the gripping device and the counter jaw being secured to the gripping device.

4. The method of any one of the preceding claims, wherein said steps (c)-(e) are repeated at least one time.

5. The method of any one of the preceding claims, wherein said steps (b)-(f) are repeated without the stump harvester being moved, and a new stump being harvested during each repeated cycle.

6. The method of any one of the preceding claims, wherein the stump har- vester is successively moved between operative positions, in which stumps are pulled out of the ground and placed in a substantially string- shaped storing area after treatment.

7. A gripping device for use in harvesting of stumps (42), comprising: means (31) for mounting of the gripping device (30) to a stump harvester (20); a cutting jaw (33) and a counter jaw (34) for gripping and cutting of a stump (42); an intermedi- ate member (35) configured to connect the mounting means (31) to the counter jaw (34) and the cutting jaw (33); and means for moving the cutting jaw (33) and the counter jaw (34) between an open position and a closed position, the mounting means (31) comprising a quick coupling (32), and the intermediate member (35) comprising a rotatable turning ring (36).

8. The gripping device of claim 7, wherein the cutting jaw (33) is articulated on the gripping device (30).

9. The gripping device of claim 7, wherein the counter jaw (34) is secured to the gripping device (30).

10. The gripping device of any one of claims 7-9, further comprising a pad- ding portion (39) which is provided on the counter jaw (34) and which is configured to pad ground digged into.

11. A stump harvester, comprising a bucket arm (22) and a rotatable gripping device (30) as claimed in any one of claims 7-10, said gripping device being mounted by means of a quick coupling.