GB2279223A - Method and equipment for felling and processing trees - Google Patents

Abstract

The tree is sawn, trimmed, pollarded and cut into trunk sections by a working head (harvester) 7 carried by a crane 3. At least during pollarding the tree is tilted by the working head 7 into a horizontal positon and the working head held, so that the top can be pushed into the infeed 4 of a shredder 11 or thrown over its collecting area, so that at least the top enters the shredder 11 and is reduced in size to coarse pieces. The vehicle 1 used carries the slewable crane 3 with the working head 7, the shredder 11 with infeed 4 or collecting area (23 Figure 2) and optionally a container 13 arranged on the working vehicle 1 or attached to the latter, into which the shredded material from the shredder 11 is transported by a conveyor (15 Figure 3). <IMAGE>

Description

METHOD AND EQUIPMENT FOR FELLING AND PROCESSING TREES The invention relates to a method and a mobile machine for felling and processing trees.

The aim of the invention is to combine operations previously performed separately, e.g. fuelling, trimming and cutting to length of trees, and utilisation of the waste wood thereby produced, and to convert the waste wood into a form preferably suitable for thermal utilisation.

Because of the worldwide increase in energy consumption and the so-called greenhouse effect there is a greater need to use energy sources which do not cause additional introduction of carbon dioxide into the atmosphere. Such an energy source is the branches and tops of felled trees, which were previously left in the forest. When these branches and tops are burnt they produce the same amount of carbon dioxide as when rotting in the forest. Hence the branches and tops can be burnt in power plants and the energy utilised for district heating and/or electricity. Acidification of the forest soil by excessive quantities of rotting tree waste is thus also prevented.

In conventional logging methods a vehicle which carries a crane with a working head (harvester) at the jib end is provided. The tree to be felled is gripped by the harvester, sawn off at the base, tilted into a horizontal position, trimmed in front of the vehicle at right angles to its longitudinal direction and cut into sections of predetermined length. If the trunk is less than a certain minimum diameter near the top, the trimming and cutting-to-length operations are terminated and the top laid aside. A working head (harvester) suitable for this purpose is already known, for example, from EP-A-O 428 530.

A second crane vehicle with a gripper tool subsequently collects the tops and places them in an integrated shredder, where they are reduced to coarse chips. The coarse chips are either left as fertiliser in the forest or collected in a container designed as a trailer and removed for further processing or combustion. If the tops remain unshredded in the forest, they form an ideal breeding ground for pests such as the bark beetle, because they dry out slowly.

A vehicle which picks up branches or whole trees already lying on the ground, places them in an integrated chopper and collects the coarse chips in a container is already known from DE-C 25 51 271.

Another vehicle which can fell trees with a harvester mounted on a crane, whereby the trees are then placed vertically from above into a shredder without being tilted or trimmed and the resulting coarse chips can be collected in a likewise integrated container, is known from DE-A 31 41 940 Al.

WO 89/12383 shows details of a working head or harvester, as can be used within the framework of the invention.

The already known methods and the mechanical equipment used for them have disadvantages. If the trees are fully shredded, as in the last-mentioned method, there is no possibility of cutting the valuable trunks to length and stacking them prior to subsequent processing in sawmills. In the other methods described at least two vehicles and two separate operations are required to process branches or tops. On the one hand this is a cost and time factor, while on the other two vehicles cause greater erosion damage on the sensitive forest soil than would be the case with a single vehicle.

The task of the invention is to devise a method and equipment which enable trees to be felled, trimmed trunk sections obtained and at least the tops and optionally also the branches prepared for thermal utilisation in one operation.

According to the invention, the problem is solved by the method specified in claim 1 and the machine specified in claim 5. The subclaims contain further advantageous forms of embodiment of the invention.

With performance of all process steps by a single mobile machine material, time and labour can be saved. The forest soil is protected, because only one vehicle takes over all the work.

A single motor for the vehicle drive and the shredder is adequate; its power may be lower than is the case in the already known equipment, because more time is available for shredding the top. The top can still be shredded while the next tree is being felled and tilted. As only one motor need be used, the entire vehicle can be of relatively light construction, which additionally reduces the load on the forest soil.

The machine according to the invention can also trim the trees wholly or partially in the infeed area of the shredder, so that some of the branches are also shredded. The other branches or even all the branches fall to the ground on the logging track and form a mat of branches for protection of the forest soil.

The trunk sections cut to length can be stacked at the side of the logging track. By contrast the tops are-thrown on to the collecting area of the shredder or pushed into its infeed and processed into chips or pieces, so that they never remain in the forest and promote the breeding of pests.

With the method and equipment according to this invention coarse wood chips or pieces can be manufactured at a more favourable price and burned e.g. in a thermal power plant.

Further advantages of the method and equipment according to the invention are evident from the following description of exemplified embodiments with reference to the drawings.

Fig. 1 shows a perspective, simplified view of equipment according to an initial embodiment of the invention, Fig. 2 shows a side view of another embodiment of the invention, Fig. 3 shows an alternative embodiment, the collecting container being attached as a separate tilting trailer and Fig. 4 shows a side view of a further embodiment.

According to Fig. 1 an infeed 4 facing forwards with driven infeed rollers, which leads to a shredder 11 in the form of a so-called drum-type hogger or disc-type hogger behind the driver's cab la, is located next to the driver's cab la of the vehicle 1. A rotating knife disc, which cuts the material supplied by the infeed 4 into uniform chips, is located within the roughly circular casing of the shredder 11.

A table 4a located in front of the infeed roller gap can be provided to facilitate the introduction and alignment of tops, branches and the like. These are carried by the air flow generated by the shredder itself or by a blower via a shaft 8 to a container 13 arranged on the vehicle.

A crane 3 likewise arranged on the vehicle carries a working head 7 designed as a so-called "harvester" on its jib 5. Such a harvester is already known. Its main components are a chain saw 6, two driven feed rollers 17 to grip the tree trunk and push it forwards and two or more curved trimming knives 19, which can be placed around the trunk. The working head or harvester 7 is mounted on the jib 5 of the crane 3 in such a way that it can be swivelled by a hydraulic control cylinder into the vertical or horizontal working position. These details are known, for example, from WO 89/12383.

As shown, the motor 25 for driving the vehicle and also the different working units can be arranged between the shredder 11 and the container 13 on the chassis. However, it can also be arranged elsewhere, e.g. under the driver's cab la.

The crane 3 is slewable about a vertical axis (not shown) on the chassis. Alternatively the crane 3 together with the driver's cab la and the shredder 11 with infeed 4 can be pivoted on the chassis by means of a live ring. In this case the shaft 8 must be suitably pivotable so that it can follow the swivelling movements of the shredder 11.

The equipment operates as follows: with the harvester head 7 in the vertical position a tree is gripped and cut by the chain saw 6. The tree trunk is pushed by the driven feed rollers 17, the trimming knives 19 cutting off the branches, which fall to the ground, as indicated at 22. The progressively trimmed trunk is cut by the chain saw 6 into round timber sections of predetermined length, which are likewise placed on the ground, as indicated at 24. Finally a top 26 remains, its trunk being too thin for use. At the latest at this time, but optionally already during trimming, the working head 7 is swivelled into the horizontal working position. The top 26 held by the working head 7 is moved by the crane 3 in front of the infeed 4 and then pushed by the feed rollers 17 into the infeed 4, where it is gripped by the infeed rollers and fed to the shredder 11.

In the preferred exemplified embodiment shown in the drawing the opening of the infeed 4 faces forwards. However, it is also possible to modify the vehicle in such a way that the infeed opening faces sideways.

Fig. 2 shows a cross-country vehicle 1 of already known design, preferably with an articulated and swing axle; it carries a crane 3, on the jib 5 of which a working head 7, e.g. a harvester of the type known from EP-A-O 428 530, is mounted.

This has a gripper tool to surround the trunk, a saw for felling and cutting to length, driven rollers for pushing the trunk and stripper elements for breaking off the branches. The vehicle 1 also carries a shredder 11, e.g. a mill or coarse chopper or wood crusher, which is mounted at the front end of the vehicle 1, and a container 13, which is provided at the rear of the vehicle 1 and connected to the shredder 11 via a conveyor 15, e.g. a screw conveyor, for transport of the chips or pieces of wood. The motor 25 for driving the vehicle is also used as the drive unit for the shredder 11 and conveyor 15.

During operation the vehicle 1 according to the invention moves along the logging track formed by felling of the trees to the trees to be felled. When the vehicle is stationary the tree trunk is held at the base by the gripper tool of the working head 7 mounted on the vehicle crane 3 and cut by its saw. The tree felled in this way is held by the working head 7, tilted into the horizontal position and brought into a working position 21 near the logging track at right angles to and in front of the vehicle 1 and partially over the collecting area 23 of the shredder 11. The harvester 7 then begins to trim the tree and cut the trunk to required lengths. The branches fall on to the collecting area 23 of the shredder 11 and are reduced in size by the latter.

As soon as the useful part of the trunk is cut to length, the remaining top is allowed to fall on to the collecting area 23, so that it can likewise be processed in the shredder 11.

The relatively coarse crushed material is transported by the screw conveyor 15 or the like from the shredder 11, e.g. a wood crushing mill, to the container 13. It is advisable to design the container 13 as a tipping container.

In the case of particularly sensitive soils it is advisable to carry out the trimming in that part of the working area 21' which is in front of the collecting area 23 of the shredder 11, so that the branches fall on to the logging track, where they form a mat, which helps to prevent erosion damage.

An alternative embodiment of the equipment is shown in Fig. 3.

This provides for the arrangement of the shredder 11 at the rear of vehicle 1 and attachment of the collecting container 13 for the shredded material as a trailer. The motor 25 is located at the front end. In this form of construction a conveyor belt transports the chips from the shredder 11 and then allows them to fall into the collecting container 13 via a feed opening or a feed hopper 27 at the front end of the trailer. In this way it is ensured that the chips fall into the collecting container even if the vehicle and the trailer are positioned at an angle to one another. The chips are carried from the front part of the collecting container, the feed hopper 27, by a screw 15' into the centre of the collecting container 13.

A further advantageous embodiment of the invention is shown in Fig. 4. This embodiment conforms essentially to that in Fig. 2, except that the shredder 11 is located between the crane 3 and the collecting container 13.

The advantage of the last two embodiments mentioned is that vehicles already obtainable on the market can be suitably converted and used without major modifications.

These two embodiments differ in their operating principle from the example in Fig. 2 in that the tree branches, which are still separated from the trunk in front of the vehicle, cannot enter the shredder. After trimming of the trunk the top is cut off and allowed to fall on to the collecting area 23 of the shredder.

The tops and if necessary the branches are shredded in the shredder 11 preferably into a relatively coarse form, which is particularly suitable for thermal utilisation, e.g. in a thermal power station. The energy input or the motor power for such shredding is lower than e.g. for chopping into fine chips as required for particle boards or the like. Mills or wood shredders for coarse size reduction are available on the market.

The mobile machine according to the embodiments shown in Figs.

1-4 is an expensive item of equipment, which should preferably be used continuously for the felling and processing of trees.

When the container 13 is filled with chips from the shredder 11, it would be uneconomical to drive the machine away from the logging track and through the forest via a lengthy route to an acceptance point for the chips and interrupt the actual felling work for that length of time. Instead it is advantageous to drive a transport vehicle with a collecting container into the logging track as far as the machine, so that it can receive the chips from the container 13. For this purpose a blower 31, which can be driven by the motor 25 and can remove the chips from the container 13 via a shaft 33 and discharge them into container of a following transport vehicle (not shown), is provided at the rear end of the container 13 in the embodiment according to Fig. 4. The chips can be fed to the suction side of the blower 31 by the suitably extended conveyor 15 on the bottom of the container 13. Alternatively, the container 13 can also be equipped with a scraper bottom of known design. The discharge end of the shaft 33 can be slewable to distribute the chips in the container of the transport vehicle. Transfer equipment 31, 33 of this type can, of course, also be provided in the embodiments according to Figs. 1-3.

In a further form of construction (not shown) a lifting and tipping device is provided, with which the container 13 can be raised and tipped backwards to empty its contents into the loading container of a following transport vehicle.

Claims (15)

1. A method for felling and processing trees, each tree being sawn and tilted into the horizontal position by a working head (harvester) carried by a crane and then held in the horizontal position by the working head and trimmed, pollarded and cut into trunk sections, wherein at least during pollarding, the working head is held in such a position that the cut-off top enters the infeed of a shredder and is reduced to coarse pieces in the latter.

2. A wethod according to claim 1, wherein the working head is held above a collecting area of the shredder in such a way that at least the top is thrown into the shredder.

3. A method according to claim 1, wherein the top remaining after the cutting to length is held in a horizontal position by the working head and pushed into the infeed of the shredder.

4. A method according to any preceding claim, wherein the material reduced to coarse pieces is collected from the shredder in a container and fed to the further, e.g. thermal, utilisation.

5. A mobile machine for felling and processing trees with a crane slewable on a vehicle with a working head (harvester) for felling, trimming, pollarding and cutting to length of the tree trunks, a shredder with a wood crusher, which reduces the supplied material to coarse pieces, is arranged on the working vehicle and that the working head is adjustable by the crane into such a position in relation to the shredder that the material falling during trimming and/or pollarding enters the shredder.

6. A machine according to claim 5, wherein the shredder has an upper collecting area and the working head can be adjusted into a discharge position above the collecting area.

7. A machine according to claim 5, wherein the shredder has an infeed and that the working head can be moved in a horizontal working position by the crane in front of the opening of the infeed and can be actuated to push a top held by it into the infeed.

8. A machine according to any of claims 5 to 7, wherein a conveyor is provided, which conveys shredded material from the shredder into a container arranged on the working vehicle or attached to the latter.

9. A machine according to any of claims 5 to 8, wherein the shredder is arranged at the front end of the vehicle in the working direction.

10. A machine according to any one of claims 5 to 9, wherein the motor of the vehicle also serves as the drive motor of the crane, and working head, the shredder and/or the conveyor.

11. A machine according to any of claims 5 to 10, wherein the shredder is a drum-type hogger with a rotating knife disc.

12. A machine according to any one of claims 5 to 11, wherein a transfer conveyor for transport of the shredded material into a receiving vehicle is provided on the container.

13. A machine according to claim 7, wherein the infeed of the shredder faces forwards in the working direction of the vehicle.

14. A method substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

15. A machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.