Note: Descriptions are shown in the official language in which they were submitted.
SPECIFICATION I 0 5 ~ Y ~
The invention relates to the harvesting of trees, and it covers
the logging process from standing tree to ready product at the roadside.
It relates particul~rly to the felling o~ a standing tree (that is,
cutting it off from its stump), delimbing and topping ~cutting off
branches and cutting ofi the tree top), bucking (cutting the tree trunk
into desired lengths)7 as well as accumulating, forwarding (delivery
to roadside) and unloading of these cut lengths of tree trunk, known
as bolts.
A wide variety of apparatus and methods are known and employed
in harvesting trees. In some cases, a tree is felled, a separate
-~; appar~tus is used to delimb it, and separate machines are used to buck
it and to lGad the resulting bolts for accumulation and forwarding.
These single function machines have not proven economical- In other
cases, tree harvesting machines are provided, which perform a series
of tree harvesting operations. However, known multifunctional tree
harvesting machines are too complicated and heavy because of the use
of excessive tree handling motions.
In the disclosure of Canadian Patent No. 982, 455, awarded
to Leveque, the patentee outlines the disadvantages inherent in large
harvesting machines, designed for large trees in southern forests, when
they are applied to Canadian conditions. Large pulpwood trees are
moderately heavy in relation to other objects and loads handled
, by mobile vehicles. However, really severe machine requirements result
-~ when a tree is handled, non-vertically, by a grasping point near its
base, because the extended mass of the tree generates very high moments.
High loads and moments require heavy felling head and felling boom
structures and associated hydraulic actuators. Increased bo~m assembly
~` weight, itself, demands a stronger and heavier asse~bly. This vicious
`, 30 circle is increasingly aggravated as the boom is articulated in more
planes. F~rther, for heavy loads and heavy booms, a heavy vehicle
structure is required, both to carry the ~oom assemDly and load, but
also to provide stability when they are extended. EXperience indicates
that machine cost is directly related vehicle weight. Finally, great
size and weight drastically reduce mobility in the rough terrain, deep
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snow, and soft ground common in can~dian logging areas.
In answer to these difficultie6, Levesque's patent contemplates
a machine which is essentially an excavator - type platform and cab,
rotatabley mo?lnted on a group of tracked drive units, and carrying
a felling ~nd processing head mounted on a tiltable and line~rly
extensible box boorn. The resulting machine is quite simple and
; undoubtedly stable - but does not accumulate or forward the wood
it fells and processes.
Including the forwarding function in a tree harvester is not
always advantageous. Nevertheless, it is accepted that in many cases
it is useful to have one machine fell and process trees and forward
~ the resulting bolts to the roadside.
; Canadian Patents 860,o80, awarded to Xamilton, and 770,802
; awarded to Busch, as well as United States Patent 3,556,183 awarded
'
to the ~atter, describe tree harvesting machines which include
accumulation and forwarding among their functions. These patents refer
to somewhat similar machine configurations. Both machines have fully
articulated booms carrying felling and grasping heads which lodd
the felled trees into a separate delimbing and bucking device.
; 20 This device is located, with repect to the woodbunk, so that logs
-; are advanced over the woodbunk during delimbing, and fall into it
upon bucking.
A~though machines having the delimbing and bucking device separate
from the felling device potentialiy allow the operator to direct
the felling of one tree while the previous tree is being processed,
1 this advantage is seldom realized in practice because of operatorj
preoccup~tion with bulky processing mechanisms. Two definite disadv n-
tages are inherant in these machines. First, the tree must be orought
into register and grasped twice, which slows and complicates processing.
& cond, a separate bucking shear is required in aadition to the felling
shear. Because shears are heavy ana expens~ve, this duplication
is particularly undesirable-
Both the Hamilton and ~usch machines use an end unloading woodbunkas has been usual with tree harvesters. This requires that the woodounk
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be loc~ted at one end of the vehicle with no fixed ob6tructions beyond it.
Usually~ as in these machines, the woodbunk is mounted at the rear of
the vehicle. Because harvesters often work their way forward through
a bush, felling occurs, much o~ the time, arround the ~ront o~ the
vehicle. Under these circumstances, the wood must travel an extended
path from the stump to the woodbunk.
In the Busch machine, the wood is shifted to the rear mounted
; woodbunk by a fixed processing assembly rather than the felling boom.
But, in the embodiment shown in that patent, this would preclude the use
of the articulated centre pivot type of vehicle which has proven cost-
effective in much of Canada's woodlands. In the Ha~ilton machine,
; a mid-ship mounted boom carries the tree to a processing assembly mounted
over the woodbunk. Because of its mid-ship mounting the boom must be
reasonably long and fully articulated- consequently it would be heavy
and expensive.
The Hamilton patent also envisions an alkernative embodiment in which
the felling and processing units are combined at the end of the felling
bocm thus eliminating double tree grasping and duplicate shears. However,
by adding more weight to the boom end, this arangement makes it more
desirable than ever that the boom motion be kept short and simple. This is
a requirement that i~ not facilitated by the Hamilton configuration.
In Canadi~n Patent 965~335, awarded to Kurelek, a machine is
envisioned which uses a boom mounted felling and processing head to drop
bolts into a rear mounted, rear unloading, woodbunk, via a bolt-directing
' ramp. While the machine is useful for both short-wood and tree-length
harvesting, it would be most aavantageously employed for the latter.
Thls is because the woodbunk declines to the rear so that long bolts
or tree trunks may be carried with their forward ends extending over
the forward portion of the vehicle, provided only that their centres
, 30 of gravity lie within the len~th of the woodbunk. This permits
a desirable short motion from the tree stump to the processing position.
Obviously, this short motion would not be available if the machine were
used for short-wood harvesting because the forward bolt butts, and hence
the processing ~osition, could not extend so far forward. ~urther,
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the machine disclosed ~n the Kurelek p~tent uses a long, double
artic~lated (that i8, both vertically and horizontally) and extensible
boom. This permits harvesting a group of trees fro~ Q single vehicle
position, but it does not take particular &dvantage of the short path
I`rom stump to processing position. Finally, it should be noted that
a double articulated boom is generally required whenever the boom and
woodbunk are mounted on different halves of an articulated vehicle in order
to compensate for the variable angular relationship between the vehicle
halves.
The present invention relates generally to a simplified and improved
machine for harvesting trees in the form of shortwood bolts. The machine
takes the form of a vehicle having a trough-like woodbunk and a boom
mounted tree felling and processing head, both mounted at the same end
of the vehicle. T~e tree felling andprocessing head is of the known type
in which a drive wheel or chain engages a grasped tree trunk and, after
the tree is felled by a head-mounted shear, advances the trunk axially
in the butt direction, through encircling delimbing k~ives, simultàneously
delimbing the trunk and repositioning it so that the felling shear can
also be used to buck it. The axial path which the trunk follows during
` 20 processing will be referred to as the processing axis, and is generally
fixed with respect to the felling head. The boo~ and felling head are
articulated so that the head can be moved between three general positions:
1. Near the ground in front of the vehicle, with the processing axis
. generally vertical and the plane of action of the shear adjacent
the ground, for grasping and felling stan~ing trees;
- 2. Near the ground in front of the vehicle, with the processing axis
generally horizontal, for grasping fallen trees;
3. Above and in front of the woodbunk, with the processing axis lying
horizontally above the upper load level of the woodbunk, and with
the shearing plane lying in the front plane of the woodbunk,
for simultaneous processing and loading of the tree.
In one preferred embodiment of the machine, the woodbunk consists
of a trough-shaped crib, so~ewhat longer than the desired bolt length,
and mounted longitudinally on the vehicle fr~e 3etween the front wheels,
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the forward portions of tracks, or other such side-mounted locomotive
de~lces. The right side of the woodbunk is fixed and the operator's
cab is mounted outboar of it. The left side of the woodbunk comprises
a gate which extends out over the left front vehicle wheel this ~ate can
be selectively pivoted about a longitudinal ~xis which lies near the left
edge o~ the vehicle and at about the same level as the top of the vehicle
wheels. Several chains are each connected between the inner edge of the
gate and the top of the fixed right wall of the woodbunk. The length
of these chains is such that, when the gate is closed, they lie
transversely across the bottom of the woodbunk, and when the gate is
opened, they are raised and tensioned, forming an inward extension of
the unloading ramp provided by the open gate~
Another aspect of this preferred embodiment is that the felling ~oom
comprises a laterally duplicated parallelogram linkage extending forward
from the front of the woodbunk. One rigid frame forms the outer link
of both side - by - side parallelograms, and carries the felling and
processing head which is pivotally mounted to it by a pair of head pivots.
'! The parallelogram and head pivots are all m~tually parallel and are
generally horizontal and transverse to the vehicle frame.
`I 20 In a more speeific aspect of this invention, the vehicle comprises
-~- articulated front and rear units with the woodbunk, felling boom, and
.
cab mounted on the front unit and the engine mounted on the rear unit.
The configuration of this invention overcomes several of the
disadvantages cited with respect to known tree harvesting machines.
,,
The side unloading woodbunk is simple and uses few moving parts - only
a single pivoting gate and its hydraulic actuator, a~d several transverse
chains. The gate and chain arrangement allows the wo~dbunk to extend
downwards to the vehicle frame to permit a low lo~ded centre of gravity,
and at the same tirne provides a means for side unloading over the large
di~neter wheels. Becau6e of this facility, the wood~unk may be mounted
between the front wheels of the vehicle ~ith a felling boom mounted
directly in front of it. This permits short bolts of eight or twelve
foot length to be extended over, and dropped into the woodbunk by a known
type of axially-log-adv~ncing felling and processing head mounted on
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a ~ery short, light and rigid felling bo~n.
The pivoting gate of the woodounk can be selectively partly opened
and shut by the operator between the accumulation of successive bolts.
This action joggles the transverse chains passing under the accumul~ted
load and provides a means by which the operator can laterally redistribute
the accumulated bolts. Because bolts in the woodbunk can be laterally
redistributed~ it is practical to drop a succession of logs into
the woodbunk from a single overhead processing position. As a result it
is possible to use a felling boon which is singley articulated and
is transversely fixed with respect to the vehicle frame. This lack
of lateral articulation confers signifigant structural advantages because
the boom pivots can be widely spaced on a laterally duplicated boom
structure. Such a structure, as incorporated in the preferred embodiment,
causes a tree being felled and processed to remain substantially in
the plain of symmetry of the boom and this minimizes torsional loads
on the boom. A further advantage of the laterally fixed boom is that trees
are always lifted in a plane lying generally along the longitudinal axis
of the vehicle - this reduces the minimum vehicle track and weight
~e' required to provide vehicle stability.
A particular advantage of the parallelogram ~oom linkage incorporated
in the preferred embodiment is that the three head positions re~uired
in accordance with the invention, are achieved with simple slider-crank
'i hydraulic actuator linkages in which the cranks travel through arcs
limited to about ninety degrees. This results in the efficient use
;; of hydraulic energy and permits economically sized hydraulic actuators.
i These and other advantages obtained by the present invention by means
of its novel configuration will be apparent from the following description
of the preferred embodiment of the invention and will be more explicitly
s cited in the appended claims.
In the drawings which illustrate the preferred embodiment
Figure 1 is a perspective view of the tree harvester.
Figure 2 is a side elevation of the tree harvester, during
shearing and felling o~ a tree.
Figure 3 i6 a side elevation of the tree harvester, during
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processing of a tree.
Figure 4 is a side elevation Or the harve6ter during
forwarding of bo~ts to the ro~side.
Fieure 5 is a front elevation of the tree harve6ter during
unloading of bolts.
Figure 6 is a front elevation of the tree harvester at
a later stage of unloading.
Referring to Figure 1, the preferred embodiment of a tree harvesting
machine in accordance with the present invention conprises five major
assemblies : an articulated vehicle 1 , a cab 2 , a woodbunk 3 ,
a felling boom 4 , and a felling and processing head 5.
The rear frame 10, of the articulated vehicle 1, bear~ the power unit 35
while the front frame 20 carries the woodbunk 3, the cab 2, and
the felling boom 4 which in turn carries the felling and processing
head 5.
The woodbunk 3 is oriented with its longitudinal axis parallel
- to the longitudinal axis of the vehicle front frame 20. The woodbunk
rear wall 41 is perpendicular to these axis and is located adjacent
the point of vehicle articulation 21 (appears in Figure 2). The right
side woodbunk wall 25 lies just inside the right front vehicle wheel 26
and rises vertically to a level so~ewhat above the full load level of
' the woodbunk. The right side wall 25 is fixed and is used to support
;~ the cab 2 which is carried in front of and above the right front vehicle
wheel 26. me left side woodbunk wall 28 (appears in Figure 5 and 6)
is also fixed but is relatively low, extending upwards to just above
the left front vehicle wheel 27. At this level the left wall 28 extends
horizontally outward over the wheel 27 to provide mounting points 29
(appear in Figures 5 and 6) for a pivoting gate 6 which provides
the closure for the upper left side Or the woodbunk.
The gate 6 is a rigid longitudinal frame which appears " L 'shaped
in a front elevation (as in Figures 5 and 6).Hydrdulic actuators 29
,;
are interposed between the left side woodbllnk wall 28 and the gate 6
for pivoting the latter about the longitudinal axis formed by the mounting
s points 29. Several chains 18 are attached to the inner edge o~ the gate 6
,
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at one end, and near the top of the right side wul~ 25 at the other end.
The length of the chains 18 is such that when the gate 6 i6 in the
closed position (as shown in Figure 1) they lie transver~ely across
the bottom of the wo~dbunk; as the gate is rotated through intermediate
positions ( as shown in Figure 5 ) to the fully open pOSitiOII
(Figure 6), the chains are raised and then tensioned. By this means,
the opening rotation Or the gate 6 opens the left side of the woodbunk 3,
raises the accumulated bolts 30 (Figures 5 and 6) a~ove the left front
wheel 27~ snd proviaes a ramp for the bolts to roll by gravity off
the side of the harvesting machine.
The felling boom 4 comprises: two vertical towers 8, rigidly mounted
to the front vehicle frame 20 directly in front of the woodbunk 3; four
parallel and very generally horizontal links 40, extending forward,
two from each tower 8; and a vertical H - shaped frame 9 carried
by the outer ends of the horizontal links 10. All the felling boom
pivots are horizontal and transverse to the vehicle front frame.
The felling boom 4 thus forms a laterally duplicated parallelogram
linkage articulated for vertical planar motion. By the action of hydraulic
actuators 22 attached to the horizontal links 40, the ' H " frame 9
can be curvilinearly translated between a lowered p~sition near the ground
in front of the vehicle (as shown in Figures 1 and 2) to a raised
position adjacently above and in front of the woodbunk 3 (as shown
in Figures 3 and 4).
The felling and processing head 5 is generally of the known type
`Aj characterized by a tree advancing means 14 which engages a grasped tree 31
(~igures 2 and 3) and, after felling, advances the tree trunk axially,
in the butt direction, through encircling delimDing knive5 13 and tree
clamps 12, to simultaneous].y delimb the tree trunk and reposition it so
the felling shear 11 can also be used to buck it.
The felling head frame 15~ which mounts the various tree processing
devices, is itself mounted to the H frame 9 of the felling boom 4
by a pair of head pivots with a horizontal transverse axis. A pair
of hydraulic actuators 23 (appearing in Figure 2) are interposed between
the ~ frame 9 and the felling head frame 15 for selectively rotating
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the latter with respect to the former. The approximate limits of
this rotation are lndicated by the orientation~ of the felllng and
processing head shown in Figure 2 and Figure 3 and hereafter called
respectively, the vertical and horizontal head orientations. The lateral
spacing of the two parallelogram linkages, whîch comprise ~he felling
b~om 4, is wide enough that the felling and processing head 5 may be
oriented either vertical~y or horizontally without following the f~lling
boon 4 regardless of the position of the latter.
The general method of operation of a tree harveGting machine
in accordance with the invention is depicted in Figures 2 to 5.
In Fi~ure 2~ the harvester operator has manoeuvered the ~ehicle
so as to locate the standing tree against the frame of the felling head
which is oriented vertically and is lowered by the felling boom
to the de6ired shearing height. The shearing blades, tree clamps,
and delimbing knives are opened wide during this approach.
Through the activation of hydraulic valves in the cab, the operator
then closes the tree clamps and delimbers which encircle the tree and
~7, cl~mp it rigidly against the felling head frame and tree trunk drive
cleats. Then the shear blades are swung together and then reopened,
shearing the tree from its stump. Next, the operator raises and tilts
to the horizontal position both the felling head and the tree clamped
to it. This action may be automatically hydraulically ter~inated with
the result that the tree assumes a consistent position, its trunk about
parallel to the axis of, and somewhat above the woodbunk, the sheared
end of the trunk being even with the front end of the woodbunk.
The operator then activates the trunk drive which pulls the tree trunk
axially through the felling head. Thus, as shown in Figure 3, the branches
are stripped off by the delimbing knives and fall clear of the machine,
while at the same time the cleared trunk is extenled over the wocdbunk.
The flag, item 45 6hown in Figure 3 is a plate mounted on the rear
wall of the woodbunk, and lin~ed to hydraulic valving such that when
the trunk end strikes it, the trunk drive is automatically stoppeh,
the shear bl&des close together and then re-open, ana the trunk drive
reumes. In this manner, a series of bolts of the desired length are
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~ut~natically 6heared off and dropped ln the required longltudinal
position into the woodbunk.
The operator observes this series o~ automatic cycles and is able,
by selectively jerking the gate and att~ched transverse chains~ to
laterally redistribute the accwmulated bolts within the woodbunk.
When the operator observes that the remaining part of the tree
is too thin to make another bolt, he stops the tree trunk drive and
opens the tree clamps and delimbing arms which results in the top
of the tree falling clear, in front of the machine. Finally, the operator
lowers and tilts the felling head to the shearing position (Figure 1)
and approaches the next tree to be harvested. When the woodbunk gets
full, the operator leaves the felling head in the delimbing position
Figure 2, and proceeds to the roadside or any other desired unloading
point. Unloading is achieved as shown in Figure 5 and 6 by rotating
the gate. This draws up on the unloading cables, raising the bolt load
until it rolls by gravity over the gate as depicted in Figure 6.
While a particular, preferred embodiment of the invention has
been described, it will be understood that various modifications
- and changes can be made to the embodiment without departing from
the essential nature of the invention. Th~refore, the em~odiments
- of the invention, in which an exclusive property and privilege is
claimed, are defined as follows:
