FI20245724A1 - FELLING DEVICE FOR HARVESTING SMALL TIMBER AND METHOD FOR FELLING SMALL TIMBER - Google Patents

Abstract

The invention relates to a felling unit (1) comprising: a main body (100) comprising a feeding system (200), a cutting system (300), and an intermittent storage (400). The feeding system (200) comprises at least a first rotating feeder (210) and a second rotating feeder (220) for feeding wood through the cutting system (300) and into the intermittent storage (400), the feeders (210; 220) each being rotationally actuated about respective rotation axes (x1; x2) with at least one actuator. The cutting system (300) comprises a first actuated cut element (310) and a second non-actuated cut element (320) arranged such that the movement of the first actuated cut element (310) drives the wood against the second non-actuated cut element (320). The intermittent storage (400) is arranged such that the feeding system (200) and the cutting system (300) feed the cut wood into the intermittent storage (400). The invention also relates to a method for continuous felling small dimensioned wood.

Description

FELLING UNIT FOR HARVESTING SMALL DIMENSIONED WOOD

AND AMETHOD FOR FELLING SMALL DIMENSIONED WOOD

FIELD OF THE INVENTION

The present invention relates to a felling unit intended for cutting and harvesting small dimensioned wood and to a method for felling small dimensioned wood.

BACKGROUND OF THE INVENTION

Great amount of renewable energy is left unutilized in forests all around the world as small dimensioned wood, sometimes also referred to as energy wood, is difficult, slow, inefficient, and not cost-effective to fell and harvest with the cur- rent commercially available machinery on the market. Small dimensioned wood refers to wood which does not qualify as timber and includes for example small- diameter wood from thinning or small dimensioned wood being harvested from seedling stands and young forests. Further, to be able to ensure favourable growth conditions for logs, small-dimensioned wood must be removed from forests in con- nection with forest management. Young forests wherein said small dimensioned wood is not actively managed also pose a serious threat of wildfires during droughts, thus in turn potentially affecting the environment and the climate nega- tively. Therefore, there is an imperative need for working and efficient solutions for managing the small dimensioned wood such that the energy stored therein can be utilized economically while the environmental risks are simultaneously man- aged.

The traditional harvesting heads aimed at harvesting large trees are mainly used for single-tree processing and cannot be as such efficiently used for a 25 — the purpose of managing the young forests having small dimensioned wood. The

N working principle of the traditional harvesters is generally to grab the tree with a 3 claw grip, and then to fell it with reciprocating motion either with sawing, pinching,

O or guillotine tools. Both of these felling operations for large trees reguire high z power machinery and large units which are difficult to operate in challenging ter- > 30 rain and tight spaces. Further, the single-tree processing of traditional harvesting

N heads causes high number of interruptions during harvesting and thus is highly 3 inefficient in harvesting of small dimensioned wood where the quantity of the trees

N is significantly higher than when larger trees are harvested.

These issues have been attempted to be solved previously, and there are also known felling units intended for harvesting small dimensioned wood in particular. These known solutions utilize two continuously actuated circular saws or crushers thatare driven in opposite directions in order to pass the wood through the cutting system. Use of two continuously actuated cutting elements requires more maintenance and introduces unnecessary weight to the felling unit. Further, inthe known solutions the cutting systems utilize very dull saws or crushers to fell the trees by forcing the trees between the two actuated saws or crushers transfer- ring a great deal of the forces to the axes they are connected to. So, such felling translates to high forces acting on the cutting system and the felling unit as whole and requires high power from the machinery. This in turn requires the machinery, the power sources, and the operating system to be dimensioned to handle such forces without breaking and results in overall heavier, more robust, and unneces- sarily high-powered felling units that are not cost effective to produce or utilize.

Therefore, there exists a clear need for an improved felling unit that can be used in mechanically performed young forest management to reduce the risk of — forest fires more economically and to alleviate the above outlined issues in current felling units.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to provide a felling unit so as to alleviate the above disadvantages and to provide a felling unit with improved felling characteristics. The objects of the invention are achieved by a felling unit which is characterized by what is stated in the independent claim. The preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on the idea of providing the felling unit with an improved cutting system comprising a first actuated cut element and a second non- actuated cut element acting as a counter blade adapted to co-operate with aid of a

N feeding system to better cut small dimensioned wood. This way, the felling unit is

N more reliable, provides a cleaner cut on the wood, and can be implemented with a <Q lighter construction, thus improving overall efficiency of the harvesting operation.

S It has been noted in praxis that by performing the felling with the felling

E 30 — unit according to the invention, cleaner cuts can be performed on the small dimen- + sioned wood, instead of crushing the wood, which decreases the power and forces

S reguired to perform the cutting operation. This in turn allows the structure of the

S felling unit and the power sources to be better optimized for the felling operation & and both fuel use, initial costs, running costs, and operating costs can be reduced compared to the solutions present in the market.

Further, the felling unit of the invention better enables mechanical maintenance performed with machinery on young forests, thus directly providing a solution for decreasing the chances of wildfires that are caused by lack of mainte- nance while simultaneously obtaining economic benefits.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which figure 1 shows an elevated perspective view of a felling unit according to an embodiment of the invention; figure 2 shows a lower perspective view of the felling unit of figure 1 wherein particularly the cutting system of the felling unit can be seen from below; figure 3 shows a front view of the felling unit of figure 1; figure 4 shows a bottom view of the felling unit of figure 1; and figure 5 shows a flow chart of an example method for continuous felling of small dimensioned wood.

DESCRIPTION OF AT LEAST ONE EMBODIMENT

The felling unit 1 according to the invention for harvesting small-dimen- sioned wood is intended to be coupled to a movable working machine. The working machine may be wheeled or tracked. The felling unit 1 is preferably fitted to a boom of a movable work machine, such as a forest tractor or a harvester to allow for better control of the position and tilting of the felling unit. Alternatively, the felling unit 1 may also be directly coupled to a movable working machine without

N 25 the use of a boom, for example by replacing the bucket in a wheel loader with the

N felling unit 1. In such configuration the position of the felling unit is mainly con- 3 trolled with the movement of the working machine itself. The felling unit is prefer-

S ably coupled to the working machine through a tilting element, which allows the = felling unit 1 to be tilted and rotated in necessary directions to improve control and 3 30 usability of the felling unit 1.

N Figure 1 shows a felling unit 1 comprising a main body 100 comprising 3 a feeding system 200, a cutting system 300, and an intermittent storage 400. This

N configuration allows a batch process for harvesting small dimensioned wood. The cutting system 300 allows plurality of wood to be cut simultaneously or continu- ously, while the feeding system 200 feeds the wood into the intermittent storage

400 wherein a predetermined amount of wood can be stored depending on the siz- ing of the intermittent storage. By storing the wood into the intermittent storage 400, the wood is bunched by the felling unit 1 and can be thus efficiently handled once the felling operation is interrupted. The bunched wood can then be emptied from the intermittent storage 400 as a pile, and thus the wood can be easily col- lected. Based on the sizing of the intermittent storage 400 the harvesting operation can be continuously performed for significant time periods before the intermittent storage 400 must be emptied, thus resulting in efficient felling operation.

The feeding system 200 comprises at least a first rotating feeder 210 and a second rotating feeder 220 feeding wood into and through the cutting system 300 and further after cutting into the intermittent storage 400. This allows the op- erator to only bring the felling unit 1 into vicinity of the tree, and the feeding system 200 automatically and continuously guides the trees into the felling unit 1 to a cor- rect position for felling, thus improving user friendliness of the felling unit by re- ducing the accuracy demands. The feeders 210; 220 are each being rotationally ac- tuated about respective rotation axes x1; x2 with at least one actuator. The rotation directions of the rotation axes x1;x2 are opposite one another, such that the rota- tion feeds the wood between the rotation axes x1;x2.

The cutting system 300 comprises a first actuated cut element 310 and a second non-actuated cut element 320 arranged such that the movement of the firstactuated cut element 310 drives the wood against the second non-actuated cut element 320. The rotation direction of the first actuated cut element 310 is the same as the rotation direction of the first feeder 210, thus driving together in co- operation the wood against the second non-actuated cut element 320 acting as a — counter blade. This is a simple to manufacture, cost effective, and light weight so- < lution for improving the cutting properties of the cutting system 300. The counter

N blade particularly provides a cutting or a slicing action on the wood compared to

N the sawing or grinding action asserted by the first actuated cut element 310, thus = resulting in a cleaner cut and less forces acting on the felling unit 1. Small dimen- © 30 sioned wood can be more easily sliced than large trees. Use of non-actuated counter

E blade also simplifies the maintenance of the felling unit 1 by utilizing fewer moving < parts. A further advantage of the second non-actuated cut element 320 is that it

S bears the load of the wood during felling and before the wood is fed into the inter-

N mittent storage. This is particularly advantageous compared to previous solutions

N 35 where two actuated cut elements are used. Load on the rim of an actuated cutting element exerts downward forces on the rim, thus possibly even tilting the actuated cut element increasing friction and power losses, resulting in damages, faster dete- rioration of the cut element, or power leaks in the felling operation.

The intermittent storage 400 is arranged such that the feeding system 200 and the cutting system 300 feed in co-operation the cut wood into the inter- 5 mittent storage 400. In other words, the intermittent storage is arranged behind the cutting system 300 and the feeding system 200 in feeding direction F of the felling unit 1. This allows the wood to be automatically bunched and collected to the intermittent storage simply by powering the feeding and the cutting systems 200;300. This gathering of the cut wood facilitates continuous felling of small di- —mensioned wood, and allows for faster felling and harvesting, making it more eco- nomically viable.

In the embodiment of figure 1, the first actuated cut element 310 and the second non-actuated cut element 320 are arranged offset in the axial direction x. This allows the cut elements 310; 320 to be positioned such that they may over- lap, and the contours of each cut element can be better designed to improve the co- operation between the cut elements, resulting in improved cutting action. Particu- larly, in the embodiment of figure 1 the second non-actuated cut element 320 is positioned above the first actuated cut element 310. This configuration provides the advantage that the first actuated cut element 310 drives the wood below the — second non-actuated cut element 320 while the feeding system 200 drives wood above the second cut element 320, thus improving the balance of the driving forces on the wood resulting in a cleaner cut, and decreasing possibilities of the wood leaning or tilting during the cutting process. Alternatively, the second non-actuated cut element 320 could be also positioned below the first actuated cut element to ensure that the wood cut by the first actuated cut element 310 is easier deposited < into the intermittent storage 400.

N In the embodiment of figure 1, the first actuated cut element 310 and

N the second non-actuated cut element 320 overlap each other when viewed from = above or below, as can be seen in figure 2, for instance. In the embodiment of figure © 30 1, the overlapping is arranged such that the second cut element 320 extends above

E the first actuated cut element 310 and covers it at least partially. This allows the < entire cutting section to be covered by a cutting element 310;320 in order to ensure

S that the wood is completely cut. This facilitates operation and efficiency of the

N felling unit 1 as stuck situations resulting from wood not being entirely cut before

N 35 attempting to insert it into the intermittent storage 400 can be avoided, and thus downtime of the felling unit 1 can be decreased. Alternatively, the second cut element 320 may also extend below the first actuated cut element 310.

In the embodiment of figure 1, a cutting edge 321 of the second non- actuated cut element 320 is arranged angled towards the intermittent storage 400 relative to a feeding direction F defined by the feeding system 200. The feeding di- rection F is perpendicular to the rotation axes x1;x2 and determined by the co-op- eration of the rotation of the axes x1;x2. The second non-actuated cut element 320 being angled facilitates cutting and slicing of the wood and reduces impacts caused by the wood coming in contact with the second non-actuated cut element 320. The cutting edge is particularly angled towards the intermittent storage 400 which in turn further facilitates guiding the wood into the intermittent storage 400. The cut- ting edge 321 is preferably angled on a cutting plane set by the first actuated cut element 310 and the second non-actuated cut element 320.

Preferably, the cutting edge 321 of the second non-actuated cut element 320 comprises a straight edge, and/or a curved concave edge, and/or a curved con- — vex edge. In the embodiment of figure 1, the second non-actuated cut element 320 comprises a combination of a straight edge and a curved concave edge. Particularly, the cutting edge 321 is divided into two sections where a first edge section 321a comprises a straight edge and the second edge section 321b comprises a curved edge. In this configuration the first edge section 321a is closer to the second rota- — tion axis x2 which pushes the wood along this straight edge. The second edge sec- tion 321b is closer to the first rotation axis x1 which pushes the wood against this concave curved edge, where this curvature allows the wood to glide on the edge instead of colliding against it straight on, thus facilitating the cutting properties of the cutting system 300.

In the embodiment of figure 1, the second non-actuated cut element 320 < is rigidly mounted on the main body 100 with bolts. However, any suitable way of

N mounting the non-actuated cut element 320 can be used. Detachable mounting el-

N ements such as bolts are preferred, as it allows the second non-actuated cut ele- = ment 320 to be replaced if damaged or dulled. Alternatively, the second non-actu- © 30 ated cut element 320 can also be integrally formed in the main body 100.

E In an embodiment not illustrated, the second non-actuated cut element < 320 is suspension mounted on the main body 100 such that the second non-actu-

S ated cut element 320 may yield. This is particularly useful in situations wherein the

N wood is jammed or stuck against the second non-actuated cut element 320 and

N 35 forcing the wood further against the second non-actuated cut element 320 would cause high force peaks on the felling unit. With aid of suspension, these spikes in forces can be alleviated and the peaks can be lowered. By yielding with the force, and with aid of the feeding system 200 and the first actuated cut element 310, the cutting of the wood is improved and possible damages to the felling unit 1 can be avoided. The suspension can be implemented for example with traditional springs, adjustable hydraulic springs, or adjustable pneumatic springs, for instance. After the yielding, the suspension returns the second non-actuated cut element 320 back to its original position.

In an embodiment not illustrated, the second non-actuated cut element 320 is circular and bearing mounted on the main body 100 such that the second non-actuated cut element 320 is able to freely rotate. This bearing mounting can be implemented on the same rotation axis x2 as the second feeder 220, such that the rotation of the axis x2 is not conveyed to the second non-actuated cut element 320. Alternatively, the non-actuated cut element 320 can also be bearing mounted on a parallel non-concentric axis, or a separate concentric axis in order to avoid — possible forces of the rotating axis x2 affecting the non-actuated cut element 320 during cutting when wood exerts pressure on it. Alternatively, the second non-ac- tuated cut element 320 may also be elliptical and bearing mounted on the main body 100 such that the elliptical cut element is able to rotate about a rotation axis.

The elliptical profile of the cut element introduces a varying cutting surface during the felling operation, which at some points may yield from the wood while simul- taneously introducing increased cutting forces elsewhere on the wood. This ellip- tical bearing mounted cut element can be paired with the suspension mounting mentioned before.

Preferably, the first actuated cut element 310 comprises a round saw blade or an elliptical saw blade, particularly a toothed round saw blade or a toothed < elliptical saw blade. Even more preferably, the first actuated cut element 310 com-

N prises a chain saw blade. Both of these are readily available sawing solutions that

N can be obtained on the market. A particularly well working chain saw blade is de- = scribed in more detail in patent publication US57656004A, for instance. © 30 In the embodiment of figure 1, a first actuator actuates the rotation of

E the first feeder 210 and the first actuated cut element 310, and a second actuator <+ actuates the rotation of the second feeder 220. In this case the first actuated cut

S element 310 and the first feeder 210 are arranged on the same axis x1 that drives

N the rotation of both of these elements. This allows that the first actuator can be

N 35 dimensioned to be more powerful than the second actuator, as the first motor prac- tically powers the cutting action and half of the feeding, while the second actuator is only involved in feeding. The rotating motion of the rotating axes x1;x2 can be actuated with actuators by use of direct drive or power transmission elements for transmitting the motion of the actuators into rotating motion of the axes x1;x2.

Such transmission elements are chains or power transmission belts, for example.

Alternatively, the first actuated cut element 310 and the first feeder 210 can be separately actuated with separate actuators and thus be arranged on sepa- rate axes. The felling unit 1 may also comprise gearing in order to alter the gear ratios of the first cut element 310 compared to the first feeder 210 in order to ob- tain different rotation speeds while utilizing the same actuator.

Preferably, the at least one actuator is a hydraulic motor, a pneumatic motor, or an electric motor. Hydraulic motor is particularly preferable, as hydraulic power needed for the hydraulic motor is typically well available in the booms of work machines, and the hydraulic motor is also an efficient, durable and mainte- nance-free actuator.

In the embodiment of figure 1, the first feeder 210 and the second feeder 220 each comprise a plurality of feeding flaps 211; 221 for feeding the wood into the felling unit 1. Said embodiment comprises 4 feeding flaps 211; 221, which is the most preferable configuration, where the feeding flaps 211; 221 are evenly spaced on each feeder 210; 220 such that the angle between each feeding flap 211; 221 is substantially 90 degrees. Also, other quantities of feeding flaps 211; 221 can be used, preferably 3 to 8 feeding flaps 211; 221. However, the disadvantage with too high quantity of feeding flaps 211; 221 is that the feeding flaps 211; 221 may inter- fere with larger pieces of wood, thus negatively affecting the performance of the felling unit 1. Similarly, the disadvantage with not enough feeding flaps 211; 221 is — that the feeding volume slows down with same rotation speed, and same feeding < frequency is not obtained.

N Preferably, the feeding flaps 211; 221 extend in axial direction of the

N rotation axes x1; x2 for at least 50% of the axes x1; x2. This facilitates feeding the ? wood in upright position and not allowing the wood to tilt or fall during feeding,

S 30 — which could cause operational issues such as jamming or clogging of the felling unit

E 1. x Preferably, the feeding flaps 211; 221 are preferably elastic and durable 5 material such as natural rubber, for instance. Also, other suitable materials may be

N used which provide suitable strength and flexibility profiles to be able to perform

N 35 properly.

Preferably, the feeding flaps 211; 221 comprise a substantially rectangular profile and/or extend continuously along the rotation axes x1; x2.

In the embodiment of figure 1, the rotation axis x1 of the first feeder 210 and the rotation axis x2 of the second feeder 220 are parallel and are spaced apart such that an opening O is formed between the rotation axes x1; x2 for feeding the wood into the intermittent storage 400, and the feeding flaps 211; 221 are dimen- sioned such that the length 11 & 12 of the feeding flaps 211; 221 are at least 50% of the width of the opening O. This ensures that the feeders 210; 220 are able to main- tain contact with the wood during the entire cutting process, and both the feeding and cutting operations are better supported.

In the embodiment of figure 1, the rotation speed of the first axis x1 and the second axis x2 are the same, and the rotation phases of each feeder 210; 220 are offset related to each other such that the feeding flaps 211 of the first feeder 210 do not collide with the feeding flaps 221 of the second feeder 220. This allows the feeding flaps 211;221 having above-described dimensions to be used without the feeding flaps 211; 221 interfering with operation of one another.

In the embodiment of figure 1, the rotation of the rotation axes x1;x2 can be reversed and be rotated in a second direction opposite the first direction. By reversing the rotation, the feeders 210;220 can be used to mechanically empty the intermittent storage 400. This helps to minimize the unloading time and does not require outside tools for the emptying. The felling unit 1 can also be simultaneously tilted downward, such that the feeding direction F is away from the ground, mean- ing that the unloading direction is towards the ground, and the unloading is facili- tated with gravity.

In an embodiment not illustrated, the felling unit 1 further comprises an athird actuated cut element below the second non-actuated cut element 320. Pref- < erably, said third actuated cut element may be formed as an elongated chain saw

N blade. The position of the third actuated cut element can be altered by rotating it

N about a rotation axis located on a first end of the third actuated cut element. In that = instance a cutting portion of the third actuated cut element is located on a second © 30 end opposite the first end. Alternatively, the position of the third actuated cut ele-

E ment can be altered by moving it linearly. In both cases the movement of the third < actuated cut element can be actuated with a separate actuator, such as a hydraulic

S or pneumatic cylinder. Further, in both cases the actual cutting motion is prefera-

N bly performed with a chain saw blade powered by a separate actuator, for example

N 35 — ahydraulic motor or an electric motor. This allows much higher speeds to be used in the third actuated cut element, which in turn supports the felling of the felling unit 1. Such cut elements themselves are known per se from different applications in traditional harvester heads. Preferably, the third actuated cut element covers more than 25% of the opening O between the rotation axes x1;x2. Even more pref- erably the third actuated cut element covers 50% of the opening O between the rotation axes x1; x2.

Figure 5 illustrates a flow chart of an embodiment of a felling method for felling small dimensioned wood. This method may be implemented for felling small dimensioned wood with the felling unit 1 illustrated in figures 1 to 4. The embodiment comprises steps of A providing a suitable felling unit 1, preferably as described before in this description; B feeding small dimensioned wood into the cutting system 300 by bringing the felling unit 1 in contact with the wood, C felling the wood by driving the wood against the second non-actuated cut element 320 by use of the feeding system 200 and the first actuated cut element 310, and finally D storing D the wood temporarily in an intermittent storage 400.

Preferably, the felling unit is a felling unit particularly intended for har- vesting small dimensioned wood.

It will be obvious to a person skilled in the art that the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims. i

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Claims (16)

1. A felling unit (1) comprising: a main body (100) comprising a feeding system (200), a cutting system (300), and an intermittent storage (400); wherein the feeding system (200) comprises at least a first rotating feeder (210) and a second rotating feeder (220) for feeding wood through the cutting system (300) and into the intermittent storage (400), the feeders (210; 220) each being rotationally actuated about respective rotation axes (x1; x2) with at least one actu- ator; the cutting system (300) comprises a first actuated cut element (310) and a second non-actuated cut element (320) arranged such that the movement of the first actuated cut element (310) drives the wood against the second non-actu- ated cut element (320); and the intermittent storage (400) is arranged such that the feeding system (200) and the cutting system (300) feed the cut wood into the intermittent storage (400).

2. The felling unit (1) according to claim 1, wherein the first actuated cut element (310) and the second non-actuated cut element (320) are arranged offset in the axial direction (x), preferably such that the second non-actuated cut element (320) is positioned above the first actuated cut element (310).

3. The felling unit (1) according to claim 2, wherein the first actuated cut element (310) and the second non-actuated cut element (320) overlap, such — that the second non-actuated cut element (320) extends above the first actuated < cut element (310) and covers it at least partially. N &

© 4. The felling unit (1) according to any of the preceding claims 1 to 3, = wherein the second non-actuated cut element (320) is suspension mounted on the 9 30 main body (100) such that the second non-actuated cut element (320) may yield. E

3 5. The felling unit (1) according to any of the preceding claims 1 to 3, 5 wherein the second non-actuated cut element (320) is rigidly mounted on the main O body (100) or integrally formed on the main body (100).

6. The felling unit (1) according to any of the preceding claims 1 to 5,

wherein a cutting edge (321) of the second non-actuated cut element is arranged angled towards the intermittent storage (400) relative to a feeding direction (F) defined by the feeding system (200).

7. The felling unit (1) according to any of the preceding claims, wherein the cutting edge (321) of the second non-actuated cut element (320) comprises a straight edge, and/or a curved concave edge, and/or a curved convex edge.

8. The felling unit (1) according to any of the preceding claims, wherein the cutting edge (321) of the second non actuated cut element (320) comprises a first edge section (321a) and a second edge section (321b), wherein the first edge section (321a) comprises a straight edge and the second edge section (321b) com- prises a curved edge.

9. The felling unit (1) according to claim 1, wherein the second non-ac- tuated cut element (320) is circular and bearing mounted on the main body such that the second non-actuated cut element (320) is able to freely rotate.

10. The felling unit (1) according to any of the preceding claims, wherein the first actuated cut element (310) comprises a round saw blade, an elliptical saw blade, or a chain saw blade.

11. The felling unit (1) according to any of the preceding claims, wherein a first actuator actuates the rotation of the first feeder (210) and the first actuated cutelement (310), and a second actuator actuates the rotation of the second feeder < (220). S 6 12. The felling unit (1) according to any of the preceding claims, wherein ? the first feeder (210) and the second feeder (220) each comprise a plurality of feed- S 30 = ing flaps (211; 221) for feeding the wood into the felling unit (1). I = x 13. The felling unit (1) according to any of the preceding claims, wherein 5 the rotation axis (x1) of the first feeder (210) and the rotation axis (x2) of the sec- N ond feeder (220) are parallel and are spaced apart such that there is an opening N 35 — (O) between the rotation axes (x1; x2) for feeding the wood into the intermittent storage, and the feeding flaps (211; 221) are dimensioned such that the length (11

& 12) of the feeding flaps (211; 221) are at least 50% of the width of the opening

(0).

14. The felling unit (1) according to claim 13, wherein the rotation speed of the first axis (x1) and the second axis (x2) are the same, and the rotation phases of each feeder (210; 220) are offset related to each other such that the feed- ing flaps (211) of the first feeder (210) do not collide with the feeding flaps (221) of the second feeder (220).

15. The felling unit (1) according to any of the preceding claims, wherein the felling unit (1) is a felling unit (1) for harvesting small dimensioned wood.

16. A felling method for continuous felling small dimensioned wood, the method comprising: providing (A) a felling unit 1 according to claim 1, feeding (B) small dimensioned wood into the cutting system (300) by bringing the felling unit 1 in contact with the wood, felling (C) the wood by driving the wood against the second non-actu- ated cut element (320) by use of the feeding system (200) and the first actuated cut element (310), storing (D) the wood temporarily in an intermittent storage (400). i N O N © I © O I = <t N K LO + N O N