Felling head with offset arms

The accumulator and harvesting arms in a front cut felling head are offset to one side of the machine so as to hold a bundle of cut trees more to one side than the other so as to create more room in front of the accumulator arms to the side of the bundle in which to cut and receive a freshly cut tree.

FIELD OF THE INVENTION

This invention relates to forestry equipment, and in particular to felling heads.

BACKGROUND OF THE INVENTION

Feller bunchers having felling heads for cutting and accumulating cut trees are well known in forestry operations. Most of them are front cut heads with the head mounted on either the front of a drive to tree vehicle or on the front of a vehicle mounted boom in the case of a boom to tree machine. There have been two basic approaches to accumulating arm geometries in such machines in the past. One approach is dual symmetric arms. These would accumulate the first tree in the middle of the head. These provide good control and power, are suitable for larger trees, and can be used to pick up trees off of the ground, but limit the space available in front of the arms to cut subsequent trees as the head is fed forwardly through the tree during the cutting operation. More recently, single accumulator arm designs have been used, particularly for felling heads that are designed to accumulate larger numbers of smaller trees. The single arm permits the trees to be accumulated off of the center of the head, and thus permits more variety in the shape of the accumulating area, and generally larger accumulation areas. The single arm is not as effective in controlling one or two very large trees, however, and cannot be used for picking up cut trees off of the ground.

SUMMARY OF THE INVENTION

The present invention provides a front cut felling head for a drive to tree or boom to tree feller buncher with an accumulation area that is offset from the center of the head, but still retains the ability to control large trees, even a single very large tree, and to pick up cut trees off of the ground. A large accumulation felling head is therefore provided that can be used with a variety of tree sizes.

A felling head of the invention has an arm design that allows more efficient use of the accumulation area. In a design of the invention, two accumulating arms are provided to accumulate cut trees off of the center of the head. The arm on one side is offset rearwardly and toward the center of the head, and the arm on the other side is offset away from the center of the head. Preferably, the arm set (including both arms), is rotated such that the tree is drawn back into the pocket and offset to one side of the pocket, toward one side of the space between the arms. Since the first tree cut is to one side of the pocket, more room is left on the butt plate outward of the accumulator arms to allow for subsequent cutting of more and larger trees. Prior link-synchronized arms tended to position the accumulated trees centered in the accumulation pocket. Doing this limited the room available to cut subsequent trees, as there wasn't enough room left on the butt plate to fit other trees, especially if the first accumulated trees were quite large. The present invention positions the accumulated trees offset from the center of gravity using two accumulating arms that leave as much room as possible for the cutting of more trees off center of the accumulated bunch as the head is fed forwardly through the tree.

Because the accumulated trees are to one side of the pocket in a head of the invention, the harvesting arms need to accommodate this repositioning of the load. This is accomplished by making the harvesting arm on the side where the trees are accumulated with more curvature on the side holding the trees, to reach further outwardly before turning inwardly to clear the accumulated trees, thus not disrupting the bunched trees. The opposing harvesting arm is straighter for pushing the cut trees towards the accumulating side. This design allows the arm to be synchronized for picking up trees on the ground, and also allows both harvesting arms to engage the accumulated trees for more hold and control while swinging the head or traveling with trees in the pocket.

The accumulating arms are also shaped non-symmetrically like the harvesting arms, with the accumulating arm on the accumulating side having more curvature on the tree holding side than the accumulating arm on the other side. The two sets of arms preferably have mating shapes so that the accumulated tree or trees are not disrupted when they are held by one of the sets of arms and the other set of arms is closed over it or them.

The foregoing and other objects and advantages of the invention will appear in the detailed description which follows. In the description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring toFIGS. 1A-5, a front cut felling head10of the invention has a frame12that pivotally mounts a set of hydraulically-driven harvesting arms14and16and a set of hydraulically-driven accumulating arms18and20. Each of the accumulating arms18and20has an outer arm18A and20A, respectively, and an inner arm18B and20B, respectively. The outer arms are held in the positions illustrated inFIGS. 1-5by springs and can pivot relative to the respective inner arms so that they can be withdrawn from a bundle of trees to introduce the freshly cut tree to the bundle, and then the accumulating arms after having been withdrawn from the bundle are clamped back around the new bundle of trees, including the freshly cut tree. The outer arms18A and20A pivot relative to the respective inner arms18B and20B so that they can move out of the way behind the freshly cut tree, or else the freshly cut tree would block the withdrawal of the arms18and20from the bundle.

The head10has a cutting blade26that is driven by a motor (typically, hydraulic, not shown) and includes a plurality of peripherally-mounted cutting teeth at its outer perimeter, which when the blade26is driven rotatably cut a kerf in the tree to fell the tree. After the tree is fully cut, the harvesting arms14and16are closed to push the cut tree into the pocket, and hold it. The butt end of the tree moves onto butt plate28, which is right above the blade26, as the tree is being cut. With a high speed disc saw felling head as illustrated, the cut can be made extremely quickly and so the tree goes from being supported by the stump to being supported by the feller buncher very quickly.

The butt ends of the freshly cut trees of the accumulated trees are supported on the buttplate28, but they are also tightly clamped by either the accumulating arms18and20, the harvesting arms14and16or both sets of arms. For example, the first tree cut may be clamped by both sets of arms. Then, the harvesting arms are opened, while maintaining the accumulating arms closed around the first tree, to clamp on to the next tree to be cut. When that tree is cut, while maintaining the harvesting arms closed, the accumulating arms are opened and then reclosed around the bundle of two trees. This process is continued until the accumulating arms can hold no more trees, or there is no room in front of the accumulating arms to cut another tree.

Above the blade26, the frame12defines a generally U-shaped area that is known as the pocket30. The pocket30has walls that enclose the butt ends of the trees at the sides to restrain the butt ends from moving too much so that the trees cannot tip out of the frame12. At the top end of the frame12, the frame12has a horn32that serves a similar purpose above the two sets of arms. Thus, in general, the bundle of trees is restrained by one or both sets of arms, the pocket30and the horn32, and may be supported on the buttplate28.

Referring toFIG. 6, a top schematic view of the felling head10is illustrated showing the horn32and an alternate horn33in phantom lines. While the horn32may be a preferred shape for many applications, the horn33shape was used to createFIGS. 7-21, which show the head in various conditions. The principles are the same, only the particular shape differs.

Referring toFIGS. 6-8, either the accumulating arms and the associated structures are shown or the harvesting arms and associated structures are shown. That is true for all ofFIGS. 6-19. In the figures, various circles are shown, which indicate different tree diameters.FIG. 6shows the accumulating arms closed around a tree of the smallest diameter for instance.

In the figures, the points about which the various arms are pivoted to the frame12are axis40for arm18, axis42for arm20, axis44for arm14, and axis46for arm16. A link48is pivotally connected between the inner arms18B and20B so that those arms move in synchronization. Axis50is the axis of a hydraulic actuator51that is pinned at one end to the frame12and at the other end to arm20B, to cause both of the accumulating arms18,20to move. Similarly, a link52is pinned with both ends pivotally attached to the arms14and16so that they also move in synchronization, and an axis54is the axis of a hydraulic actuator55having one end pinned to the frame12and the other end pivotally pinned to the arm16so that the harvesting arms14and16are moved by the cylinder55. Both sets of arms are said to be link synchronized since the arms of each set, either the accumulating arm set18,20or the harvesting arm set14,16, move in synchronization with one another, being restrained by the respective link48or52.

FIG. 7illustrates the harvesting arms wide open andFIG. 8illustrates the accumulating arms wide open. In each figure, axis58indicates the center axis of the head10and the driving direction of the vehicle to which the head10is mounted, which goes through the axis about which the saw blade26rotates, and is the direction that the head10is fed through a tree during the cutting operation. The center about which the blade26rotates is indicated at point60. The head10cuts trees from the front of the head and therefore is for a drive to tree feller buncher or a front cut boom to tree feller buncher, meaning that the head10is mounted to the front of a wheeled or tracked vehicle, or to a boom at the front of the vehicle, and the axis58is parallel or aligned with the forward or boom extension direction of the vehicle. Trees are cut at the front of the head10, as that is the machine direction, whether the feller buncher is being driven forwardly during cutting or the boom, if the head10is boom mounted, is being extended.

The array of different sized trees illustrated are all accumulated off center relative to the axis58. The centers of these trees are shown inFIG. 7, all being to the right of the axis58. The first trees are each positioned in a spot such that one of the accumulating arms is tangent to the tree, and from the arrangement of the pivot axes of the arms, all of the tree centers are right of the central axis58of the head10. The harvesting and accumulating arms on the left, or operator's view, side of the head10are shaped to push the trees over to the right side and the harvesting and accumulating arms on the right side are shaped so as to be more curved than the associated left side arms on their inner surfaces that hold the trees to make room to receive and accumulate the trees on the right side. From side to side, therefore, the arms of each pair are non-symmetrical. In addition, the axes of rotation44and40of the respective arms14and18on the operator's view (left) side of the head10are not coaxial. In addition, both sets of arms are shaped complimentarily to one another so as to minimize disruption or changing location or orientation of the tree or trees accumulated when being held by one set of arms and the other set of arms is closed over the accumulated tree or trees.

It addition, it is noted that trees are drawn into the pocket toward one side of the space between the arms of each pair of accumulator or harvesting arms. In other words, the center of the first tree drawn into the pocket will be to the right of a line drawn at the midpoint of a line between the two pivot points of the arms that is perpendicular to the line between the two pivot points. This is true for the accumulator arms and for the harvesting arms. Another way of saying this is that the center of the accumulation pocket is offset from the center of the space between both pairs of arms, or that trees are drawn to one side of the space between the pivot points of the arms.

Axis58represents the central axis of the head10in the direction of forward movement of the vehicle on which the head10is mounted, which may be a tracked or wheeled vehicle, with or without a boom on which the head may be mounted. If mounted on a boom, the forward longitudinal axis58is determined by the direction of forward extension of the boom, and if not mounted on a boom it is determined by the forward driving direction of the vehicle. Line62is a line drawn between the two centers40and42, which are the pivot axes of the respective accumulating arms18,20. Line62is not at a right angle to the line58, which if it were would appear horizontal inFIG. 8, but is rotated or angled from the perpendicular position to an obtuse or angled orientation relative to the line58. This is because the pivot point40is further back than the pivot point42, relative to axis58and the forward direction58of the head10. This rotates the sweep zone of the set of accumulating arms18and20so that the arms pull the trees that they accumulate to the right side of the axis58. It is preferable to pull them to the right side, because on most machines, the operator is sitting to the left of center so that the operator has a better view to the left side of the head than to the right side, as the post or frame12of the head can block the view to the right. Positioning the cut trees to the right of center creates more room on the left side of the head, the operator's view side, to cut a new tree. In addition, the center of the first accumulated tree is also to the right of a line drawn at the midpoint of line62and perpendicular to line62, which results in the center of the pocket being offset from the center of the space between the pivot points of the two arms18and20.

Referring toFIG. 9, a line66connects the pivot point centers44and46. Line66is also at other than a right angle to the forward longitudinal axis58of the head10and vehicle to which it is mounted, so that the harvesting arms14and16also tend to pull trees being cut toward the accumulation area, which is mainly on the right side of the axis58. In addition, the center of the first accumulated tree is also to the right of a line drawn perpendicular to line66at the midpoint of line66, which results in the center of the pocket being offset from the center of the space between the pivot points of the two arms14and16.

The pocket30and the horn32are both deeper on the right side of the axis58as well, which is also to the right of the above mentioned lines drawn perpendicular to the lines62and66at the midpoints of those lines. Which horn shape32or33is used is a fine point, with horn32being preferred, as with either, the trees will still be pulled to the right side of the central axis58. The horn32shape is preferred since it tends to contact a single tree in the accumulation pocket on two sides rather than just one, for better stability.

FIG. 10shows the accumulating arms18and20closed around the largest of the tree sizes illustrated, which may be for example approximately 22 inches in diameter. The relatively straighter outer arm18B tends to move the tree to the right and the curve of the outer arm20B on the inner side of the arm20B creates room so that the tree can move to the right. As stated above, the outer arm18B can pivot relative to the inner arm18A about axis70, but cannot pivot outwardly further than as illustrated inFIG. 10, and its inward pivoting is limited by one or more springs (not shown, but commonly understood by persons skilled in the art). Similarly, outer arm20B pivots about axis72relative to inner arm20A but cannot pivot further outwardly than as illustrated inFIG. 10, and its inward pivoting is opposed by suitable springs (not shown, but commonly understood by those skilled in the art).

FIGS. 11-18are views similar toFIGS. 9 and 10but alternately showing the harvesting and accumulating arms closed about different sizes of the first tree to be cut. In these figures, it should be noted that the amount of space outside of the accumulating arms18and20and in the pocket is significantly greater on the left side of the forward axis58than it is on the right side. Arch78is the path of the tooth tips, so that is where cutting begins and ends. By shifting the space to the left, when the head10is driven forwardly through the tree, a larger tree can be cut for each size of first tree cut, or for a given number and size of trees held by the accumulator arms18,20. The pivot axis40of the arm18is also shifted rearwardly relative to where it otherwise would be, and also relative to axis42of arm20, which helps create more room in front of the arm18for cutting a new tree when the arm18is holding a given size and number of trees. The pivot axis44of the arm14is also shifted rearwardly from where it otherwise would be, and also relative to axis46of arm16, which helps arm14push trees in a direction more toward the accumulation zone of the head10.

FIG. 19shows the head with the horn32drawn in.FIGS. 20 and 21show a bundle or bunch of three trees held by the accumulating arms and one additional tree being cut in the area between the outside of the accumulating arms and the inside of the harvesting arms. The operator of the head would cut the new tree to the left side of forward travel axis58as illustrated. The additional freshly cut tree80illustrated inFIG. 21could be cut all the way through by withdrawing arms18and20before finishing the cut on tree80, which would create room for the tree80to be drawn in to the bunch of already accumulated trees. The accumulating arms18and20are spaced a sufficient distance above the butt plate28so that the blade26will sever smaller trees without the need to open the accumulating arms. Since the center line of the bunch or bundle of trees held by the accumulating arms18and20is offset to the right of the axis58, the harvesting arm16must be made with more curvature so that it goes forwardly further before it turns in, than would be the case if the bunch was centered relative to the head10. Thus, the accumulating arms hold the bundle of trees so that the center or axis of symmetry of the accumulated tree(s) is to one side of the forward central axis of the head. This creates more room on the other side to cut the next tree, and allows accumulating more and bigger trees than other heads with centered accumulation.

It should be noted that this arrangement could be reversed to accumulate more trees to the left of the center line58than to the right, but this is not preferred since doing so may obstruct the vision of the driver to see the new tree being cut.

Preferred embodiments of the invention have been described in considerable detail. Many modifications and variations to the embodiments described will be apparent to those skilled in the art. Therefore, the invention should not be limited to the embodiments described, but should be defined by the claims that follow.