Note: Descriptions are shown in the official language in which they were submitted.
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TTTTT~' OF T~T~ T~v~ ON: BRUSH FT~TTTNG HT~An
FI~Tln OF T~ TNVT~NTTON
The present invention relates to felling heads, and
more particularly to a brush felling head for tractor vehicles.
BACKGROUND OF TH~ TNV~NTTON
Debrushing felling heads are used in many
circumstances, for removing brush on a brush covered terrain.
lo The felling head is usually installed on a tractor vehicle, and
controlled by the vehicle driver.
A first common application of the debrushing felling
heads is in tree plantations, e.g. pine or cedar plantations.
The tree rows therein are laterally spaced from one another by
about six feet, and the brush will often reach between one foot
and four feet in height, and in the latter case can become
higher than the growing trees themselves. Of course, this is
highly undesirable, since it then hampers significantly the
growth of the trees due to the lack of sun light reaching the
trees. The motorized debrushing vehicle is destined to be
driven between the tree rows to cut down the undesirable brush
which grows there.
Usually, manual means are used for removing the brush
located between the trees of a same row, where the debrushing
vehicle could not reach without damaging or killing the trees,
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and thus the finishing job is accomplished by hand once the main
debrushing operation is done between the rows by the vehicle.
Debrushing is also accomplished in remote locations,
such as along highways or power line paths to maintain the
right-of-way in these locations, at regular spaced-apart time
intervals. A debrushing vehicle can then become very useful,
since in such large areas, manual debrushing is out of the
question, being too time-consuming.
It is known in the debrushing industry to use
debrushing or felling heads installed on tractor vehicles to
accomplish this task. These debrushing heads are often equipped
with a rotatable circular saw blade which depends from a frame
installed at the front end of the tractor vehicle and which is
movable relative thereto due to a boom and arm assembly holding
the blade. Thus, by selectively moving the blade transversely
across the brush, debrushing of the terrain can be accomplished.
Such a brush cutter is shown in US patent No.
4,769,977 issued in 1988 to D.E. Milbourn. The brush cutter
workhead is installed at the frontward free end of an arm
pivotally hinged upon a boom, the latter being hingedly secured
to the tractor vehicle. Hydraulic cylinders control the
movement and position of the workhead at all times. The
workhead comprises inter alia a circular saw blade, the rotating
axis of which can be oriented in a rather wide range of angles
to allow horizontal, vertical or inclined cutting paths through
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the brush. However, this workhead cannot be moved sideways
relative to the tractor vehicle. Moreover, the operator has to
continuously move the workhead to compensate for uneven ground
surfaces when debrushing larger areas, to prevent the saw blade
from being damaged by engaging the earth, rocks or other natural
ground materials with its cutting edge. Although the shroud
provided around the blade has walls which project downwardly
under the saw blade level, these thin walls are likely to cut
through the ground under the weight of the workhead and the
force applied thereon by the hydraulic system if forced against
the ground, thus effectively allowing the saw blade to reach the
ground level and be damaged during use.
This last disadvantage has been partly solved in US
patent No. 4,468,917 issued in 1984 to P.-G. Mellgren. The
brush cleaning apparatus shown in this patent has a frontwardly
projecting workhead equipped with a rotatable circular saw
blade, supported at the frontward free end of a work arm. The
debrushing device of Mellgren also comprises a very large frame
installed over and around the tractor vehicle, and pivoted at
the approximate center of gravity thereof for vertical
displacement of the saw blade. A rounded skid hub downwardly
depends under the saw blade axis, to prevent accidental ground
engagement of the blade by a sliding engagement of the hub on
the ground surface during the tractor vehicle course. This is
true for an even flat ground surface.
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However, due to the fact that the rounded semi-
spherical hub has a single contact point on the ground, if the
ground under the blade becomes suddenly uneven or inclined, the
blade may be allowed to accidentally engage the ground and
damage itself. Indeed, the single ground-contact point hub does
not compensate ground sloping, but only height differences of
the ground under the blade, upon sliding displacement of the hub
over ground.
The Mellgren patent further provides horizontal pivot
means linking the work arm assembly to the tractor vehicle, to
allow horizontal pivotal displacement of the workhead, so as to
confer a moderately wide access range to the saw blade. This is
an improvement, when compared to the previously mentioned
Milbourn patent.
The Mellgren patent discloses a single saw blade, as
with the Milbourn patent.
Canadian patent No. 1,135,599 issued in 1982 to J.
Denis shows a pair of circular saw blades installed in side-by-
side configuration, and a cover for preventing high velocity
airborne projectiles issuing from the blades to endanger the
immediate environment around the rotating blades. The two saw
blades rotate in opposite directions, so as to draw the brush
between them and then accomplish a shearing effect thereon,
combined with the cutting properties of each blade. The blades
rotational axes are slightly longitudinally offset relative to
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.~
the direction of travel of the vehicle, so as to allow them to
be slightly inwardly offset towards one another. A radial play
has to exist between the two coplanar blades, to prevent them
from highly undesirable mutual contact during use, and the
longitudinal and inward offsets allow the blades to prevent a
brush plant or tree from being engaged, along a line parallel to
the direction of travel, between the two blades and remain at
least partly uncut, due to this play. However, this offset of
the blades may result in an unstable engagement of the blades
upon larger trees, due to the unequal engagement of the two
blades on the tree.
The Denis patent moreover requires the controller to
adjust the vertical height of the saw blades relative to the
ground continuously, to prevent ground engagement thereof, as
with the Milbourn patent.
OBJ~CTS OF T~ INV~NTION
It is therefore the gist of this invention to provide
a brush felling head that allows debrushing with suitable
cutting means, while concurrently self-adjusting the height of
the cutting means relative to the ground without the
intervention of the tractor vehicle driver.
Another object of the present invention is to provide
brush converging means for biasing the brush towards the cutting
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means.
It is another object of this invention that the
cutting means be a pair of overlapping discoid saw blades.
SUMMARY OF T~ INV~TION
The present invention relates to a brush felling head
for tractor vehicles.
More particularly, the present invention relates to a
felling head for debrushing brush covered terrain, destined to
be operatively installed at the front end of a tractor vehicle,
comprising:
a) a rigid workhead frame defining a front end and a rear
end;
b) hinge means for pivotally linking said workhead frame
to the tractor vehicle and for allowing at least pivotal
displacement about a horizontal axis and a linear vertical
displacement of said workhead frame relative to the tractor
vehicle;
c) a cutting member defining a flat lower surface and
being installed on said workhead frame front end, said cutting
member lower surface being destined to clear ground level and to
be substantially parallel thereto in an operative debrushing
position;
d) at least two laterally spaced elongated ground engaging
members, fixedly and integrally anchored to said workhead frame,
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located vertically beneath the plane of said flat cutting member
lower surface and being parallel thereto; and
e) power means, for rotatingly powering at least said
cutting member;
s wherein in said operative debrushing position, said ground
engaging members continuously engage the ground under the bias
of the load of said workhead frame during forward motion of said
tractor vehicle, to maintain said cutting member flat lower
surface substantially parallel to the ground and to maintain
automatic ground clearance thereof.
Preferably, the brush felling head further comprises
hydraulic means acting on said hinge means and on said workhead
frame for selectively and remotely controlling the vertical
position and the orientation around a horizontal axis of said
workhead frame relative to the tractor vehicle, and further for
dampening vertical movements of said workhead frame when said
ground engaging members temporarily release ground under major
ground surface variations.
Preferably, said cutting member comprises a lower and
an upper discoid saw blades rotatably fixed to said workhead
frame so as to be rotatable in opposite directions, with said
lower blade being slightly vertically downwardly offset relative
to said upper blade and constituting said cutting member flat
lower surface, said lower and upper blades having vertically
partly overlapping rotational cutting paths.
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Preferably, each said discoid saw blade comprises a
lower and an upper adjacent, axially aligned, overlying,
distinct and integrally fixed discs having a common outer
periphery, said discs being provided with a number of equally
peripherally spaced, fixedly attached though removable teeth
radially projecting beyond said outer periphery and nested
alternately under and over said blade in openings made in the
corresponding said lower or upper disc.
Preferably, the brush felling head further comprises
brush converging means integrally installed on said workhead
frame and projecting ahead of said front end in a divergent
fashion, for biasing the brush in a convergent fashion towards
said pair of saw blades.
Preferably, said brush converging means comprises a
pair of rigid arms frontwardly projecting ahead of said workhead
frame front end in a divergent fashion.
Preferably, said hinge means comprises a horizontal
pivot member for further selectively allowing sideward pivotal
displacement of said workhead frame.
Preferably, said ground engaging means is a pair of
flat, elongated, laterally spaced-apart skates integrally
installed on said workhead frame near said cutting members.
Preferably, said hinge means comprises at least one
parallelogram including four hinged, rigid bars, said hydraulic
means acting on said at least one parallelogram and on said
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workhead frame for controlling the position of the latter.
The present invention also relates to a felling head
for debrushing brush covered terrain, destined to be operatively
installed at the front end of a tractor vehicle, comprising:
a) a rigid workhead frame defining a front end and a rear
end;
b) hinge means comprising a pair of parallel
parallelograms forced into common pivotal movements, each said
parallelogram having four rigid bars hingedly attached so as to
form a said parallelogram, said hinge means being destined to
pivotally link said workhead frame to the tractor vehicle and to
allow pivotal displacement about a horizontal axis and a linear
vertical displacement of said workhead frame relative to the
tractor vehicle;
c) a lower and an upper discoid saw blades rotatably fixed
to said workhead frame so as to be rotatable in opposite
directions, with said lower blade being slightly vertically
downwardly offset relative to said upper blade, said lower and
upper blades having vertically partly overlying rotational
cutting paths, said lower saw blade being destined to be located
slightly over ground and substantially parallel thereto in an
operative debrushing position;
d) a pair of flat, elongated, laterally spaced-apart
skates integrally and fixedly installed on said workhead frame
near said saw blades, being parallel thereto and at least
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slightly under the level thereof;
e) a pair of hydraulic cylinders acting on said
parallelograms and on said workhead frame for selectively and
remotely controlling the vertical position and the orientation
around a horizontal axis of said workhead frame relative to the
tractor vehicle, and further for dampening the movements of said
workhead frame when severe ground level gradients are
encountered; and
f) power means, for powering said saw blades into rotation
and for powering said hydraulic cylinders;
wherein in said operative debrushing position, said skates
continuously engage the ground under the bias of the load of
said workhead frame during forward motion of said tractor
vehicle, to maintain said lower and upper blades substantially
parallel to the ground and to maintain automatic ground
clearance thereof.
The invention further relates to a felling head
assembly for attachment to the chassis of a motor vehicle ahead
thereof, the felling head assembly comprising:
a) an open rigid main frame;
b) a pair of first and second saw mounts, rotatably
mounted to said main frame parallel to one another and in
laterally spaced fashion, each saw mount including an elongated
upright rotatable shaft, a housing for enclosing at least part
of said shaft, and a rotatable cutting blade transversely
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mounted integrally to a bottom end of each said shaft and
adapted to cut about a horizontal plane, with each of said
cutting blades defining a peripheral cutting edge margin;
c) first power means, for power rotating said first and
second rotatable shafts in counterrotation relative to one
another;
d) a pair of fore and aft extending longitudinal skate
members, mounted on laterally opposite sections of the bottom
face of said main frame and located in radially outwardly spaced
fashion from the corresponding said counterrotating blades, said
skate members extending within a plane parallel to and being
downwardly offset from said saw blades so that a ground
clearance is positively maintained between said saw blades
including said peripheral cutting edge margins thereof and the
underlying ground level, for preventing blade damage as well as
for providing optimum brush stumps felling height;
e) attachment means, for releasable coupling of said
felling head to the motor vehicle, and including a parallelogram
linkage, hingedly mounted at its front end to said felling head
main frame for both up and down motion and concurrent fore and
aft motion of said felling head, and a hitch coupling, for
pivotally mounting the rear end of said parallelogram linkage to
a hitch anchor member integral to the motor vehicle chassis for
lateral shifting motion of said felling head sidewisely of the
motor vehicle; and
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f) second power means, including integral dampening means
and cooperating with said parallelogram linkage to maintain said
saw blades within a selected planar cutting orientation relative
to ground; said second power means further enabling power fore
and aft tilting, power lifting, power lowering, and lateral
power tilting of said felling head main frame and associated
cutting blades relative to the motor vehicle, said second power
means further providing dampening effect on the swinging motions
of said felling head responsively to ground level irregularities
upon forward displacement of the motor vehicle.
D~.sC~TPTTON OF T~ PRAWTNGS
In the annexed drawings:
Figure 1 is a side elevation of the felling head of
the invention, with attachment coupling operatively installed on
the front portion of a tractor vehicle shown in phantom lines,
resting on flat even ground;
Figure 2 is a front elevation of the felling head and
tractor of figure 1, the tractor being again showed in phantom
lines;
Figure 3 is a top plan view of the felling head of the
invention, suggesting in phantom lines the frontward end of the
tractor vehicle ceiling, and showing the two circular blades
thereof;
Figure 4 is a side elevation of the felling head of
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the invention, with the workhead frame being power displaced to
a raised position relative to the ground as a result from a
linear, non-pivotal vertical displacement;
Figures 5 to 7 are side elevations showing the felling
head in various operative ground-engaging position, over
different uneven or inclined ground conditions, with
corresponding vertical linear and/or pivotal displacement of the
workhead frame, so as to suggest the considerable
manoeuvrability thereof;
Figure 8 is a top plan view of the felling head,
installed on the front portion of a tractor vehicle illustrated
in phantom lines and sidewardly pivoted relative to the
frontward direction of travel of the tractor vehicle, and
further suggesting an alternate opposite sideward pivoted
position of the felling head in phantom lines, to show the wide
range of horizontal pivotal displacement of the felling head
relative to the tractor vehicle vertical attachment coupling
axle;
Figure 9 is an exploded perspective view, at an
enlarged scale, of a preferred embodiment of saw blade member of
the invention; and
Figure 10 is a top plan view of the pair of associated
saw blade members at an enlarged scale, in operative position,
suggesting their partly overlying rotational directions.
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..
D~TAITl~n D~.sCRIPTION OF T~ P~ RRED EMBODIM~NTS
Figures 1 to 3 show a felling head 20 according to a
preferred embodiment of the invention, for debrushing a terrain.
As suggested in the drawings, felling head 20 is destined to be
operatively installed at the front end of a tractor vehicle V,
as known in the art.
Felling head 20 comprises a rigid workhead frame 22
defining a front end 22a and a rear end 22b, the latter being
pivotally linked to the tractor vehicle V front end through the
instrumentality of hinge means in the form of an attachment
coupling 24, in a manner which will be described hereinafter.
Workhead frame 22 comprises a number of rigidly linked
truss beams 26a to 26n. As shown in the drawings, three
downwardly divergent top truss beams 26a, 26b, 26c form a
pyramid-like apex at 28. The lower extremities of beams 26a,
26b are linked at the workhead frame front end 22a to downwardly
elbowed side truss beams 26d, 26e, respectively. The latter,
together with top beam 26c, are rearwardly oriented and all
three are attached to an underlying horizontal plate 26f, from
which frontwardly project two spaced-apart horizontal side beams
26g, 26h. Downwardly and outwardly inclined lateral beams 26i,
26j originate at the forward extremity of beams 26g, 26h and are
reinforced by reinforcement beams 26k, 261 and by upwardly
oriented short beams 26m, 26n. A pair of parallel, spaced-
apart, downwardly extending deflector sheet plates 27, 27 depend
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from side beams 26g, 26h and are as long as the latter. In
figure 1, only the left-hand side deflector plate 27 is visible,
since the right-hand side deflector plate is hidden behind the
latter.
Felling head 20 further comprises cutting members 30
(which will be further described hereinafter) operatively
attached to workhead frame 22 and installed in an opening
located centrally of said workhead frame 22, between lateral
beams 26i, 26j; and also comprises elongated ground-engaging
members in the form of a pair of elongated skates 32, 34 fixedly
installed at the lower end of lateral beams 26i, 26j.
The particular configuration of workhead frame 22 is
given as a preferred embodiment thereof, though it is understood
that the invention is not limited thereto. Indeed, there are
only a few essential features that workhead frame 22 must
comprise, as follows:
a) it must have a very good overall rigidity, to prevent
it from being bent or damaged during use, considering the
important stresses which will be transmitted thereto;
b) it must have an open area at its lower central portion
to receive the cutting members 30 therein; and
c) it must have a pair of beams 26i, 26j that downwardly
extend under cutting members 30 to support the skates 32, 34.
The configuration of the workhead frame is thus shown
as being one fonctional embodiment thereof, though it is
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understood that other suitable configurations or truss beam
arrangements would also be proper.
Figures 2, 3 and lo show that cutting members 30
comprise a lower and an upper discoid saw blades 36, 38
rotatably mounted to workhead frame 22 spacedly parallel to
ground between lateral beams 26i, 26j by means of vertical
rotors 40, 42, with lower blade 36 being slightly vertically
downwardly offset relative to upper blade 38.
Figure 9 illustrates lower saw blade 36, though it is
understood that upper saw blade 38 is identical thereto. Blade
36 comprises a lower and an upper adjacent, axially aligned,
overlying, distinct and integrally fixed discs 44, 46 having an
equal diameter and a common outer periphery. Discs 44, 46 are
preferably welded to one another, and have welding holes 47a,
47b for providing welding edges at radially intermediate
locations on the body of blade 36. Holes 47a are located on
lower disc 44 and do not register with the holes 47b located on
upper disc 46, so as to form access ports through which welding
of the two discs can be accomplished. The pair of discs 44, 46
is provided with a number, e.g. four as shown in the drawings,
of equally peripherally spaced, fixedly attached though
removable quadrangular elongated teeth 48. Teeth 48 radially
project beyond said outer periphery and are nested alternately
under and over blade 36 in complementary quandrangular notches
50 made in the corresponding lower or upper disc 44, 46. That
16
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is to say, lower disc 44 has a pair of notches 50, 50,
peripherally spaced by a 180~ angle, which are each engaged by a
saw tooth 48, each tooth 48 being sized to conformingly and
nestingly fit into its corresponding notch 50 and fixedly rest
5 against upper disc 46 therein by means of a bolt (not shown)
engaging axially aligned bores 52, 54 in upper disc 46 and tooth
48, respectively. Upper disc 46 also has a pair of notches 50,
50 peripherally spaced by a 180~ angle which are each engaged by
a saw tooth 48, each tooth 48 being sized to conformingly and
nestingly fit into its corresponding notch 50 and fixedly rest
against lower disc 44 therein by means of a bolt (not shown)
engaging axially aligned bores 56, 54 in lower disc 44 and tooth
48, respectively, with teeth 48 nested in upper disc 46 being
positioned at a 90~ angle relative to the teeth 48 nested in
15 lower disc 44. The fact that teeth 48 are removable facilitates
replacement thereof when they become worn or damaged during use.
Also, as best shown in figure 9, a pair of half-moon
shaped ears 57 are located on the opposite side edges of each
notch 50 and inwardly project therein, to conformingly engage
20 complementary half-moon grooves 58 located on the teeth 48. The
mating ears 57 and grooves 58 engagement helps prevent
accidental undesirable radial disengagement of teeth 48 from
blade 36 under load.
It can further be seen in figures 9 and 10 that each
25 notches 50 has at its inner corners small rounded grooves 60,
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62, that help prevent structural integrity failure of the discs
44, 46 under load stress concentration at these particular
stress concentration focal points.
Also, as shown in figure 10, the quadrangular teeth 48
are preferably not rectangular but rather have the shape of a
parallelogram, and define a leading cutting edge 48a which is
aligned with the diameter of the corresponding blade 36, 38.
This confers a greater resistance to the blade assembly 36, 38,
due to a partial distribution of the stress longitudinally in
teeth 48, instead of solely transversely as would be the case
were the teeth 48 to be rectangular.
Each blade 36, 38 is provided with an axial through-
bore 64, 66 which is destined to be engaged by rotor 40, 42,
respectively, for driving blades 36, 38 into rotation.
The cutting members 30 could be different from a pair
of discoid saw blades 36, 38 as illustrated. For example, a
single saw blade could be used instead of a pair of partly
overlying saw blades, though it is understood that the latter is
the preferred embodiment for the present invention and brings
about the best results in debrushing. Other suitable cutting
members could also be used.
In any event, cutting means 30 defines a lower flat
surface that is destined to accomplish debrushing parallel to
the ground and with a minimum ground clearance, for reasons that
will be explained hereinafter. In the case of the preferred
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embodiment of the invention, this lower flat surface is defined
by the lower blade 36. If there was to have only a single saw
blade, then this blade would constitute the lower flat surface
of cutting members 30.
As explained hereinabove, lower and upper blades 36,
38 are edgewisely overlapping, so as to have overlapping
rotational cutting paths, slightly vertically spaced from one
another. Furthermore, it can be seen in figure 10 that the
angle of incidence of the teeth 48 is oriented in opposite
rotational directions. Consequently, blades 36, 38 are destined
to rotate in opposite directions, as suggested by arrows A1 and
A2 in figure 10, to trap the brush between the two blades and
thus combine a shearing effect of the two adjacent blades on the
brush elements, to the distinct cutting effect of each blade 36,
38.
Figures 1 and 3 show that attachment coupling 24
comprises an anchoring member 68 fixedly attached to a chassis
extension Va at the front end of the tractor vehicle V.
Anchoring member 68 has a pair of vertically spaced-apart
horizontal plates 70, 72 which hold a frontmost vertical pivot
axle 74, the latter being power rotated for rotation in either
clockwise or counterclockwise rotation by any suitable power
means. For example, this power means could include a chain
assembly 73, extending generally horizontally and meshing with
the lower section of vertical pivot axle 74 and with an idle
19
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vertical stud 71 located between front axle 74 and rear
attachment bracket Va. A horizontal hydrualic ram 75 extending
orthogonally to axle 74 would power rotate axle 74 by
conventional coupling with the gear chain 73, namely by
anchoring its cylinder part to frame 70 and its piston end part
to the idle stud 71, so that reciprocating horizontal motion of
ram 75 will translate into rotational motion of the vertical
axle 74.
Attachment coupling 24 further comprises a pair of
rigid hinged truss parallelograms 76, 78 which are parallel to
one another. Each hinged parallelogram, e.g. parallelogram 78
in figure 1, has a first plate 80 which is integrally carried by
and horizontally pivots around pivot axle 74, a pair of parallel
elongated laterally spaced bars 82, 84 hingedly and spacedly
attached thereto, and a short frontmost transverse link bar 86
opposite plate 80 and hingedly linking the front ends of lateral
bars 82 and 84. The pivot pin 88 joining the pairs of lower
bars 82 and transverse bars 86 also pivotally mounts workhead
frame horizontal plate 26f. A pivot pin 90 joining the pairs of
upper bars 84 and transverse bars 86 also carries a ram 92. A
third and a fourth pivot pins 89, 91 are located at the junction
of lower bars 82 and plate 80, and at the junction of upper bars
84 and plate 80, respectively.
Pivots 88, 89, 90, 91 (figures 1 and 3) link the
corresponding bars of rigid parallelograms 76, 78 in a common
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pivotal movement. That is to say, each pivot stud 88, 89, 90,
91 extends transversely between the two parallelograms 76, 78,
so that each corresponding corner thereof pivots around a same
one pivot 88, 89, 90 or 91, but in any event, both
parallelograms 76, 78 always move together and have a same
position at any given time. The reason for the existence of two
parallelograms 76, 78 is to improve the structural rigidity of
attachment coupling 24.
The felling head 20 further comprises a front and a
rear hydraulic cylinders 92, 94 centrally and longitudinally
disposed. Rear cylinder 94 is pivotally installed at its rear
extremity on pivot axle 91 and at its front extremity on pivot
axle 88, while front cylinder 92 is pivotally installed at its
rear extremity on pivot axle 90 and at its front extremity on a
pivot axle 96 mounted on truss beam 26c, near apex 28.
Both hydraulic cylinders 92, 94, together with the saw
blades rotors 40, 42 and the horizontal cylinder 75, are all
remotely selectively controlled from a control box inside the
driver's cab of the tractor vehicle V.
The elongated skates 32, 34 have a flat, horizontal
main body destined to flatly slide upon the ground surface, and
have end tips that are curved or bent upwards, to help skates
32, 34, to slide over uneven ground surfaces.
Figures 2 and 3 show that felling head 20 further
comprises ground-spaced brush converging means in the form of a
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pair of rigid arms 98, 100 frontwardly projecting ahead of the
upper portion of workhead frame front end 22a in a divergent
fashion. Arms 98, 100 are integrally installed on workhead
frame 22 at the junction of upper beams 26a, 26b with elbowed
arms 26d, 26e, respectively, and are horizontally disposed, to
effectively bias the brush elements towards the central part of
rotors 40, 42, into the overlying most effective portion of
blades 36, 38.
The brush converging means preferably further comprise
ribbed sleeve members constituting the outer surface of rotors
40, 42, as shown in the drawings: the rotor sleeve members 40,
42 have several integral, peripherally spaced-apart, vertical
ribs 40a, 42a (figures 1 and 2) that will rotate simultaneously
with counter rotating rotors 40, 42 to also effectively bias the
brush elements towards the central portion of rotors 40, 42, and
to shear with the cutting edges of ribs 40a, 42a the brush at a
height intermediate cutting members 30 and arms 98, 100.
In use, as shown in figures 1 to 3, the felling head
22 is destined to be attached at the front end of a tractor
vehicle V, by means of anchoring member 68, and is destined to
rest on the ground G in operative position. Felling head 20 is
correctly sized to allow skates 32 to be located under the
cutting means lower surface, i.e. lateral beams 26i, 26j
downwardly extend beyond the level of the cutting means lower
blade 36, where skates 32, 34 are located. Felling head 32
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~.
engages the ground with skates 32, 34, and blades 36, 38 may
thus be kept positioned spacedly over ground, this ground
clearance being due to their rigid link with skates 32, 34 by
means of workhead frame 22. The ground clearance of blades 36,
38 is preferably between 5 and 7,5 centimeters, although any
suitable desired ground clearance may be chosen when assembling
the felling head 20. In this respect, it is envisioned that
there be provided means for adjusting in situ the ground
clearance of blades 36, 38 relative to the ground, e.g. by
including telescopic lateral beams 26i, 26j that support skates
32, 34.
When the tractor vehicle V advances to accomplish its
debrushing operation, the incoming upstanding brush elements
(small trees, plants, etc...) will converge towards the discoid
saw blades 36, 38 under the bias of convergent arms 98, 100 and
of the ribbed rotor sleeves 40, 42, to be felled at a section
thereof just above ground level. As shown in figure 4, the
vehicle operator may decide to lift the felling head 22 spacedly
over ground, in a raised position, either to move at greater
speed without debrushing a terrain, or to temporarily accomplish
debrushing at higher above-ground level. Usually, however, the
felling head 22 will be used with its skates 32, 34 engaging the
ground during debrushing operations; this last position is
called the "felling head operative debrushing position".
Figures 4 to 7 suggest the high versatility of the
CA 022l0l40 l997-07-lO
invention, characterized by the combination of the elongated
ground-engaging skates 32, 34 with the truss parallelograms 76,
78. The hinged though rigid parallelograms 76, 78 allow:
a) a pivotal displacement of workhead frame 22 about a
horizontal axis (figures 6 and 7), i.e. in a vertical plane
parallel to the direction of travel of the tractor vehicle when
the latter is aligned with the workhead frame 22; this pivotal
displacement can be mainly controlled by retracting/extracting
the piston rod of front cylinder 92; and
b) a linear, non-pivotal vertical displacement of workhead
frame 22 relative to the tractor vehicle (figures 4 and 5); this
vertical linear displacement can be mainly controlled by
retracting/extracting the piston rod of rear cylinder 94.
Furthermore, figure 8 shows that the vertical pivot
axle 74 allows the felling head 20 to pivot within a horizontal
plane from a first left-hand side limit position at 20 (shown in
full lines in figure 8) to a second right-hand side limit
position at 20' (shown in phantom lines in figure 8). The
maximum angle ~ between these two limit positions is
approximately 135~, though it is understood that with only minor
modifications to the present felling head configuration, it
could be possible to allow pivotal movement of the felling head
over a much wider range, e.g. equal to or even more than 180~.
Thus, it can be seen in figures 4 to 8 that the
25 felling head according to the present invention can be
24
CA 02210140 1997-07-10
controlled so as to be moved in many different directions. As
seen in figure 5, when the ground G is lower under felling head
20 than under the tractor vehicle, felling head 20 can be
positioned vertically lower than under flat ground conditions to
engage the ground and continue its debrushing operation
undisturbed. In figures 6 and 7, it is shown that although
there is a sudden angular difference between the ground under
the felling head 20 and the tractor vehicle, the saw blades will
be allowed to remain parallel to the ground directly under them
and thus continue their debrushing operation. Indeed, the
elongated skates 32, 34, having bent extremities, can gradually
slidingly engage the sloping ground surface, concurrently
biasing the integrally linked workhead 22 into a corresponding
pivotal movement. The skates will be forced towards a flat
engagement with the ground under the load of workhead frame 22,
and thus the parallel blades 36, 38 will also be biased
automatically towards a position parallel to the ground, without
any intervention from the tractor vehicle driver.
Thus, it is understood that the felling head 20 of the
present invention allows a much greater freedom of movement than
the prior art devices. Indeed, it is rather free to move in
independant directions relative to the tractor vehicle to which
it is attached. This freedom of movement is acquired through
the instrumentality of the parallelogram hinge means 24,
together with the hydraulic attachment pivot assembly 74, the
CA 02210140 1997-07-10
components of the latter being already known in the art.
Workhead frame 22 may accomplish its linear vertical
displacement and its vertical pivotal movement either without
any intervention of the vehicle driver, under the bias of its
own weight upon skates 32, 34 engaging an uneven or sloping
ground surface, or under the selected intervention of the
driver, who can activate one or both hydraulic cylinders to
correspondingly move the workhead frame 22. The horizontal
pivotal displacement, however, can only be accomplished through
a selected intervention of the driver, and cannot be left to
move freely under the ground surface impulses thereon, for in
this latter case it would be difficult or even impossible to
controle the direction of the workhead frame 22.
It is compulsory that the ground-engaging skates be
elongated to confer a linear ground engagement to workhead frame
22, thus to ensure that the workhead frame 22 will tilt upwardly
upon the skates engaging an inclined terrain. This is a major
advantage over the prior art Mellgren patent cited in the
Background of the Invention section of this disclosure, in which
the semi-spherical skid hub confered a narrow, almost punctual,
ground engagement to the workhead frame, thus only allowing the
workhead frame to tilt or pivot under engagement of inclined or
uneven terrain around the rearwardly positioned pivotal axis.
Due to the length of the pivotal lever in the Mellgren patent,
this pivotal movement is substantially equal to a linear
26
CA 02210140 1997-07-10
vertical displacement, and no effective tilting of the skid hub
is accomplished to compensate for uneven ground surfaces.
It is envisioned that other ground engaging means be
used instead of skates. For example, each skate could be
replaced by at least one pair of wheels aligned towards the
front end of the workhead frame, which would ensure a linear
contact of the ground engaging means with the ground at all
times, to tilt the workhead frame accordingly under displacement
over uneven or inclined terrain. Also, caterpilar endless chain
bands could be used. In any event, the ground-engaging means
must be elongated, for reasons explained hereinabove.
The hydraulic cylinders 92, 94 have an additional
advantage, in that they dampen the movements of workhead frame
22 during temporary upward swinging motions responsive to ground
surface irregularities.
Also, another advantage of the double blade
configuration of the saw blades is that the brush which has been
cut down will mostly accumulate in a furrow-like heap centrally
between the tree rows, due to the centrally convergent counter
rotational directions of two saw blades. This will help to
clear the portion of the rows close to the trees, where the
workmen will have to manually finish the debrushing job between
the trees of a same row. Thus, the cut-down brush will be less
likely to be in their way, due to its mostly central location.
Also, the purpose of the pair of rearwardly projecting parallel
CA 02210140 1997-07-10
deflector plates 27, 27 located behind rotors 40, 42 is to
deflect most of the brush thrust outwardly by the high-velocity
counter rotating blades 36, 38 into the furrow-like heap.
It is understood that any modifications which do not
deviate from the scope of the present invention are considered
to be included therein. For example, the brush converging means
could also be full light-weight panels or tubular arcuate arms.
Also, it could be possible to manufacture the felling
head of the invention without any of the two hydraulic
cylinders, though it would then become impossible to remotely
and selectively raise the workhead frame above ground unless
other means are incorporated on the felling head therefor.
It is understood that throughout the present document,
when reference to horizontal or vertical directions is made,
this is done in view of the tractor vehicle and felling head
being aligned with one another and positioned over straight,
flat, even, horizontal ground. Of course, it is possible and
likely that the tractor vehicle and felling head will eventually
engage uneven or non horizontal ground: appropriate directions
would then obviously have to be suitably substituted.
