METHOD OF AND APPARATUS FOR EXTRACTING TREE STUMPS

Abstract: Apparatus for extracting a tree stump (12) comprises a base structure (14) adapted to engage with the ground surface around the stump, gripping means (22) for gripping the tree stump, and lifting means (18.1, 18.2) for forcibly displacing the gripping means upwardly with respect to the base structure while reacting downwardly on the base structure.

Description: Method of, and apparatus for, extracting tree stumps THIS INVENTION relates to a method of, and apparatus for, extracting tree stumps. According to the invention there is provided a method of extracting a tree stump, which comprises placing a base structure on the ground adjacent the tree stump in such a manner that the base structure engages the ground on opposite sides of the tree stump; gripping the tree stump with gripping means; and forcibly displacing the gripping means upwardly by lifting means which reacts downwardly on the base structure . The area of contact between the base structure and the ground may at least partly surround the tree stump, extending from one of said sides to the other. The lifting means may comprise a pair of hydraulic rams which are arranged diametrically opposite one another with respect to the tree stump. Further according to the invention there is provided tree stump extracting apparatus which comprises : a base structure adapted to engage with the ground surface on opposite sides of a tree stump; gripping means for gripping the tree stump; and lifting means for forcibly displacing the gripping means upwardly with respect to the base structure while reacting downwardly on the base structure. The apparatus may include a beam extending from one side of the base structure to the other, the lifting means comprising a first hydraulic ram extending from one side of the base structure to one end of the beam and being connected to the beam by a first pivot connection and a second hydraulic ram extending from the opposite side of the base structure to the other end of the beam and being connected to the beam by a second pivot connection, and the gripping means being suspended from a region of the beam between the first and second pivot connections. Each of the hydraulic rams may be held in an erect condition with respect to the base structure by means of two or more stays. The first hydraulic ram may be held immovably in the erect condition by means of at least three of said stays, and the second hydraulic ram may be held in the erect condition by a pair of diametrically opposed stays, the second hydraulic ram being connected to the base structure by a third pivot connection, and said opposed stays being arranged such that the second hydraulic ram is able to pivot with respect to the base structure about the third pivot connection. In an alternative construction the lifting means may comprise a first hydraulic ram and a second hydraulic ram, the first hydraulic ram being connected to one side of the base structure by a first pivot connection, and the second hydraulic ram being connected to the other side of the base structure by a second pivot connection; the first and second hydraulic rams extending upwardly and towards one 5 another and being connected together at their upper ends by a common pivot connection; and each of the hydraulic rams being held in an erect condition with respect to the base structure by means of a pair of diametrically opposed stays which are arranged such j _0 that the hydraulic ram is able to pivot with respect to the base structure about the respective first or second pivot connection. The stays referred to above may each comprise a flexible, tensionable element, and means for l~ tensioning the tensionable element. In one embodiment the gripping means may comprise two or more jaws for gripping the tree stump therebetween. In another construction the gripping means may comprise a noose for encircling the tree 0 stump. The invention will now be described in more detail, by way of example, with reference to the accompanying drawings. In the drawings: 5 Figure 1 is a vertical section, on line I-I in Figure 2, of tree stump extracting apparatus in accordance with one embodiment of the invention; Figure 2 is a horizontal section on line II-II in Figure 1; 0 Figure 3 shows one of the stays forming part of the apparatus; Figure 4 is a vertical section of tree stumpo extracting apparatus in accordance with another embodiment of the invention, on line IV-IV in Figure 5 ; and Figure 5 is a plan view of the apparatus of Figure 4. Referring first to Figures 1 and 2, reference numeral 10 generally indicates apparatus for extracting a tree stump 12. The apparatus comprises a base structure 14, and a beam 16 extending from one side of the base structure to the other. The beam is supported on the base structure by means of a pair of hydraulic rams 18.1 and 18.2. From the beam 16 there is suspended gripping means 22 for gripping the tree stump 12. As can best be seen in Figure 2, the base structure 14 comprises three sturdy structural members such as inverted U-section beams 24.1, 24.2, and 24.3 arranged on three sides of a rectangle, the beam 24.2 extending beyond the corner where it meets the beam 24.3, to form an extension 26. On the underside of the beams there is welded a spreader pad or plate 28. Gusset plates 30 which extend between the beams and the spreader plate 28 are provided to strengthen the structure. The base structure 14 further comprises, on the fourth side of the rectangle, a gate 32 which, at each opposite end thereof, is connected to the adjacent sides 24.1, 24.3 by means of a connector pin 34. When one of the pins 34 has been removed, the gate can be swung open, pivoting about the pin at the other end . The beam 16 comprises two parallel plates 36 each with an opening 38 therein to lighten the structure. The hydraulic ram 18.1 is connected at the bottom to the beam 24.1 by means of a pivot connection 40.1 and at the top to the one end of the beam 16 by means of a pivot connection 42.1. Likewise, the hydraulic ram 18.2 is connected at the bottom to the 5 beam 24.3 by means of a pivot connection 40.2 and at the top to the other end of the beam 16 by means of a pivot connection 42.2. The hydraulic ram 18.1 is held in an erect condition by means of a pair of diametrically opposed 0 stays 44.1 and 44.2 which, at the top, are connected to the cylinder of the hydraulic ram and, at the bottom, to opposite ends of the beam 24.1. The stays 44.1 and 44.2, the hydraulic ram 18.1, and the pivot axis of the pivot connection 40.1 lie in the same 5 plane. This allows the hydraulic ram 18.1 to tilt somewhat about the pivot connection 40.1, in the direction of arrows A. The hydraulic ram 18.2 is held in an upright condition by means of three stays 44.3, 44.4, and o 44.5. The stays 44.3 to 44.5 are all at the top connected to the cylinder of the hydraulic ram 18.2. At the bottom, the stays 44.3 and 44.4 are connected to the beam 24.2, on opposite sides of the beam 24.3, whereas the stay 44.5 is connected to that end of the beam 24.3 which is adjacent the gate 32. It will be seen that the lower ends of the stays 44.3, 44.4, and 44.5 lie at the apices of a triangle, and thus they hold the cylinder of the hydraulic ram 18.2 immovably in the erect condition. The structure of the stays 44.1 to 44.5 will be described in more detail hereinafter, with reference to Figure 3. The gripping means 22 comprises a pair of arms 46 which are each, at the lower end thereof, fitted with a pronged gripping pad 48. The gripping pads 48 are connected to the respective arms by means of a pivot connection 50. The arms 46 are each connected to the beam 16 by means of a pivot connection 52 and extend upwardly beyond the pivot connections 52. Between the upper ends of the arms 46 there is a hydraulic ram 54, this being connected, at opposite ends thereof, to the arms by means of pivot connections 56. The stay 44.1 is illustrated in more detail in Figure 3. The stay comprises a length of chain 58 which, at the bottom, is connected via a shackle 60 to the beam 24.1, and a screw shackle 62 which, at the upper end thereof, is connected via a shackle 64 to the cylinder of the hydraulic ram. The stay can be tensioned or untensioned by turning the screw shackle 62. In use, the apparatus 10 will be transported from one tree stump to the other by means of a vehicle which is provided with a hydraulic pump of sufficient power to drive the apparatus. The hydraulic rams 18.1, 18.2, and 54 will be connected to the hydraulic pump of the transport vehicle by means of suitable control valves and hydraulic hoses. At the start of a stump extracting operation the hydraulic rams 18.1 and 18.2 will both be in the retracted condition, as illustrated in the drawings. Also, the hydraulic ram 54 will be in the retracted condition, so as to hold the gripping means 22 in an open condition. When the vehicle has arrived at a tree stump which is to be extracted, the gate 32 is opened and the apparatus manouvred around the tree stump and the gate 32 then closed. The apparatus is then lowered until the spreader plate 28 rests on the ground surface. The apparatus will now support itself on the ground . Next, the hydraulic ram 54 is extended, causing the arms 46 to pivot about the pivot connections 52 and the gripper pads 48 to grip the tree stump 12 between them. Hydraulic oil is now pumped to the hydraulic rams 18.1 and 18.2 to extend them, thus displacing the beam 16 upwardly and extracting the tree stump 12. As mentioned above, the stays 44.3, 44.4, and 44.5 hold the cylinder of the hydraulic ram 18.2 immovably in position, whereas the hydraulic ram 18.1 can tilt somewhat in the direction of arrows A. This tilting movement will be required if the one hydraulic ram extends somewhat more than the other. Indeed, the one hydraulic ram may deliberately be extended more than the other, and this can be done in an alternating fashion, to assist in extracting the tree stump 12. When the hydraulic rams 18.1 and 18.2 have reached the end of their strokes, the hydraulic ram 54 is operated to open the gripping means, thus releasing the extracted stump. The apparatus can now be lifted and transported to the next stump that is to be extracted . If desired, the beam 16 may be provided with a vibrator which may be operated when the tree stump has been extracted and is still gripped in the gripping means 22. This will have the effect of shaking the tree stump and so ridding it of excess soil. It is to be noted that, during the extraction process, the hydraulic rams 18.1 and 18.2 react downwardly on the base structure 14. No forces are transmitted to the vehicle used to transport the apparatus 10 from one tree stump to another, the base structure 14 bearing the full downward load resulting from the extraction process. The only purpose of the vehicle is therefore to transport the apparatus from one tree stump to the next and to provide the necessary hydraulic power. It will be appreciated that the gate 32 may be fixed instead of being openable ' . In this event, it will be necessary for the apparatus to be dropped over the tree stump 12 from above, instead of being ' sable to move it into position horizontally. It will also be appreciated that the base structure 14 need not necessarily have a rectangular shape in plan view. It may, for example, be D-shaped or round . Although the gripping means 22 illustrated comprises two opposed jaws, it will be appreciated that three or more peripherally spaced jaws may be used if it is desired to spread the gripping forces acting on the tree stump more evenly around the circumference of the stump. Referring now to Figures 4 and 5, reference numeral 70 generally indicates tree stump extracting apparatus according to another embodiment of the invention. The same reference numerals as in Figures 1 and 2 are used to designate the same parts or parts having an equivalent function. The base structure 14 differs from that in the Figures 1 and 2 embodiment in that it does not include the extension 26. Instead of having a beam as in the Figures 1 and 2 embodiment, the hydraulic rams 18.1 and 18.2 of the apparatus 70 are, at the top, connected together by a common pivot " connection 72. From the pivot connection 72 there is suspended a cable noose 74 which is used to grip the tree stump 12. The hydraulic ram 18.1 is supported by two stays 44.6 and 44.7.. Likewise, the hydraulic ram 18.2 is supported by two stays 44.8 and 44.9. The stays 44.6 to 44.9 have the same general construction as the stay 44.1 illustrated in Figure 3. The stays 44.6 and 44.7, the ram 18.1, and the pivot axis of the pivot connection 40.1 lie in the same plane, so that the hydraulic ram 18.1 can tilt about the pivot axis of the connection 40.1. Likewise, the stays 44.8 and 44.9, the ram 18.2, and the pivot axis of the pivot connection 40.2 are in the same plane, so that the ram 18.2 can tilt about the pivot axis of the pivot connection 40.2.

Claims: CLAIMS : 1. A method of extracting a tree stump, which comprises placing a base structure on the ground adjacent the tree stump in such a manner that the base structure engages the ground on opposite sides of the tree stump; gripping the tree stump with gripping means; and forcibly displacing the gripping means upwardly by lifting means which reacts downwardly on the base structure. ~ • A method as claimed in claim 1, wherein the area of contact between the base structure and the ground at least partly surrounds the tree stump, extending from one of said sides to the other. 3. A method as claimed in claim 1 or claim 2, wherein the -lifting means comprises a pair of hydraulic rams which are arranged diametrically opposite one another with respect to the tree stump. 4. Tree stump extracting apparatus which comprises : a base structure adapted to engage with the ground surface on opposite sides of a tree stump; gripping means for gripping the tree stump; and lifting means for forcibly displacing the gripping means upwardly with respect to the base structure while reacting downwardly on the base structure. 5. Apparatus as claimed in claim 4, wherein the base structure is adapted to engage with the ground surface over an area of contact which at least parly surrounds the tree stump, extending from one of said sides to the other. 6. Apparatus as claimed in claim 4 or claim 5, which includes a beam extending from one side of the base structure to the other, the lifting means comprising a first hydraulic ram extending from one 5 side of the base structure to one end of the beam and being connected to the beam by a first pivot connection and a second hydraulic ram extending from the opposite side of the base structure to the other end of the beam and being connected to the beam by a i second pivot connection, and the gripping means being suspended from a region of the beam between the first and second pivot connections. 7. Apparatus as claimed in claim 6, wherein each of the hydraulic rams is held in an erect condition • 5 with respect to the base structure by means of two or more stays. 8. Apparatus as claimed in claim 7, wherein the first hydraulic ram is held immovably in the erect condition by means of at least three of said stays, 0 and wherein the second hydraulic ram is held in the erect condition by a pair of diametrically opposed stays, the second hydraulic ram being connected to the base structure by a third pivot connection, and said opposed stays being arranged such that the second 5 hydraulic ram is able to pivot with respect to the base structure about the third pivot connection. 9. Apparatus as claimed in claim 4 or claim 5, wherein the lifting means comprises a first hydraulic ram and a second hydraulic ram, the first hydraulic 0 ram being connected to one side of the base structure by a first pivot connection, and the second hydraulic ram being connected to the other side of the base structure by a second pivot connection; wherein the first and second hydraulic rams extend upwardly and towards one another and are connected together at 5 their upper ends by a common pivot connection; and wherein each of the hydraulic rams is held in an erect condition with respect to the base structure by means of a pair of diametrically opposed stays which are arranged such that the hydraulic ram is able to pivot 0 with respect to the base structure about the respective first or second pivot connection. 10. Apparatus as claimed in any one of claims 7 to 9, wherein each of the stays comprises a flexible, tensionable element, and means for. tensioning the 5 tensionable element. 11. Apparatus as claimed in any one of claims 4 to 10, wherein the gripping means comprises two or more jaws for gripping the tree stump therebetween. 12. Apparatus as claimed in any one of claims 4 to o 10, wherein the gripping means comprises a noόse for encircling the tree stump. 13. A method of extracting a tree stump, substantially as herein described and illustrated. 14. Tree stump extracting apparatus substantially 5 as herein described and illustrated.

Inventors: VANDENBERG BERNARDUS JAN, VANDENBERG, BERNARDUS, JAN
Applicants: VANDENBERG BERNARDUS JAN, VANDENBERG, BERNARDUS, JAN
Application year: 1988
Main classification: A01G23
IPC codes: A01G23