IE54691B1 - A mobile forest thinning machine - Google Patents

Description

This invention relates to a mobile forest thinning machine.

During the last decades, the final felling in forestry has been mechanized very thoroughly. Due to the fact that this final felling was carried out as clear-felling, there has been no need to pay attention to the damage caused by the machines on the remaining trees. The most essential feature was to achieve high capacity and thereby good economy.

The problems are much greater when juvenile forest is to be thinned and when it is tried to mechanize this work. The concern and problems are briefly illustrated in the following points; 1. Due to inter alia shortage of wood, juvenile forest must be thinned so that remaining trees can grow faster and yield stems with a greater volume. It is further necessary to make use of the thinned small stems for energy purposes and as contribution to pulp. 2. Manual thinning is physically a very heavy job in this very trying environment. Cold and snow in wintertime, heat, rain and insects in summertime are a few of may environmental problems. 5409 I -33. Manual thinning is at present very expensive, so that there is a great demand for thinning by machine. 4. For transporting wood out of the stand, strip roads must be cut through the area. In order not to interfere with and deteriorate the productive ground in the forest, the strip roads must not be arranged too close to each other. The minimum distance should be about 30 m, but greater distances imply a more productive forest ground area and thereby a substantial increase in total growth.

. When it was tried to reach with long crane booms into the stand in order to fell and to pull the wood to the strip road, the following problems have arisen: booms with great length of about 15 m or more are technically advanced, expensive and heavy. ~ when a tool is attached to the tip of such a long arm, an exceptionally high lifting moment is required in order to balance and control the extended boom with load from a vehicle parked on the strip road. Heavy vehicles cause great damage on the ground and thereby give rise to deteriorated growth. a long boom is slow to operate and damages too many of the remaining trees, so that these trees in future cannot deliver fully satisfactory wood. -4owing to concealing branches and to a long distance, the driver cannot have a good view and, therefore, cannot select the trees which are most suitable to be thinned. - the driver's concentration on the work thus rendered difficult results in an unacceptably high stress. It is difficult to judge the distance at great distances when the tool must be positioned with good precision. - the outward and inward movements of a long and heavy boom cause long cycle times for every single tree. This is unacceptable from a cost point of view, because the thinned trees generally have a small volume. The volume capacity per time unit is too low to be profitable.

The aforesaid problems are solved or reduced by using a mobile tree thinning machine according to the present invention, comprising a drive unit housing equipment for operation of the machine and a logging unit, which is latter supported on a dirigible and driven wheel and is connected to and movable relative to the drive unit via a telescopic arm structure, the logging unit comprising a driver's cab, a pivotal boom at the end of which a felling unit is located and a device for clamping the root-end of cut trees, said arm structure housing hydraulic and -5electric lines from the drive unit to the logging unit for operating the same from the driver's cab and being retractable to a position over the drive unit to form the units into a single entity for transportation of the machine between tree thinning places, characterized in that the drive unit is two-wheeled and connected to the logging unit via a pivotal link between the drive unit and the arm structure with a bracket carried by the drive unit and with the telescopic arm projecting from said bracket and housing said lines, which pivotal link permits the two units to be set at an angle of more than 90° relative to each other, and the two-wheeled drive unit is provided with a lowerable support for stabilizing the unit when the logging unit is set at an angle and moved out.

An embodiment of the mobile thinning machine according to the invention is now described by way of example, with reference to the accompanying drawings, in which Figures 1, 2 and 3 are schematic lateral, front and plan views, respectively, of the machine in its transport position, Figure 4 shows the machine carrying out thinning, and Figure 5 is a perspective view with surroundings. -6Ιη Figures 1 and 2 a drive unit is generally designated by 1 and a logging unit by 2. The drive unit is supported on two wheels 3a and 3b and houses the equipment for motor and hydraulic operation. The drive unit further is provided forwardly with two supporting legs 4 which individually can be folded down hydraulically.

The logging unit 2 is supported on a dirigible and driven supporting wheel 5 in a fork 6, which is mounted pivotally in the lower leg of a beam frame 7. Said leg in its turn carries the driver's cab 8, which is provided with a limpid dome 9 enabling the driver to have an unlimited view forward, upward and to both sides. This is of special importance at thinning. On the upper leg of the beam frame an attachment 10 is mounted pivotally in the horizontal plane and has two transverse axles 11 and 12. About the firstmentioned axle 11 the base section of a telescopic boom 13 is mounted (see also the dash-dotted extended position), and between the second axle 12 and a lug on the base section of the boom a hydraulic device 14 is located. The outermost section of the boom carries pivotally a felling unit of conventional type generally designated by 15. Said felling unit comprises a frame 16, a schematically indicated grapple device 17, a cutting member 18 and a hydraulic device 19. The hydraulic device 19 operates to stabilize and position said felling unit. -ΊΑ clamping bunk 20 is mounted beneath the floor of the driver's cab and can be moved in and out and be operated hydraulically in a way not shown in detail. The clamping bunk 20 is for supporting and clamping the cut end of cut trees to enable them to be trailed behind the logging unit.

The forward end of the drive unit 1 constitutes one part of an articulate pivotal link 21, the other part of the articulate pivotal link has a continuation extending first upward and thereafter inclined backward to form a bracket 22. This bracket terminates in bearing plates 23 where the innermost section of a telescopic arm 24 is mounted about axle 25. The outermost section of the telescopic arm, which in Figure 1 is shown fully retracted, is supported at its end about a horizontal axle in the rearward end of the lower leg of the beam frame 7, and the beam frame can be pivoted by means of a hydraulic device 26 (see Figure 4) inserted between a point on the other section of the arm and the yoke of the beam frame.

It appears from the aforesaid that the driver's cab is entirely relieved of external loads from the telescopic boom, supporting wheel, clamping bunk and telescopic arm, in that the beam frame takes up all these loads. The driver's cab can hereby also effectively be insulated from 5463 ; -8vibrations and resonance sound.

At the end o£ the bracket 22 a winch 27 is attached, the wire of which runs within the telescopic arm 24 and is anchored in the beam frame 7.

It is finally to be mentioned that the supporting legs 4 of the drive unit as well as the beam frame 7 preferably are provided with automatic levelling means, which always maintain the driver's cab in the horizontal plane, irrespective of whether the ground is inclined forward, rearward or to the side.

The arrangement described above operates as follows. The machine, in the transport position shown in Figure 1, is driven on a strip road to a selected thinning route. Here the driver lowers the supporting legs 4 for the drive unit 1 and sets the logging unit 2 by the pivotal link 21 through an angle of about 90°C relative to the direction of said strip road. This position is indicated by dashdotted lines in Figure 4. The driver thereafter moves out the logging unit to a strategic place in the route by driving and steering the supporting wheel 5 and extending the telescopic arm 24. Thereafter the boom 13 is extended to the selected tree for thinning. When the. tree has been grabbed and felled, the clamping bunk 20 is pushed out, 5460 ί -9and the tree is dragged thereon. The procedure is thereafter repeated for the second tree for thinning within the reach of the pivotal boom, as illustrated in Figure 5. The driver thereafter operates the logging unit back to the strip road and retracts the telescopic arm.

This occurs primarily by reversing the driving direction of the supporting wheel, but upon demand (for example, when the tree bundle on the clamping bunk is heavy and the ground at the same time is inclined upward or includes heavy obstacles in the ground) the winch is used. Upon arrival at the strip road the tree bundle is unloaded by retracting the clamping bunk. When this has been completed, the logging unit is bent to the side of the drive unit, the retracted telescopic arm is moved to abut the bracket, the supporting legs are lifted, and the boom is pivoted to the position shown in Figure 1, preferably gripping simultaneously the telescopic arm. The machine is now ready for transport to the next thinning route.

In addition to the rational thinning described above, the following advantages are obtained: (a) When the machine in its transportation position has to pass by steep lateral hillsides the stability of overturning can be substantially increased by setting the pivotal link at such an angle that the 09 -10supporting wheel is moved from the centre substantially to the side in the direction of inclination, and at the same time the supporting wheel is swung to run parallel to the two other wheels, λ further contribution to the stability is that the centre of gravity of the telescopic arm is moved in the opposite direction to the supporting wheel when the pivotal link is set at an angle. (b) Owing to the rearwardly inclined, relatively long bracket, the logging unit requires a minimum of space at the swing movement on the strip road. Good balancing is also obtained as well as an increased boom length within the limited width of the strip road. Furthermore, the clearance above local raising sections of the terrain is good when the telescopic arm is extended. (c) As the supporting wheel beneath the driver's cab is dirigible with unrestricted steering deflections, it is possible to change the driving more or less rapidly from a first direction to the opposite one.

This property is especially favourable when it is desired to quickly turn the machine in transport position on a strip road or a narrow traffic road. (d) When both supporting legs are pressed strongly against the ground, the entire logging unit is lifted so that its supporting wheels have no ground 4 6 9 1 -11contact. When only one supporting leg is pressed strongly against the ground, the wheel of the drive unit on the same side is lifted off the ground. This property is very important from a service and repair point of view. (e) The three wheels are driven hydrostatically each by its wheel motor. During country driving preferably all wheel drives are engaged, while during roaddriving the drive on one or two wheels can be disengaged in order to correspondingly increase the hydraulic force on the remaining wheel or wheels and thereby increase the transport speed.

It will of course be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

Claims (7)

1. &ΑΙΜ£

1. A mobile tree thinning machine, comprising a drive unit housing equipment for operation of the machine and a logging unit, which is latter supported on a dirigible and 5 driven wheel and is connected to and movable relative to the drive unit via a telescopic arm structure, the logging unit comprising a driver's cab, a pivotal boom at the end of which a felling unit is located and a device for clamping the root-end of cut trees. said arm structure 10 housing hydraulic and electric lines from the drive unit to the logging unit for operating the same from the driver's cab and being retractable to a position over the drive unit to form the units into a single entity for transportation of the machine between tree thinning 15 places, characterized in that the drive unit is twowheeled and connected to the logging unit via a pivotal link between the drive unit and the arm structure with a bracket carried by the drive unit and with the telescopic arm projecting from said bracket and housing said lines, 20 which pivotal link permits the two units to be set at an angle of more than 90° relative to each other, and the two-wheeled drive unit is provided with a lowerable support for stabilizing the unit when the logging unit is set at an angle and moved out. 5 4 ϋ 3 -132. λ thinning machine as defined in claim 1, characterized in that said bracket has a length corresponding substantially to the retracted telescopic arm and is inclined backward with respect to said arm 5 structure to abut and receive the retracted telescopic arm.

2. 3. A thinning machine as defined in claim 1 or 2, characterized in that a winch is attached on said bracket for telescoping together the sections of the telescopic 10 arm, which winch is operated from the driver's cab, and the winch wire runs through the telescopic arm out to the logging unit.

3. 4. A thinning machine as defined in any one of the preceding claims, characterized in that said support 15 consists of two supporting legs, each of which can be lowered and lifted individually for levelling the drive unit on upwardly, downwardly or laterally inclined ground, and also the logging unit pivotally connected to the end of the telescopic arm remote from the drive unit about a 20 vertical axis is provided with levelling means to maintain the driver's cab horizontal.

4. 5. A thinning machine as defined in any one of the preceding claims, characterized in that the driver's cab i> i'J -J -14is entirely relieved by a beam frame, with which the end of the telescopic arm engages.

5. 6. A thinning machine as defined in any one of the preceding claims, characterized in that the clamping 5 device can be moved hydraulically in and out from beneath the floor of the driver's cab.

6.

7. A mobile tree thinning machine, substantially as hereinbefore described with reference to the accompanying drawings.