Note: Descriptions are shown in the official language in which they were submitted.
~B2
The present invention relates to an improved tree
delimbing apparatus.
The invention more pa~ticularly relates to an
improved delimbing apparatus o~ the type which grips a felled
tree at one cnd and moves delimbitlg mcans over thc txeQ Erom
its one end to its other end.
Numerous apparatus ~or yripping and delimbing a
felled tree are presently known and used throughout the world.
Almos-t all these known apparatus employ a straight, rigid or
telescopic boom movable relative to a base. ~he base carries
means for gripping the tree and the boom carries means for
delimbing the tree. Movement of the boom relative to the base
while the tree is gripped effects delimbing of the tree.
If the known apparatus employing such a movable boom
are quite efficient in use, they have some drawbacks however.
Indeed, either a rigid ortelescopic boom requires an apparatus
having a relatively massive base to properly support and
operate the boom. In addition, a rigid boom is quite long
and can make it difficult to position and/or manoeuvre the
apparatus in crowded woodlot areas. On the other hand, a
telescopic boom while effectively shortening the boom to
make p~sitioning and/or manoeuvring less difficult, is quite
complicated in construction and subject to more maintainence
than rigid booms.
It is the purpose of the present invention to provide
an improved delimbing apparatus of the type which grips a felled
tree at one end and moves delimbing means along the tree,
which apparatus avoids, or at least minimizes, some of the
problems encountered with the known apparatus.
In accordance with -the present invention, a simple
delimbing apparatus is provided which needs no massive boom
support and which takes up little space in positioning and/or
manoeuvring.
The delimbin~ apparatus according to the present
invention employs an articulated mast in place of a ri~id or
telescopic boom. Tlle mast is fixed at one end to the base
which also carries a gripplng unit. The mast is hinged ln
the middle and carries a delimbiny unit at its other end.
The mast can be folded in two to minimize the space requirement
and make the apparatus easy to move in crowded woodlot areas.
The apparatus is provided with a plurality of simple actuators
for unfolding the mast to move the delimbing unit carried by
the mast away from base and to delimb a tree held by the
gripping unit mounted on the base.
The delimbing unit of the improved apparatus according
to the invention comprises a support means pivotably mounted at
the end of the mast about a central axis perpendicular to the
vertical plane in which the mast extends, and at least two
delimbing members mounted under the support means.
In accordance with a first embodiment of the invention,
the support means is freely mounted at the end of the mast to
let the delimbing unit afloat~> with respect to the tree to be
delimbed. Preferably, the unit is very compact in size and
comprises two two-way delimbing members only, which are
longitudinally offset and symmetrically positioned with respect
to the central axis of the support means.
In accordance with another embodiment of the invention
the support means comprises a support beam pivotably mounted
intermediate its ends to the end of the mast, and at least one
delimbing head mounted at one end of the support beam. This
delimbing head incorporates the delimbing members of the
delimbing unit and their actuating means. On the other hand,
the support beam extends in the same vertical plane as the
mast and advantageously acts as positioning means for the
~ 2 -
delimbing he~d since in use, it wil~ stay generally parallel
to the llne of tree by mere rotation about its pivot as the
delimbing unit is moved, and thus it will keep the delimbing
head in the most opexative posi-tion with respect to the tree~
Therefore, the delimbing unit wi~l away move ~rom the base in
a straight line generally following the tree being delimbed.
Advantageously the delimbing unit can be used for
grasping a felled tree and positioning it in the apparatus
before delimbing it.
The lmproved delimbing apparatus according the
present invention may also include means for improving the
~exibility and speed of the apparatus in delimbing trees of different
lengths and/or trees with different limb arrangements. In
accordance with the present invention, the tree gripping unit
on the base of the appara-tus may further include stop
means for use in locating a tree to be delimbed. The gripping
unit, including the stop means, is movably mounted on the
- base so that its position, relative to the mast, can be
changed depending on the length and/or type of tree to be
delimbed, even during the delimbing operation.
The invention is particularly directed toward a
tree delimbing apparatus comprising:
a base,
a gripping unit mounted on the base, for gripping
a tree
an articulated mast having a first arm hinged at
one end to the base and a second arm hinged at one end to the
other end of the first arml
- a delimbing unit mounted at the other end of the
second arm, this delimbing unit comprising support means
pivotably mounted at the other end of the second arm, about
a central axis perpendicular to the vertical plane in which
62
both arms of the mast extend; at least two delimbing members
mounted under the supportmeans; and means Eor actuating these
delimbing mem~ers, this delimbing unit acting as grasping
means for grasping and positioning a felled tree to be delimbed
in the apparatus with one end gripped by the gripping unit,and
as delimbing means for delimbing the so posi-tioned tree, and
` means for moving the arms of the mast relative to
; the base and to each other to move the delimbing uni~ away
from the gripping unit, said moving means including a first
actuator pivotably connected between the base and the first
arm to move the first and second arms relative to the base,
` and a second actuator pivotably connected between the first
and second arms to move the second arm relative to the first
one.
The invention will be better understood with
reference to the following non-restictive description of a
plurality of preferred embodiments thereof, taken in connection
~` with the accompanying drawings in which:
Fig. 1 is an elevation view of a first embodiment of
delimbing apparatus according to the invention mounted on a
i vehicle;
Fig. 2 is an enlarged elevation view of the
delimbing apparatus shown on Fig. l;
`` Fig. 3 is an enlarged side elevation view of the
delimbing unit of the apparatus shown on Figs. 1 and 2;
Fig. 4 is a detail view of one end of the delimbing
unit of Fig. 3;
Fig. 5 is a detail view of the other end of the
delimbing unit of Fig. 3;
Fig. 6 is a detail side view oE the tree gripping
unit of the apparatus shown of Fig~ 1 and 2;
Fig. 7 is a detail front end view of the tree
.
; gripping unit shown in Fig. 6;
Fig. 8 is an elevation view of a second embodiment of
appara-tus according to the invention mounked on ~ vehicle;
Fi~. 9 is ~n eleva-tion view of a thixd embodiment
oE clclilrlbincJ apparatlls ~ccording to thc lnventlon;
Fi~. 10 is a detail front elevation view of the
delimbing unit of the appara~us shown of Fig. 9;
Fig. 11 is a detail top plan view of the delimbing
unit of Fig. 10,
Fig. 12 is an elevation view of a fourth embodiment
of delimbing apparatus according to the invention; and
Fig. 13 is a schematic diagramm of a hydraulic
circuit that can be used ~or actuating the mast.
The improved delimbing apparatus 1 as shown on
Figs. 1 and 2, has a base 3 for use in mounting the apparatus
on a vehicle carrier 5 as shown in Fig. 1 or an~ other support. The
vehicle 5 carries equipment 7 for providing p~wer to opera~e the delimbing
apparatus 1. The power equipment 7 is preferably hydraulic
but can be electrical. The vehicle 5 also carries an operator
cab 9 from which an operator can operate both the vehicle and
the delimbing apparatus 1.
The delimbing apparatus carries an unit 11 on its
base 3 for securely gripping a tree "T" to be delimbed
adjacent its large end "E". The gripping unit 11 includes
a support 13 which can be fixed to the base 3, and more
particularly to a cantilevered jib 15 projecting horizontally
from the top of a post 17. The jib 15 and post 17 are
parts of the base 3. The support 13 is located at one side
of the jib 15 and can be fixed directly to it. Preferably
however the support 13 is mounted adjacent a side 19 of
a cantilevered guide member 2I which member extends horizontall~ -
rearwardly from jib 15 and alongside it. The support 13 is
6~
slidably mounted on -the guide member 21 as will be described.
A fixed jaw 23 is formed integral with the support
13 and extends under the member 21, down from its other side
25, and slightly inwardly as shown if Figs. 6 and 7. A
movable jaw 27 ls attachcd with a pivot 29 to the bottom of
support 13 to the one side 19 of guide 21 and extends down
and slightly inwardly. Means are provided for moving the
movable jaw 27 toward or away from the fixed jaw 23 to grip
or release a tree between them. These moving means can
comprise a hydraulic actuator 31 mounted at one end with a
pivot 33 to the top of the support 11. The other end of the
actuator 31 is mounted with a pivot 35 to the end of a short
arm 37 extending laterally from the end of the movable jaw 27
adjacent the pivot 29. Extension of the actuator 31 will
move the jaw 27 toward the fixed jaw 23 about the pivot 29,
to tightly grip a tree between them.
The delimbing apparatus 1 includes an articulated
mast 41 as shown in Figs. 1 and 2 composed of a first generally
straight arm 43 and a second generally straight arm 45 joined
together at adjacent ends by a pivot 47. The other end of
first arm 43 is connected to the end of the jib 15 of the
base 3 by a pivot 49. ~ delimbing unit 51 is connected to the
other end of second arm 45 by a pivot 53. The pivots 47, 49,
and 53 extend generally horizontally transverse to the jib
15, and parallel to each other.
Means are provided for rnoving the mast 41 relative
to the base 3 in a manner to move the delimbing unit 51
in a relatively straight line toward and away from the grip-
ping means 11. The line along which the delimbing unit 51
is moved generally corresponds to the longitudinal axis 57
of a s-traight tree held at its end by the gripping unit 11
The means for moving the mast 41 comprise a first mast
~.
hydraulic actuator 59 and a second mast hydraulic actuator
61. The first actuator 59 is connected at one end by a pivot
63 to the top of -the jib 15 near the pivot 49 connecting the
first leg 43 to the cnd of jib 15. The other end of first
actuator 59 is connected by a pivot 65 to the outer, top
side of the first arm 43 part way along ist length. The
second actuator 61 is connected at one end by a pivot 67 to
the inner, bottom side of the first arm 43 near the pivot
47 joining both arms together. The actuator 61 is also
pivotably connected at its side by a pivot 69 to the second
~` arm 45 near the pivot 47.
In operation, the two mast actuators 59 and 61 are
moved in synchronism to move the delimbing means 51 in the
~ desired straight line path. A hydraulic circuit (showing
`~ in greater detail in Fig. 13), is controlled by the operator
` in the cab 9, to operate the actuators 59 and 61 synchronously
` in a manner to achieve the desired movement.
' In accordance with the first embodiment of the
invention illustrated on Figs. 1 to 7, the delimbing unit 51
` 20 comprises support means which includes a support beam 71
pivotably connected near its inner end 73 to the end oE the
~.,
second arm 45 of the mast by the pivot 53. The support
~ means of the delimbing unit supports a first delimbing head 75
!~ mounted at the outer end 77 of the beam 71 and a second
delimbing head 141 mounted at the inner end 73 thereof.
As can be easily understood, the first delimbing
head 75 mounted at the outer end of the beam 71 advantageously
increases the delimbing reach of the mast 41 by adding the
length of the support bearn 71 between the pivot 53 and the
head 75, to the actual reach of both arms of the mast.
The delimbing head 75 as shown in Figs. 3 and 4
incorporates a pair of curved, longitudinally offset delimbing
-- 7 --
.~
members 81 and 83. Each member 81 and 83 is mounted adjacent
one end with a pivot 85 and 87 respectively to the sides of
the delimbing head 75. The delimbing members 81 and 83
project down f~om the sides of head 75 and are curved toward
each othcx below the head. Means are provided for moving the
member 81 and 83 inwardly toward each other and upwardly
toward the base 89 of the delimbing head. The moving means
comprise first and second hydraulic actuators 91 and 93.
The first actuator 91 is pivotably mounted at one end with a
pivot 95 to the upper end of delimbing head 75 at one sideO
The other lower end of the actuator 91 is mounted with a
pivot 99 to a short arm 101 projecting upwardly and outwardly
- from the delimbing member 81 adjacent its pivot mounting.
The second actuator 93 is also pivotably mounted at one end
with a pivot 103 to the upper end of the delimbing head
75 at its other side. The other end of the ac-tuator 93 is
mounted with a pivot 105 to a short arm 107 projecting upwardly
and outwardly from the delimbing member 83 adjacent its pivot
mounting. Operation of the actuators 91 and 93 will move the
delimbing members 81 and 83 inwardly and upwardly about the
pivots 85 and 87 with respect to the head 75 to cross and
tightly hold a tree against the base 89. The leading edge
lll of base 89, and the leading edges 113 and 115 of
delimbing members 81 and 83 delimb the held tree as the head
75 is moved forwardly along the tree.
The delimbiny head 75 also carries a pair of cutters
117 and 119 just behind the delimbing members 81 and 83.
Each cutter 117 and ll9 is mounted with a pivot 121 and 123
respectivaly to the head 75. The pivots 121 and 123 are located
adjacent the center of the head and just above the level
of the base 89. Hydraulic actuators 125 and 127 move the
cutters 117 and 119 down and together about the pivots
-- 8 --
.
121 and 123 to cut off the top of the tree being delimbed
after delimbing is completed. The upper ends of the actuators
125 and 127 are mounted on the pivots 95 and 103 respectively.
The actuator 125 is mounted with a pivot 129 at its lower end
to the mounting plates 131 located on the top o the cutter
117 and outwardly of the pivo~ 121. The actuator 127 is
similarly mounted with a pivot 133 at its lower end to the
mounting plates 135 located on the top of the cutter 119
and outwardly of the pivo-t 123. Operation of the actuators
125 and 127 moves the cutters about the pivots 121 and 123.
As aforesaid, in accordance with this first embodiment
of the invention, a second delimbing head 141 is mounted at
the inner end 73 of the support beam 71, as shown in Figs.
1 to 7. This second head 141 is similar to the first delimbing
head 75 but does not have cutting means. As shown in Figs.
3 and 5, the second head 141 has a pair of downwardly extending,
longitudinally offset inwardly curved delimbing members 143
and 145. Hydraulic actuators 147, 149 move the delimbing
members 143 and 145 inwardly and upwardly toward the base
151 of the second head ]41 to delimb the tree. This second
head 141 will delimb any limbs not delimbed, or incompletely
delimbed by the Eirst delimbing head.
The delimbing head 75 alone or spaced apart delimbing
heads 75 and 141 on the delimbing unit 51 may advantageously
be used to grasp and position a felled tree to be delimbed in
the apparatus 1. The delimbing unit 51 position the large
end of the tree within the gripper unit 11 which is then
actuated to tightly grip the tree therein between its jaws
23 and 27. The delimbing unit 51 is then repositioned, if
necessary, adjacent the gripping unit 11 and the delimbing
members in both delimbing heads 75 and 141 are moved to a
delimbing position against the tree. The delimbing members
: ~ ~L42~6;~
~ `
simultaneously push the tree against the base of the heads.
The mast 41 is then actuated to move the delimbing unit 51
away from the grlpping means 11 while the gripping means
holds the tree end. ~s the delimbing unit move away, the
lcading cdges on the base of both oE ~hc delimber heads and
the leading edyes on both sets of the delimber members
` delimb the tree. When the top of the tree is reached, the
movement of the delimbing means is stopped and the cutters
117 and 119 are actuated to top off the delimbed tree.
' 10 As the delimbing unit 51 is moved outwardly, the
support beam 71 will stay generally parallel to the line
of tree, pivoting freely about pivot 53. However, to ensure
that the support beam 71 stays parallel to the desired line
~` of movement of the delimbing means, a hydraulic actuator 155
can be connected between the support beam 71 and the second
leg 45 of the mast. The actuator 155 is connected with a
' pivot 157 at one end to the support beam 71 in front of the
' pivot 53. The other end of actuator 155 is connected with a
pivot 159 to the front of leg 45 about midway along its length
The operation of actuator is synchronized with the operation
of the actuators 59 and 61 so that as the mast 4]. is unfolded,
the actuator 155 operates to retain the support beam 71 in a
~` generally horizontal line, parallel to the desired line of
movement of the delimbing unit 51.
A stop plate 161 can be provided on the gripping
unit 11. The stop plate 161 is located to the re-ar of the
gripping jaws 23 and 27 and is connected to a rearward
extension 163 of support 11. The end "E" of the tree "T"
to be delimbed is abutted against the stop plate 161 to
properly locate the tree before the gripping uni-t 11 are
actuated. Preferably the stop plate 161 is pivotably
connected at its upper edge to the support extension by a
-- 1 0 --
6~:
pivot-165. A hydraulic actuator 167 is provided to move the
stop plate 161 about pivot 165 between an operative, vertical
position, as shown in Fig. 2 and an inoperative, horizontal
position. The actuator 167 is connected at one end by a
pivo~ 1~9 to the top oE suppor~ 11 an~ a~ lts o~hcr ~nd by
a pivot 171 to a rearward extension 173 of stop plate 16i.
The arrangement permits the plate 161 to be moved out of the
way if a particularly long tree is to be delimbed. Long
trees are delimbed in two stages with the tree moved back
relative to the gripping unit 11 after the first stage of
delimbing to reposition it for the second stage. With the
stop plate-161 moved to an inoperative position, the tree
can be easily repositioned.
The gripping unit 11, including the stop plate 161,
can be rigidly fixed to the base 3. Preferably however,
the gripping means is movable mounted on the base for limited
movement in a horizontal direction toward or away from the
mast 11. Such movement gives the apparatus wider flexibility
in handling trees of different length, andjor different limb
arrangements. Some trees may have limbs only in their
upper portion, and long trees of this type could be handled
in one stage by movin~ the gripping unit 11 rearwardly of the
mast. In addltion to increasing the flexibility of the
apparatus, movement of the gripping means away from the mast
carried out while moving the mast, permits to substantially
increase the delimbing speed and force. In this regard, comparative
tests have shown that the combined movement of the gripping
means 11 and mast 41 permits to reach a delimbing speed of
about 550 to 600 feet per minute, as compared to about 400
to 450 feet per minu-te obtained with the most of the known
delimbing machines.
To movably mount the grippiny unit 11, a straight
~ 11 -
Z
guide member 21 projects rearwardly from the ront end of the
jib 15 of the base 3 as previously stated. The guide member
21 extend alongside the jib 15 and is cantilevered. A sleeve
175 is fixed to the side of the support 13 of the gripping
unit 11. The sleeve 175 slides over and along the guide
member 21. A screw 177 is mounted above the guide member 21.
The screw 177 is parallel to the guide member 21 and extends
rearwardly from the front end of the jib 15. The screw 177
can be cantilevered or mounted at its ends on the guide member
21. ~eans (not shown) are provided in -the jib 15 for rotating
the screw 177. The screw 177 is threaded through a connector
179 mounted on top of the sleeve 175. Rotation of the screw
177 in either direction will, through the connector 179, move
the gripping unit 11 in either direction along the guide
member 21 to reposition it relative to the mast. As aforesaid,
movement of the gripping unit 11 can be synchronized to the
movement of the mast in any desired manner.
Fig. 8 shows a second embodiment of the invention.
In this figure, the parts of the apparatus identical to those
already described with reference to figs. 1 to 7 have been
identified with the same reerence numbers.
In accordance with this second embodiment, the
apparatus comprises one single delimbing head 141 only and
no hydraulic actuator for pivotable moving the support beam
71 with respect to the second leg 45. In operation, the
support beam 71 will bear against the tree and with stay
parallel to the line thereof by free rotation about its pivot
as the delimbing unit 51 is moved. The self-positioning o
the beam with respect to the line of the tree will keep the
delimbing head 141 in the most operative position with respect
-~o the tree, with the delimbing members 81 and 83 perpendicular
to the line of the tree. To improve self-positioning of the
- 12 -
,. .
beam 71, guide means (not shown) can be mounted on the beam
at the end thereo~ opposite to the delimbing head 141.
Figs. 9 to 11 show a third embodiment of the
invention, which embodiment is particularly interesting
as it is less complicated as the first and second ones. In
these figures, the parts of the apparatus identical to those
already described with reference to igs. 1 to 7 have been
identified with the same reference numbers.
In accordance with this third embodiment, the
lower end o~ the post 17 forming part of the base 3 is
connected by a pivot 181 to a support brace 183 rigidly fixed
to the vehicule carrier (not shown). The pivot 181 has an
axis perpendicular to the vertical plane in which the mast 41
extends and means are provided for tilting the base 3 and
therefore the whole mast about this axis. These means for
tilting the base comprise a hydraulic actuator 185 connected
at one end by a pivot 187 to the support brace 183 and at the
other end by a pivot 189 to the cantilevered jib 15 of the
base 3. This particular arrangement advantageously provides
for supplemental adjustment in height of the mast 41 and
better positioning of the delimbing unit 51 when it is
necessary. If necessary, a tensioning cable 182 extending
from the front upper end to the jib 15 to the rear end of
the cantileved guide member 21 can be used for reinforcing
this-guide member 21.
In addition to the above feature, the apparatus
comprises a delimbing unit 191 substantially di~ferent in
shape and size, from the delimbi.ng units 51 described herein-
above in connection with Figs 1 to 7 and 8. This delimbing
unit 191 which is better illustrated on Figs. 10 and 11, is
very compact in size and comprises a support frame 193 freely
connected to the other end of the second arm 45 by a pivot 195
- 13 -
extending across the branches 197 and 199 of a stirrup 201
fixed to the arm 45. The a~is 203 of the pivot 195 advanta-
geously passes subtantially in the middle of'the frame,193
in a direction perpendicular to the vertical plane in which
bo-th legs of the mast ~1 extend, as the pivot 53 was in the two
first embodiments.
As the support Erame 193 is free to rotate about its
pivot 195 within the stirrup 201 the whole delimbing unit 191
may freely follow the trunk of the tree T to be delimbed even
if this trunk is not straight, when the arms of the mast 41
are opened by the actuator 61. In other words, the delimbing
unit 191 is free to "float" along the tree.
The support frame 193 acts as a support for a pair
of delimbing members 205 and 207 that are longitudinally
offset and symmetrically arranged with respect to the pivot
195. The members 205 and 207 are mounted onto the frame 193
adjacent one of their ends by means of pivots 209 and 211.
The members 205 and 207 projects down from the sides of the
frame and are curved toward each other below it.
Means are provided for moving the members 205 and
207 inwardly toward each other and upwardly toward the frame
lg3 of the delimbing unit. The moving means compri.se first
and second hydraulic actuators 213 and 215. The first actuator
213 is pivotably mounted at one end with a pivot 217 to the
frame. The other lower end of the actuator 213 is mounted
- with a pivot 219 to a short arm 221 projecting upwardly and
inwardly from the delimbing member 205 adjacent its pivot
mounting. The second actuator 215 is also pivotably mounted
at one end with a pivot 223 to frame. The other end of the
30- actuator 215 is mounted with a pivot 225 to a short arm 227
projecting upwardly and inwardly from the delimbing membex 207
adjacent its pivot mounti.ng. Operation of the actuators 213
~4Z~6;;2
.
and 215 will move the delimbing members 205 and 207 inwardly
and upwardly about the pivots 209 and 211 with respect to the
frame 193 to cross and tightly hold a tree against this frame.
Th~ leading edge 229 of the frame 193, and the leading edges
231 and 233 oE the cle~imhing mcmbers 205 and 207 delimb the
held tree as the unit 191 is moved forwardly along the tree.
}le delimbing frame 198 ma~ also carry a pair of
cutters 235 and 237 between the delimbing members 205 and 207.
Each cutter 235 and 237 is mounted on the frame with a pivot
239 and 241. The pivots 239 and 241 are located adjacent the
center of the frame just above its level. Hydraulic actuators
243 and 245 are provided for moving the cutters 235 and 237
down and together about the pivots 239 and 241 to cut off the
top of the tree being delimbed after delimbing is completed.
The upper ends of the actuators 2q3 and 245 are mounted with
pivots 247 and 249 to the ends of shorts arms projecting
upwardly and outwardly from the cutters 235 and 237 respectively.
The actuator 243 is mounted with a pivot 251 at its lower end
to the frame while the actuator 245 is similarly mounted with
a pivot 253 at its lower end to the frame. Operation of the
actuators 243 and 245 moves the cutters about the pivots 239
and 241.
The main advantage of this structure lies in that
it makes the delimbing unit 191 very compact while efficient.
Fig. 10 shows a fourth embodiment oE the invention,
which actually is a mere variant of the third embodiment
shown in figs. 9 to 11. In this figure, the parts of the
apparatus identical to those already described with reference
to figs. 1 to 11 have been identified with the same reference
i 30 numbers.
This fourth embodiment of the invention differs
from the third one only in the structure and position of the
- 15 ~
~2~
second actuator of the mast. Instead oE using a second
actuator 61 consisting of a hydraulic cylinder transversally
mounted between the arms 41 and 43 of the mast near the pivot
47, use is made of a hydraulic cylinder 261 connected at one
end by a pivot 263 to the inner bottom side oE the fi.rst
arm 43 near the pivot 49 joining it to the base. The
cylinder 261 is connected at the other end to the central
pivot 263 to a pair of pivotable links 265 and 267 that
are respectively connected by means of pivots 271 and 273
to the arms 43 and 45 of the mast 41 near -the pivot 47.
As can be easily understood, operation of the
cylinder 261 will cause deformation of the irregular
parallelgram formed by the upper ends of the arms 43 and 45
and the links 265 and 267 about -their respective pivots, and
thus will move the second arm 45 relative to the first one
43 in one way or the other.
Last of all, Fig. 13 is a schematic diagramm of a
hydraulic circuit that can be used for actuating the mast.
This circuit basically includes a fluid tank 301,
a pump 303 operated by the motor of the apparatus, a pair of
manually operated valves 305 and 307 for operating the mast
actuators 59 and 61 (or 59 and 261) from the cab 9 of the
apparatus and a relief valve 325. Contrary to the hydraulic
circuits used in the known delimbing apparatuses in which a pump
is required for each actuator, the hydraulic circuit of the
apparatus according to the invention requires only one pump
for operating both mast actuators. This substantial saving
in the energy requested or operating the apparatus according to
the invention and delimbing a tree, results from the structure
and operation of the articulated mast 41. Indeed, when the
mast is operated for delimbing a tree, the centers of gravity of
both arms move downwards and the potential energy to which
amounts the movement of the arm weights can be easily recovered and
- 16 ~
-
and used for saving an additional pump.
In operation, for retracting the mas~, the valves
305 and 307 whose internal arrangements are shown in Fi~. 13
. are both moved downwardly. In this case, the pressurized
Eluid arriving Erom a check valve 309 passes via the valve
305 into the head 311 of the cylinder 59 to move upwardly
the first arm 43. The :Eluid in the bottom 313 oE the cylinder
: is then directed towards the second valve 307 via a connecting
pipe 315 and another check-valve 317, from which it passes
10 into the head 319 of the cylinder 61 (or 261) to retract the
second arm 45 against the first one, the fluid in the
bottom 321 of the second cylinder being recycled to the
~ fluid tank 301.
For opening out the mast and delimbing a tree,
the valves 305 and 307 must both be moved upwardly. In this
particular position, the pressurized fluid arriving from
the pump 303 passes via the valve into the bottom 313 of
the cylinder 59. The fluid in the head 311 of the same
cylinder which is compressed simultaneously by the pressure
applied by the fluid onto the surface of the piston 323
inside -the bottom 313 and by the weight of the arm 43
which pulls the piston 323, then passes via the valve 307 to
the bottom 321 of the second cylinder 51 (or 261) which
operates the second arm 45~ Therefore, as can be seen, the
extra-energy resulting from the movement of the arms is
recovered by the first actuator and used to increase the
power transmitted to the second one.
Of course, other modifications could be made to
the invention which is only limited by the following claims.
