CA2196728A1 - Actuator driven slewing mechanism for timber processing workhead - Google Patents
Actuator driven slewing mechanism for timber processing workheadInfo
- Publication number
- CA2196728A1 CA2196728A1 CA002196728A CA2196728A CA2196728A1 CA 2196728 A1 CA2196728 A1 CA 2196728A1 CA 002196728 A CA002196728 A CA 002196728A CA 2196728 A CA2196728 A CA 2196728A CA 2196728 A1 CA2196728 A1 CA 2196728A1
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- Canada
- Prior art keywords
- support structure
- workhead
- actuator
- slewing
- actuators
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C1/00—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles
- B66C1/68—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles mounted on, or guided by, jibs
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manipulator (AREA)
Abstract
There is provided a slewing assembly for a timber handling apparatus of the type having a workhead connected to a support structure. The workhead is rotatable about a slew axis with respect to the support structure. The assembly provides a slewing mechanism for relative rotational movement of the workhead and the support structure about the slew axis.
The assembly also provides a drive mechanism for imparting the relative rotational movement of the workhead and the support structure. The drive mechanism comprises two actuators, each actuator having a fixed end and a moveable end, the moveable ends of the actuators being linearly extendible and retractable with respect to the fixed ends of the actuators along an actuating axis. One end of each actuator is rotatably attached to the workhead and the other end of each actuator is rotatably attached to the support structure. Each actuator is positioned to apply a force to the slewing mechanism at a point radially distant from the slew axis upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator. This causes the relative rotational movement of the workhead and the support structure. The actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
The assembly also provides a drive mechanism for imparting the relative rotational movement of the workhead and the support structure. The drive mechanism comprises two actuators, each actuator having a fixed end and a moveable end, the moveable ends of the actuators being linearly extendible and retractable with respect to the fixed ends of the actuators along an actuating axis. One end of each actuator is rotatably attached to the workhead and the other end of each actuator is rotatably attached to the support structure. Each actuator is positioned to apply a force to the slewing mechanism at a point radially distant from the slew axis upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator. This causes the relative rotational movement of the workhead and the support structure. The actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
Description
ACTUATOR DRIVEN SLEWING MRC~ANISM FOR
TIMBER PROCESSING wo~R~R~n FIELD OF lNV~N-llON
The present invention relates generally to the field of timber handling and processing workheads and more particularly, to an actuator driven slewing mechanism for a timber felling head that allows for relative rotational movement between the felling head and a boom or other support structure to which the felling head is connected.
BACRGROUND OF lNV~lION
It is common in the tree harvesting industry for timber handling or processing workheads to be mounted on the end of a boom or other like support structure attached to an all-terrain vehicle through a swinging link, known in the art as a dangle connection. This dangle connection enables the workhead to swivel freely on the end of the boom. Such machines are capable of a variety of timber handling and processing functions depending upon the type of workhead employed. For example, there are workheads which are adapted to fell trees, delimb trees, remove bark and load or carry processed logs onto transport vehicles or into storage areas.
It is also common for such machines to use hydraulic cylinders fixed to the boom to pivot the workhead in a plane aligned with the boom. In addition, most harvesting machines are capable of rotating the timber handling workhead about the boom axis for a total of 30~ or 40~ of rotational movement.
Some harvesting machines, however, are capable of between 180~
and 270~ or more of rotational movement of the timber handling workhead about the boom axis. The larger degrees of rotational movement, known to those skilled in this art as high-angle rotation, have been achieved by a variety of gearing means including rack and pinion sets driven by hydraulic cylinders, gearsets wherein the driving pinions are coupled to hydraulic cylinders, and geartrains driven by hydraulic motors or a combination of chain drives, planetary gear reducers and hydraulic motors.
21 Y672~
An example of a prior art harvesting machine designed for what is termed in the art as "straight-ahead" operation, in which a workhead is capable of pivotal movement, is provided by United States Patent No. 4,491,163 issued on January 1, 1985 in the name of Kurelek. This patent teaches that hydraulic cylinders may be used to drive a crank arm and link member which in turn rock or swivel the workhead in a vertical plane aligned with the boom.
Another example of hydraulic cylinders being used to obtain swivel or swinging motion may be found in United States Patent No. 5,123,462 issued on June 23, 1992 in the name of Davision. The harvesting machine according to Davision is a heavy duty brush cutter used in connection with forestry management and right-of-way clearing. This patent teaches that a pair of boom turning cylinders mounted to steel lugs, which are in turn welded to each side of a cutter boom, swing the cutter boom from side to side about its vertical turning axis.
Hydraulic cylinders have also been used in connection with a timber handling workhead, specifically a tree felling head, to raise and lower a saw guard of the felling head which in turn enables the felling of larger diameter trees as .
disclosed in United States Patent No. 4,921,024 issued on May 1, 1990 and identifying as the inventors, Wiemeri and Mitchell. This patent teaches that extension and retraction of hydraulically powered pistons causes a moveable guard portion which is attached to a fixed guard portion by a hinge to be raised and lowered to selectively expose or overlay a saw blade.
Gilbert-Tech Inc. of Roberval, Quebec markets a timber handling workhead, specifically a tree felling head under the trade-mark GILBERT 1000 Series, which achieves 180~ of rotational movement. The Gilbert tree felling head is rotated by two vertically disposed hydraulic cylinders actuating a 21 i672~
gear segment and a pinion gearset. One end of each of the hydraulic cylinders is pivotally attached to a disc saw housing of the tree felling head and the other end of each of the hydraulic cylinders is pivotally attached to the gear segment in the gearset. Extension and retraction of the hydraulically powered pistons turns the gear segment which turns a smaller gear mounted on a bearing and causes a larger gear to climb around the smaller gear to rotate the tree felling head freely about the axis of the pinion gear.
In another prior art device, Denharco of Saint Hyacinthe, Quebec achieves 240~ of rotational movement of a timber handling workhead, specifically a tree felling head marketed under the trade-mark DENHARCO CS5500 RTA felling head side tilt mechanism, by using a conventional chain drive, a planetary gear reducer and a hydraulic motor. The hydraulic motor through the gear reducer drives a pinion which in turn drives the chain to rotate the felling head around the boom adaptor.
A further example of a prior art device is a tree felling head marketed by Quadco Equipment Inc. of Montreal, Quebec as the Model 2OB Centre Tower Saw Head. This device achieves 240~ of rotational movement by using a gearset wherein the driving pinions are couped to two hydraulic cylinders via cranks. The gearset resides inside the felling head. The driving pinions mesh with a larger gear which is attached to the boom adaptor. The hydraulic cylinders are fed with .
pressurized oil through a hydraulic timing valve to ensure rotation of the tree felling head. A rotary timing valve changes the direction of the oil flowing into the hydraulic cylinders such that the cylinders are either pulling or pushing on the cranks. When one of the cylinders is at its maximum torque, the other cylinder is not generating any torque and visa versa. The cranks translate the linear motion of the hydraulic cylinders into rotary motion which drives the 21 ~672~
gearset to rotate the tree felling head about the axis of the boom adaptor.
Quadco has another device which achieves 270~ of rotational movement of a tree felling head using a conventional design consisting of two hydraulic motors driving a geartrain to rotate the felling head.
There are several advantages to harvesting machines having timber handling or processing workheads with high-angle rotation. These include the ability to harvest trees at any angle, which is particularly useful in a blow-down situation, and the ability to control the fall of the trees. As well, these machines allow for the flexibility to place the felled bunches of trees in a particular location for skidding, with the end result being larger and fewer piled bunches for fast and easy skidding to the landing. In addition, the skidder payload is improved without the need for multiple bunching.
Environmentally, high-angle rotation is also advantageous in that it m; n; mi zes the damage to forest growth and reduces feller buncher and skidder travel. Less machine travel means more operator comfort and less machine fatigue.
While the prior art devices capable of high-angle rotation possess the above-described advantages, generally they are complex arrangements involving many mechanical parts which require constant and specific maintenance. For example, gear segment and pinion gearsets and other types of gearsets must be serviced and maintained via lubrication and greasing on a regular basis due to the clogging debris from felled trees. The complex nature of the gearsets requires speci-fic maintenance by experienced mechanics and causes down time for the machine operator. Increased maintenance means higher operating costs and down time for the machine operator resulting in decreased productivity and lower profits. As well, many of the prior art devices do not provide for ready 21 ~6728 s maintenance access to hydraulic supply lines in a compact design.
Therefore, there has developed a need for a timber handling or processing workhead capable of high-angle rotation which overcomes these disadvantages.
SUMMARY OF lN V~N 1 ION
According to a broad aspect of the present invention, there is provided a slewing assembly for a timber handling apparatus of the type having a workhead connected to a support structure, the workhead being rotatable about a slew axis with respect to the support structure, the slewing assembly comprising: (a) a slewing means for relative rotational movement of the workhead and the support structure about the slew axis; (b) a drive means for imparting the relative rotational movement of the workhead and the support structure, the drive means comprising two actuators, each actuator having a fixed end and a moveable end, the actuators each provid-ing means for linearly extending and retracting the moveable ends thereof with respect to the fixed ends thereof along an actuating axis, one end of each actuator being rotatably attached to the workhead and the other end of each actuator being rotatably attached to the support structure; wherein each actuator is positioned to apply a force to the slewing means at a point radially distant from the slew axis thereof upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator to thereby effect the relative rotational movement of the workhead and the support structure, and wherein the actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
According to another broad aspect of the present invention, there is provided a slewing assembly for a timber handling apparatus of the type having a workhead connected to a support structure, the workhead being rotatable about a slew axis with respect to the support structure, the slewing assembly comprising: (a) a slewing mechanism for relative rotational movement of the workhead and the support structure about the slew axis; (b) a drive mechanism for imparting the relative rotational movement of the workhead and the support structure, the drive mechanism comprising two actuators, ~ach actuator having a fixed end and a moveable end, the moveable ends of the actuators each being linearly extendible and retractable with respect to the fixed ends thereof along an actuating axis, one end of each actuator being rotatably attached to the workhead and the other end of each actuator being rotatably attached to the support structure; wherein each actuator is positioned to apply a force to the slewing mechanism at a point radially distant from the slew axis thereof upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator to thereby effect the relative rotational movement of the workhead and the support structure, and wherein the actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
With reference to preferred embodiments of the present invention, the slewing means or slewing mechanism comprises a first cylindrical bearing surface provided with the support structure which is in relative rotational contact with a corresponding second cylindrical bearing surface provided with the workhead. Preferably, the first cylindrical bearing surface is an elongate cylindrical extension that is attached to the support structure, with the cylindrical extension being received within the second cylindrical bearing surface which is concentrically disposed therearound. The second 21 9~728 cylindrical bearing surface may be defined by a plurality of annular bearings.
In one embodiment, the elongate cylindrical extension has a free terminal end and another terminal end adjacent to the support structure, and the extension provides a retaining plate attached to the free terminal end and disposed substantially normal to the slew axis. The elongate cylindrical extension further provides an annular shoulder at the terminal end thereof adjacent to the support structure, such that the retaining plate and annular shoulder define opposed thrust bearing surfaces extending radially around the elongate cylindrical extension. The annular bearings may have a generally L-shaped cross-sectional configuration to thereby provide corresponding radially extending surfaces for relative rotational contact with the thrust bearing surfaces.
Advantageously, the elongate cylindrical extension may be provided with a through passage for hydraulic supply lines for timber handling means of the workhead.
According to further preferred embodiments, the slewing assembly further comprises a sensing means for each actuator, the sensing means detecting a dead position of the respective actuator. This dead position is obtained when the actuating axis of the actuator intersects with the slew axis during the relative rotational movement of the workhead and its support structure. Upon detection of the dead position of the actuator by the sensing means, the direction of linear translation of the actuator is reversed.
In yet further preferred embodiments, the actuating axis of each actuator is located in the plane substantially perpendicular to the slew axis of the workhead. Each actuator may be rotatably attached at each end thereof by means of a pin connection. The ends of the actuators which are attached to the support structure for the workhead are positioned '~1 q6728 substantially radially equidistant from the slew axis in one preferred orientation. Likewise, the ends of the actuators which are attached to the workhead may be positioned substantially radially equidistant from the slew axis. In an unrotated position of the workhead, the ends of the actuators which are attached to the workhead are located on a line which is substantially parallel to another line on which is located each of the ends of the two actuators which are attached to the support structure. Alternatively, the ends of the actuators which are attached to the support structure may be positioned at the same location.
The slewing assembly according to preferred embodiments of the invention may have a drive means or drive mechanism which provides only two actuators or may alternatively provide more than two actuators, such as three actuators.
Each of the actuators is preferably a hydraulic cyli~der.
In this manner, each hydraulic cylinder may be made selectively capable of extension and retraction in a float mode. In such a float mode, unpressurized hydraulic fluid is permitted to respectively draw into and drain away from each cylinder in response to loading thereof.
BRIEF DESCRIPTION OF DRAWINGS
For purposes of illustration and understanding of the present invention, but not of limitation, reference will be made to the following drawings in describing various aspects and preferred embodiments of the present invention, in which:
Figure 1 is a perspective view of a timber handling workhead, specifically a tree felling head, mounted to a boom support structure of an all-terrain vehicle, which felling head comprises the slewing mechanism according to a preferred embodiment of the present invention;
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Figure 2 is a side elevation of the tree felling head of Figure 1, showing a boom adaptor for attachment of the felling head to the boom support structure and showing a linkage means connected thereto for pivotal movement of the felling head with respect to the boom support structure;
Figure 3 is a cross-sectional view of the tree felling head of Figure 2, taken along line 3-3 of Figure 1, showing in detail the structure of the slewing mechanism according to a preferred embodiment of the present invention;
Figure 4 is an end elevation of the tree felling head, partially in cross-section, viewed adjacent the boom support structure (not shown) and showing the preferred positioning of two hydraulic cylinders for the slewing mechanism according to a preferred embodiment of the present invention;
Figure 5 is a side elevation of a cylindrical bearing surface and boom adaptor of the slewing mechanism shown in Figure 4, by means of which the tree felling head rotates about a slew axis with respect to the boom support structure;
Figure 6 is an end elevation of the cylindrical bearing surface and boom adaptor of Figure 5, viewed adjacent the boom support structure (not shown);
Figure 7 is a top plan view of the cylindrical bearing surface and boom adaptor of Figure 5;
Figure 8 is a cross-section of the cylindrical bearing surface and boom adaptor of Figure 7, taken along the line 8-8';
Figures 9a, 9b and 9c are schematic diagrams illustrating the operation of the slewing mechanism of Figure 4, viewed in end elevation adjacent the boom support structure (not shown), and displaying in sequence three positions of clockwise 21 9672~ -movement of the tree felling head as it rotates from an unrotated or mid-point position, through to a dead or toggle position associated with one of the hydraulic cylinders of the slewing mechanism, and ending with a fully rotated clockwise position.
Figures lOa, lOb and lOc are schematic diagrams illustrating the operation of the slewing mechanism of Figure 4, viewed in end elevation adjacent the boom support structure (not shown), and displaying in sequence three positions of counterclockwise movement of the tree felling head as it rotates from an unrotated or mid-point position, through to a dead or toggle position for one of the hydraulic cylinders of the slewing mechanism, and ending with a fully rotated counterclockwise position.
Figure 11 is a graph of wrist torque applied to the slewing mechanism of Figure 4, plotted as a function of angular displacement of the tree felling head from the mid-point position;
Figure 12 is a schematic layout of an electrohydraulic circuit adapted for operating and controlling the hydraulic cylinders of the slewing mechanism according to a preferred embodiment of another aspect of the present invention;
Figure 13 is a detailed schematic layout of a bank of hydraulic control valves and relays associated with the electrohydraulic circuit of Figure 12; and Figure 14 is a cross-sectional view of the cylindrical bearing surface and boom adaptor of the slewing mechanism of Figure 5, showing a swivel manifold block mounted on the slewing mechanism for through passage of hydraulic supply lines from the boom support structure to timber handling means of the workhead.
--- 2~ q6728 Figure 15 is an end elevation of the swivel manifold block of Figure 14, showing four swivel manifold spools for the hydraulic supply lines;
Figure 16 is a partial cross-sectional view of the swivel manifold block of Figure 14, taken along line 16-16' of Figure 15, showing the positioning of a swivel manifold spool within the block;
Figure 17 is a schematic diagram illustrating an alternate positioning of the two hydraulic cylinders for the slewing mechanism, by means of attachment at a common point;
and Figure 18 is a schematic diagram illustrating the positioning of three hydraulic cylinders for the slewing mechanism, again by means of attachment at a common point.
DETATT~Rn DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figure 1, the slewing mechanism of the present invention is shown in a timber handling workhead of the type having a felling head 40 connected to a support structure in the form of a boom structure generally shown by reference numeral 20.
The boom support structure 20 is connected to an all-terrain vehicle 10 of the kind well known to those skilled in this art, which includes an operator cab 12, an endless track driving system 14, and a turntable 16 upon which the cab base 18 is mounted for rotation. The boom support structure 20 includes an inner arm portion 22 and an outer arm portion 24 each portion having a first and second end. The inner arm portion 22 and the outer arm portion 24 are capable of pivotal movement relative to one another at the junction of the second end of the inner arm portion and the first end of the outer 2'1 ~672~
arm portion about pivot location 26. The first end of the inner arm portion 22 is pivotally mounted to the cab base 18 as at pivot location 28. The second end of the outer arm portion 24 is pivotally connected to the boom adaptor 50 as at pivot location 62. Extension and retraction of a hydraulic actuator 30 causes the inner arm portion 22 to pivot in a vertical plane about pivot location 28. A further hydraulic actuator 32 controls the angle between the inner arm portion 22 and the outer arm portion 24. Extension and retraction of the hydraulic actuator 32 causes the outer arm portion 24 to pivot in a vertical plane relative to the inner arm portion 22 about pivot location 26.
Turning more specifically to Figures 2 and 3, the felling head 40 of the preferred embodiment is mounted in a fixed fashion, known to those skilled in this art, to the end of the outer arm portion 24 of the boom support structure 20 by means of a boom adaptor or support structure adaptor 50. A linkage means, known to those skilled in this art as a crank assembly, 60, is connected to the boom adaptor 50 for pivotal movement of the felling head about pivot location 62. Crank assembly 60 comprises a link members 64 and a crank arm 70. Link member 64 has a first end pivotally connected, as at 66, to the boom adaptor 50 and a second end which is pivotally connected, as at 68, to one end of crank arm 70. A piston rod 72 of hydraulic cylinder 74 is pivotally connected at its cylinder end to a bracket 76 on the outer arm portion 24 of the boom support structure 20. The other end of crank arm 70 is pivotally connected, as at 78, to the outer arm portion 24 of the boom support structure 20, such that the crank arm 70 extends upwards from the outer arm portion 24. Thus, extension and retraction of piston rod 72 of the hydraulic cylinder 74 causes crank assembly 60 to pivot the felling head 40 in a vertical plane, aligned with the boom support structure 20, about the pivot location 62. This downwar~
articulation of the felling head via the crank assembly provides the felling head with an additional degree of tilt to 21 ~67~8 approach a position that is nearly parallel to the ground when the boom support structure is at full extension.
The felling head 40 according to a preferred embodiment of the present invention is a disc saw felling head having an upright box section structural element 41 acting as a main member for the entire felling head and timber handling means in the form of a grappling means and cutting means. The grappling means consists of a single accumulator arm 42 and two standard harvesting arms 43, both known to those skilled in this art. The cutting means is provided in the lower portion of the felling head and includes a circular saw blade 44 (Figure 1) mounted in a plane perpendicular to the general longitudinal axis of the felling head. The saw blade 44 is located within a saw blade housing 45 having a top surface 47 and a bottom surface 49. A saw motor 44A drives the circular saw blade 44. Two skiis 46 are affixed to the bottom surface 49 of the saw blade housing 45 and a log pusher 48 protrudes from the front of the saw blade housing as shown in Figures 2 and 3.
Referring to Figures 3 through 8, the slewing means for rotational movement of the felling head 40 with respect to the boom support structure 20 is next explained. Those skilled in this art will readily appreciate that the present invention may be adapted to other timber handling and processing apparatus employing various timber handling and processing means, such as workheads for felling, delimbing, debarking, bucking, carriage and loading of trees, or combinations thereof.
The slewing means according to a preferred embodiment of the present invention comprises a first male cylindrical bearing surface, provided with the boom support structure, which is in relative rotational contact with a corresponding second female cylindrical bearing surface provided with the felling head. Preferably, the first male cylindrical bearing surface is an elongate cylindrical extension 52 that is attached to the boom support structure 20 by means of the boom adaptor 50 as shown in more detail in Figure 5. The boom adapter 50 provides, at one end thereof, means for respective pivotal attachment to the link member 64 of the crank assembly 60 and to the second arm portion 24 of the boom support structure 20. Such means for pivotal attachment may be in the form of a bracket assembly 51.
Preferably, the second female cylindrical bearing surface is located in a cavity or receptacle 54 (Figure 3) in the felling head 40. The second female cylindrical bearing surface is concentrically disposed to receive the first male cylindrical bearing surface therewithin. Preferably, the second female cylindrical bearing surface is defined by a plurality of annular bearings, such as two annular bearings 80, 82, which are housed in the receptacle 54 and which have a generally L-shaped cross-sectional configuration. This L-shaped configuration provides axial thrust bearing surfaces 80a, 82a and radial bearing surfaces 80b, 82b on each of the annular bearings 80, 82, as shown in Figure 5. The annular bearings may be constructed from brass or some other suitable material known to those skilled in this art.
The elongate cylindrical extension 52 has a free terminal end to which is fixedly attached a removable retaining plate 56 by means of bolts 57 or the like, and another terminal end, adjacent to the boom adaptor 50, around which is disposed an annular shoulder 58. The removable retaining plate 56 and annular shoulder 58 together act to constrain the felling head against excessive longitudinal movement within the receptacle 54 along the direction of the slew axis AA'. The removable retaining plate 56 and the annular shoulder 58 define opposed axial thrust bearing surfaces 56a, 58a which extend radially around the elongate cylindrical extension 52, as shown in Figure 5. The axial thrust bearing surfaces 56a, 58a correspond with the respective axial thrust bearing surfaces 21 ~6728 80a, 82a of the annular bearings 80, 82 and are in relative rotational contact therewith. The elongate cylindrical extension 52 also defines radial bearing surface 52a which extends along the longitudinal length thereof, as shown in Figure 5. The radial bearing surface 52a on the cylindrical extension 52 corresponds with the respective radial bearing surfaces 80b, 82b of the annular bearings 80, 82 and are in relative rotational contact therewith. In a preferred embodiment of the present invention, the bracket assembly 51, the elongate cylindrical extension 52, the removable retaining plate 56 and the annular shoulder 58 are fixed the one to the other by means of a screwed and welded engagement or the like.
The elongate cylindrical extension 52 may be constructed from hardened steel or from some other suitable material known to those skilled in this art. Advantageously, the elongate cylindrical extension may be made hollow to allow for through passage of hydraulic supply lines 200 to the timber handling means of the felling head 40.
The two annular bearings 80 and 82 are concentrically arranged with respect to the elongate cylindrical extension 52 and are fixed within the receptacle 54 to allow relative rotational movement between the elongate cylindrical extension 52 and the annular bearings 80, 82 about the slew axis AA', as shown in Figures 3 and 5. As explained in greater detail below, this relative rotational movement, upon engagement of the drive means, produces rotational movement of the felling head 40 about the slew axis AA~ with respect to the boom support structure 20. Those skilled in this art will appreciate that although the described embodiment of the invention provides annular bearings 80, 82 in the form of bushings, other bearing surfaces such as those comprisin$
roller or ball bearings could also be adapted for use with the present invention.
The drive means for imparting the relative rotational movement of the felling head 40 with respect to the boom support structure 20 according to another aspect of the present invention is described with reference to Figures 4 and 9 to 13. The drive means comprises at least two actuators, preferably a first hydraulic cylinder 90 having a piston rod 94 and a second hydraulic cylinder 92 having a piston rod 96.
The hydraulic cylinders are of a conventional nature well known to those skilled in this art, as more fully described below. These hydraulic cylinders, when used as a means of rotational drive together with the slewing mechanism according to the present invention, eliminate the necessity of any form of gearsets or other transmission gearing to achieve the desired degree of high-angle rotation. In a preferred embodiment of the present invention, the cylinder ends of hydraulic cylinders 90 and 92 are rotatably attached adjacent the top surface 47 of the saw blade housing 45 of the felling head 40 by pin connections as at pivot locations 98 and 100 respectively, for instance by means of a pin and a spherical alloy steel ball bushing or the like. Similarly, the terminal ends of piston rods 94 and 96 are rotatably attached to the boom adaptor 50 as at pivot locations 102 and 104, respectively. Those skilled in this art will appreciate that the reverse mounting of the hydraulic cylinders may also be employed according to embodiments of the invention, as is the mounting of the first cylinder in one orientation and the second cylinder in the other. The cylinder ends of hydraulic cylinders 90 and 92 are fixed and the terminal ends of piston rods 94 and 96 are moveable along an actuating axis of each hydraulic cylinder. In a preferred embodiment of the invention, hydraulic cylinders 90 and 92 each have an actuating axis which is located in a plane substantially perpendicular to the slew axis of the felling head. The preferred angular positioning and spatial orientation of hydraulic cylinders 90 and 92 is described in greater detail herebelow.
The hydraulic cylinders 90 and 92 are preferably double-acting in nature, in that the piston rods 94 and 96 are -capable of being driven to retract and extend. The piston rods of the cylinders achieve powered linear extension and retraction by way of pressurized fluid chambers of a conventional nature controlled by electrohydraulic directional control valves 106 as shown in Figure 3, of the type capable of handling at least 4000 pounds per square inch, for example, the valve L9OLS marketed by the VOAC Hydraulics company of Mt.
Prospect, Illinois or the like. Those skilled in this art will appreciate that hydraulic cylinders 90 and 92 should be installed such that the cylinders do not ever produce a .
"bottoming out" of the piston rods 94 and 96 at each extreme end of the cylinder portion, whether the piston rod is fully extended or fully retracted within the cylinder. In other words, better mechanical integrity is achieved when the hydraulic cylinders provide oil relief at each extreme position of the piston rod, which is the result of the unused stroke of the piston rod.
With reference to Figures 9(a) to 9(c) and lO(a) to lO(c), extension and retraction of piston rod 94 of hydraulic cylinder 90 creates a force along an actuating axis BB' thereof which is located in a plane substantially perpendicular to the slew axis AA'. This force is applied to the slewing means at a point radially distant from the slew axis AA', to thereby effect the rotational movement of the felling head 40 with respect to the boom support structure 20.
Similarly, extension and retraction of piston rod 96 of hydraulic cylinder 92 creates a force along an actuating axis CC' thereof which is located in a plane substantially perpendicular to the slew axis AA'. This force is likewise applied to the slewing means at a point radially distant from the slew axis AA' to thereby effect the rotational movement of the felling head 40 with respect to the boom support structure 20. In the preferred embodiment of the present invention, the extension and retraction of the piston rods of hydraulic cylinders 90 and 92 are phase timed, or synchronized, by way of sensing means, preferably in the form of two proximity - 21 967~
sensing devices 108 and 109, shown in Figures 3 and 14, as described in greater detail herebelow. In what follows, reference to extension and retraction of hydraulic cylinders 90 and 92 shall mean extension and retraction of the piston rods 94 and 96 within the cylinders.
In their preferred positioning and orientation, the cylinder ends of hydraulic cylinders 90 and 92 are rotatably attached adjacent the top surface 47 of the saw blade housing 45 substantially radially equidistant from the slew axis AA' as best shown in Figure 4. The distance between the cylinder ends does not change in the preferred embodiment because the cylinder ends are fixed to the saw blade housing 45. The angle ~ between the actuating axis BB' and the line YY'., and the angle ~' between the actuating axis CC' and the line YY', as shown in Figure 4, change depending upon the different phases or synchronization of the extension and retraction of the hydraulic cylinders. When the felling head 40 is in an unrotated or midpoint position, as best shown in Figure 4, the angles a and ~' are equal and were chosen in the preferred embodiment because this was the angle which provided both firm structural mounting of the hydraulic cylinders and permitted rotation of the felling head 40 about the slew axis AA' without the piston rods 94 and 96 interfering with one another or traversing the slew axis AA'. In addition, the position of hydraulic cylinders 90 and 92 was chosen in the preferred embodiment such that when one cylinder is in its dead or toggle position, defined in more detail below, the other cylinder is in the position of applying m~;mllm torque to the slewing means, as shown in Figures 9(b) and lO(b).
The terminal ends of piston rods 94 and 96 are also positioned substantially radially equidistant from the slew axis AA' as shown in Figure 4, and are rotatably attached to the boom adaptor 50 which is pivotally attached to the boom support structure 20. Neither the distance between the terminal ends and the slew axis AA' nor the angle 0, as shown 2~ ~6728 in Figure 4, changes in the preferred embodiment during the different phases or synchronization of the extension and retraction of the hydraulic cylinders. When the felling head 40 is in an unrotated or midpoint position, as best shown in Figure 4, the terminal ends of piston rods 94 and 96 are located in a line that is substantially parallel with a line which intersects the cylinder ends of the corresponding hydraulic cylinders 90 and 92. Moreover, hydraulic cylinders 90 and 92 are positioned with the terminal ends of piston rods 94 and 96 being angled towards the slew axis AA'.
The phased timing or synchronization of hydraulic cylinders 90 and 92 will next be described with reference to Figures 9(a) to 9(c) and lO(a) to lO(c). In the preferred embodiment of the present invention, when the felling head 40 is in an unrotated or midpoint position, as shown in Figure 9(a), the terminal ends of piston rods 94 and 96 are each located at angle of approximately 17~ below the line XX' which intersects the slew axis AA'. For rotation of the felling head 40 in a clockwise direction when viewed from the boom support structure 20, hydraulic cylinder 92 is powered to retract, and hydraulic cylinder 90 is simultaneously powered to extend, until the felling head 40 assumes the position as shown in Figure 9(b). At the position shown in Figure 9(b), the felling head 40 has rotated approximately 40~ about the slew axis AA' in a clockwise direction from the unrotated or midpoint position of Figure 9(a).
The position of the hydraulic cylinders shown in Figure 9(b) defines the dead or toggle position of hydraulic cylinder 92, in that no torque is being applied to the slewing means by hydraulic cylinder 92. This dead or toggle position occurs when the actuating axis CC' associated with hydraulic cylinder 92 intersects with the slew axis AA~ during rotational movement of the felling head 40. In the preferred embodiment of the invention, a sensing means is used to detect the dead or toggle position of each of the hydraulic cylinders 90 and 21 9672~
92. The sensing means is described in greater detail below.
When the sensing means detects that hydraulic cylinder 92 has attained the dead or toggle position, the direction of linear translation of hydraulic cylinder 92 is reversed so that the cylinder is thenceforth powered to extend rather than retract.
For the felling head 40 to continue to rotate clockwise from the position of Figure 9(b), hydraulic cylinder 92, having attained its dead or toggle position and having now reversed its direction of linear translation, extends while hydraulic cylinder 90 simultaneously further extends so that felling head 40 assumes the fully rotated position as shown in Figure s(c). Mechanical stops 93 and 95, as shown in Figures 3, 5 and 14, are used on the felling head to prevent it from rotating beyond the fully rotated position. Mechanical stops 93 and 95 prevent the felling head from rotating beyond the fully rotated clockwise or counter-clockwise positions shown in Figures 9(c) and lO(c), by abutment against corresponding stops 193, 195 located on the boom adaptor. The mechanical stops are metal weldments or the like.
At the clockwise fully rotated position of the slewing mechanism, the terminal ends of piston rods 94 and 96 are still at an angle of approximately 17~ below the line XX' and the felling head 40 has rotated approximately 100~ about the slew axis AA' in a clockwise direction from the unrotated or midpoint position of Figure 9(a). To reverse direction from the position shown in Figure 9(c), each of hydraulic cylinders 90 and 92 is powered to retract, thereby returning the felling head 40 towards the position of Figure 9(b). When the position of Figure 9(b) is attained, again the sensing means associated with hydraulic cylinder 92 causes cylinder 92 to reverse direction, whereupon cylinder 92 is powered to extend rather than retract. The felling head 40 is then returned to the unrotated or midpoint position set out in Figure 9(a) by the powered extension of hydraulic cylinder 92 and the continued powered retraction of hydraulic cylinder 90.
- 21 ~67~8 For rotation of the felling head 40 from the unrotated or midpoint position shown in Figure lO(a) in a counter-clockwise direction, when viewed from the boom support structure, hydraulic cylinder 90 is powered to retract and hydraulic cylinder 92 is simultaneously powered to extend, until the felling head 40 assumes the position shown in Figure lO(b). At the position shown in Figure lO(b), the felling head 40 has rotated approximately 40~ about the slew axis AA~
in a counter-clockwise direction from the unrotated or midpoint position of Figure lO(a).
The position of the hydraulic cylinders shown in Figure lO(b) defines the dead or toggle position of hydraulic cylinder 90, in that no torque is being applied to the slewing means by hydraulic cylinder 90. This dead or toggle position occurs when the actuating axis BB' associated with hydraulic cylinder 90 intersects with the slew axis AA' during rotational movement of the felling head 40. When the sensing means associated with hydraulic cylinder 90 detects that the dead or toggle position has been attained, the direction of linear translation of hydraulic cylinder 90 is reversed so that the cylinder is thenceforth powered to extend rather than retract. For the felling head 40 to continue to rotate counter-clockwise from the position of Figure lO(b), hydraulic cylinder 90, having attained its dead or toggle position and having now reversed its direction of linear translation, extends while hydraulic cylinder 92 simultaneously further extends so felling head 40 assumes the fully rotated position as shown in Figure lO(c). Mechanical stop 95 prevents the felling head from rotating beyond the fully rotated counter-clockwise position shown in Figure lO(c).
At the counter-clockwise fully rotated position of the slewing mechanism, the terminal ends of piston rods 94 and 96 are still at an angle of approximately 17~ below the line XX' and the felling head 40 has rotated approximately 100~ about the slew axis AA' in a counter-clockwise direction from the 21 q6728 unrotated or midpoint position of Figure lO(a). To reverse direction from the position shown in Figure lO(c), each of hydraulic cylinders 90 and 92 is powered to retract, thereby returning the felling head 40 towards the position of Figure lO(b). When the position of Figure lO(b) is attained, again the sensing means associated with hydraulic cylinder 90 causes cylinder 90 to reverse direction, whereupon cylinder 90 is powered to extend rather than retract. The felling head 40 is then returned to the unrotated or midpoint position set out in Figure lO(a) by the powered extension of hydraulic cylinder 90 and the continued powered retraction of hydraulic cylinder 92.
In the preferred embodiment, the sensing means for detecting the dead or toggle position of each hydraulic cylinder consists of two proximity sensing devices 108 and 109. Sensing device 108 detects position changes of hydraulic cylinder 90 and sensing device 109 detects position changes of hydraulic cylinder 92. The proximity sensing devices detect positional changes through changes in magnetic fields and are of a conventional nature known to those skilled in this art, for instance both of the proximity sensing devices in the preferred embodiment are of the type IAS-20-A13-S made by Rechner Industries of Germany. Such proximity sensing devices detect the presence of a metal object which is located within a distance of approximately 5 millimetres from the device.
Therefore, in a preferred embodiment of the present invention, a raised portion or a metal end plate 107 (Figure 5), approximately 3/8 of an inch thick, is affixed by weldment or the like to extend from the outer end surface of retaining plate 56. The outer end surface of retaining plate 56 is not itself within the 5 mm range of the proximity sensors, but the outer end surface of metal end plate 107 is within said range.
When the metal end plate 107, by rotation of the felling head 40, crosses the field of detection of the proximity sensor, which occurs when either of hydraulic cylinders 90 and 92 are in the dead or toggle position, the proximity sensor detects the presence of the metal end plate and signals a reversal of 21 q6728 -the direction of linear translation of the cylinder in the dead or toggle position as more fully described below.
When hydraulic cylinder 90 is in the dead or toggle position, proximity sensing device 108, shown in Figure 3, detects the presence of the metal end plate 107 and signals the hydraulic circuit shown in Figure 12 by means of electric relays 110 to reverse the direction of linear translation of that cylinder by redirecting the flow of oil into hydraulic cylinder 90. A similar signal is generated by proximity sensing device 109 when it detects the presence of the metal end plate 107 due to hydraulic cylinder 92 being in the dead or toggle position. Accordingly, the direction of linear translation of hydraulic cylinder 92 is reversed by redirecting the flow of oil into that cylinder. Thus, the effect of reversing the direction of linear translation of a hydraulic cylinder at the dead or toggle position associated with that cylinder is to further rotate the felling head 40 about the slew axis AA' such that the felling head reaches its maximum angle of rotation. Those skilled in this art will appreciate that other types of sensors may be employed to effect the above-described sensing means, for example, the proximity sensor may be substituted by a contact or mechanical switch. Alternatively, rotary valves or the like may be used to detect the positional changes of the felling head itself.
The position and spatial orientation of hydraulic cylinders 90 and 92 as described above allows for the avoidance of the central zone 99 as schematically shown in Figures 4, 9 and 10. The central zone 99 allows for passage of the hydraulic supply lines 200 for the various powered devices of the workhead, such as the accumulator arm 42 and the harvesting arms 43, or the saw motor 44A, through the centre of the elongate cylindrical extension 52 of the boom adaptor 50 as shown in Figure 14. This preferred central passage of the hydraulic supply lines is yet another aspect of the present invention and is achieved by means of a swivel - 21 ~6728 manifold block and spools as described in greater detail herebelow.
A preferred hydraulic circuit for the felling head 40 of the present invention is described with reference to Figures 12 and 13. Those skilled in this art will appreciate that alternative hydraulic circuit layouts may also be used in order to operate and control the various felling head devices mentioned above. The preferred circuit 120 for use with the present invention includes proximity sensor circuits 122a, 122b and float sections 124a,124b, each of which are described in greater detail below.
With reference to Figure 12, the circuit 120 comprises a first pressure source 125, such as a hydraulic pump, to supply hydraulic fluid to a bank 126 of directional control valves 106, which bank includes the float sections 124a, 124b. The bank 126 in turn is in fluid commlln;cation with clamp cylinders 128a, 128b and with hydraulic cylinders 90 and 92.
The clamp cylinders respectively actuate the accumulator arm 42 and the harvesting arms 43 of the felling head 40, previously described. The hydraulic cylinders 90 and 92 actuate the slewing means for the felling head 40, also previously described.
A second pressure source 130, such as a hydraulic pump, supplies hydraulic fluid to saw motor 44A. The saw motor 44A
is for driving circular saw blade 44, referred to above. A
check valve 132 is disposed in parallel to the saw motor 44A
to allow for continued operation of the saw motor on power off. Each of the circuit segments associated with the hydraulic pumps 125 and 130 provide respective return lines 134 and 136 to tank 137. A drain 138 is provided to tank 144 for actuation solenoids 142 (Figure 13) associated with the directional control valves 106 of bank 126. Likewise, a case drain 146 to tank 144 is provided for saw motor 44A.
- 2~ q6728 Turning now to Figure 13, each of the directional control valves 106 of bank 126 is preferably a four-way, three-position valve which is biased to the centre position. At the centre position of each valve 106, the respective cylinders 9o, 92, 128a and 128b are locked hydraulically. At either end position of the valves 106, hydraulic fluid is supplied so as to respectively extend and retract the piston rods of each cylinder. A pair of actuation solenoids 142 is associated with each of the valves 106 in order to activate the valves away from their biased centre position. Each activation solenoid 142 of the said pair is a two-position hydraulic spool, respectively controlled by means of operator pushbuttons 148 or the like. In Figure 13, the pushbuttons for the actuation solenoids of the circuit segments for the hydraulic cylinders 90 and 92 of the slewing means are shown, but those that would be associated with clamp cylinders 128a, 128b are omitted for sake of convenience, as those skilled in this art will readily be able to derive an appropriate arrangement of operator controls to activate the actuation solenoids associated with clamp cylinders 128a, 128b.
Each pushbutton 148 for the circuit segment of the slewing means provides a signal to its associated actuation solenoid pair 142 through paired relays 110. Each paired set of relays 110 is powered by a respective proximity sensor 108, 109 as previously described. Thus, when hydraulic cylinder 90 or 92 reaches its dead or toggle position, the relays 110 are switched, thereby causing power to be discontinued from one actuation solenoid 142 and supplied to the other actuation solenoid 142 of the solenoid pair associated with the particular cylinder 90 or 92. Relays 110 therefore effect the reversing of direction of linear translation of hydraulic cylinders 90 and 92 at the dead or toggle position associated with these cylinders, to allow for further rotation of the felling head 40 so that it reaches its maximum angle of rotation, all as previously described.
- - - - - - - - -26 21 '~6128 The float sections 124a, 124b associated with the respective hydraulic cylinders 90 and 92 each comprise two two-way, two-position spools 150. When all of the spools 150 for both cylinders 90 and 92 are activated by means of a common pushbutton (not shown) or other suitable operator control means, each port at the central position of the valve 106 is placed in fluid commlln;cation with tank, thereby permitting each of the hydraulic cylinders 90 and 92 to extend and retract in a float mode. In this mode, unpressurized hydraulic fluid may be drawn into and drained away from each cylinder in response to loading thereof. Those skilled in this art will appreciate that other means may be employed in order to implement the above-described float mode, for instance, the three-position valves 106 of the slewing means circuit segment may be substituted with valves that provide an additional position to put each of the relevant ports of the valve to tank.
In operation, once an operator has felled a tree and has oriented the felled tree in a desired position by actuation of the slewing means and boom for the felling head, the operator may then engage the float mode in order to effect a release of the hydraulically locked actuators of the slewing means. This will achieve a damped fall for the tree to the location of skidding. The float mode therefore enables a skilled operator to place a felled tree to the ground more quickly, without the need for operator controlled and powered movements of the slewing means, provided the operator is ~atisfied with the expected trajectory of the tree prior to engaging the float mode. In addition, the skilled operator may use the float mode to move a felled tree while it is on the ground by dragging the trunk end of the felled tree to a desired location for loading or skidding.
With reference to Figure 14, 15 and 16, the elongate cylindrical extension 52 of the boom adaptor 50 is associated with a fluid delivery means consisting of a swivel manifold block 210 for through passage of hydraulic supply lines 200 for controlling and driving the various powered devices of the felling head 40. The swivel manifold block 210 is constructed of ductile iron or the like and comprises a retaining plate 214 which attaches the block to the felling head 40 by means of bolts 224 or the like and an end plate 226. The swivel manifold block has been equipped with an aperture 222 for alignment purposes during assembly.
There are four swivel manifold spools 212 which are housed within the swivel manifold block 210 as best shown in Figure 15. The end plate 226 prevents the spool from lateral movement out of the swivel manifold block as seen in Figure 16. Each swivel manifold spool is substantially cylindrical and constructed of hardened steel or the like which creates a bearing surface 212a thereby allowing the spool to rotate within the swivel manifold block 210. Four hydraulic supply lines 200 pass through the swivel manifold block 210 and deliver fluid into each of the four swivel manifold spools via conduits 228 as shown in Figure 15. The spools are provided with apertures 218 in fluid commlln;cation with the downstream hydraulic supply lines for the various powered devices in the felling head 40. In this way, the swivel manifold block and spools reduce the torsion that would normally be applied to the hydraulic supply lines if they were carried to the felling head 40 or passed through the slewing means uninterrupted.
By using hydraulic cylinders as a means for driving rotational movement of the felling head 40 with respect to the boom support structure 20, many of the problems associated with complex gearset arrangements are eliminated. For example, wear and tear on the slewing mechanism and the level of machine maintenance will both be expected to be reduced.
Fewer engaging and locking parts is expected to ml n;m~ ze down time caused by clogging debris from felled trees which in turn reduces operating costs and increases productivity.
21 967~8 In addition, by providing the swivel manifold block and spools, the length of the hydraulic supply hoses to the felling head 40 may be reduced since there is no need for the rotational movement of the felling head to be accommodated by slack in the supply hoses. This results in a compact design which m; n i m; zes hose chaffing and snagging during field use of the felling head 40.
Finally, those skilled in this art will appreciate that the inventive concept in any of its foregoing aspects can be incorporated, adapted or modified in many different constructions, so that the generality of the preceding description is not to be superseded by the particularity of the attached drawings. For instance, as shown schematically in Figure 17, an alternate positioning for two hydraulic cylinders 90a, 92a is to attach the actuating rod end of the cylinders to a common point 300a located on the boom adaptor.
As shown schematically in Figure 18, a further alternative is the use of three hydraulic cylinders 90b, 92b and 90c whose actuating rod ends are attached at common point 300a on the boom adaptor. Thus, these and various other alterations, modifications or additions may be incorporated into the various constructions and arrangements of parts and devices described herein without departing from the spirit or scope of the present invention.
TIMBER PROCESSING wo~R~R~n FIELD OF lNV~N-llON
The present invention relates generally to the field of timber handling and processing workheads and more particularly, to an actuator driven slewing mechanism for a timber felling head that allows for relative rotational movement between the felling head and a boom or other support structure to which the felling head is connected.
BACRGROUND OF lNV~lION
It is common in the tree harvesting industry for timber handling or processing workheads to be mounted on the end of a boom or other like support structure attached to an all-terrain vehicle through a swinging link, known in the art as a dangle connection. This dangle connection enables the workhead to swivel freely on the end of the boom. Such machines are capable of a variety of timber handling and processing functions depending upon the type of workhead employed. For example, there are workheads which are adapted to fell trees, delimb trees, remove bark and load or carry processed logs onto transport vehicles or into storage areas.
It is also common for such machines to use hydraulic cylinders fixed to the boom to pivot the workhead in a plane aligned with the boom. In addition, most harvesting machines are capable of rotating the timber handling workhead about the boom axis for a total of 30~ or 40~ of rotational movement.
Some harvesting machines, however, are capable of between 180~
and 270~ or more of rotational movement of the timber handling workhead about the boom axis. The larger degrees of rotational movement, known to those skilled in this art as high-angle rotation, have been achieved by a variety of gearing means including rack and pinion sets driven by hydraulic cylinders, gearsets wherein the driving pinions are coupled to hydraulic cylinders, and geartrains driven by hydraulic motors or a combination of chain drives, planetary gear reducers and hydraulic motors.
21 Y672~
An example of a prior art harvesting machine designed for what is termed in the art as "straight-ahead" operation, in which a workhead is capable of pivotal movement, is provided by United States Patent No. 4,491,163 issued on January 1, 1985 in the name of Kurelek. This patent teaches that hydraulic cylinders may be used to drive a crank arm and link member which in turn rock or swivel the workhead in a vertical plane aligned with the boom.
Another example of hydraulic cylinders being used to obtain swivel or swinging motion may be found in United States Patent No. 5,123,462 issued on June 23, 1992 in the name of Davision. The harvesting machine according to Davision is a heavy duty brush cutter used in connection with forestry management and right-of-way clearing. This patent teaches that a pair of boom turning cylinders mounted to steel lugs, which are in turn welded to each side of a cutter boom, swing the cutter boom from side to side about its vertical turning axis.
Hydraulic cylinders have also been used in connection with a timber handling workhead, specifically a tree felling head, to raise and lower a saw guard of the felling head which in turn enables the felling of larger diameter trees as .
disclosed in United States Patent No. 4,921,024 issued on May 1, 1990 and identifying as the inventors, Wiemeri and Mitchell. This patent teaches that extension and retraction of hydraulically powered pistons causes a moveable guard portion which is attached to a fixed guard portion by a hinge to be raised and lowered to selectively expose or overlay a saw blade.
Gilbert-Tech Inc. of Roberval, Quebec markets a timber handling workhead, specifically a tree felling head under the trade-mark GILBERT 1000 Series, which achieves 180~ of rotational movement. The Gilbert tree felling head is rotated by two vertically disposed hydraulic cylinders actuating a 21 i672~
gear segment and a pinion gearset. One end of each of the hydraulic cylinders is pivotally attached to a disc saw housing of the tree felling head and the other end of each of the hydraulic cylinders is pivotally attached to the gear segment in the gearset. Extension and retraction of the hydraulically powered pistons turns the gear segment which turns a smaller gear mounted on a bearing and causes a larger gear to climb around the smaller gear to rotate the tree felling head freely about the axis of the pinion gear.
In another prior art device, Denharco of Saint Hyacinthe, Quebec achieves 240~ of rotational movement of a timber handling workhead, specifically a tree felling head marketed under the trade-mark DENHARCO CS5500 RTA felling head side tilt mechanism, by using a conventional chain drive, a planetary gear reducer and a hydraulic motor. The hydraulic motor through the gear reducer drives a pinion which in turn drives the chain to rotate the felling head around the boom adaptor.
A further example of a prior art device is a tree felling head marketed by Quadco Equipment Inc. of Montreal, Quebec as the Model 2OB Centre Tower Saw Head. This device achieves 240~ of rotational movement by using a gearset wherein the driving pinions are couped to two hydraulic cylinders via cranks. The gearset resides inside the felling head. The driving pinions mesh with a larger gear which is attached to the boom adaptor. The hydraulic cylinders are fed with .
pressurized oil through a hydraulic timing valve to ensure rotation of the tree felling head. A rotary timing valve changes the direction of the oil flowing into the hydraulic cylinders such that the cylinders are either pulling or pushing on the cranks. When one of the cylinders is at its maximum torque, the other cylinder is not generating any torque and visa versa. The cranks translate the linear motion of the hydraulic cylinders into rotary motion which drives the 21 ~672~
gearset to rotate the tree felling head about the axis of the boom adaptor.
Quadco has another device which achieves 270~ of rotational movement of a tree felling head using a conventional design consisting of two hydraulic motors driving a geartrain to rotate the felling head.
There are several advantages to harvesting machines having timber handling or processing workheads with high-angle rotation. These include the ability to harvest trees at any angle, which is particularly useful in a blow-down situation, and the ability to control the fall of the trees. As well, these machines allow for the flexibility to place the felled bunches of trees in a particular location for skidding, with the end result being larger and fewer piled bunches for fast and easy skidding to the landing. In addition, the skidder payload is improved without the need for multiple bunching.
Environmentally, high-angle rotation is also advantageous in that it m; n; mi zes the damage to forest growth and reduces feller buncher and skidder travel. Less machine travel means more operator comfort and less machine fatigue.
While the prior art devices capable of high-angle rotation possess the above-described advantages, generally they are complex arrangements involving many mechanical parts which require constant and specific maintenance. For example, gear segment and pinion gearsets and other types of gearsets must be serviced and maintained via lubrication and greasing on a regular basis due to the clogging debris from felled trees. The complex nature of the gearsets requires speci-fic maintenance by experienced mechanics and causes down time for the machine operator. Increased maintenance means higher operating costs and down time for the machine operator resulting in decreased productivity and lower profits. As well, many of the prior art devices do not provide for ready 21 ~6728 s maintenance access to hydraulic supply lines in a compact design.
Therefore, there has developed a need for a timber handling or processing workhead capable of high-angle rotation which overcomes these disadvantages.
SUMMARY OF lN V~N 1 ION
According to a broad aspect of the present invention, there is provided a slewing assembly for a timber handling apparatus of the type having a workhead connected to a support structure, the workhead being rotatable about a slew axis with respect to the support structure, the slewing assembly comprising: (a) a slewing means for relative rotational movement of the workhead and the support structure about the slew axis; (b) a drive means for imparting the relative rotational movement of the workhead and the support structure, the drive means comprising two actuators, each actuator having a fixed end and a moveable end, the actuators each provid-ing means for linearly extending and retracting the moveable ends thereof with respect to the fixed ends thereof along an actuating axis, one end of each actuator being rotatably attached to the workhead and the other end of each actuator being rotatably attached to the support structure; wherein each actuator is positioned to apply a force to the slewing means at a point radially distant from the slew axis thereof upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator to thereby effect the relative rotational movement of the workhead and the support structure, and wherein the actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
According to another broad aspect of the present invention, there is provided a slewing assembly for a timber handling apparatus of the type having a workhead connected to a support structure, the workhead being rotatable about a slew axis with respect to the support structure, the slewing assembly comprising: (a) a slewing mechanism for relative rotational movement of the workhead and the support structure about the slew axis; (b) a drive mechanism for imparting the relative rotational movement of the workhead and the support structure, the drive mechanism comprising two actuators, ~ach actuator having a fixed end and a moveable end, the moveable ends of the actuators each being linearly extendible and retractable with respect to the fixed ends thereof along an actuating axis, one end of each actuator being rotatably attached to the workhead and the other end of each actuator being rotatably attached to the support structure; wherein each actuator is positioned to apply a force to the slewing mechanism at a point radially distant from the slew axis thereof upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator to thereby effect the relative rotational movement of the workhead and the support structure, and wherein the actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
With reference to preferred embodiments of the present invention, the slewing means or slewing mechanism comprises a first cylindrical bearing surface provided with the support structure which is in relative rotational contact with a corresponding second cylindrical bearing surface provided with the workhead. Preferably, the first cylindrical bearing surface is an elongate cylindrical extension that is attached to the support structure, with the cylindrical extension being received within the second cylindrical bearing surface which is concentrically disposed therearound. The second 21 9~728 cylindrical bearing surface may be defined by a plurality of annular bearings.
In one embodiment, the elongate cylindrical extension has a free terminal end and another terminal end adjacent to the support structure, and the extension provides a retaining plate attached to the free terminal end and disposed substantially normal to the slew axis. The elongate cylindrical extension further provides an annular shoulder at the terminal end thereof adjacent to the support structure, such that the retaining plate and annular shoulder define opposed thrust bearing surfaces extending radially around the elongate cylindrical extension. The annular bearings may have a generally L-shaped cross-sectional configuration to thereby provide corresponding radially extending surfaces for relative rotational contact with the thrust bearing surfaces.
Advantageously, the elongate cylindrical extension may be provided with a through passage for hydraulic supply lines for timber handling means of the workhead.
According to further preferred embodiments, the slewing assembly further comprises a sensing means for each actuator, the sensing means detecting a dead position of the respective actuator. This dead position is obtained when the actuating axis of the actuator intersects with the slew axis during the relative rotational movement of the workhead and its support structure. Upon detection of the dead position of the actuator by the sensing means, the direction of linear translation of the actuator is reversed.
In yet further preferred embodiments, the actuating axis of each actuator is located in the plane substantially perpendicular to the slew axis of the workhead. Each actuator may be rotatably attached at each end thereof by means of a pin connection. The ends of the actuators which are attached to the support structure for the workhead are positioned '~1 q6728 substantially radially equidistant from the slew axis in one preferred orientation. Likewise, the ends of the actuators which are attached to the workhead may be positioned substantially radially equidistant from the slew axis. In an unrotated position of the workhead, the ends of the actuators which are attached to the workhead are located on a line which is substantially parallel to another line on which is located each of the ends of the two actuators which are attached to the support structure. Alternatively, the ends of the actuators which are attached to the support structure may be positioned at the same location.
The slewing assembly according to preferred embodiments of the invention may have a drive means or drive mechanism which provides only two actuators or may alternatively provide more than two actuators, such as three actuators.
Each of the actuators is preferably a hydraulic cyli~der.
In this manner, each hydraulic cylinder may be made selectively capable of extension and retraction in a float mode. In such a float mode, unpressurized hydraulic fluid is permitted to respectively draw into and drain away from each cylinder in response to loading thereof.
BRIEF DESCRIPTION OF DRAWINGS
For purposes of illustration and understanding of the present invention, but not of limitation, reference will be made to the following drawings in describing various aspects and preferred embodiments of the present invention, in which:
Figure 1 is a perspective view of a timber handling workhead, specifically a tree felling head, mounted to a boom support structure of an all-terrain vehicle, which felling head comprises the slewing mechanism according to a preferred embodiment of the present invention;
- - 21 9672~
Figure 2 is a side elevation of the tree felling head of Figure 1, showing a boom adaptor for attachment of the felling head to the boom support structure and showing a linkage means connected thereto for pivotal movement of the felling head with respect to the boom support structure;
Figure 3 is a cross-sectional view of the tree felling head of Figure 2, taken along line 3-3 of Figure 1, showing in detail the structure of the slewing mechanism according to a preferred embodiment of the present invention;
Figure 4 is an end elevation of the tree felling head, partially in cross-section, viewed adjacent the boom support structure (not shown) and showing the preferred positioning of two hydraulic cylinders for the slewing mechanism according to a preferred embodiment of the present invention;
Figure 5 is a side elevation of a cylindrical bearing surface and boom adaptor of the slewing mechanism shown in Figure 4, by means of which the tree felling head rotates about a slew axis with respect to the boom support structure;
Figure 6 is an end elevation of the cylindrical bearing surface and boom adaptor of Figure 5, viewed adjacent the boom support structure (not shown);
Figure 7 is a top plan view of the cylindrical bearing surface and boom adaptor of Figure 5;
Figure 8 is a cross-section of the cylindrical bearing surface and boom adaptor of Figure 7, taken along the line 8-8';
Figures 9a, 9b and 9c are schematic diagrams illustrating the operation of the slewing mechanism of Figure 4, viewed in end elevation adjacent the boom support structure (not shown), and displaying in sequence three positions of clockwise 21 9672~ -movement of the tree felling head as it rotates from an unrotated or mid-point position, through to a dead or toggle position associated with one of the hydraulic cylinders of the slewing mechanism, and ending with a fully rotated clockwise position.
Figures lOa, lOb and lOc are schematic diagrams illustrating the operation of the slewing mechanism of Figure 4, viewed in end elevation adjacent the boom support structure (not shown), and displaying in sequence three positions of counterclockwise movement of the tree felling head as it rotates from an unrotated or mid-point position, through to a dead or toggle position for one of the hydraulic cylinders of the slewing mechanism, and ending with a fully rotated counterclockwise position.
Figure 11 is a graph of wrist torque applied to the slewing mechanism of Figure 4, plotted as a function of angular displacement of the tree felling head from the mid-point position;
Figure 12 is a schematic layout of an electrohydraulic circuit adapted for operating and controlling the hydraulic cylinders of the slewing mechanism according to a preferred embodiment of another aspect of the present invention;
Figure 13 is a detailed schematic layout of a bank of hydraulic control valves and relays associated with the electrohydraulic circuit of Figure 12; and Figure 14 is a cross-sectional view of the cylindrical bearing surface and boom adaptor of the slewing mechanism of Figure 5, showing a swivel manifold block mounted on the slewing mechanism for through passage of hydraulic supply lines from the boom support structure to timber handling means of the workhead.
--- 2~ q6728 Figure 15 is an end elevation of the swivel manifold block of Figure 14, showing four swivel manifold spools for the hydraulic supply lines;
Figure 16 is a partial cross-sectional view of the swivel manifold block of Figure 14, taken along line 16-16' of Figure 15, showing the positioning of a swivel manifold spool within the block;
Figure 17 is a schematic diagram illustrating an alternate positioning of the two hydraulic cylinders for the slewing mechanism, by means of attachment at a common point;
and Figure 18 is a schematic diagram illustrating the positioning of three hydraulic cylinders for the slewing mechanism, again by means of attachment at a common point.
DETATT~Rn DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figure 1, the slewing mechanism of the present invention is shown in a timber handling workhead of the type having a felling head 40 connected to a support structure in the form of a boom structure generally shown by reference numeral 20.
The boom support structure 20 is connected to an all-terrain vehicle 10 of the kind well known to those skilled in this art, which includes an operator cab 12, an endless track driving system 14, and a turntable 16 upon which the cab base 18 is mounted for rotation. The boom support structure 20 includes an inner arm portion 22 and an outer arm portion 24 each portion having a first and second end. The inner arm portion 22 and the outer arm portion 24 are capable of pivotal movement relative to one another at the junction of the second end of the inner arm portion and the first end of the outer 2'1 ~672~
arm portion about pivot location 26. The first end of the inner arm portion 22 is pivotally mounted to the cab base 18 as at pivot location 28. The second end of the outer arm portion 24 is pivotally connected to the boom adaptor 50 as at pivot location 62. Extension and retraction of a hydraulic actuator 30 causes the inner arm portion 22 to pivot in a vertical plane about pivot location 28. A further hydraulic actuator 32 controls the angle between the inner arm portion 22 and the outer arm portion 24. Extension and retraction of the hydraulic actuator 32 causes the outer arm portion 24 to pivot in a vertical plane relative to the inner arm portion 22 about pivot location 26.
Turning more specifically to Figures 2 and 3, the felling head 40 of the preferred embodiment is mounted in a fixed fashion, known to those skilled in this art, to the end of the outer arm portion 24 of the boom support structure 20 by means of a boom adaptor or support structure adaptor 50. A linkage means, known to those skilled in this art as a crank assembly, 60, is connected to the boom adaptor 50 for pivotal movement of the felling head about pivot location 62. Crank assembly 60 comprises a link members 64 and a crank arm 70. Link member 64 has a first end pivotally connected, as at 66, to the boom adaptor 50 and a second end which is pivotally connected, as at 68, to one end of crank arm 70. A piston rod 72 of hydraulic cylinder 74 is pivotally connected at its cylinder end to a bracket 76 on the outer arm portion 24 of the boom support structure 20. The other end of crank arm 70 is pivotally connected, as at 78, to the outer arm portion 24 of the boom support structure 20, such that the crank arm 70 extends upwards from the outer arm portion 24. Thus, extension and retraction of piston rod 72 of the hydraulic cylinder 74 causes crank assembly 60 to pivot the felling head 40 in a vertical plane, aligned with the boom support structure 20, about the pivot location 62. This downwar~
articulation of the felling head via the crank assembly provides the felling head with an additional degree of tilt to 21 ~67~8 approach a position that is nearly parallel to the ground when the boom support structure is at full extension.
The felling head 40 according to a preferred embodiment of the present invention is a disc saw felling head having an upright box section structural element 41 acting as a main member for the entire felling head and timber handling means in the form of a grappling means and cutting means. The grappling means consists of a single accumulator arm 42 and two standard harvesting arms 43, both known to those skilled in this art. The cutting means is provided in the lower portion of the felling head and includes a circular saw blade 44 (Figure 1) mounted in a plane perpendicular to the general longitudinal axis of the felling head. The saw blade 44 is located within a saw blade housing 45 having a top surface 47 and a bottom surface 49. A saw motor 44A drives the circular saw blade 44. Two skiis 46 are affixed to the bottom surface 49 of the saw blade housing 45 and a log pusher 48 protrudes from the front of the saw blade housing as shown in Figures 2 and 3.
Referring to Figures 3 through 8, the slewing means for rotational movement of the felling head 40 with respect to the boom support structure 20 is next explained. Those skilled in this art will readily appreciate that the present invention may be adapted to other timber handling and processing apparatus employing various timber handling and processing means, such as workheads for felling, delimbing, debarking, bucking, carriage and loading of trees, or combinations thereof.
The slewing means according to a preferred embodiment of the present invention comprises a first male cylindrical bearing surface, provided with the boom support structure, which is in relative rotational contact with a corresponding second female cylindrical bearing surface provided with the felling head. Preferably, the first male cylindrical bearing surface is an elongate cylindrical extension 52 that is attached to the boom support structure 20 by means of the boom adaptor 50 as shown in more detail in Figure 5. The boom adapter 50 provides, at one end thereof, means for respective pivotal attachment to the link member 64 of the crank assembly 60 and to the second arm portion 24 of the boom support structure 20. Such means for pivotal attachment may be in the form of a bracket assembly 51.
Preferably, the second female cylindrical bearing surface is located in a cavity or receptacle 54 (Figure 3) in the felling head 40. The second female cylindrical bearing surface is concentrically disposed to receive the first male cylindrical bearing surface therewithin. Preferably, the second female cylindrical bearing surface is defined by a plurality of annular bearings, such as two annular bearings 80, 82, which are housed in the receptacle 54 and which have a generally L-shaped cross-sectional configuration. This L-shaped configuration provides axial thrust bearing surfaces 80a, 82a and radial bearing surfaces 80b, 82b on each of the annular bearings 80, 82, as shown in Figure 5. The annular bearings may be constructed from brass or some other suitable material known to those skilled in this art.
The elongate cylindrical extension 52 has a free terminal end to which is fixedly attached a removable retaining plate 56 by means of bolts 57 or the like, and another terminal end, adjacent to the boom adaptor 50, around which is disposed an annular shoulder 58. The removable retaining plate 56 and annular shoulder 58 together act to constrain the felling head against excessive longitudinal movement within the receptacle 54 along the direction of the slew axis AA'. The removable retaining plate 56 and the annular shoulder 58 define opposed axial thrust bearing surfaces 56a, 58a which extend radially around the elongate cylindrical extension 52, as shown in Figure 5. The axial thrust bearing surfaces 56a, 58a correspond with the respective axial thrust bearing surfaces 21 ~6728 80a, 82a of the annular bearings 80, 82 and are in relative rotational contact therewith. The elongate cylindrical extension 52 also defines radial bearing surface 52a which extends along the longitudinal length thereof, as shown in Figure 5. The radial bearing surface 52a on the cylindrical extension 52 corresponds with the respective radial bearing surfaces 80b, 82b of the annular bearings 80, 82 and are in relative rotational contact therewith. In a preferred embodiment of the present invention, the bracket assembly 51, the elongate cylindrical extension 52, the removable retaining plate 56 and the annular shoulder 58 are fixed the one to the other by means of a screwed and welded engagement or the like.
The elongate cylindrical extension 52 may be constructed from hardened steel or from some other suitable material known to those skilled in this art. Advantageously, the elongate cylindrical extension may be made hollow to allow for through passage of hydraulic supply lines 200 to the timber handling means of the felling head 40.
The two annular bearings 80 and 82 are concentrically arranged with respect to the elongate cylindrical extension 52 and are fixed within the receptacle 54 to allow relative rotational movement between the elongate cylindrical extension 52 and the annular bearings 80, 82 about the slew axis AA', as shown in Figures 3 and 5. As explained in greater detail below, this relative rotational movement, upon engagement of the drive means, produces rotational movement of the felling head 40 about the slew axis AA~ with respect to the boom support structure 20. Those skilled in this art will appreciate that although the described embodiment of the invention provides annular bearings 80, 82 in the form of bushings, other bearing surfaces such as those comprisin$
roller or ball bearings could also be adapted for use with the present invention.
The drive means for imparting the relative rotational movement of the felling head 40 with respect to the boom support structure 20 according to another aspect of the present invention is described with reference to Figures 4 and 9 to 13. The drive means comprises at least two actuators, preferably a first hydraulic cylinder 90 having a piston rod 94 and a second hydraulic cylinder 92 having a piston rod 96.
The hydraulic cylinders are of a conventional nature well known to those skilled in this art, as more fully described below. These hydraulic cylinders, when used as a means of rotational drive together with the slewing mechanism according to the present invention, eliminate the necessity of any form of gearsets or other transmission gearing to achieve the desired degree of high-angle rotation. In a preferred embodiment of the present invention, the cylinder ends of hydraulic cylinders 90 and 92 are rotatably attached adjacent the top surface 47 of the saw blade housing 45 of the felling head 40 by pin connections as at pivot locations 98 and 100 respectively, for instance by means of a pin and a spherical alloy steel ball bushing or the like. Similarly, the terminal ends of piston rods 94 and 96 are rotatably attached to the boom adaptor 50 as at pivot locations 102 and 104, respectively. Those skilled in this art will appreciate that the reverse mounting of the hydraulic cylinders may also be employed according to embodiments of the invention, as is the mounting of the first cylinder in one orientation and the second cylinder in the other. The cylinder ends of hydraulic cylinders 90 and 92 are fixed and the terminal ends of piston rods 94 and 96 are moveable along an actuating axis of each hydraulic cylinder. In a preferred embodiment of the invention, hydraulic cylinders 90 and 92 each have an actuating axis which is located in a plane substantially perpendicular to the slew axis of the felling head. The preferred angular positioning and spatial orientation of hydraulic cylinders 90 and 92 is described in greater detail herebelow.
The hydraulic cylinders 90 and 92 are preferably double-acting in nature, in that the piston rods 94 and 96 are -capable of being driven to retract and extend. The piston rods of the cylinders achieve powered linear extension and retraction by way of pressurized fluid chambers of a conventional nature controlled by electrohydraulic directional control valves 106 as shown in Figure 3, of the type capable of handling at least 4000 pounds per square inch, for example, the valve L9OLS marketed by the VOAC Hydraulics company of Mt.
Prospect, Illinois or the like. Those skilled in this art will appreciate that hydraulic cylinders 90 and 92 should be installed such that the cylinders do not ever produce a .
"bottoming out" of the piston rods 94 and 96 at each extreme end of the cylinder portion, whether the piston rod is fully extended or fully retracted within the cylinder. In other words, better mechanical integrity is achieved when the hydraulic cylinders provide oil relief at each extreme position of the piston rod, which is the result of the unused stroke of the piston rod.
With reference to Figures 9(a) to 9(c) and lO(a) to lO(c), extension and retraction of piston rod 94 of hydraulic cylinder 90 creates a force along an actuating axis BB' thereof which is located in a plane substantially perpendicular to the slew axis AA'. This force is applied to the slewing means at a point radially distant from the slew axis AA', to thereby effect the rotational movement of the felling head 40 with respect to the boom support structure 20.
Similarly, extension and retraction of piston rod 96 of hydraulic cylinder 92 creates a force along an actuating axis CC' thereof which is located in a plane substantially perpendicular to the slew axis AA'. This force is likewise applied to the slewing means at a point radially distant from the slew axis AA' to thereby effect the rotational movement of the felling head 40 with respect to the boom support structure 20. In the preferred embodiment of the present invention, the extension and retraction of the piston rods of hydraulic cylinders 90 and 92 are phase timed, or synchronized, by way of sensing means, preferably in the form of two proximity - 21 967~
sensing devices 108 and 109, shown in Figures 3 and 14, as described in greater detail herebelow. In what follows, reference to extension and retraction of hydraulic cylinders 90 and 92 shall mean extension and retraction of the piston rods 94 and 96 within the cylinders.
In their preferred positioning and orientation, the cylinder ends of hydraulic cylinders 90 and 92 are rotatably attached adjacent the top surface 47 of the saw blade housing 45 substantially radially equidistant from the slew axis AA' as best shown in Figure 4. The distance between the cylinder ends does not change in the preferred embodiment because the cylinder ends are fixed to the saw blade housing 45. The angle ~ between the actuating axis BB' and the line YY'., and the angle ~' between the actuating axis CC' and the line YY', as shown in Figure 4, change depending upon the different phases or synchronization of the extension and retraction of the hydraulic cylinders. When the felling head 40 is in an unrotated or midpoint position, as best shown in Figure 4, the angles a and ~' are equal and were chosen in the preferred embodiment because this was the angle which provided both firm structural mounting of the hydraulic cylinders and permitted rotation of the felling head 40 about the slew axis AA' without the piston rods 94 and 96 interfering with one another or traversing the slew axis AA'. In addition, the position of hydraulic cylinders 90 and 92 was chosen in the preferred embodiment such that when one cylinder is in its dead or toggle position, defined in more detail below, the other cylinder is in the position of applying m~;mllm torque to the slewing means, as shown in Figures 9(b) and lO(b).
The terminal ends of piston rods 94 and 96 are also positioned substantially radially equidistant from the slew axis AA' as shown in Figure 4, and are rotatably attached to the boom adaptor 50 which is pivotally attached to the boom support structure 20. Neither the distance between the terminal ends and the slew axis AA' nor the angle 0, as shown 2~ ~6728 in Figure 4, changes in the preferred embodiment during the different phases or synchronization of the extension and retraction of the hydraulic cylinders. When the felling head 40 is in an unrotated or midpoint position, as best shown in Figure 4, the terminal ends of piston rods 94 and 96 are located in a line that is substantially parallel with a line which intersects the cylinder ends of the corresponding hydraulic cylinders 90 and 92. Moreover, hydraulic cylinders 90 and 92 are positioned with the terminal ends of piston rods 94 and 96 being angled towards the slew axis AA'.
The phased timing or synchronization of hydraulic cylinders 90 and 92 will next be described with reference to Figures 9(a) to 9(c) and lO(a) to lO(c). In the preferred embodiment of the present invention, when the felling head 40 is in an unrotated or midpoint position, as shown in Figure 9(a), the terminal ends of piston rods 94 and 96 are each located at angle of approximately 17~ below the line XX' which intersects the slew axis AA'. For rotation of the felling head 40 in a clockwise direction when viewed from the boom support structure 20, hydraulic cylinder 92 is powered to retract, and hydraulic cylinder 90 is simultaneously powered to extend, until the felling head 40 assumes the position as shown in Figure 9(b). At the position shown in Figure 9(b), the felling head 40 has rotated approximately 40~ about the slew axis AA' in a clockwise direction from the unrotated or midpoint position of Figure 9(a).
The position of the hydraulic cylinders shown in Figure 9(b) defines the dead or toggle position of hydraulic cylinder 92, in that no torque is being applied to the slewing means by hydraulic cylinder 92. This dead or toggle position occurs when the actuating axis CC' associated with hydraulic cylinder 92 intersects with the slew axis AA~ during rotational movement of the felling head 40. In the preferred embodiment of the invention, a sensing means is used to detect the dead or toggle position of each of the hydraulic cylinders 90 and 21 9672~
92. The sensing means is described in greater detail below.
When the sensing means detects that hydraulic cylinder 92 has attained the dead or toggle position, the direction of linear translation of hydraulic cylinder 92 is reversed so that the cylinder is thenceforth powered to extend rather than retract.
For the felling head 40 to continue to rotate clockwise from the position of Figure 9(b), hydraulic cylinder 92, having attained its dead or toggle position and having now reversed its direction of linear translation, extends while hydraulic cylinder 90 simultaneously further extends so that felling head 40 assumes the fully rotated position as shown in Figure s(c). Mechanical stops 93 and 95, as shown in Figures 3, 5 and 14, are used on the felling head to prevent it from rotating beyond the fully rotated position. Mechanical stops 93 and 95 prevent the felling head from rotating beyond the fully rotated clockwise or counter-clockwise positions shown in Figures 9(c) and lO(c), by abutment against corresponding stops 193, 195 located on the boom adaptor. The mechanical stops are metal weldments or the like.
At the clockwise fully rotated position of the slewing mechanism, the terminal ends of piston rods 94 and 96 are still at an angle of approximately 17~ below the line XX' and the felling head 40 has rotated approximately 100~ about the slew axis AA' in a clockwise direction from the unrotated or midpoint position of Figure 9(a). To reverse direction from the position shown in Figure 9(c), each of hydraulic cylinders 90 and 92 is powered to retract, thereby returning the felling head 40 towards the position of Figure 9(b). When the position of Figure 9(b) is attained, again the sensing means associated with hydraulic cylinder 92 causes cylinder 92 to reverse direction, whereupon cylinder 92 is powered to extend rather than retract. The felling head 40 is then returned to the unrotated or midpoint position set out in Figure 9(a) by the powered extension of hydraulic cylinder 92 and the continued powered retraction of hydraulic cylinder 90.
- 21 ~67~8 For rotation of the felling head 40 from the unrotated or midpoint position shown in Figure lO(a) in a counter-clockwise direction, when viewed from the boom support structure, hydraulic cylinder 90 is powered to retract and hydraulic cylinder 92 is simultaneously powered to extend, until the felling head 40 assumes the position shown in Figure lO(b). At the position shown in Figure lO(b), the felling head 40 has rotated approximately 40~ about the slew axis AA~
in a counter-clockwise direction from the unrotated or midpoint position of Figure lO(a).
The position of the hydraulic cylinders shown in Figure lO(b) defines the dead or toggle position of hydraulic cylinder 90, in that no torque is being applied to the slewing means by hydraulic cylinder 90. This dead or toggle position occurs when the actuating axis BB' associated with hydraulic cylinder 90 intersects with the slew axis AA' during rotational movement of the felling head 40. When the sensing means associated with hydraulic cylinder 90 detects that the dead or toggle position has been attained, the direction of linear translation of hydraulic cylinder 90 is reversed so that the cylinder is thenceforth powered to extend rather than retract. For the felling head 40 to continue to rotate counter-clockwise from the position of Figure lO(b), hydraulic cylinder 90, having attained its dead or toggle position and having now reversed its direction of linear translation, extends while hydraulic cylinder 92 simultaneously further extends so felling head 40 assumes the fully rotated position as shown in Figure lO(c). Mechanical stop 95 prevents the felling head from rotating beyond the fully rotated counter-clockwise position shown in Figure lO(c).
At the counter-clockwise fully rotated position of the slewing mechanism, the terminal ends of piston rods 94 and 96 are still at an angle of approximately 17~ below the line XX' and the felling head 40 has rotated approximately 100~ about the slew axis AA' in a counter-clockwise direction from the 21 q6728 unrotated or midpoint position of Figure lO(a). To reverse direction from the position shown in Figure lO(c), each of hydraulic cylinders 90 and 92 is powered to retract, thereby returning the felling head 40 towards the position of Figure lO(b). When the position of Figure lO(b) is attained, again the sensing means associated with hydraulic cylinder 90 causes cylinder 90 to reverse direction, whereupon cylinder 90 is powered to extend rather than retract. The felling head 40 is then returned to the unrotated or midpoint position set out in Figure lO(a) by the powered extension of hydraulic cylinder 90 and the continued powered retraction of hydraulic cylinder 92.
In the preferred embodiment, the sensing means for detecting the dead or toggle position of each hydraulic cylinder consists of two proximity sensing devices 108 and 109. Sensing device 108 detects position changes of hydraulic cylinder 90 and sensing device 109 detects position changes of hydraulic cylinder 92. The proximity sensing devices detect positional changes through changes in magnetic fields and are of a conventional nature known to those skilled in this art, for instance both of the proximity sensing devices in the preferred embodiment are of the type IAS-20-A13-S made by Rechner Industries of Germany. Such proximity sensing devices detect the presence of a metal object which is located within a distance of approximately 5 millimetres from the device.
Therefore, in a preferred embodiment of the present invention, a raised portion or a metal end plate 107 (Figure 5), approximately 3/8 of an inch thick, is affixed by weldment or the like to extend from the outer end surface of retaining plate 56. The outer end surface of retaining plate 56 is not itself within the 5 mm range of the proximity sensors, but the outer end surface of metal end plate 107 is within said range.
When the metal end plate 107, by rotation of the felling head 40, crosses the field of detection of the proximity sensor, which occurs when either of hydraulic cylinders 90 and 92 are in the dead or toggle position, the proximity sensor detects the presence of the metal end plate and signals a reversal of 21 q6728 -the direction of linear translation of the cylinder in the dead or toggle position as more fully described below.
When hydraulic cylinder 90 is in the dead or toggle position, proximity sensing device 108, shown in Figure 3, detects the presence of the metal end plate 107 and signals the hydraulic circuit shown in Figure 12 by means of electric relays 110 to reverse the direction of linear translation of that cylinder by redirecting the flow of oil into hydraulic cylinder 90. A similar signal is generated by proximity sensing device 109 when it detects the presence of the metal end plate 107 due to hydraulic cylinder 92 being in the dead or toggle position. Accordingly, the direction of linear translation of hydraulic cylinder 92 is reversed by redirecting the flow of oil into that cylinder. Thus, the effect of reversing the direction of linear translation of a hydraulic cylinder at the dead or toggle position associated with that cylinder is to further rotate the felling head 40 about the slew axis AA' such that the felling head reaches its maximum angle of rotation. Those skilled in this art will appreciate that other types of sensors may be employed to effect the above-described sensing means, for example, the proximity sensor may be substituted by a contact or mechanical switch. Alternatively, rotary valves or the like may be used to detect the positional changes of the felling head itself.
The position and spatial orientation of hydraulic cylinders 90 and 92 as described above allows for the avoidance of the central zone 99 as schematically shown in Figures 4, 9 and 10. The central zone 99 allows for passage of the hydraulic supply lines 200 for the various powered devices of the workhead, such as the accumulator arm 42 and the harvesting arms 43, or the saw motor 44A, through the centre of the elongate cylindrical extension 52 of the boom adaptor 50 as shown in Figure 14. This preferred central passage of the hydraulic supply lines is yet another aspect of the present invention and is achieved by means of a swivel - 21 ~6728 manifold block and spools as described in greater detail herebelow.
A preferred hydraulic circuit for the felling head 40 of the present invention is described with reference to Figures 12 and 13. Those skilled in this art will appreciate that alternative hydraulic circuit layouts may also be used in order to operate and control the various felling head devices mentioned above. The preferred circuit 120 for use with the present invention includes proximity sensor circuits 122a, 122b and float sections 124a,124b, each of which are described in greater detail below.
With reference to Figure 12, the circuit 120 comprises a first pressure source 125, such as a hydraulic pump, to supply hydraulic fluid to a bank 126 of directional control valves 106, which bank includes the float sections 124a, 124b. The bank 126 in turn is in fluid commlln;cation with clamp cylinders 128a, 128b and with hydraulic cylinders 90 and 92.
The clamp cylinders respectively actuate the accumulator arm 42 and the harvesting arms 43 of the felling head 40, previously described. The hydraulic cylinders 90 and 92 actuate the slewing means for the felling head 40, also previously described.
A second pressure source 130, such as a hydraulic pump, supplies hydraulic fluid to saw motor 44A. The saw motor 44A
is for driving circular saw blade 44, referred to above. A
check valve 132 is disposed in parallel to the saw motor 44A
to allow for continued operation of the saw motor on power off. Each of the circuit segments associated with the hydraulic pumps 125 and 130 provide respective return lines 134 and 136 to tank 137. A drain 138 is provided to tank 144 for actuation solenoids 142 (Figure 13) associated with the directional control valves 106 of bank 126. Likewise, a case drain 146 to tank 144 is provided for saw motor 44A.
- 2~ q6728 Turning now to Figure 13, each of the directional control valves 106 of bank 126 is preferably a four-way, three-position valve which is biased to the centre position. At the centre position of each valve 106, the respective cylinders 9o, 92, 128a and 128b are locked hydraulically. At either end position of the valves 106, hydraulic fluid is supplied so as to respectively extend and retract the piston rods of each cylinder. A pair of actuation solenoids 142 is associated with each of the valves 106 in order to activate the valves away from their biased centre position. Each activation solenoid 142 of the said pair is a two-position hydraulic spool, respectively controlled by means of operator pushbuttons 148 or the like. In Figure 13, the pushbuttons for the actuation solenoids of the circuit segments for the hydraulic cylinders 90 and 92 of the slewing means are shown, but those that would be associated with clamp cylinders 128a, 128b are omitted for sake of convenience, as those skilled in this art will readily be able to derive an appropriate arrangement of operator controls to activate the actuation solenoids associated with clamp cylinders 128a, 128b.
Each pushbutton 148 for the circuit segment of the slewing means provides a signal to its associated actuation solenoid pair 142 through paired relays 110. Each paired set of relays 110 is powered by a respective proximity sensor 108, 109 as previously described. Thus, when hydraulic cylinder 90 or 92 reaches its dead or toggle position, the relays 110 are switched, thereby causing power to be discontinued from one actuation solenoid 142 and supplied to the other actuation solenoid 142 of the solenoid pair associated with the particular cylinder 90 or 92. Relays 110 therefore effect the reversing of direction of linear translation of hydraulic cylinders 90 and 92 at the dead or toggle position associated with these cylinders, to allow for further rotation of the felling head 40 so that it reaches its maximum angle of rotation, all as previously described.
- - - - - - - - -26 21 '~6128 The float sections 124a, 124b associated with the respective hydraulic cylinders 90 and 92 each comprise two two-way, two-position spools 150. When all of the spools 150 for both cylinders 90 and 92 are activated by means of a common pushbutton (not shown) or other suitable operator control means, each port at the central position of the valve 106 is placed in fluid commlln;cation with tank, thereby permitting each of the hydraulic cylinders 90 and 92 to extend and retract in a float mode. In this mode, unpressurized hydraulic fluid may be drawn into and drained away from each cylinder in response to loading thereof. Those skilled in this art will appreciate that other means may be employed in order to implement the above-described float mode, for instance, the three-position valves 106 of the slewing means circuit segment may be substituted with valves that provide an additional position to put each of the relevant ports of the valve to tank.
In operation, once an operator has felled a tree and has oriented the felled tree in a desired position by actuation of the slewing means and boom for the felling head, the operator may then engage the float mode in order to effect a release of the hydraulically locked actuators of the slewing means. This will achieve a damped fall for the tree to the location of skidding. The float mode therefore enables a skilled operator to place a felled tree to the ground more quickly, without the need for operator controlled and powered movements of the slewing means, provided the operator is ~atisfied with the expected trajectory of the tree prior to engaging the float mode. In addition, the skilled operator may use the float mode to move a felled tree while it is on the ground by dragging the trunk end of the felled tree to a desired location for loading or skidding.
With reference to Figure 14, 15 and 16, the elongate cylindrical extension 52 of the boom adaptor 50 is associated with a fluid delivery means consisting of a swivel manifold block 210 for through passage of hydraulic supply lines 200 for controlling and driving the various powered devices of the felling head 40. The swivel manifold block 210 is constructed of ductile iron or the like and comprises a retaining plate 214 which attaches the block to the felling head 40 by means of bolts 224 or the like and an end plate 226. The swivel manifold block has been equipped with an aperture 222 for alignment purposes during assembly.
There are four swivel manifold spools 212 which are housed within the swivel manifold block 210 as best shown in Figure 15. The end plate 226 prevents the spool from lateral movement out of the swivel manifold block as seen in Figure 16. Each swivel manifold spool is substantially cylindrical and constructed of hardened steel or the like which creates a bearing surface 212a thereby allowing the spool to rotate within the swivel manifold block 210. Four hydraulic supply lines 200 pass through the swivel manifold block 210 and deliver fluid into each of the four swivel manifold spools via conduits 228 as shown in Figure 15. The spools are provided with apertures 218 in fluid commlln;cation with the downstream hydraulic supply lines for the various powered devices in the felling head 40. In this way, the swivel manifold block and spools reduce the torsion that would normally be applied to the hydraulic supply lines if they were carried to the felling head 40 or passed through the slewing means uninterrupted.
By using hydraulic cylinders as a means for driving rotational movement of the felling head 40 with respect to the boom support structure 20, many of the problems associated with complex gearset arrangements are eliminated. For example, wear and tear on the slewing mechanism and the level of machine maintenance will both be expected to be reduced.
Fewer engaging and locking parts is expected to ml n;m~ ze down time caused by clogging debris from felled trees which in turn reduces operating costs and increases productivity.
21 967~8 In addition, by providing the swivel manifold block and spools, the length of the hydraulic supply hoses to the felling head 40 may be reduced since there is no need for the rotational movement of the felling head to be accommodated by slack in the supply hoses. This results in a compact design which m; n i m; zes hose chaffing and snagging during field use of the felling head 40.
Finally, those skilled in this art will appreciate that the inventive concept in any of its foregoing aspects can be incorporated, adapted or modified in many different constructions, so that the generality of the preceding description is not to be superseded by the particularity of the attached drawings. For instance, as shown schematically in Figure 17, an alternate positioning for two hydraulic cylinders 90a, 92a is to attach the actuating rod end of the cylinders to a common point 300a located on the boom adaptor.
As shown schematically in Figure 18, a further alternative is the use of three hydraulic cylinders 90b, 92b and 90c whose actuating rod ends are attached at common point 300a on the boom adaptor. Thus, these and various other alterations, modifications or additions may be incorporated into the various constructions and arrangements of parts and devices described herein without departing from the spirit or scope of the present invention.
Claims (19)
1. A slewing assembly for a timber handling apparatus of the type having a workhead connected to a support structure, the workhead being rotatable about a slew axis with respect to the support structure, the slewing assembly comprising:
(a) a slewing means for relative rotational movement of the workhead and the support structure about the slew axis;
(b) a drive means for imparting the relative rotational movement of the workhead and the support structure, the drive means comprising two actuators, each actuator having a fixed end and a moveable end, the actuators each providing means for linearly extending and retracting the moveable ends thereof with respect to the fixed ends thereof along an actuating axis, one end of each actuator being rotatably attached to the workhead and the other end of each actuator being rotatably attached to the support structure;
wherein each actuator is positioned to apply a force to the slewing means at a point radially distant from the slew axis thereof upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator to thereby effect the relative rotational movement of the workhead and the support structure, and wherein the actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
(a) a slewing means for relative rotational movement of the workhead and the support structure about the slew axis;
(b) a drive means for imparting the relative rotational movement of the workhead and the support structure, the drive means comprising two actuators, each actuator having a fixed end and a moveable end, the actuators each providing means for linearly extending and retracting the moveable ends thereof with respect to the fixed ends thereof along an actuating axis, one end of each actuator being rotatably attached to the workhead and the other end of each actuator being rotatably attached to the support structure;
wherein each actuator is positioned to apply a force to the slewing means at a point radially distant from the slew axis thereof upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator to thereby effect the relative rotational movement of the workhead and the support structure, and wherein the actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
2. The slewing assembly according to Claim 1, wherein the actuating axis of each actuator is located in a plane substantially perpendicular to the slew axis.
3. The slewing assembly according to Claim 2, wherein each actuator is rotatably attached at each end thereof by means of a pin connection.
4. The slewing assembly according to Claim 1, wherein the ends of two actuators which are attached to the support structure are positioned substantially radially equidistant from the slew axis.
5. The slewing assembly according to Claim 1, wherein the ends of the actuators which are attached to the support structure are positioned at the same location.
6. The slewing assembly according to Claim 5, wherein the drive means provides only two actuators.
7. The slewing assembly according to Claim 5, wherein the drive means provides only three actuators.
8. The slewing assembly according to Claim 4, wherein the ends of two actuators which are attached to the workhead are positioned substantially radially equidistant from the slew axis.
9. The slewing assembly according to Claim 8, wherein in an unrotated position of the workhead, the ends of two actuators which are attached to the workhead are located on a line which is substantially parallel to another line on which is located each of the ends of the two actuators which are attached to the support structure.
10. The slewing assembly according to Claim 1, wherein the slewing means comprises a first cylindrical bearing surface provided with the support structure which is in relative rotational contact with a corresponding second cylindrical bearing surface provided with the workhead.
11. The slewing assembly according to Claim 10, wherein the first cylindrical bearing surface is an elongate cylindrical extension that is attached to the support structure, the cylindrical extension being received within the second cylindrical bearing surface which is concentrically disposed therearound.
12. The slewing assembly according to Claim 11, wherein the second cylindrical bearing surface is defined by a plurality of annular bearings.
13. The slewing assembly according to Claim 12, wherein the elongate cylindrical extension has a free terminal end and another terminal end adjacent to the support structure, the elongate cylindrical extension providing a retaining plate attached to the free terminal end thereof and disposed substantially normal to the slew axis, the elongate cylindrical extension further providing an annular shoulder at the terminal end thereof adjacent to the support structure, the retaining plate and annular shoulder defining opposed thrust bearing surfaces extending radially around the elongate cylindrical extension, and wherein two of the annular bearings have a generally L-shaped cross-sectional configuration to thereby provide corresponding radially extending surfaces for relative rotational contact with the thrust bearing surfaces.
14. The slewing assembly according to Claim 13, wherein the elongate cylindrical extension provides a through passage therein for supply lines for timber handling means of the workhead.
15. The slewing assembly according to Claim 9, wherein each of the actuators is a hydraulic cylinder.
16. The slewing assembly according to Claim 13, wherein the support structure is a boom and the elongate cylindrical extension has a boom adaptor providing a bracket for connection to the boom.
17. The slewing assembly according to Claim 16, further comprising a sensing means for each actuator, the sensing means detecting a dead position of the respective actuator, the dead position being attained when the actuating axis of the actuator intersects with the slew axis during the relative rotational movement of the workhead and the boom, and wherein a direction of linear translation of the actuator is reversed upon detection of the dead position of the actuator by the sensing means.
18. The slewing assembly according to Claim 15, wherein each hydraulic cylinder is selectively capable of extension and retraction in a float mode, wherein unpressurized hydraulic fluid is permitted to respectively draw into and drain away from each cylinder in response to loading thereof.
19. A slewing assembly for a timber handling apparatus of the type having a workhead connected to a support structure, the workhead being rotatable about a slew axis with respect to the support structure, the slewing assembly comprising:
a slewing mechanism for relative rotational movement of the workhead and the support structure about the slew a drive mechanism for imparting the relative rotational movement of the workhead and the support structure, the drive mechanism comprising two actuators, each actuator having a fixed end and a moveable end, the moveable ends of the actuators each being linearly extendible and retractable with respect to the fixed ends thereof along an actuating axis, one end of each actuator being rotatably attached to the workhead and the other end of each actuator being rotatably attached to the support structure;
wherein each actuator is positioned to apply a force to the slewing mechanism at a point radially distant from the slew axis thereof upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator to thereby effect the relative rotational movement of the workhead and the support structure, and wherein the actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
a slewing mechanism for relative rotational movement of the workhead and the support structure about the slew a drive mechanism for imparting the relative rotational movement of the workhead and the support structure, the drive mechanism comprising two actuators, each actuator having a fixed end and a moveable end, the moveable ends of the actuators each being linearly extendible and retractable with respect to the fixed ends thereof along an actuating axis, one end of each actuator being rotatably attached to the workhead and the other end of each actuator being rotatably attached to the support structure;
wherein each actuator is positioned to apply a force to the slewing mechanism at a point radially distant from the slew axis thereof upon extension and retraction of the moveable end of the actuator with respect to the fixed end of the actuator to thereby effect the relative rotational movement of the workhead and the support structure, and wherein the actuators are each positioned such that the actuating axes associated therewith do not all intersect the slew axis at the same time during the relative rotational movement of the workhead and the support structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002196728A CA2196728A1 (en) | 1997-02-04 | 1997-02-04 | Actuator driven slewing mechanism for timber processing workhead |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002196728A CA2196728A1 (en) | 1997-02-04 | 1997-02-04 | Actuator driven slewing mechanism for timber processing workhead |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2196728A1 true CA2196728A1 (en) | 1998-08-04 |
Family
ID=4159827
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002196728A Abandoned CA2196728A1 (en) | 1997-02-04 | 1997-02-04 | Actuator driven slewing mechanism for timber processing workhead |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2196728A1 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6758286B2 (en) | 2002-06-26 | 2004-07-06 | Volvo Motor Graders Limited | Motorgrader circle drive |
| EP1889537A3 (en) * | 2006-08-16 | 2008-08-27 | John Deere Forestry Oy | Control of a boom construction and a tool articulated thereto |
| US7938154B2 (en) | 2009-06-12 | 2011-05-10 | Waratah Nz Limited | Timber-working head with feed wheel adaptor plate |
| US8862340B2 (en) | 2012-12-20 | 2014-10-14 | Caterpillar Forest Products, Inc. | Linkage end effecter tracking mechanism for slopes |
| WO2019086768A1 (en) * | 2017-11-06 | 2019-05-09 | Lauri Ketonen | A felling head for a multi-process machine |
| EP3769611A1 (en) * | 2019-07-22 | 2021-01-27 | Deere & Company | A timber working device and a method for a timber working device |
-
1997
- 1997-02-04 CA CA002196728A patent/CA2196728A1/en not_active Abandoned
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6758286B2 (en) | 2002-06-26 | 2004-07-06 | Volvo Motor Graders Limited | Motorgrader circle drive |
| EP1889537A3 (en) * | 2006-08-16 | 2008-08-27 | John Deere Forestry Oy | Control of a boom construction and a tool articulated thereto |
| US8430621B2 (en) | 2006-08-16 | 2013-04-30 | John Deere Forestry Oy | Control of a boom construction and a tool articulated thereto |
| US9345204B2 (en) | 2006-08-16 | 2016-05-24 | John Deere Forestry Oy | Control of a boom construction and a tool articulated thereto |
| US7938154B2 (en) | 2009-06-12 | 2011-05-10 | Waratah Nz Limited | Timber-working head with feed wheel adaptor plate |
| US8862340B2 (en) | 2012-12-20 | 2014-10-14 | Caterpillar Forest Products, Inc. | Linkage end effecter tracking mechanism for slopes |
| WO2019086768A1 (en) * | 2017-11-06 | 2019-05-09 | Lauri Ketonen | A felling head for a multi-process machine |
| CN111372445A (en) * | 2017-11-06 | 2020-07-03 | L·凯托宁 | Cutting head for a multiple-operation machine |
| CN111372445B (en) * | 2017-11-06 | 2022-06-14 | L·凯托宁 | Cutting head for a multiple-operation machine |
| US11606918B2 (en) | 2017-11-06 | 2023-03-21 | Lauri Ketonen | Felling head for a multi-process machine |
| EP3769611A1 (en) * | 2019-07-22 | 2021-01-27 | Deere & Company | A timber working device and a method for a timber working device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20030204 |