The present invention relates to a feeding device for trees in the multi-function unit of a forest machine, such as delimbing or cutting machine. The device comprises at least one roller mounted for rotation about an axis perpendicular to the feeding direction of a tree. The circumferential surface of said roller is provided for transferring or guiding the tree during the rotational movement of the roller.

In conjunction with multi-function units of various forest machines, such as various processors and harvesters, there are used tree feeding devices emplo¬ ying generally rollers having a rubber covering. The rollers are provided for displacing or guiding a tree by means of their rotational movement. The problem in said rollers is their weight, which is a drawback especially in mobile forest machines.

US Patent 3,981,336 shows a feeding device in which some efforts for lighter rollers have been made by forming the support surface for a tree of transverse ribs. Even if the construction is so made slightly lighter, there still remains the problem of ensuring satisfactory function when feeding trees with varying external forms.

The object of the invention is to accomplish a tree feeding device without the above-mentioned drawbacks to be used in forest machines. For achieving said goal the feeding device according to the invention is mainly characterized in that the circumferential surface is attached to the opposite end parts of the roller and it is flexible between said end parts. A flexible circumferential surface can easily be so formed that it will be light in order to avoid the

undesired high weight of the roller. By virtue of its flexibility the surface will well adapt oneself to external shapes of trees being of different sizes.

The feeding device according to the invention has various advantageous embodiments. The distance between the end parts of the roller can be variable in the direction of the rotational axis of the roller, and in this case the material constituting the circumferen- tial surface needs not necessarily be of variable length between its attaching points. According to one preferred variant the end parts of the roller can be rotatable with regard to each other. The end parts of the roller can also be unrotatable with regard to each other and their mutual distance can be fixed, and for effecting the flexibility of the circumferen¬ tial surface it is constituted of a material of variable length in the direction of the surface between said attaching points.

The circumferential surface can be constructed of flexible, elongate elements extending between said attaching points, such as of fibres, wires or chains.

In addition, there are some possibilities to prevent a tree from rotating and to orientate the elongate elements, to be discussed hereinafter.

The invention will be described in the following in more detail with reference to the accompanying dra¬ wings, wherein

Fig. 1 shows the roller of a feeding device in accordance with the invention in perspecti- ve view.

Fig. 2 shows an embodiment of the feeding device

in conjunction with a tree harvesting machine, and

Fig. 3 shows an embodiment of the roller end of the feeding device in sectional view taken along the axis of rotation.

Figure 1 depicts a roller 1 provided for displacing and guiding a tree and mounted in a feeding device employed in a forest machine, such as in a processor or harvester. The axis of rotation of the roller is indicated by dash and dot line A. The end parts la and lb of the roller consist of disc-shaped pieces situated perpendicularly to the axis A. The pieces are provided for rotation about the axis A and fixed to each other through a connecting element 2 extending at the axis A. The circumferential surface 3 of the roller 1 forms the surface that will be in contact with the tree to be displaced. The circumferential surface is so suspended between the the end parts la and lb of the roller that it is able to bend itself between the attaching points according to the shapes of the tree. Because the roller 1 is in a way hollow inside the circumferential surface, except for the connecting element 2, the roller has a light construc¬ tion.

In Figure 1 the circumferential surface of the roller is constituted of approximately parallel flexible elongate elements 3a situated between the attaching points in the end parts la and lb. The elements are spaced at sufficiently close intervals so that they could well support the tree and also transmit force for displacing the tree by virtue of the rotational movement of the roller. The term circumferential surface shall in this context be understood to mean such surface that can be imagined to be the outer surface of a plane in which the elements in contact

with the tree are lying. Said plane is of more or less concave shape in cross-section along the axis A, depending on the shape of the tree.

The mutual distance of the end parts la and lb of the roller in the direction of axis A can be fixed, the flexibility of the circumferential surface being accomplished by the changing length of the material between the attaching points in the end parts la and lb. For example the elements 3a shown in Fig. 1 can thus be elastic in the longitudinal direction. The mutual distance of the end parts la and lb of the roller can, however, be also variable in the direction of axis A, and the circumferential surface 3 need not necessarily be of variable length between the above- mentioned attaching points in this case, but it can be formed of a relatively non-stretching material, which is flexible enough so as to accommodate the circumferential surface to the shapes of the tree. In this case the elements 3a shown for example in Fig. 1 can be non-stretching fibres. When the end parts la and lb are movable in respect of each other in the direction of axis A, their distance thus changes as the shape of the circumferential surface 3 supporting the tree changes in such a manner that when the said shape is more concave, the end parts la and lb are correspondingly more close to each other.

Fig. 1 shows also such a construction in which the end parts la and lb are able to rotate in respect of each other about axis A. If the mutual distance of the end parts la and lb is at the same time variable in the direction of axis A, the angle of the elongate elements 3a relative to axis A will consequently increase as the end parts move more close to each other and vice versa. If the roller is a driving roll it is possible to allow the power transmission to affect only one of the end parts, la, and the power

causing the rotation of the other one, lb, will be transmitted to this part through the circumferential surface 3. This provision makes it possible to get a strong hold of a tree, and the circumferential surface can be well pressed against the tree by means of the end parts rotatable in respect of each other. In the case of Fig. 1 the said provision causes the attaching points of the elongate elements 3 in the driving end part la to be always ahead of the attaching points of the same elements in the opposite end part lb. The mutual distance of the end parts rotatable in respect of each other can also be fixed, but a variable distance allows to improve the adaptation of the circumferential surface to the tree shapes and its g ip on the tree.

In Fig. 2 is shown an embodiment of the feeding device of the invention, mounted in conjunction with a forest machine. The number of rollers 1 is in this case two, and their circumferential surfaces 3 lie opposite to each other so as to leave a space threbetween for feeding a tree between the rollers. At least one of the rollers 1 is a driving roller. The mutual distance of the rollers can be made variable by any arrangement known as such. In the example of Fig. 2 the rollers are of the type as presented by Fig. 1. The circumfe¬ rential surfaces 3 of the rollers are constituted by elongate elements 3a, the end parts la and lb of the rollers are capable of rotating relative to each other and the mutual distance of the end parts is variable in the direction of axis A. In the opposite rollers rotating in opposite directions in the manner shown by arrows, the feeding direction of the tree being indicated by arrow B, the attaching points of the elongate elements 3a which are ahead of those in the other end part lb are situated in the end parts la of the same side (in Fig. 2 on the machine side) in order to prevent the tree from rotating. By the above

provision it is possible to cause the force tending to rotate the tree, originating from the direction of the elongate elements 3a supporting the tree, to be opposite to that in the opposite roller, thus resulting in that the forces cancel each other. In the practice this effect is achieved by allowing the drive in the driving roll to be effective only in one of the end parts, in which part the attaching points will be in a more advanced position than those in the opposite end par .

It must, however, be noted that in the device of Fig. 2 also any other rollers within the scope of the invention can be used, resulting in a lighter structure and the improvement of the manoeuvrability of trees.

The circumferential surface 3 of the roller 1 can be formed also in another way than from the above-descri¬ bed, mainly parallel elongate elements 3a. The circum- ferential surface can be formed e.g. of a sheet or woven mat, in principle of any material with the flexibility and strength properties required by the invention and with suitable frictional properties for transmitting the tree feeding power to the tree.

One variant is to provide the elongate elements crosswise between the end parts la and lb, and this variant is described in more detail in the following. Fig. 3 shows one end part lb of the roller in the feeding device of the invention. The end part comprises two separate parts 4 and 5 provided for rotation about axis A, said parts being capable of rotating with regard to each other as well. The parts 4 and 5 are, however, so positioned that they are retained together in the direction of axis A. In the opposite end part la there are also mutually rotatable and axially inseparable parts 4 and 5. The end parts are further interconnected by means of a connecting element

2 in accordance with Fig. 1. To the first part 4 are affixed elongate elements 3a' directed mainly in one direction, and in the second part 5 are provided elongate elements 3a' ' directed crosswise with regard to the former ones. The elements 3a' leaving the first part 4 are affixed to the part 4 in the opposite end part la, and the elements 3a'' leaving the second part 5 are affixed to the part 5 rotatable with regard to the part 4 in the opposite end part la. The parts 4 and 5 can be shaped in various ways, for example they can be discs which are placed one inside the other in the way as shown by Fig. 3, or the second part 5 can be constituted of a circumferential part mounted rotatably on the first part 4, etc.

The elements 3a' and 3a'' can be made to cross each other in the desired way, for example so that the bisector line for the angle formed by the elements 3a' and 3a' ' is parallel to axis A, by suitably turning the parts relative to each other. In this way no forces tending to rotate the tree are present. This can be realized for example so that the distance between the end parts la and lb is variable in the direction of axis A, in which event the drive can be connected in one of the end parts to the part receiving the elements directed to one of the directions and in the opposite end part to the part receiving the elements that extend across the former elements. Said "tractive" parts rotate through the elements 3a' and 3a'' the remaining two parts.

It will be understood that the elongate elements 3a' and 3a'' can be affixed in each end part la and lb to the same body, in which event there is no separate parts 4 and 5. The end parts are preferably non- rotatable with regard to each other. Their mutual distance can be variable in the direction of axis A, the length of the elements 3a' and 3a' ' between the

attaching points thus being invariable, or said distance can be invariable, said length consequently being variable.

If the mutual distance between the end parts la and lb of a roller falling within the scope of the inventi¬ on is variable in the direction of axis A, they can be shifted to rest position be means of a force applying member disposed between the end parts la and lb. The end parts of the roller can move towards each other against said force during the operation. The force can be effected for example by means of a push spring indicated by reference numeral 6 in Fig. 1. The fo ce can also be provided with the help of the pressure of hydraulic fluid and the push spring can be replaced by a hydraulic cylinder. As the end parts are moved towards each other against the force, it is also ensured that the circumferential surface 3 is sufficiently taut.

The invention can be realized in many ways construc- tionally. The connecting element 2 between the end parts of the roller allows to provide the desired relative movements of the end parts. If the end parts are able to move relative to each other in the directi¬ on of axis A but they are mutually non-rotatable, the connecting element 2 affixed with its opposite ends to the end parts la and lb can be of variable length but non-rotatable. The other movements can be realized in an analogical manner.

The materials forming the circumferential surface 3 can be of sufficiently strong and flexible materials possessing at the same time suitable frictional properties, as presented hereinabove. Such materials are for example some plastics, metals, ceramic mate¬ rials, various composites, etc. If elongate elements 3a are used as the elements constituting the circumfe-

rential surface they can be for example metal wires, metal chains, plastic ropes of for example composite structure, or they can be of strong elasto ere con¬ taining for example reinforcements, allowing the change of length in case the end parts are immovable.

The invention is not restricted to only the feeding device shown by Fig. 2 having two rollers constructed according to the invention. The invention encompasses all feeding devices employed in the multi-function units of forest machines, such as delimbing or cutting machines, having at least one such roller supporting and feeding a tree that has the characteristics defined by claim 1. The other member guiding the tree on the opposite side can be a normal roller, for example a roller having a fixed circumferential surface.