Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TREE DELIMBING DEVICE
FIELD OF THE INVENTION
The present invention relates to a device for delimbing felled trees and, more
particularly, to a device having a device including two independently movable
pairs
of limb-stripping levers which .are pivotable for engaging the bole of a tree
being
drawn longitudinally through the device.
BACKG'~ROUND OF THE INVENTION
It is known to remove Limbs from trees by encircling the tree trunk or bole
with curved cutting blades and either moving the curved blades along the
length of the
tree, or pulling the tree longitudinally through the curved blades. My prior
U.~.
Patent Nos. 4,749,012, 4,899,794., and 5,515,895, describe self aligning limb-
stripping devices for
delimbing trees in which curved cutting and limb stripping levers having
cutting
blades are carried by a rectangular support frame supported for pivotal
movement in
both vertical and horizontal planes so that the limb stripping blades are
automatically
maintained in proper alignment with respect to the longitudinal axis of the
tree as the
tree is drawn longitudinally th~raugh the device in a generally horizontal
orientation.
A pair of curved limb stripping levers having curved cutting blades are spaced
about
the longitudinal axis of the device and are pivotable toward and away from
each other
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for enya;ing and disengaging a tree bole. The limb stripping levers and blades
are'
positioned and configured to substantially encircle a tree bole disposed in
the device,
except for the bottom portion of the tree bole for which a fixed bottom
cutting blade is
provided for removing limbs thert:liom.
The delim'bing devices disclosed in the aforementioned patents are relatively
inexpensive to manufacture and maintain, and are highly effective and
efficient for
removing limbs from trees having, a bole diameter of up to about 14 inches.
However,
in certain applications, trees having bole diameters of up to about 24 inches
must be
delimbed. For these larger trees, the curved limb stripping levers and cutxing
blades
1o are not capable of encircling the uppermost portions of the tree bole and,
consequently, limbs on these uppermost portions are not removed by the device.
To handle such larger trees effectively and efficiently, I have developed an
improved delimbing device described in my U.S. Patent No. 5,887,635.
The delimbing apparatus described in the '635 patent employs two pairs of
15 curved limb-stripping levers and a fixed bottom cutting blade for removing
limbs
from a lower portion of the trunk. The two pairs of limb-stripping levers work
in
tandem to strip limbs from the top and upper side portions and from the upper
side:
portions and lower side portions of the tree, and are pivotable to accommodate
a wide
2 0 range of tree diameters. The device is highly effective at stripping limbs
from trees
having trunk diameters of from about 4 inches up to at least about 26 inches.
It has
been found, however, that particularly when the bottom cutting blade
encounters a
limb that joins the trunk at a knot having a large diameter, the bottom
cutting blade
tends to cut the limb off at the base of the knot closest to the trunk. This
cutting path
25 through the limb can be substantially longer than the axial distance
through the limb a
short distance outward of the trunk. Consequently, the bottom cutting blade
must cut
through a greater limb thickness than it would have to if it were able to cut
the limb a
short distance outward of the trunk. This effect is particularly
disadvantageous
because when the butt end of the tree is grasped in the grappler of a knuckle
boom
3 0 loader and placed into the device, the largest limbs of the tree tend to
cause the tree to
rotate so that the largest limbs are: at the bottom of the tree. Thus, the
largest cutting
distances tend to 'be experienced by the fixed bottom cutting blade. In some
cases,
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this can result in damage to the bottom cutting blade.
Furthermore, when a crooked tree is pulled through the limb-stripping device,
in some cases the bottom cutting blade can did into a crooked portion of the
trunk and
thus impede free movement of~the tree through the device. Crooked trees can
also
result in large forces being imposed on the bottom cutting blade, which can
damage
the blade.
SLi~lVi.rlRY OF THE INVENTION
The present invention overcomes the above-noted drawbacks associated with
my prior limb-stripping devices by providing a limb-stripping device having a
support frame which supports at least one pair of curved limb-
stripping levers that are pivotally supported for movement toward and away
from
each other, and a bottom cutting blade mounted to the support frame and
positioned to
remove limbs from a lower portion of a tree being pulled through the device,
the
bottom cutting blade being arranged to support at least a portion of the
weight of a
tree and being movably mounted to the support frame so as to move in response
to
forces imposed by a tree on the bottom cutting blade.
In accordance with one preferred embodiment of the invention, the bottom
cutting blade is rnounted so as to move downward in response to forces imposed
by a
2 0 tree generally downward on the bottom cutting blade. The bottom cutting
blade is
thus able to deflect downwardly so as to allow knots or other protruding
portions of a
tree to pass smoothly over the blade. Additionally, the movable cutting blade
is less
prone to being damaged by large farces imposed on the blade by large limbs
and~'or
crooked portions of a trunk, because the blade tends to yield or give way in
response
2 5 to the forces rather than digging in.
Preferably, the bottom cutting blade is biased toward an upper position by a
spring device. Various types of spring devices can be used, including a fluid-
operated
spring device such as a hydraulic cylinder.
The bottom cutting blade preferably includes a curved cutting blade affixed to
3 0 a blade plate, and the device preferably includes track members defining a
vertical
track within which the blade plate is slidably disposed such that the bottom
cutting
blade structure is vertically movable relative to the support frame.
Advantageously, a
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blocking member is attached to the blade plate below the curved cutting blade,
the
blocking member being configured to block passage of debris into a gap between
the
blade plate and a forward one of the track members.
In a preferred embodiment of the invention, the track members comprise a
forward plate and a rearward plate oriented generally vertically and spaced
apart
along the longitudinal axis of the limb-stripping device so as to define the
track within
which the blade plate slides. The blocking member is attached to the blade
plate
above an upper edge of the forward plate. Advantageously, the blocking member
comprises a rod affixed to and extending transversely along the blade plate
generally
l0 parallel to the curved cutting blade.
In accordance with another preferred embodiment of the invention, the bottom
cutting blade structure includes a curved primary cutting blade attached to an
upper
end of the blade plate, and a secondary cutting blade attached to the blade
plate and
spaced below the primary cutting blade. The secondary cutting blade has a
forward
cutting edge preferably located rearward of a forward cutting edge of the
primary
cutting blade. The secondary cutting blade assists in turning cut portions of
a limb
downwardly away from the primary cutting blade and cutting those portions off
so
that pieces of the tree cut by the bottom cutting blade structure do not
interfere with
other structure of the limb-stripping device below the cutting blade.
2 o In some preferred embodiments of the invention, the limb-stripping device
includes at least one roller rotatably mounted in the support frame downstream
of the
bottom cutting blade structure to facilitate sliding a tree through the device
supported
in part by the roller. The roller preferably is mounted such that an uppermost
surface
of the roller on which the tree rests is at the same vertical level as the
bottom cutting
2 5 blade structure when the bottom cutting blade structure is in the upper
position. Still
more preferably, the device includes a pair of rollers rotatably mounted in
the support
frame to facilitate sliding a tree through the device.
In accordance with an alternative embodiment of the invention, the bottom
cutting blade is movable forward and rearward rather than up and down. More
3 0 specifically, the blade is mounted so as to be pivotable about an axis
that extends
transverse to the longitudinal axis of the device and is located vertically
lower than
the bottom cutting blade such that the bottom cutting blade is pivotable in
a.forward
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and rearward direction. The limb-stripping device in this embodiment further
includes a device operable to urge the bottom cutting blade forward against
rearward
forces imposed on the bottom cutting blade by a tree being pulled through the
device.
Advantageously, the device for urging the bottom cutting blade forward
comprises an
impact tool operable to periodically transmit impact forces in a forward
direction to
the bottom cutting blade structure. Thus, as the tree is drawn through the
device, the
tree.tends to pivot the bottom cutting blade in a rearward direction, but the
impact tool
continually impacts the bottom cutting blade structure in a forward direction
so as to
drive the bottom cutting blade forward through a limb being stripped from the
tree.
io
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages will become apparent from the following
description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a perspective view of the device supported on one end of a knuckle
15 boom loader and showing a tree trunk being pulled through the device by the
grapple
of the knuckle boom loader;
FIG. 2 is a perspective view of the device in isolation, showing the curved
limb-stripping levers in open positions in preparation for receiving the bole
of a tree;
FIG. 3 is a front elevational view of the device with the limb-stripping
levers
2 0 in the open positions;
FIG. 4 is a fragmentary top elevational view of the device, showing the
mounting of the limb-stripping levers on rotational drive tubes and support
shafts;
FIG. S is front elevational view of the device showing the limb-stripping
levers engaging a tree bole of a first larger diameter disposed in the
assembly, and
2 5 showing in phantom lines the limb-stripping levers engaging a tree bole of
a second
smaller diameter;
FIG. 6 is a front elevational view similar to FIG. 5, showing the limb-
stripping
levers engaging a tree bole of a predetermined maximum diameter, the first
(forward)
pair of levers engaging opposite side and lower portions of the tree bole and
the
3 0 second (rearward) pair of levers engaging opposite side and upper portions
of the tree
bole;
FIG. 7 is a cmss-sectional view taken on line 7-7 of FIG. 6, illustrating one
of
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the bevel plates for deflecting cut pieces outwardly and away from the cutting
blade;
FIG. 8 is a perspective view of yet another embodiment of the invention
having a movably mounted bottom cutting blade and a pair of rollers proximate
the
curved limb-stripping levers;
FIG. 9 is a perspective view of a partial assembly of the device of FIG. 8,
showing in greater detail the structure for movably mounting the bottom
cutting
blade;
FIG. 10 is a cross-sectional view taken on line 10-10 of FIG. 8, showing a
tree
positioned in the device in preparation for being pulled through the device;
FIG. 11 is a cross-sectional view taken on line 11-11 of FIG. 10;
FIG. 12 is a cross-sectional view taken on line 12-12 of FIG. 10;
FIG. 13 is a sectioned side elevation of another preferred embodiment of a
bottom cutting blade in accordance with the present invention; and
FIG. 14 is a side elevation, partly in section, of yet another embodiment of
the
1 S present invention in which the bottom cutting blade is pivotable forward
and rearward
and is impacted by an impact tool in a forward direction so as to drive the
bottom
cutting blade through a limb.
DETAILED DESCRIPTION OF THE DRAWINGS
2 o With reference to FIG. 1, a limb-stripping device 10 in accordance with a
first
preferred embodiment of the invention is shown supported on an extension of a
knuckle boom loader 12. The knuckle boom loader 12 may be of any suitable type
and includes a lower frame 13 supporting a pivotal platform 14 on which is
mounted a
suitable operator enclosure 15 and a boom having crane arms 17, 18 supporting
a
2 5 grapple 16 on the free end thereof. The crane arms 17, 18 and the grapple
16 are
operated in conventional manner by means of hydraulic cylinders (not shown).
The knuckle boom loader 12 is typically used for picking up felled trees which
have already been delimbed either to cut them into shorter lengths and place
them on
a truck for transportation or to place them on a truck in their full lengths
without
3 o cutting them into shorter lengths. The trees are normally skidded or
dragged from the
forest and stacked adjacent the knuckle boom loader 12, after having had the
limbs
cut therefrom in the woods by a hand chain saw operation. However, by
providing
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the device 10 on the knuckle boom loader 12, this time-consuming hand chain
saw
operation is avoided. Instead, the felled trees can be stacked next to the
knuckle
boom loader 12 before having their limbs removed, and the knuckle boom loader
operator can carry out the delimbing operation in an efficient and economical
manner
by simply drawing a tree through the device 10 after the tree is lifted from a
stack of
felled trees to be loaded onto the truck. The delimbed tree can then either be
cut into
shorter lengths and loaded onto the truck, or loaded onto the truck without
further
cutting.
With reference to FIGS. 2-6, the device 10 is of the same type as described in
1 o my earlier U.S. Patent Nos. 4,749,012, 4,899,794, and 5,515,895, and
includes a
rectangular support frame having a rearwardly inclined front end wall 20,
opposite
inwardly inclined side walls 22 and 23, and a top plate 24. A front bearing
plate 26 is
affixed to the support frame and extends vertically upwardly therefrom
adjacent the
juncture between the front end wall 20 and the top plate 24. A left rear
bearing plate
28 is affixed to the support frame and extends vertically upwardly therefrom
adjacent
a rear edge of the left side wall 22, the left rear bearing plate 28 forming a
front wall
of a left-side enclosure 30 for housing a pair of actuators, as further
described below.
A right rear bearing plate 32 is affixed to the support frame and extends
vertically
upwardly therefrom adjacent a rear edge of the right side wall 23, the right
rear
2 0 bearing plate 32 forming a front wall of a right-side enclosure 34 for
housing a second
pair of actuators, as further described below.
A first pair of curved cutting and limb-stripping levers 36, 36' is supported
adjacent the front end wall 20 by a pair of horizontal longitudinally
extending support
shafts 38, 38' which are parallel to a longitudinal axis of the device
defining a feed
2 5 direction for a tree through the device. Left support shaft 38 has a front
end supported
in a bearing in front bearing plate 26 and a rear end supported in a bearing
in left rear
bearing plate 28. Right support shaft 38' has a front end supported in a
bearing in
front bearing plate 26 and a rear end supported in a bearing in right rear
bearing plate
32. Sleeved over the support shafts 38, 38' are left and right rotatable
support tubes
3 0 40 and 40', respectively, which are rotatable about the respective support
shafts 38,
38'. The curved limb-stripping levers 36, 36' are secured to the rotatable
support
tubes 40, 40', respectively, for rotation therewith. Thus, rotation of the
support tubes
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40, 40' in one direction or the other causes the limb-stripping levers 36, 36'
to be
rotated toward or away from each other, as can be seen by comparing FIG. 4
which
shows the levers in open positions in preparation for receiving a tree bole,
with FIGS.
and 6 which show the levers in various closed positions engaging tree boles of
5 various diameters.
The limb-stripping levers 36, 36' have respective curved cutting blades 42,
42' _
fixed to their inner curved surfaces and extending generally longitudinally
forward
thereof, and collectively define a tree-encircling cutting opening
therebetween for
longitudinal movement of a tree trunk in one direction through the cutting
opening, as
illustrated in FIG. 1. The limb-stripping levers 36, 36' and cutting blades
42, 42' are
positioned and configured to encircle opposite side and lower portions of a
tree bole
of a predetermined maximum diameter. Advantageously, the limb-stripping levers
36, 36' and cutting blades 42, 42' are positioned and configured for removing
limbs
from opposite side and lower portions of a tree bole having a diameter of up
to about
24 inches, as illustrated in FIG. 6 which depicts a tree bole of the
predetermined
maximum diameter disposed within the device. Additionally, a stationary lower
cutting blade 44 is affixed to the front bearing plate 26 for engaging a
bottom portion
of the tree for removing limbs therefrom which would otherwise not be removed
by
the limb-stripping levers 36, 36'.
2 o The device 10 includes a second pair of curved limb-stripping levers 46
and
46' supported downstream of the first pair of limb-stripping levers 36, 36'.
The
second limb-stripping levers 46, 46' are mounted on rotatable support tubes
48, 48',
respectively, each of which is supported by a pair of bearings. Left support
tube 48 is
supported at its rear end by a bearing 50 secured to a rear wall (not shown,
but
2 5 indicated by phantom line 51 in FIG. 4) of the left-side enclosure 30, and
is supported
partway along its length by a bearing 52 secured to the left rear bearing
plate 28. The
support tube 48 extends forwardly from the left rear bearing plate 28, and
limb-
stripping lever 46 is attached to this forwardly extending portion of support
tube 48.
Similarly, right support tube 48' is supported at its rear end by a bearing
50'
3 0 secured to a rear wall (not shown, but indicated by phantom line 51 in
FIG. 4) of the
right-side enclosure 34, and is supported partway along its length by a
bearing 52'
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secured to the right rear bearing plate 32. The support tube 48' extends
forwardly
from the right rear bearing plate 32, and limb-stripping lever 46' is attached
to this
forwardly extending portion of support tube 48'.
The second limb-stripping levers 46, 46' have respective curved cutting blades
54, 54' fixed to their inner curved surfaces and extending generally
longitudinally
forward thereof. The limb-stripping levers 46, 46' and cutting blades 54, 54'
are
positioned and configured to engage opposite side and upper portions of a tree
bole of
the predetermined maximum diameter, preferably about 24 inches as previously
noted, as illustrated in FIG. 6. To this end, the support tubes 48, 48' are
spaced
14 horizontally outward of and vertically above the support tubes 40, 40' of
the first pair
of limb-stripping levers 36, 36'. The second pair of limb-stripping levers 46,
46',
further define, together with the first pair of limb-stripping levers 36, 36',
a tree-
encircling opening for longitudinal movement of a tree trunk through the
device 10, as
illustrated in FIG. 1.
The limb-stripping levers 36, 36' and 46, 46' are opened and closed by a
plurality of hydraulic cylinders. With reference to FIGS. 3, 4, and 6, support
tubes
40, 40' each includes a pair of longitudinally spaced-apart depending crank
arms 56,
56', respectively, located between the left and right enclosures 30 and 34 and
beneath
a cover plate 58 which extends longitudinally through the device 10 and
shields the
2 0 support tubes 40, 40' from being contacted by the tree trunk as it is
pulled through the
device. The lower ends of the crank arms 56 are pivotally attached to the rod
ends of
a pair of hydraulic cylinders 58, 58'. The cylinder ends of hydraulic
cylinders 58, 58'
are pivotally attached via brackets 57, 5T to a pair of support brackets 76,
76' which
provide attachment points for supporting the device, as further described
below.
2 5 Retraction of the piston rods of hydraulic cylinders 58, 58' causes the
levers 36, 36' to
close toward each other and engage a tree positioned in the device. The
hydraulic
cylinders 58, 58' are each configured with two chambers separated from each
other by
a piston or ram attached to the piston rod. The chamber adjacent the rod end
is
coupled via a supply line (not shown) to a suitable supply of pressurized
hydraulic
3 o fluid, and the chamber adjacent the cylinder end is coupled via a return
line to an
accumulator (not shown) having a compressible gas spring. Opening a supply
valve
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(not shown), which may be located at the knuckle boom loader 12 for operation
by the
knuckle boom loader operator, causes hydraulic fluid to be supplied to the rod-
end
chambers of the hydraulic cylinders 58, 58' so that the piston rods are
retracted, thus
causing the first pair of levers 36, 36' to be closed. Hydraulic fluid in the
cylinder-
s end chambers of the hydraulic cylinders 58, 58' is forced by the retracting
pistons into
the accumulator, causing the gas spring to be compressed. Thus, upon closing
of the
supply valve, the pressure is relieved in the rod-end chambers, and the gas
spring
expands and causes fluid to be pumped into the cylinder-end chambers to re-
extend
the piston rods and thereby open the levers 36, 36'.
The device 10 includes means for insuring that the limb-stripping levers 36
and 36' open and close in synchronism with each other. Specifically, the
rotatable
support tubes 40, 40' have respective timing gears 72, 72' coaxially attached
adjacent
their downstream ends for rotation therewith. A pair of idler spur gears 74,
74' are
connected between the timing gears 72 and 72', the timing gear 72, idler spur
gear 74,
idler spur gear 74', and timing gear 72' thus forming a gear train which
prevents non
uniform inward and outward movement of the limb-stripping levers 36, 36'.
The second pair of levers 46, 46' are opened and closed by a second pair of
hydraulic cylinders 64, 64'. The cylinder ends of the hydraulic cylinders 64,
64' are
pivotally attached to a common bracket 63 attached to the support frame at the
2 o longitudinal centerline of the device and extend upwardly and outwardly
therefrom.
The rotatable support tubes 48, 48' which support the second pair of levers
have
depending crank arms 62, 62'. The rod ends of the hydraulic cylinders 64, 64'
are
pivotally attached to the crank arms 62, 62'. The hydraulic cylinders 64, 64'
are
coupled to the pressurized fluid supply and the accumulator in opposite
fashion from
2 5 the hydraulic cylinders 56, 56', such that operating the supply valve to
supply
additional hydraulic fluid to the hydraulic cylinders 64, 64' causes the
piston rods to
extend rather than retract. Extension of the piston rods of hydraulic
cylinders 64, 64'
causes the second pair of levers 46, 46' to close. The levers 46, 46' are
opened when
the supply valve is operated to shut off hydraulic pressure to the cylinders
64, 64', via
3 o action of the accumulator as previously described.
A flow control valve (not shown) controls the opening and closing speed of
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the second levers -t6, 46'. Pref~:rably, the second levers 46, 46' are closed
after the
first levers 36, 36' have closed, and are opened after the first levers 36,
36' have
opened. By closing first, the first levers 36, 36' align the device so that
its
longitudinal axis is along the longitudinal axis of the tree, as further
described below.
The device 10 incl~:~des features permitting the device to pivot in both the
vertical and horizontal planes so that it is self aligning with the tree
bole's longitudinal
axis. The features permitting vertical and horizontal pivoting are
substantially as
disclosed in my prior U.S. Patent No. 4,899,794. Thus, the left enclosure 30
includes a bracket 76
which supports an outwardly extending horizontal pivot pin 78, and likewise
the right
enclosure 34 includes a bracket 76' with an outwardly extending horizontal
pivot pin
78'. The pivot pins 78, 78" are supported in the upper ends of upstanding
vertical legs
80, 80', of a support yoke 82 which includes a horizontal medial portion in
the form
of a plate 84 extending horizontally beneath the rectangular support frame of
the
device. Thus, the rectangular support frame is cradled for swinging or pi
votal
movement in the vertical plane between the opposite vertical legs 80, 80' of
the
support yoke 82. It is preferred that the pivot pins 78, 78' be located
slightly rearward
of the center of gravity of the dlevice 10 so that the rectangular support
frame tilts
down at the front end when the. device is not in use.
2 0 The horizontal plate 84 is attached to an upper plate 86 of a slew or
swivel
ring, and the upper plate 86 is supported in the usual manner by ball bearings
on a
lower plate 87 of the slew or swivel ring. The lower plate 87 is fixed on a
base
support plate 88 which, in turn, may be fixed on an extension of a knuckle
boom
loader such as shown in FIG. l, or which, alternatively, may be fixed on a
trailer or
2 5 other transportable vehicle to permit the device 10 to be readily moved
from one site
to another. Thus, the plates 86, 87 of the slew or swivel ring provide a
pivotal
connection for movement of the rectangular support frame in a horizontal
plane.
In operation of the device, the operator of the knuckle boom loader 12 picks
up a tree to be delimbed via the; grapple 16, which engages the butt end
portion of the
3 0 tree bole. The :fluid supply valve is in the closed position so that the
hydraulic
cylinders 58, 58' and 64, 64' position the limb-stripping levers in the open
positions as
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shown in FIG. 3. The tree is lifted to a position above the level of the
device 10 and
the butt end is then lowered into position in engagement with the curved
stationary
cutting blade 44 and between the open limb-stripping levers 36, 36' and 46,
46', as
illustrated in cross-section in FIG. 6.
When the butt end portion of the tree bole is positioned in the device 10, the
device will pivot in both the vertical and horizontal planes so as to
automatically
become aligned with the longitudinal axis of the tree. The operator then
operates the
supply valve to supply hydraulic fluid to the hydraulic cylinders 58, 58' and
64, 64' so
that the first levers 36, 36' rotate inwardly in a uniform synchronous manner
on
opposite sides of the tree trunk to encircle and resiliently engage the outer
surface of
the trunk. Any slight misalignment of the device with the trunk is corrected
by
engagement of the first levers 36, 36' with the trunk. Further in this regard,
the front
bearing plate 26 has an inwardly inclined edge surface 27 (FIG. 6) extending
upwardly toward the fixed lower cutting blade 44 so that should the trunk be
brought
into engagement with the inclined edge surface 27, the closing of the first
lever 36
will cause the trunk to ride up the inclined surface 27 and onto the bottom
blade 44,
thus preventing the trunk from becoming lodged between the first lever 36 and
the
front bearing plate 26. The second levers 46, 46' then close about the trunk.
The
knuckle boom loader operator then draws the tree through the device 10 by
moving
2 o the grapple 16 away from the device. As the tree trunk moves through the
device, the
curved blades 42, 42', 54, 54', and 44 engage and strip any outwardly
extending limbs
from the tree trunk, and the device pivots on its mount to stay aligned with
the tree
trunk. A ridged or webbed hourglass-shaped roller 89 mounted for rotation
about its
longitudinal axis is located downstream of levers 46, 46' and helps to
maintain the
2 5 tree trunk centered in the device 10 as the trunk rides over the roller
89.
The limb-stripping levers 36, 36' and 46, 46' include angled deflecting
members for deflecting cut pieces of the tree outwardly away from the cutting
blades
42, 42' and 54, 54'. Specifically, with reference to FIG. 7 depicting a cross-
section
through the limb-stripping lever 46' which is representative of the
construction of all
3 0 of the limb-stripping levers, each limb-stripping lever includes a
transversely
extending portion 90 to which the curved cutting blade, for example 54', is
attached at
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a curved inner edge of the transversely extending portion 90. The cutting
blade 54'
extends generally longitudinally forward of the transversely extending portion
90,
such that an angle of approximately 90° is formed at the juncture
therebetween. The
limb-stripping lever 46' includes an angled deflecting member in the form of a
bevel
plate 92 which is connected between the transversely extending portion 90 and
the
cutting blade 54', the bevel plate in any generally radial plane such as the
one
indicated by line 7-7 of FIG. 6 forming an angle of about 45° to about
60° relative to
the cutting blade 54'. As indicated by arrows 94 in FIG. 7, the bevel plate 92
deflects
cut pieces of the tree outwardly away from the cutting blade 54', and
particularly
prevents cut pieces from becoming jammed in the corner of the juncture between
the
blade and the transversely extending portion of the limb-stripping lever.
As illustrated in dashed lines in FIG. 5, the limb-stripping levers 36, 36'
and
46, 46' are initially moved in and resiliently held in encircling relationship
with the
full-size tree trunk adjacent its butt end. As the tree trunk is drawn through
the device
10 and the limbs are stripped therefrom from the butt end to the top end, the
diameter
of the trunk gradually diminishes and the curved cutting and limb-stripping
levers are
moved inwardly and resiliently maintained in engagement with the trunk by
continuous application of hydraulic pressure to the hydraulic cylinders until
the tree
trunk is reduced to a diameter of about 3-4 inches, as illustrated by the
small dashed
2 0 line circle of FIG. 5. If the trunk is crooked, the second levers 46, 46'
move
independently of each other to remain engaged with the trunk and to permit the
trunk
to pass through the device.
The device 10 includes a saw box 96 which houses a pivotally movable saw
98 for engaging the small-diameter top portion of the trunk to remove the top
portion
2 5 of the tree. The saw box 96 includes a housing 100 having a vertical front
guard plate
I02 and a vertical rear guard plate 104 spaced from and parallel thereto. The
saw 98
is supported between the front and rear guard plates 102,104 so as to be
pivotable
about a longitudinally extending horizontal axis at a lower end of the saw 98.
The
saw box 96 is located adjacent the forward edge of the rectangular support
frame of
3 0 the device to position the saw 98 for engaging and removing the small-
diameter top
portion of a tree which has been drawn through and is still engaged in the
cutting
CA 02302597 2000-03-22
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opening of the device.
In order to prevent limbs from pressing against and interfering with the saw
box 96 and the pivotal movement of the saw 98, a forwardly extending cutting
blade
106 is affixed to the front guard plate 102 of the saw box housing 100
adjacent an
inner edge of the guard plate 102, the cutting blade 106 extending along a
substantial
portion of the vertical inner edge of the guard plate 102. As a tree is drawn
through
the device, any limbs which are drawn over the cutting blade 106 are cut off
at that
point so that the portions of the limbs which extended outwardly beyond the
cutting
blade location are removed to prevent their interfering with the saw box.
1 o As previously noted, it has been found that when the bottom cutting blade
44
encounters a limb that joins the trunk at a knot having a large diameter, the
bottom
cutting blade 44 in some cases tends to cut the limb off at the base of the
knot closest
to the trunk, which represents a longer cutting distance than would be
experienced a
short distance outward of the trunk. FIGS. 8-12 depict an alternative
embodiment of
15 the invention having a bottom cutting blade structure that tends to
overcome this
problem so that the limb is cut off a slight distance outward of the trunk.
The limb-
stripping device 110 is similar in many respects to the device 10 previously
described,
and thus the present description primarily focuses on those aspects of the
device 110
that are different.
2 0 The device 110 includes a bottom cutting blade structure 112 mounted
upstream of the first pair of limb-stripping levers 36, 36'. The bottom
cutting blade
structure 112 includes a curved cutting blade 114 affixed at an upper edge of
a blade
plate 116 such that the cutting blade 114 extends generally normal to the
blade plate
116. The cutting blade advantageously also includes a bevel plate 117 affixed
at an
2 5 angle at the juncture between the cutting blade 114 and the blade plate
116 for
reinforcing the attachment of the blade and for the purposes previously
described in
connection with the bevel plate 92 shown in FIG. 7. The bottom cutting blade
114 is
thus positioned to strip limbs from a lower portion of a tree. It will also be
understood
that a portion of the weight of a tree is supported on the bottom cutting
blade 114 as
3 0 the tree is pulled through the device 110.
The bottom cutting blade structure further includes track members defining a
track within which the blade plate vertically slides. More particularly, the
track
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members preferably include a forward plate 118 and a rearward plate 120 that
are
fixedly mounted in vertical orientation on a bottom support member 122 of the
support frame of the device and are spaced apart in a longitudinal direction
by a
distance slightly exceeding a thickness of the blade plate 116 such that the
blade plate
freely slides in the space between the plates 118 and 120, as best seen in
FIGS. 9 and
10. The track so defined between the plates 118 and 120 is covered at its two
opposite side edges by a pair of side members 124 and 126 affixed to the
support
member 122 and to the plates 118 and 120. Grease fittings 128 advantageously
are
provided in the side members 124 and 126 for lubricating the sliding surfaces
of the
1 o blade plate 116. Thus, the blade plate 116 with the cutting blade 114
attached thereto
is vertically movable relative to the support frame of the device. A blocking
member
in the form of a rod 129 is attached to the blade plate 116 below the cutting
blade 114
and above the upper edge of the forward plate 118 in order to block debris
from
entering the gap between the forward plate 118 and the blade plate 116.
The device 110 preferably includes a spring device 130 operable to exert an
upward biasing force on the blade plate 116 so as to urge the blade plate 116
and
cutting blade 114 into an upper position. The spring device 130 advantageously
comprises a fluid-operated spring device, such as a hydraulic or pneumatic
cylinder.
The spring device 130 in the illustrated embodiment is disposed generally
between the
2 0 forward and rearward plates 118 and 120 within a recess or cut-out 132
defined in a
lower edge of the blade plate 116. Where the longitudinal dimension of the
spring
device 130 measured along the axis of the limb-stripping device 110 exceeds
the
thickness of the blade plate 116, as shown, the forward and rearward plates
118 and
120 can also include recesses 133. A lower end of the spring device 130 is
connected
2 5 to the support member 122 and the upper end of the spring device engages
the blade
plate 116 and applies a force thereto in an upward direction. The upward
movement
of the blade plate 116 is limited by a pair of bolts 134 extending axially
between and
connecting the forward and rearward plates 118 and 120 and passing through a
pair of
vertically elongate slots 136 formed in the blade plate 116. Accordingly, when
the
3 0 downward force on the cutting blade 114 is less than the biasing force
exerted by the
spring device 130, the spring device 130 will move the blade plate 116 and
cutting
blade 114 into an upper position wherein the bolts 134 contact the lower ends
of the
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elongate slots 136 as shown in FIG. 9. Conversely, when the total downward
force
exerted on the cutting blade 114 exceeds the biasing force exerted by the
spring
device 130, the cutting blade 114 and blade plate 116 will be moved downward.
The spring device 130 preferably is operable to exert an increasingly greater
upward force on the blade plate 116 as it is compressed by downward movement
of
the blade plate and cutting blade. The spring device 130 preferably is
operable to
exert a force on the blade plate 116 that significantly exceeds the force
exerted by
each of the limb-stripping levers 36, 36' and 46, 46' on the tree. For
example, where
each of the limb-stripping levers exerts a force of about 700 pounds on the
tree in
l0 steady state (i.e., non-dynamic) operation, the spring device 130
advantageously
exerts a force of about 1400 pounds on the blade plate 116 when the blade
plate is in
the upper position. It will be appreciated, of course, that the biasing force
for each of
the limb-stripping levers and the spring device 130 that is most advantageous
in a
given application will depend on a number of factors, including the overall
size of the
limb-stripping apparatus. The maximum vertical travel of the cutting blade 114
and
blade plate 116 advantageously is about 0-2 inches, and more preferably about
1 inch.
The limb-stripping device 110 preferably also includes at least one, and more
preferably two, rollers 140 rotatably mounted in the support frame of the
device such
that the rollers freely rotate about respective axes that extend transverse to
the
2 0 longitudinal axis of the device. The rollers 140 are positioned to support
a trunk of a
tree being pulled through the device 110 and to be rotated by the rearward
movement
of the tree so as to facilitate free movement of the tree. An upstream one of
the rollers
140 preferably is mounted adjacent the forward limb-stripping levers 36, 36'
and a
downstream one of the rollers 140 is mounted adjacent the rearward limb-
stripping
2 5 levers 46, 46'.
Various types of rollers can be used. In the illustrated embodiment, each
roller 140 is formed by a pair of circular end plates 144 that define central
circular
apertures through which an axle and bearing assembly 146 extends. The axle and
bearing assembly 146 of each roller is rotatably mounted via a bracket
structure 148
3 0 to the support member 122 of the support frame. A plurality of generally
radially
oriented plate-shaped petals or spokes 150 are spaced about the circumference
of the
roller and mounted between the end plates 144. Each roller 140 is preferably
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constructed to include projecting members 142 configured to dig into the tree
to
reduce slippage of the tree relative to the rollers. Any configuration of
projecting
members effective to reduce slippage between the tree and the rollers can
suitably be
used. In the illustrated embodiment, the projecting members 142 comprise wedge-
shaped outer ends of the spokes 150 extending outward of the periphery of the
end
plates 144. Alternatively, the projecting members can be formed as bumps or
points
on the periphery of each end plate 144 and extending outward of the spokes
150.
The rollers 140 are preferably configured and positioned so that an uppermost
surface of each roller that engages and supports the tree is at the same
vertical level as
an upper surface of the bottom cutting blade 114 when the cutting blade 114 is
in its
upper position. Accordingly, the tree is supported on the rollers 140 and
rolls
therealong as the tree is pulled through the device, and the bottom cutting
blade 114 is
positioned against the trunk. Downward movement of the tree as a whole is
prevented by the rollers 140, but portions of the tree protruding below the
upper
surfaces of the rollers, such as limbs and/or crooked portions of the trunk,
can cause
the cutting blade 114 to be moved further downward against the biasing force
of the
spring device 130. For example, when the bottom cutting blade 114 encounters a
downwardly protruding knot, the force exerted on the cutting blade 114 by the
knot
will tend to cause the cutting blade 114 to be depressed downwardly so that
the knot
2 0 can pass over the blade. As soon as the knot clears the blade 114, the
blade is moved
back up against the trunk by the spring device 130. Thus, instead of digging
into the
knot and possibly damaging the good wood in the trunk as a fixed bottom blade
might
do, the movable blade 114 allows the knot to ride over the blade and then
springs
back. When the blade 114 encounters a limb, it cuts through the limb adjacent
to or
2 5 close to the trunk. It will be understood that the bevel angle on the
blade 114 can be
adjusted to provide a smooth cut through limbs and the like.
Portions of the tree cut by the bottom cutting blade 114 in some cases can
interfere with the structure of the device 110 below the blade 114. To help
alleviate
this situation, an alternative embodiment of the invention, shown in FIG. 13,
includes
3 0 a secondary cutting blade 152 affixed to the blade plate 116 and spaced
below and
parallel to the cutting blade 114. The forward cutting edge 154 of the
secondary
cutting blade 152 is located rearward of the forward cutting edge 156 of the
primary
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cutting blade 114. The secondary cutting blade 152 helps turn cut pieces of
the tree
downward and cuts them off so that they do not interfere with the structure
below the
secondary cutting blade. The primary and secondary blades can be formed as a
layered structure such that the secondary blade provides structural
reinforcement to
the primary blade.
A further alternative embodiment of the invention is depicted in FIG. 14. The
limb-stripping device in accordance with this embodiment includes a blade
plate 116'
that is pivotally connected at its lower end to the support member 122 of the
support
frame such that the blade plate 116' pivots about an axis that extends
transversely to
1 o the longitudinal axis of the limb-stripping device. Accordingly, as
illustrated in
phantom lines in FIG. 14, the cutting blade 114 affixed to the upper end of
the blade
plate 116' is movable forward and rearward by virtue of the pivotal motion of
the
blade plate 116'. An impact tool 160 is mounted in the support frame and
includes a
reciprocating member 162 arranged to engage a rear surface of the blade plate
116'.
The impact tool 160 is operable to reciprocatingly move the member 162 so as
to
periodically impact the blade plate 116' in the forward direction. The blade
plate 116'
preferably includes a hardened portion or insert 164 for tolerating the
impacts without
substantial deformation. As a tree is pulled through the limb-stripping device
and
slides along the bottom cutting blade 114, the tree tends to pivot the blade
plate 116'
2 0 and the cutting blade 114 rearward, but the impact tool 160 impacts the
blade plate
116' to drive it forward and cause the cutting blade 114 to cut part of the
way through
any limb encountered by the blade. Following a given impact, the motion of the
tree
will again cause the blade 114 to be moved rearward, but the succeeding impact
will
again drive the blade forward to cut further through the limb. Thus, the
cutting blade
2 5 114 is periodically and continually driven forward to cut through limbs.
The impact
tool 160 preferably comprises a pneumatic impact tool such as an air hammer or
the
like. Suitable impact tools for use with the present invention are sold under
the name
Rammer Hammer.
It will be appreciated that the forward and rearward motion of the cutting
3 o blade 114 can be accomplished in various ways. The illustrated embodiment
has the
blade 114 attached to a pivotal blade plate 116', but alternatively the blade
can be
mounted on a structural member that translates forward and rearward, the
important
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factor being that the blade be movable in forward and rearward directions.
In the drawings and specification there have been set forth particular and
preferred embodiments of the invention, and these embodiment have been
described
in considerable detail and with the aid of specific terms. However, such
specific
terms are used in an illustrative and descriptive sense only, and the terms
employed
and the form and arrangement of features of the illustrated and described
embodiments are not to be regarded as limiting the scope of the invention
defined in
the claims.
