AU2019100069A4 - Tree stump elimination device - Google Patents

Abstract

A cutting device that can be used, among other things, for efficiently removing items such as extant trees and vegetation by cutting the subterranean root systems in situ with a powered multi-blade system. Among other uses, the cutting device may be implemented and deployed as a powered multi-blade device with cyclic, reciprocating or ellipsoid cutting action and motion path compensating blade design that severs root and other comparable matter such as cable in situ, providing high efficiency not seen in conventional straight-bladed systems. I C-> 1> "'N <N, N Is~, N> L1Cs, _* 'N Is g flu <in, * ~, 'N 0

Description

[0001] This disclosure claims the benefit of the priority of U.S. Provisional Application Serial No. 61/936,672, filed February 6, 2014, and entitled ''Cutting Device' ' .

[0002] This application relates to a tree stump elimination device hereinafter referred to a the ''cutting device'', for example, a mechanical device for efficiently removing extant trees, vegetation, and/or sub-surface entanglements.

BACKGROUND [0003] Clearing vegetation for cultivation or cropping or reclamation is a task undertaken around the world. Land clearance is undertaken on virgin forest or may be undertaken as part of land re-generation and re-purposing and reclamation, which requires removal of extant vegetation. Vegetation may include small trees and undergrowth and/or large trees. All trees and vegetation have root systems/root balls/stumps of one kind or another and these root systems are an impediment to the preparation of the ground in readiness for cultivation, cropping, and the like.

[0004] In many areas of the planet (particularly the Northern Hemisphere) exposed cut stumps, after tree harvesting, may lead to rotting fungus infestations (e.g. Heterobasidian annosum, Armillaria) that decimate productivity in subsequent tree plantings. This can necessitate stump removal, post-harvest by expensive, heavy, energy intensive, tracked vehicles (>20tonnes) that extensively disturb the area of stump removal (promoting erosion and soil acidification) and compact the adjacent ground (slowing the root growth/productivity of subsequent plantings). Preventative stump removal is for example practiced in Scandinavia where foresters are encouraged to use non-chemical control methods. Stump retention (i.e. leaving them in situ post-harvest) may also promotes the spread of the Pine Weevil (Hylobius abietis) which causes similarly severe economic losses by ring-barking and killing coniferous seedlings.

2019100069 26 Jan 2019

Note here that in current practice stump removal is carried out as a separate activity some time after the completion of tree harvesting.

[0005] Current stump removal practices indiscriminately removes considerable attached root mass and soil entrained in that root mass. This has the disadvantage of:

a. depriving the soil of important nutrients that would otherwise come from the decomposition of those roots,

b. requiring excess entrained soil removal practices that add to stump removal costs and,

c. adding to the transport cost where stumps are shipped with unwanted roots and entrained soil attached

d. increasing biomass contamination (entrained soil) where the stumps are used for biofuel - leading to deleterious slag formation in biomass conversion furnaces [0006] In countries such Finland and Sweden harvested stumps are used as a renewable biofuel in meeting their national, mandated, fossil fuel reduction targets. The current high energy cost and capital intensity of stump removal hinders this practice in those countries and limits the spread of this practice to other countries .

[0007] The cutting device herein may make possible:

a. Cheaper, faster, more efficient stump removal (harvesting) with lighter vehicles and equipment that makes the use of stumps an economically realistic source of biomass/biofuel by halving stump removal costs (half of current practice costs are related to the labour, capex, operation and maintenance of the heavy tracked removal machinery required by current practice) .

b. Precise separation of the stump from the attached root mass so that important nutrients are retained in the soil for the next tree plantings.

2019100069 26 Jan 2019

c. Precise separation of the stump from the attached root mass that minimises soil disturbance (hence minimising erosion and acidification risk).

d. Expansion of stump removal activity into sloping sites where the large holes created by current practice would cause excessive erosion.

[0008] The cutting device eliminates the need to conduct stump removal (harvesting) as a separate, subsequent operation. The present invention makes possible an integrated harvesting practice where the stem (trunk) and stump may be harvested in one piece. The stem can then be separated (cut) from the stump in the course of the current normal stem sectioning (for example cutting into market lengths) process.

[0009] Current plantation forestry practice is to periodically 'thin' (or 'relieve') the tree crop of under-performing, crowncrowding or diseased trees during the course of the crop cycle. This is done by cutting the stem (trunk) from the stump - leaving the exposed stump in situ. This practice exposes the stump to rotting fungus attack (see above) which is then readily transmitted to adjacent trees by overlapping root contact underground. This can cause severe economic loss in tree plantations. The practice of thinning is also employed in the management of plantation stand margins (the forest edges) to reduce the risk of tree crop loss through windthrow or windbreak. This is especially important as climatologists predict more extreme wind events with progressive climate warming.

[0010] Land clearance is generally a labour and equipment intensive process. Regardless of whether the extant vegetation is small/light or large established trees, root systems/root balls/stumps must be removed for the ground to be suitable for cultivation.

2019100069 26 Jan 2019 [0011] In some instances, land has been used for fill and there are cables and similar materials buried but close enough to the surface to entangle plough blades and other implements used to clear and prepare ground for agricultural use or which otherwise is to be cleared of sub-surface entanglements.

[0012] Clearance of trees from land requires removal of both the above ground elements (trunk and foliage) and the root systems/root balls/stumps.

[0013] Root systems typically spread laterally around a tree rather than vertically. Lateral roots radiate from the trunk and form a network of woody tendrils. If the resultant stumps/root balls were left in the ground, they are likely to hinder use of agricultural implements and other pre-cultivation activities such as ploughing and grading.

[0014] Generally, land clearance requires deployment of heavy earth moving equipment such as tractors. This equipment uses brute force to push over vegetation such as trees, or to pull a static device such as a hook through the ground in order to pull up root systems/root balls/stumps. The hook is used to snag the root systems and drag part of the root system to the surface, where various methods are used to sever the roots in order to permit the tree to be toppled or the vegetation to be pulled out of the ground and removed.

[0015] The use of brute force necessarily requires large and powerful tractors or comparable devices to drag the hook through the ground, due to the resistance of the soil and the root systems .

2019100069 26 Jan 2019

SUMMARY [0016] The present inventor recognized that conventional land clearance techniques tend to require the use of large, cumbersome vehicles, which usually have to be brought into the site where they are not suitable for public roads. This transport to and from site adds cost, time delays and could be avoided if a smaller, more agile traction unit of the kind commonly found on farms, could be used.

[0017] Moreover, acquisition and transport of costs are directly proportional to the size of the earthmoving device in question: therefore the larger the device, the greater the cost. Consequently, where a smaller and/or less powerful device (such as the cutting device described herein) can achieve essentially the same outcome, then there are efficiency gains, cost savings and/or a reduction in ancillary consumption such as fuel and generation of carbon and exhaust gases.

[0018] The cutting device described herein is a mechanical device that can be used, among other things, for efficiently removing items such as extant trees and vegetation by cutting the subterranean root systems in situ with a powered single or multi-blade system. Among other uses, the cutting device may be implemented and deployed as a powered multi-blade device with cyclic, reciprocating or ellipsoid cutting action that severs root and other comparable matter such as cable in situ, without having to drag same to the surface. Moreover, the cutting device can be used above or below ground.

[0019] Implementations of the cutting device, and a method of using same, may include various combinations of the following features .

[0020] A cutting device may include a support frame (1), reaction force compensation arms (11) connected to the support frame (1) and configured to contact ground when the cutting device is in use, at least one moveable cutting blade (12) extending below the reaction force compensation arms (11), and

2019100069 26 Jan 2019 orbit-causing means (6, 8, and 13) for causing the moveable cutting blade (12) to orbit in an ellipsoidal pattern.

[0021] The cutting device may have two moveable cutting blades (12) configured to orbit either 180 degrees out of phase with each other in a controlled manner, or independently.

[0022] The cutting device may be configured such that each moveable cutting blade (12) is separately configured to compensate for variations in elliptical-oscillation movement.

[0023] The cutting device may further include a plurality of moveable cutting blades (12), wherein a quantity of cutting blades is proportional to a depth at which the cutting device is to operate.

[0024] The moveable cutting blade/s (12) comprise a curved member with teeth or machined cutting edge.

[0025] The cutting device may further include a vertical member (e.g., cutter bar arm 6) operatively coupled via a drive (13) to the support frame (1) such that the vertical member (6) can be oscillated vertically, and wherein the orbit-causing means (6, 8, and 13) converts vertical oscillation of the vertical member (6) to ellipsoidal motion.

[0026] A method of cutting sub-surface entities may involve extending a first cutting blade into a sub-surface location adjacent to, and in contact with, an object to be cut, and converting vertical oscillation input into elliptical motion to cause the first cutting blade to move in an elliptical pattern relative to a second cutting blade.

[0027] The toothed (or machined edge) blade/s (12) are so curved that they compensate for the ellipsoidal motion of the blades producing continuous/constant cutting contact with target sub-surface entanglements. The combination of ellipsoidal motion and blade shape motion path compensation produces a level of cutting

2019100069 26 Jan 2019 efficiency not possible with conventional straight-edged blades.

This combination of motion path and blade shape yields a continuous cutting action in the rearward and upwards segments of the ellipsoidal motion path so optimising cutting operation efficiency. Conventional straight-edged blades, by contrast, are charactarised by a momentary striking action only.

[0028] The blades (12) may be variously curved to suit the motion path (Figure3) produced by motion control linkage (8) placement and so maintain maximum cutting efficiency.

[0029] The cutting method may further include using a common drive to control a phase difference between the first and second cutting blades to maintain the phase difference at a predetermined degree .

[0030] The cutting method may further include using, for each of the first and second cutting blades, a dedicated drive to control the elliptical pattern of the respective cutting blades such that the first and second cutting blades move independently of each other.

[0031] Among other potential advantages, the disclosed cutting device, when removing trees, may prevent leaving the stump/root ball behind, which typically happened with conventional methods. Consequently, by using the disclosed cutting device, the residual stumps/root balls no longer need to be removed with large/powerful earthmoving equipment and/or manual labour intensive methods. With the stumps/root balls not left in the ground, cropping becomes less difficult, and the crop yield per unit area is increased. As a result, there is no longer a need to clear additional acreage to compensate for the area lost to otherwise extant stumps/root balls.

[0032] Further, the disclosed cutting device may decrease, or eliminate, the damage to tree trunks often caused by conventional clearance techniques and equipment. As a result, the value of the tree trunks to saw mills is increased, while decreasing the occurrence of what would otherwise be potentially

2019100069 26 Jan 2019 valuable saw-logs being discarded as waste. Moreover, because less waste vegetation (which usually is burnt) is generated, what otherwise would result in significant quantities of smoke and carbon emissions are reduced.

[0033] Much of the native timber destroyed by conventional clearing methods could otherwise be milled using on-site equipment such as the cutting device described herein.

[0034] The cutting device may be mounted on purpose-built vehicles or may be rear-mounted on common tractors featuring three-point linkage and power take-off (''PTO'') or may be frontmounted on smaller front-end loaders/bobcats/backhoes/trailers (Figures 4, 5 and 6) . This is especially of value in Third World markets where relatively small tractors are more likely to be used rather than the large bulldozers and other heavy earthmoving equipment commonly used for conventional agriculture and tree removal in Western countries.

[0035] The cutting heads (also referred to herein as ''blade/s'') may be located on the centreline of the bulldozer/power supply or it may be mounted off-centre so as to bring the cutting heads in line with or outside the wheel track. Offsetting the blade/s facilitates access to root systems not otherwise accessible to mechanical removal due to the track width or space limitations between the trees to be removed.

[0036] The cutting device described here may provide advantages over conventional root-cutting circular saws, which tend to be of limited effectiveness unless scaled up and fitted to large heavy-duty earth moving equipment of the kind usually found on construction sites.

[0037] Similarly, the cutting device described here may provide advantages over smaller circular saw units, which are suitable for common farming tractor mounting, but typically are limited with respect to the root cutting depths they can achieve, and which tend not to be configurable to facilitate inclined cutting under the stump/rootball.

2019100069 26 Jan 2019 [0038] Further, the cutting device described here may provide advantages over stump grinders (analogous to circular saws), which are used to take the stump/root ball below ground level but which tend not to extend far enough below the surface to be useful for agriculture or tree planting/replanting.

[0039] The cutting device also may obviate the need for explosives in removing of legacy stumps/rootballs.

[0040] In an implementation, the cutting device involves deployment of a blade-based cutting assembly below the ground level, at a depth appropriate to the root systems in question, so that the roots are severed in situ.

[0041] The cutting device may achieve cutting action by mounting one or more blades on a reciprocating arm which is mounted upon a mobile power source such as a tractor or other earth moving equipment by means of a support frame.

[0042] The cutting device is readily scalable. Smaller units may be attached to tractors and backhoes of the scale commonly found in farms. Large-scale versions may be mounted on heavy earthmoving equipment such as bulldozers and tracked backhoes of the kind more commonly found in large scale earthworks.

[0043] In an implementation, the cutting device uses a system of gears and levers to transfer hydraulic or mechanical motive force via the mounting arm so as to impart a cyclic and/or ellipsoidal cutting action to the blades, which are mounted at the end of the arm.

[0044] This action may take place as the device is being dragged through the ground thereby compounding the cutting action to sever root systems and cutting its way through the ground.

[0045] The device's cutting head may be deployed below the surface of the ground to a depth the operator judges sufficient to sever enough of the roots or root ball or other entangling material, to permit their removal and thereby facilitate

2019100069 26 Jan 2019 ploughing or other activities that would otherwise be impeded by the presence of sub-surface roots or other entanglements.

[0046] In operation, the cutting heads may be deployed to cut through the roots in situ. Where a root system is severed on one side of the tree, the tree's support is greatly reduced and the tree may be pushed over readily; this process will generally bring the main part of the root system to the surface, which simplifies removal of the tree and the root-ball.

[0047] Once the roots have been severed, those parts of the root system remaining in the ground may be left or may be removed, depending on the circumstances and/or desired outcome.

2019100069 26 Jan 2019

Drawing Descriptions [0048] Figs. 1A-1E are, respectively, end, side, operator's end, top, and bottom views of a cutting device having an asynchronous cutting arm in which two blades orbit 180 degrees out of sync or independently.

[0049] Figs. 2A-2D are, respectively, side, top, bottom, and end views of a cutting device having a single cutting arm with twin blades.

[0050] Figure 3 shows the changes in the ellipsoid motion imparted upon the blade/s by changing the relative separation distance of the mechanisms imparting vertical and horizontal movement to the cutter bar/blade/s.

[0051] Figs. 4 and 5 illustrate operation aspects of the cutting device.

[0052]

Fig. 6 illustrates a trailer-mounted operation option.

2019100069 26 Jan 2019

	Detailed Description
0053]	A single or multiple metal or ceramic blades are

mounted on an arm which is moved vertically or tangential to the ground through hydraulic, electric or mechanical power. Blade

motion is	then converted to ellipsoidal via a motion control
linkage/s	(8) .
[0054]	In an implementation, multiple blades are mounted one
above the	other on a cutter bar arm. Each blade is separately

configured to compensate for variations in ellipticaloscillation movement. The number of blades can be increased proportional to the depth at which the cutter bar arm is to operate .

[0055]

In an implementation, a counter-travelling, double

blade is installed on the cutter bar arm. Alternatively, a single

blade may	be installed on the cutter bar arm.
[0056]	The cutting blades at the end of the cutter bar arm

move in an ellipsoidal path, presenting a cutting motion with sub-surface entanglement contact time in the rearward and upward portions of any one movement cycle of the blade assembly.

This results in a controlled dynamic cutting motion, rather than the simple limited contact striking action that would result from a non-motion compensating conventional straight blade. Hence the blade shape is designed to complement the ellipsoidal motion, so as to enhance/optimise the cutting action.

[0057]

In an implementation, one cutter bar arm is attached

to a support frame. Alternatively, there may be a multiplicity of cutter bar arms, each connected to the support frame.

[0058]	In an implementation, a fixed shoe-like arrangement
is fitted	to the support frame. This shoe-like fitting would
remain in	contact with the ground during root cutting operations

by sliding over the ground as the cutter bar arm travels through the ground with the oscillating blades cutting below the surface. This shoe-like arrangement uses contact with the ground

2019100069 26 Jan 2019 to absorb and/or prevent bucking and heaving reaction forces otherwise likely to be transferred through the cutter bar arm back up to the support frame and the unit upon which the present cutting device is attached.

[0059] In an implementation, the cutter bar arm is powered so as to achieve a vertical oscillation. This may be achieved by use of, for example, the output of a fence post auger gearbox. This gearbox would be mounted 90 degrees to the vertical. It would provide the cutter bar arm's vertical movement via a linkage to which the same vertical mount or mast that the gearbox (driving the cutting arm) was mounted. This mast may then be raised or lowered to enable the cutter bar arm to be forced or lowered into the ground as the cutter bar arm oscillates vertically to engage/cut tree roots or other entanglements .

[0060] In an implementation, a second cutter bar arm, may be installed. This arm is parallel to the other, and its blade assembly oscillates out-of-phase (also referred to as ' 'out of sync) or independently with the other. By this configuration, one blade may be cutting during the rearward/lifting (vertical) portion of the ellipsoid cycle, while the other is in the forward/lowering portion of the cycle.

[0061] As used herein, ''out of phase'' (or equivalently, ''out of sync'') means a predetermined or fixed degree of asynchronicity between two or more cutter bar arms, e.g., 180 degrees, or some other controlled value as the application requirements dictate. In such an arrangement, the two or more cutter bar arms may share a common drive, which controls the degree of asynchronicity between the blades in an ongoing manner. In contrast, ''independently'' means that each cutter bar arm would have its own dedicated drive, and may move in and out of phase relative to the other arm or arms as they encounter differing levels of resistance as they move through the ground.

2019100069 26 Jan 2019 [0062] In an implementation, the cutter bar arm and mast assembly may offset to the side in relation to the centreline of the tractor's wheelbase. This offset would allow the cutter bar arm to be placed closer to root system's centre or root ball than would be possible with a centre-mounted assembly.

[0063] Figs. 1A-1E are, respectively, end, side, operator's end, top, and bottom views of a cutting device having an asynchronous cutting arm in which two blades orbit 180 degrees out of sync.

[0064] Figs. 2A-2D are, respectively, side, top, bottom, and end views of a cutting device having a single cutting arm.

[0065] The elements indicated by the reference numerals 1-14 are described in the file: IP Drawing Reference Table''.

[0066] As shown in Figures 1A-1E, the support frame (numbered

1) is attached to the vehicle providing the propulsion and power supply for the device. When deployed, the unit is affixed to a means of propulsion such as a tractor or comparable vehicle which has a hydraulic power output capability or mechanical Power Take Off (PTO). The hydraulic power from the vehicle or the vehicle's PTO, provides motive power to the blade's drive assembly as noted in item 4 or, where fitted, the gearbox noted in item

5. In one iteration of the device, there is fitted a sensor which monitors the hydraulic pressure so as to cut power to one or both blade/s should one or both encounter material which is too resilient/ hard for the blade/s to cut through. A warning indicator alerts the operator who then may take appropriate action such as re-attempting to cut through the obstruction or lift the cutter bar out of the ground, proceed a certain distance thereupon re-engaging the until which then drives the cutter bar/blade/s into the ground to resume cutting.

[0067] The cutting device described herein may provide several potential advantages. For example, the elliptical

2019100069 26 Jan 2019 motion of the cutting head is such that the motion has the long axis of the ellipse in a horizontal plane rather than vertical; as a result, the cutting blade cuts on the advance stage, then backs off and clears the blade before coming forward (effectively from underneath the object being cut) to cut again.

[0068] The expression ''vertical'' refers to the motion of the blade/s relative to the surface of the ground in which they are being deployed. This is shown as the vertical axis in Figure 3.

[0069] The expression ' 'horizontal'' refers to the motion 90 degrees to the vertical motion and is shown as the horizontal axis in Figure 3.

[0070] following	Other embodiments claims .	are	within	the scope	of	the
[0071]	In one iteration of	the	device,	the mounting	as	shown
in 1 of the table above, is fixed	to the vehicle. This	is
illustrated in Figure 4.

[0072] In another iteration of the device, the mounting is capable of being swing back and up, so as to disengage the blade/s by lifting them out of the ground in a swinging or an arc-like motion. This is illustrated in Figure 5.

[0073] In another embodiment, the device may be combined with a cable laying device to complement the latter device's function of simultaneously digging a trench of varying depth and laying a conduit or pipe directly behind the trenching element of these devices. As currently deployed, the trenching device is a hook shaped fixed blade pulled through the ground behind a tractor or similar power supply but these devices are unable to operate where there are underground root systems or existing subterranean cables which entangle and impede a simple fixed blade whereas such an impediment is able to be cut in situ by the subject device which uses a powered blade array.

Description of Drawing Elements

2019100069 22 Jan 2019

Item Ref#	Description
1	Support frame (shown as dotted). Specific design determined by the type of vehicle to which the blade assembly is to be attached. The vehicle-specific interfacing structure by which the device proper (items 1-10 & 12-14) is connected to the drive vehicle. The support frame directly secures the carriage mast (item 2) and the reaction force compensation arms (the latter which provide counter-force to the blade/s cutting action). The support frame may also be used to mount a PTO-driven hydraulic pump and reservoir to power the raise/lower hydraulics (items 2 & 3) and the blade/s drive (item 13).
2	Carriage mast. Provides the means by which cutter bar/blade/s assembly is raised/lowered into the ground and which houses the hydraulic ram/s that power this movement. The carriage mast is directly connected to the support frame and provides the path by which the cutter bar carriage (item 7) moves to enable the cutter bar/s (item 10) and the blades thereon (iteml2) to enter/leave the ground.
3	Hydraulic link arms. These transfer raising and lowering power to the blade/s bar carriage. Fixed at the lower end to the blade/s bar carriage (item 2) and at the upper end to hydraulic ram housed within the carriage mast; this transfers the power by which the blade/s bar carriage (item 7) that moves to enable the blade/s bar/s (item 10) and the blades thereon (iteml2) to enter/leave the ground.
4	Hydraulic motor. This powers the cutter bar/blade assembly. This is mounted on the cutter bar/blade/s assembly drive; the rotating motion of the drive directly imparts the vertical component (as relative the ground) of the blades' (item 12) ellipsoid motion and, in concert with the motion control linkages (item 8), imparts the horizontal component (as relative to the ground i.e. 90degrees from the vertical) of the blades' ellipsoid motion producing the cutting action to the blade/s.

Description of Drawing Elements

2019100069 22 Jan 2019

5	Gearbox. This is not required in all iterations of the invention. Where applicable, the gearbox is typically mounted on the cutter bar/blade/s drive and modifies drive direction, speed and power as determined by the operator .
6	Cutter bar arm. Secured at the top by the rotating drive (13) and midway by the motion control linkages (8). The blade/s (12) are mounted on the lower end of the cutter bar/s (item 10). The cutter bar arm is the means by which ellipsoid motion is delivered to the blades. The ellipsoid motion is more fully articulated in diagram 2A which shows the changes in the ellipsoid motion which is achievable by varying the ratio of the distance traveled by the vertical and horizontal connection bars which provide the ellipsoid motion to the blade/s.
7	Cutter bar carriage. Supports the cutter bar's rotary drive [item 13] and anchors the carriage mast end of motion control linkage arm/s shown in item 7.
8	Motion control linkages. These provide the blade's horizontal cutting motion component via link between carriage & cutter bar arm [Mounted below the rotary drive (item 13) with one end fixed to the carriage mast (item 2) via a flexible linkage; and the other end fixed to the cutter bar arm/s (item 6) via flexible linkage]
9	Blade/s bar mount. Being the means of securing the blade/s mounting bar/s (item 10) to the cutter bar arm/s (item 6) .
10	Blade/s bar. Mounted at the bottom end of the cutter bar arm/s (item 9) by means of the blade/s bar mounts (item 9) and used to support the blade/s (item 12).
11	Reaction force compensation arms. These project from the support frame (item 1). During operation they provide counter-force to the upward portion of the assembly's cutting action to reduce yaw and pitch and to reduce stress upon the vehicle and the unit mounting points and hydraulic linkages.

Description of Drawing Elements

2019100069 22 Jan 2019

12	Unit's blade/s. The blade/s are shaped to maximize the period the blade/s cutting edge is in contact with the material being cut. The blades cut on the upwards/rearwards portion of the ellipsoid path, then are withdrawn on the downwards/forwards portion and re-engage on the upwards/rearwards path so long as the unit is in operation. The example (Fig.2E) blade/s cutting edge comprises a series of scalloped, longitudinal serrations.
13	Drive. This rotates to provide the blade's vertical cutting motion component via movement of the cutter bar arm. It is mounted on the cutter bar carriage (item 7); the motion of the drive directly imparts the vertical component of the blades' (item 12) ellipsoid motion and, in concert with the motion control linkages (item 8), imparts the horizontal component of the blades' ellipsoid motion. Collectively, the cutter bar arm (6), the motion control linkages (8) and the hydraulically powered rotary drive (13) form an orbit-causing means (or mechanism) for causing the moveable cutting blade (12) to orbit in an ellipsoidal pattern.
14	Asynchronous or independent (unlinked) blade/s drive.

Claims (3)

1. What is claimed is:

   1. A combination of sub-surface cutting blade ellipsoidal motion path and cutting blade shape that maximises blade contact/cutting time in operation.
2. 2. A combination of sub-surface cutting blade ellipsoidal motion path and cutting blade shape that optimises cutting operation efficiency.
3. 3. A cutting blade designed by virtue of its calculated cutting edge curvature counters the inefficient momentary contact/striking cutting action of straight-edged blades in ellipsoidal motion .