This invention relates to an improved tree felling and shaping apparatus. The invention more particularly relates to an improved tree felling and shaping apparatus of the type that can be rotated about a vertical axis regardless of the process in which the apparatus operates for tree felling or tree shaping.
Tree felling machines can be broken into two categories, feller/bunchers and feller/processors. Feller/bunchers are use for felling and piling trees. A feller/buncher has a boom with a head mounted at the end of the boom. The head has arms or other means of gripping a tree and a saw for cutting the tree at the base. After the tree has been cut, the cut tree can be processed by another machine before being shipped to its ultimate destination. An example of feller/bunchers is described in U.S. Pat. No. 5,291,926, entitled CUTTING AND SAWING UNIT PROVIDED WITH A TIMBER HANDLING ARRANGEMENT, issued to Jansson on Mar. 8, 1994.
Feller/processors, or tree felling and shaping machines are machines which can both cut trees and process the cut trees. Generally, a tree felling and shaping machine has a tree processor head which includes a central post, a cutting device at the bottom of the central post, and gripper and stripping means attached to the central post. The tree felling and shaping machine generally has a boom mounted to a vehicle and the tree processor head is typically mounted to the boom with a joint link system which has at least two degrees of freedom. The head can be tilted toward, or away from the machine about a first axis transverse to the boom. The head may also be tilted side to side about a second transverse axis, which is generally longitudinal to the boom when the head is upright, or may be pivoted about a second transverse axis which is at an angle from the first axis. These two degrees of freedom allow the head to be aligned with a tree that is not perfectly vertical. After the tree has been cut the head can be tilted about the first axis to move relative to the bottom of the machine to lay trees down transversely to the bottom for processing. During the processing period the tree processor head is in a generally horizontal position and must be freely suspended on the boom or xe2x80x9cfloatxe2x80x9d about the horizontal axis perpendicular to the tree while the tree is being shaped.
Examples of such tree felling and shaping machines are described as prior art (referring to FIGS. 2A and 2B) in U.S. Pat. No. 5,727,610, entitled COMBINED TREE FELLER AND PROCESSOR, issued to Isley on Mar. 17, 1998. The prior art feller/processor uses a universal joint to suspend the processor head from a boom in order to allow the processor head to pivot freely about a longitudinal axis and a transverse axis. However, as pointed out by Isley, mounting a processor head to a boom in a manner which provides the necessary xe2x80x9cfloatingxe2x80x9d action during processing generally precludes the use of a high speed continuously rotating saw for tree cutting because such a mounting would be incapable of controlling the saw under the action of the large gyroscopic forces. Furthermore, the un-powered universal joint is not controllable, thereby reducing the maneuverability of the feller/processor which is especially required when the feller/processor is used to pile and handle the processed trees.
Another example of tree feller/processors is described in U.S. Pat. No. 4,800,936, entitled MACHINE FOR FELLING AND SHAPING TREES, issued to Pomies et al. on Jan. 31, 1989. Pomies et al. describe a link system having an un-powered pivoting joint which provides an additional degree of angular freedom while the tree processor head is in a recumbent position for shaping trees, but is disabled while the tree processor head is in an upright position for felling trees. The un-powered pivoting joint reduces the maneuverability of the processor head in the recumbent position. Furthermore, this link system can not provide any angular adjustment of the processor head in the upright position for a selected angle to approach a target tree.
Efforts have been made to improve tree felling and shaping machines, particularly to improve the joint link system which operatively links the tree processor head and the boom in order to make the machine more maneuverable, thereby increasing the work efficiency of the tree felling and shaping machine, and reducing operation costs. One example of such efforts can also be found in U.S. Pat. No. 5,727,610 which suggests a fully powered and controllable link system. This link system however, compromises a wide selection of approaching angles of the processor head to a target tree to be cut because of limited rotational adjustment about a vertical axis when the head is in the upright position for a tree felling process so that more boom and vehicle movement is needed to compensate for this limitation.
Another example of such efforts can be found in U.S. Pat. No. 5,709,254 entitled TREE HARVESTING APPARATUS, issued to Argue on Jan. 20, 1998. A fully powered and controllable link system described by Argue includes a helical spline for permitting rotational movement of a harvesting head about a central vertical axis thereof. This provides enhanced maneuverability of the head to prevent damage to saplings or other immature timber. However, the helical spline provides limited rotational movement of the head only through a 220xc2x0 arc. Therefore, an all direction approach of the head to a target tree to be cut, cannot be achieved.
The industry continues to search for better tree felling and cutting machine designs, particularly for one which provides the capability of angular adjustment of the tree processor head in all directions of approach to a target tree during a tree felling process, and in all orientations during the tree shaping process.
It is one object of the present invention to provide an improved tree felling and shaping system.
It is another object of the present invention to provide a tree felling and shaping apparatus which is convenient to manipulate.
It is a further object of the present invention to provide a link system of a tree felling and shaping apparatus which is adapted for maximum angular adjustment about a vertical axis, thereby permitting a processor head of the apparatus to approach a target tree from any direction for cutting and de-limbing the target tree.
The present invention is directed to a fully powered and controllable link system for operatively linking a boom and a tree processor. The tree processor includes a central elongate support member and generally has an upright position in which the central elongate support member is substantially vertical for felling a tree, and a recumbent position in which the central elongate support member is substantially horizontal for shaping the tree. The link system defines first, second and third axes. The first axis is generally horizontal and a first member is adapted to be pivotally mounted to a free end of the boom for pivoting about the first axis. A first axis power actuator is attached to the first member and adapted to be connected to the boom for tilting the first member about the first axis. The second axis is perpendicular to the first axis, and a generally elongate second member is mounted at a first end thereof to the first member directly by a rotary coupling, thereby permitting the second member to rotate more than 300xc2x0, but restraining other movement thereof, relative to the first member about the second axis regardless of the upright or recumbent processor head position. A second axis power actuator is attached to the rotary coupling for actuating the rotary movement. The third axis is perpendicular to the second axis and is adapted to extend side to side with respect to the processor head and to be perpendicular to the central elongate support member of the processor head. The second member at a second end thereof is adapted to be pivotally mounted to the central elongate support member of the processor head for pivoting about the third axis. A third axis power actuator is attached to the second member and is adapted to be connected to the central elongate support member for pivoting the central elongate support member about the third axis between the upright and recumbent positions.
The present invention is also directed to a tree felling and shaping apparatus of a type having a tree processor head which includes a central elongate support member, a cutting device at a bottom of the central elongate support member, and gripper and stripping means attached to the central elongate support member. The processor head generally has a first position in which the central elongate support member is substantially vertical for felling a tree, and a recumbent position in which the central elongate support member is substantially horizontal for shaping the tree. The apparatus further includes a boom having an end mounted to a vehicle and a free end, a and a first member pivotally mounted to the free end of the boom for pivoting about a first generally horizontal axis. A first axis power actuator is positioned to link the boom and the first member for tilting the first member about the first axis. The apparatus defines a second axis perpendicular to the first axis and includes a generally elongate second member mounted at a first end thereof to the first member by a rotary coupling, permitting the second member to rotate more than 300xc2x0, preferably 360xc2x0, but restraining other movement thereof, relative to the first member about the second axis, regardless of the first or second processor head position. A second axis power actuator is attached to a rotary coupling for actuating the rotary movement. The apparatus defines a third axis of the apparatus which is perpendicular to both the second axis and the central elongate support member of the processor head, and the central elongate support member is pivotally mounted to a second end of the second member for pivoting about the third axis. A third axis power actuator is positioned to link the second member and the central elongate support member for pivoting the central elongate support member about the third axis between the substantially vertical and horizontal positions.
With such a fully powered and controllabe link system, the processor head is conveniently manipulated between its upright and recumbent positions for either tree felling or shaping processes by actuating the third axis power actuator to thereby pivot the central elongate support member of the processor head while the second axis of the apparatus is substantially maintained in a vertical position. Thus, actuating the second axis power actuation will rotate the processor header about the second axis which is in a substantially vertical position, regardless of the processor head position. This configuration provides a maximum angular adjustment to the processor head for approach to a target tree to be cut, from any direction when the processor head is in its upright position, and permits shaping and de-limbing of the cut tree in any direction when the processor head is in its substantially horizontal position.
The generally elongate second member of the tree felling and shaping apparatus according to the present invention comprises a configuration permitting the processor head to be located below the rotary coupling when the central elongate support member thereof is in the substantially vertical position. The pivoting and the rotary links of the tree felling and shaping apparatus are preferably arranged in a manner such that under the force of gravity alone the first member with all parts supported thereby, is adapted to be freely suspended from the boom when the processor head without a load is maintained in a first position. This feature advantageously allows convenient manipulation of the apparatus when the processor head is to be aligned with a target tree to be cut.
The fully powered and controllable link system not only provides maximum angular adjustment of the tree processor head for all directional orientations whether the head is in a recumbent or an upright position by also advantageously performs a universal joint function to freely suspend the tree processor head from the boom without using a conventional uncontrollable universal joint. This feature will be better understood with reference to a preferred embodiment of the present invention described hereinafter.
Other advantages and features of the present invention will also be better understood with reference to a preferred embodiment of the present invention described hereinafter.