Note: Descriptions are shown in the official language in which they were submitted.
Back~ro~md and Summary_of the Invention
This i.nvention pertains to apparatus for felling trees,
and more particularly to such apparatus which fells trees by
slicing through a tree trunk with a large blade which is opposed
by, and cooperates with, an undercutting device.
In the past, devices have been built which were intended
to fell trees, such devices incorporating one or more large
motor-driven blades. Typically, such devices were mounted on the
front end of a bulldozer or tractor~ Also typical, one or more
cutting blades extended outwardly from the front of a tractor,
and were mounted on some type of support structure. Such blades
were placed on opposing sides of a tree trunk while some type of
gripping structure, also mounted on the tractor, was clamped on
the trunk above blade level. The tree was then sheared off by
driving the blade or blades through the trunk. Other similar
devices for shearing trees were also used.
A severe problem which exists with the use of such
devices is the extreme amount of shattering and crushing of wood
in the trunk of a felled tree. Such devices create large shear
forces in a tree during cutting. These forces cause the wood in
the trunk adjacent the cut to shatter or separate. This problem
renders many of the prior art devices commercially unacceptable,
due to the fact that a large portion of a felled tree must be cut
off before the tree can be utilized by mill operators.
A general object of the present invention is to provide
an apparatus and method for felling trees which overcomes the
above-stated problems in the prior art.
A preferred embodiment of the invention is mounted Otl
the front of a tractor. A substantially planar base plate extends
outwardly from the front of the tractor substantially parallel to
the ground. In the base plate, a U-shaped notch, (having opposing
first and second sides)J suitable for receiving a tree therein,
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opens toward the ~ront of the plate so that the tractor can
approach a tree, and position the notch about such a tree. A
substantially planar blade having a convex, arc-shaped cutting
edge is pivotally attached to the base pla-te be-tween the notch
and the front of the tractor. In -this position, the blade can
be pivoted across the notch, its cutting edge sweeping from t'ne
first side of the notch toward the second side thereof. Located
adjacent the second side of the notch is an undercutting structure,
which in the preferred embodiment includes a pair of under-
beveled surfaces. Although applied specifically to the preferred
embodiment, these under-beveled surfaces are applicable to -the
invention generally, and not limited to the preferred embodiment.
One of these under-beveled surfaces is formed in the base
plate. The other is formed in an anvil which is attached to
the under surface of the base plate.
Mounted on support structure for the blade, near the
point at which the latter is pivotally attached to the base
plate, is a nozzle for spraying lubricant, such as oil. The
nozzle is directed toward the cutting surface o~ the blade. A
pump is attached to the base plate between the blade and the
- front of the tractor. The pump is actuated by a rod which
extends from the pump. A feed line connects the pump to the
nozzle. Also, an oil supply line is connected to the pump from
a source of oil on the tractor. A cam mounted on the rear edge
o~ the blade actuates the pump each time the blade returns to
its fully opened position--thus spraying oil from -the nozzle
onto the blade's cutting surface.
The blade is driven by a hydraulic ram. When a tree
is contained within the notch, the ram is actuated, and the
blade moves across the notch and through the tree at a
predetermined rate of speed. In the instant embodiment of the
invention, the blade moves from the first side of the notch
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toward the second side in approximately five ~econds. r~hen the
blade begins to move, the under-beveled surfaces are driven
into the side of the tree opposite the blade, undercutting the
tree with respect to the blade. As the blade cuts slices
through the trunk, these surfaces cause the tree to lean in the
direction of blade swinging. It is the leaning of the tree
with respec-t to blade travel speed which minimizes crushing and
shattering of the fibers wi-thin a tree trunk. Too much lean
with respect to blade travel speed causes excessive shattering;
too little lean with respect to blade travel speed causes
increased crushing.
Tests which have been performed on the instant
embodiment of the invention reveal that maximum shatter occurs
typically only about six inches up the trunk of a tree from the
point of a cut. This is true even for froæen trees and for
trees which have substantially rotten cores.
Thus, a more sepcific object of the invention is to
provide a method and apparatus which minimizes shatter and
crushing of tree fibers by undercutting the tree during slicing,
and by providing a predetermined rate of blade travel speed.
Another advantage which is obtained by felling trees
with the instant embodiment of the invention is that, due to the
effect of undercutting a tree with respect -to -the blade, the
tree always falls in the direction of blade cutting movement.
Thus, another object oE the invention is to provide
a method and apparatus for felling trees for which the direction
of tree fall is predetermined.
These and other objects and advan-tages attained by
the invention wlll hecome more ~ully apparent as the description
which follows is read in conjunction with the accompanying
drawings.
Description of the Drawings
Fig. 1 is a perspective view of a preferred em~odiment
of the invention mounted on the front of a tractor (shown in
partial view).
Fig. 2 is an enlarged cross-sectional view of a tree,
and a partial plan view of the apparatus of the invention in
position preparatory to slicing the tree.
Fig. 3 is si~ilar to Fig. 2, but shows parts in the
apparatus in the relative position which they occupy following
a slicing operation.
Fig. 4 is a fragmentary simplified front elevation of
portions in the apparatus illustrating a slicing operation.
Detailed Description of the Invention
Turning now to the drawings, and referring first to
Figs. 1 and 2, indicated generally at 10 is a tree-slicing
apparatus constructed in accordance with the present invention.
Also indicated generally, at 12 (in Fig. 1), is a tractor upon
which apparatus 10 is mounted. Included within apparatus 10
are a base plate 14 having a notch 16 therein, a blade 18 which
is pivotally attached to plate 14, and a blade drive means,
indicated generally at 20. Included within notch 16 are opposing
notch sides 22, 24. Disposed on the underside of plate 14
adjacent notch side 24 is what is referred to herein as an
undercutting means, as undercutting structure, and as an under-
beveled surface means 26.
Generally speaking, slicing and felling of a treeoccurs -through the in-teraction thereof with the several parts
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in apparatus 10 just mentioned above. In particular, felling
is accomplished with these parts in the apparatus advanced to
place a tree's trunk at a location within notch 16 for tree
trunk 28 in Fig. 2.
Still loo~ing at Figs. 1 and 2, attention is directed
to base plate 14. Plate 14 is substantially planar and is
composed of a s-trong metal, preferably steel. ~n apparatus
support frame 30 (see Fig. 1) is suspended from the front of
tractor 12. Plate 14 is attached to fxame 30 along the rear
edge of plate 14 and at vertical suppor-ts 32, 34.
Attached to the underside of plate 14 is an anvil 36
having the perimetral outline seen in dashed lines in Fig. 2.
Anvil 36 is a solid piece of metal having a thickness, in the
instant embodiment of the invention, approximately three times
that of plate 14. As can be seen in Fig. 2, anvil 36 includes
a convex edge 38 which curves in an offset manner along adjacent
notch side 24.
As has been previously mentioned, located adjacent
notch side 24 and heneath the surface of plate 14 is undercutting
structure 26. Turning now to Fig. 4, undercutting structure 26
includes what are referred to as first and second underbeveled
surfaces 42, 44. Surface 42 is formed on the underside of
plate 14, and surface 44 is formed on the underside of
anvil 36. These surfaces extend adjacent the entirety of notch
side 24. The angle formed by surface 42 (angle A] with respec-t
to the top surface of plate 14 is less than the respective
angle formed by surface 44 (angle B). Although undercutting
structure 26 includes first and second underbeveled surfaces
42, 44 in the disclosed preferred embodiment, it will be appre-
ciated that other constructions may be used which do no-t depart
from the spirit of the invention.
Blade 18 is substantially planar and has a convex arc-
shaped cutting edge 46. ~s can he seen in the cross-
sectional view of blade 18 in Fig. 4, cutting edge 46 is
tapered.
Returning again to Figs. 1 and 2, blade 18 is pivotally
attached -to plate 14, the attachment being shown generally at
48. A bolt 50 is located at -the center point of attachment 48.
shaft ~not visible) extends through concentric holes within
anvil 36 and plate 14 and extends upwardly above the surface of
plate 14. Bolt 50 is screwed into a threaded bore in the
center o~ the shaft. The shaft is keyed to the anvil and plate
so that it will not rotate. Also, blade 18 has an end portion
52 including a central bore which receives the shaEt. Includsd
within attachment 48 are conventional load bearings which interact
between end portion 52 and the shaft to allow pivotal movement of
blade 18 around the shaft. Further, attachment 48 is constructed
so that there is approximately 3/16-inch between the lower
surface of blade 18 and the top surface of plate 14.
Included within drive means 20 is an hydraulic cylinder
58 and a rod 60. Hoses 59, 61 (in Fig. 2) connect opposite ends
of cylinder 58 to a fluid system (not shown~ in the tractor which
system can supply and exhaust pressure fluid with respect to
cylinder 58 upon command from the operator. A crank assembly 55
is fixedly attached to blade 18 adjacent at-tachment 48. Rod 60
is pivotally attached to crank assembly 55 as shown. A post 62
is fixedly positioned at the rear of cylinder 58 as shown in Fig.
2. Cylinder 58 i5 pivotally attached to this post.
A thrust restraint bar 84 has one end secured to the
previously discussed shaft by bolt 50 through a conventional
eccentric tightening de~ice 90. The opposite end of bar 84 is
3~ secured to an angle structure 86. Structure B6 is fixedly attached
to plate 14, and provides a horizontal extension at ~he top
thereof to which rod 84 is bolted (see particularly Fig. 1).
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A blade guard 91 is attached to plate 14 toward the
front thereof. Guard 91 provides a protective lip over the edge
of blade 18 at the front of apparatus 10.
Finishing now the clescription of the structure of
apparatus 10, indicated generally at 92 is an automatic lubricant
or oil dispersal system, or means. Included therein are a nozzle
93, a pump 94, a rod 96, and a roA depressor, or cam, 98. A
roller follower 97 for engaging cam 98 is journaled as shown on
-the outer end of rod 96. Also, an oil delivery line 100 connects
pump 94 with nozzle 93. An oil supply line 102 provides oil to
pump 94 from the fluid system in tractor 12. Pump 94 operates in
a conventional manner, as follows: rod 96 is spring-loaded so
that it tends to push outwardly away from pump 94. When the rod
96 moves outwardly, oil is drawn into the pump from the reservoir
through line 102. When the rod moves inwardly, oil within the
pump is forced through line 100 to nozzle 92, and from there is
spray~d onto blade 18.
~ en apparatus 10 is not in the process of felling
a tree, blade 18 is in the stored position shown in Fig. 2. When
an appropriately sized tree has been selected for ~elling, the
tractor operator approaches the tree on the vehicle and maneuvers
apparatus 10 so as to locate the tree in a position in notch 16
like that shown for tree 28 in Fig. 2. In the instant embodiment
of the invention, apparatus 10 is sized to handle easily a 24-inch
diameter trunk. ~owever, with such sizing, and for optimum
results with re~pect to the amount of shattering and crushing of
fibers in a tree, it is best to limit trunk size to 22-inches in
diameter at the level of notch 16.
Once a tree is appropriately positioned as shown in
Fig. 2, the operatox actuates the pressure fluid system to provide
oil under pressure to cylinder 58 through hose 59. The pressure
is such, that with a tree contained within notch 16, it takes
approximately flve seconds for the blade to sweep across the
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notch fro~ the position shown in Fig. 2 to the position sho~7n in
Fig. 3. Of col~rse, when the blade reaches the latter position
the tree is sliced through.
It can be seen by comparing the blade positions in
Figs. 2 and 3, that when the drive system 20 is actuated, the
blade is pivoted about the shaft upon which it is mounted. As
rod 60 extends, pivoting the blade, crank assembly 55 describes
an arcuate path with the previously mentioned shaft forming the
center of the arc. Thus, it can be seen -that for the drive
system to operate in such a manner it is necessary for the end of
cylinder 58 to be pivoted on post 62, and, likewise, for rod 60
to be pivoted on the crank assembly. Thus, during the driving of
- the blade while rod 60 is extending from cylinder 58, pivoting of
the cylinder and rod is occurring about post 62 as well as about
the crank assembly.
Thrust restraint bar 84 prevents the corner of plate 14
at the location of post 62 ~rom dropping during a slicing process.
When rod 60 is extending from cylinder 58, a tremendous amount o~
force is being directed axially along cylinder 58 toward post 62.
Were it not for the presence of bar 84, blade 18 could skew out
of i-ts intended travel plane during slicing.
Directing atkention now to Fig. 4, blade 18 and under-
cutting structure 26 are shown in solid lines at the beginning of
a slicing process. Further, these components are shown in
phantom lines part way through the slicing process.
Once the slicing process begins, the force of blade 18
against the side of the tree opposite undercutting structure 26
tends to cause such s-truckure to imbed into the tree as shown in
phantom lines in Fig. 4. Sometimes, this action can cause a
slight shifting of the tractor. ~owever, generally, there is
enough play within mounting apparatus 30 so that the tractor does
not so shift.
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As can be seen from the phantom-line ~iews in Fig. 4,
as slicing proceeds, tree 28 begins to lean in the di~ection of
blade travel. This is due to the effect of undercutting structure
26 in cooperation with blade movement. As the tree begins to
lean, blade 18 can slice through the fibers within the tree as
they are gradually exposed. If blade 18 should be traveling at a
rate which is too fast compared to the rate oE tree lean, the
blade tends to crush fibers between the tip of the blade and the
underbeveled surfaces. If blade 18 is traveling at a rate too
slow compared to the rate of tree lean, shattering tends to occur
since fibers are being pulled apart because of the tension placed
thereon due to the lean of the tree.
As has been previously mentioned, the instant embodi-
ment of the invention utilizes a blade travel speed of five
seconds from the position shown in Fig. 2 to that shown in Fig. 3
while a tree is being sliced. This is controlled by the amount
of hydraulic pressure provided via hose 59 to cylinder 58. For
the instant embodiment o~ the invention, five seconds is the
optimum rate of blade travel since, either a faster or a slower
rate tends to produce more shattering and crushing o~ the fibers
during slicing process.
Directing attention particularly to Figs. 2 and 3,
e-xamination will now be made of the operation o the oil dispersal
system. ~en the slicing process begins and blade 18 starts to
travel across notch 16, roller 97 rolls on cam 98 until rod 96 is
extended as shown in Fig. 3. As will be recalled, when the rod
is extended, a suppl~ o~ oil is drawn into pump 94 via line 102.
After a tree has been felled, blade 18 returns to the position
shown in Fig. 2 when the operator actuates the pressure fluid
system to provide oil under pressure through line 61 to cylinder
58. When cam 98 reaches roller 97, rod 96 returns to the position
shown in Fig. 2. As will be recalled, this has the effect of
providing oil under pressure through line 100 to nozzle 93, with
oil then onto spraying cutting edge 46 in blade 1~. Thus, each
time the blade returns to -the position shown in Fig. 2, its Cllt-
ting edge is sprayed in preparation for the next cut to be made.
It has been found that oiling the blade greatly assists in
the slicing process, and that the hydraulic pressure utilized in
cylinder 58 to drive the blade in a slicing stroke may be reduced
by 200 to 300 pounds per-square-inch with the blade so oiled.
This reduction in pressure further decreases crushing and shat-
tering in a tree.
Thus, a dependable and sturdy apparatus for slicing
trees has been shown which results in a minimum amount of damage
to a felled tree.
While a preferred embodiment of the invention has been
described herein, it is appreciated that other variations and
modifications may be made without departing from the spirit of
the invention.
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