Note: Descriptions are shown in the official language in which they were submitted.
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_chnical Field
This invention relates generally to -tree-trim-
ming apparatus and more particularly to mobile trimming
apparatus having a circular saw mounted at the end of an
extensible boom.
Background oE the Prior Art
A common problem associated with electric utili-
ty lines, pipelines, highways, and railroads is that of
trees or o-ther plant growth encroaching into the right of
way. This encroachment .interferes with the activity
occurring within the right of way. To alleviate this
problem, various methods have been used to clear right of
ways of -this unwanted growth. A truck has been used in
which men are put into a bucket and raised by means of a
boom to the area of the unwanted grow-th. By hand or power
saw the men cut the growth from the right of way. This
method is undesirable for a number of reasons. First, i-t
is necessary to raise a man off the ground up to the area
of the unwan-ted growth. This can be dangerous in any
situation but is especially so in the situation where tree
limbs are being -trimmed from the area around power lines.
A chance of electrocution exists even if extreme caution
is used. Secondly, each time the growth within reach of
the bucket is trimmed the bucket must be lowered to its
traveling position and the truck moved to the nex-t site.
Then it is necessary to again raise the bucket into posi-
tion for trimming -the -trees. The setup involved with this
process is very time-consuming and conse~uently this
method is undesirable for most right of way clearing
applica-tions.
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Other devices have been proposed which alleviate
some of the problems associated wi-th right way of clear-
ing. It has been proposed to mount some kind of cutting
device on the end of a retractable boom which can be
controlled by an operator on or near the ground. This
boom device is then mountecl on a vehicle to give the
cutting apparatus mobility. EIowever, these prior devices
have all contained on~ or more undesirable aspects which
limit their effective use as a right of way clearing
device. For example, many of these devices are construc-
ted so that the boom has a very limited reach. ThereEore,
these cutting apparatus are ineffective for clearing right
of ways where there is very tall tree growth necessitating
a long reach. When attempts have been made to extend the
reach of the boom in these devices other undesirable side
effects have been produced. The extended boom length has
added greatly to the weight of the cutting apparatus and
it has been necessary to stabilize the device by using
outriggers mounted on the sides of the vehicle on which
the cutting apparatus is carried. Each time the device is
moved the outriggers must be lowered into their stabiliz-
ing position. This greatly increases the setup time and
thus lowers the efficiency of the device.
Another problem that must be faced when clearing
the right of way for high voltage utility lines is that of
the potential for electric shock should the boom come into
contact with the power lines. The prime objective in this
situation is to provide the maximum amount of safety for
the operator of the cut-ting apparatus. Prior art boom
tree trimming devices have been unsatisfactory in this
respect in that they have been comprised of materials
;;Lt797
which provide an electrically condu~tive path between the
high voltage lines and the operator. Thus, it has not
been safe to use these -tree--trimming devices in the prox-
imity of high voltage lines.
Brief Summary of the Invention
In order to solve some of the above-mentioned
problems associated with right of way clearing devices the
present invention is proposed. My invention comprises a
mobile support vehicle, preferably all-wheel drive.
Mounted upon the suppor-t veh:icle is a turntable rotatable
about a vertical axis. Means are provided for imparting
rotational motion to the turntable. A pedestal is pivot-
ally mounted about a horizontal axis on the turntable and
means is provided for imparting a pivotal motion to the
pedestal. A boom is mounted on the pedestal and pivots
about an axis normal to the horizontal axis defining the
pivo-tal motion of the pedestal. Means are provided for
imparting the pivotal motion to the boom. Mounted on -the
end of -the boom is a cutting means including means for
imparting cutting motion.
The tree-trimming apparatus is controlled from
an operator's station mounted on one side of the pedestal.
The operator's station is comprised of an operator's chair
and a control panel, from which all of the functions of
the apparatus are controlled. A particular advantage is
realized by allowing the pedestal to -til-t~ which enables
the operator to maintain the operator's station in an
upright and level position even on uneven terrain.
My invention provides significant advantages
over the devices which have heretofore been used -to clear
right of ways. The boom is constructed from a light-
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weight electrically nonconduc-tive flexible ma-terial such
as fiberglass. ~lthouyh portions of the booms on some
utility trucks have been constructed of non-conductive
material, it is believed that this is the only tree-
trimming apparatus capable of utilizing a boom cons-tructed
entirely of fiberglass. This construction is lightweight
and allows the tree-trimming apparatus to be used without
the necessity of outriggers mounted on the -truck for
stablization. The electrically nonconductive boom also
provides a safer working environment for the opera-tor
since there is no conductive path between the end of the
boom and the operator.
The fiberglass construction also provides the
~¦- boom with flexibility, allowing it to withstand any im-
pacts which could occur during its use. A high-speed
hydraulic motor is provided to power a large diameter
circular saw mounted a-t the end of the boom. This results
in a very high tangential velocity or tooth speed per~
mitting cuts to be made with ease. Conse~uently, the
cutting time required per tree is decreased, thus in-
creasing the number of trees which can be cut in a given
length of time.
Various advantages and features of novelty which
characterize the invention are pointed out with particu-
larity in the claims annexed hereto and forming a part
hereof. However, for a be-tter understanding of the inven-
tion, its advantages, and objects obtained by its use,
reference should be had to the drawings which form a
further part hereof, and to the accompanying descriptive
matter, in which there is illustra-ted and described a
preferred embodiment of the invention.
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Brief Descr1ption of the Drawin~
FIGURE 1 is a perspective view of the tree~trim-
ming apparatus mounted on a mobile carrier showing the
boom partially elevated.
FIGURE 2 is a perspective view of ~he rear of
-the tree-trimminy apparatus showing the boom partially
eleva-ted.
FIGURE 3 is a partial transverse section of the
boom broken away showing the relationship of the boom
sections and the boom extending and retracting mechanism.
FIGURE 4 is a sectional view of the boom taken
generally along line 4-4 of FIGURE 3.
FIGURE 5 is a cross-sec-tional view of the boom
taken generally along line 5-5 of FIGURE 3.
FIGURE 6 is a cross-sectional view of the boom
taken generally along line 6-6 of FIGURE 3.
FIGURE 7 is a partial sectional view of the
tree-trimming apparatus taken generally along line 7-7 of
FIGURE 1 showing the turntable drive assembly.
20FIGURE 8 is a schematic o the hydraulic system
which powers the tree-trimming apparatus.
Detailed Description of the Invention
The construction of the tree-trimming apparatus
can be understood with reference to FIGURES 1 and 2. The
tree-trimming apparatus is mounted upon a mobile support
vehicle 11. Mobile support vehicle 11 is preferably all
wheel drive to enable it to travel over the rough terrain
associated with many right of ways. Rotatably mounted
upon support vehicle 11 is a turntable 12. Turntable 12
is supported by rollers 13 permanently affixed to support
vehicle 11.
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Mounted upon turntable 12 is a pedestal 14.
Pedestal 14 is pivotally mounted about a horizontal axis
defined by pin 15 which secures pedestal 14 to mounting
brackets 16. Moun-ting brackets 16 are permanently affixed
to turntable 12 in any conventicnal manner. Pivotal
motion is supplied to pedestal 14 by means of a hydraulic
cylinder 20, which is pivotally mounted at point 24 to
turntable 12 and a-t point 25 to the pedestal 14. Cylinder
~- 20 is supplied with fluid under pressure from a pump 21
connected -to cylinder 20 by condui-t not shown. In the
preferred embodiment, all of the hydraulic conduit used in
the tree-trimming apparatus is electrically non-conductive
in order to provide the maximum amount of elec-trical
isolation possible should the apparatus come into contac-t
with power lines. Pump 21 is affixed to and driven by a
suitable engine 22, preferably a diesel engine, which is
exhausted through pipe 19. Diesel fuel for engine 22 is
stored in tank 23.
An operator's station 26 is affixed to one side
of pedestal 14. Operator's station 26 comprises a control
- panel 30 and an operator's chair 31. Control levers 29
are mounted on control panel 30 and provide the operator
with control over the positioning movements of the tree-
trimming apparatus. In the preferred embodiment,
operator',s station 26 is attached to pedestal 14 entirely
by electrically non~conductive material isolating the
operator from the rest of the tree-trimming apparatus.
Mounted at the end of pedestal 14 is a boom
carriage 35 which cradles boom 32. In the preferred
embodiment shown in the FIGURES the boom 32 consists of an
inner boom member 33 telescopically mounted inside an
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outer boom member 34. Boom 32 is attached to boom car-
rlage 35 by me-tal straps 36 which are secured to flanges
37 by bolts 38. Boom carriage 35 is pivotally mounted to
pedestal 14 at point 40. Pivotal mo-tion is imparted to
the boom by cylinder 41 which is pivotally connec-ted to
boom carriage 35 at point 42 and to pedestal 14 at a point
39. Cylinder 41 is supplied with fluid under pressure
from pump 21 through conduit not shown. Boom extending
and retracting motion is powered by hydraulic motor 43
which is supplied with fluid under pressure rom pump 21
by conduit not shown. A more detailed description of -the
boom ex-tending and retracting mechanism is contained
hereafter.
Mounted at the end of inner boom member 33 is
cutting assembly 44. Cu-tting assembly 44 cons:ists of a
circular saw 45 powered by a hydraulic motor 46 which is
supplied with fluid under pressure by pump 21. A saw
guard 50 is supplied to help eliminate the possibility of
debris being thrown backwards in the direction of -the
; 20 operator. Guard 50 is designed so -that it allows a maxi-
mum amoun-t of the cutting surface of circular saw 45 to be
exposed while still affording pro-tection to the operator.
In the preferred embodiment of the invention at least 240
of the circumferential surface of circular saw 45 is
unshielded by guard 50. This large saw blade exposure in-
creases the efficiency of the tree-trimming apparatus.
For example, in a typical cutting sequence the boom could
be raised to cut a limb above it using the top of circular
saw 45 as the cutting surface. A lower limb could then be
cut by lowering the boom and using -the bottom of circular
saw 45 as the cutting surface. Next, a limb far-ther away
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could be cut by extending -the boom and using the front
edge of circular saw 45 as the cutting surface. This
variety of useable cutting surfaces allows many limbs to
be cut in a short period of time. A more detailed de-
scription of the operation o1E cutting assembly 44 follows
hereafter with re~erence to FIGURES 3-6.
The system for rotating turntable 12 can be
understood with reference to FIGURE 7. A hydraulic motor
47 mounted on -turntable 12 supplies the power for impart-
ing rotational motion -to turntable 12. Hydraulic motor 47
receives fluid under pressure from pump 21. Condui-ts 48
provide the path through which fluid is supplied from and
returned to pump 21. A shaft 49 extends from motor 47
through a spring loaded pressure off brake 51 to a fixed
point on support vehicle 11 where it is held secure. As
rotational motion is imparted by hydraulic motor 47 it
causes turntable 12 to rotate since shaft 49 is secured to
suppor-t vehicle 11. Reduction of rotational speed is
achieved by use of a standard plane-tary gearing system not
shown, but connected between motor 47 and shaft 49 within
-the housing of brake 51. Spring loaded pressure off brake
51 is provided as an additional safety measure. Brake 51
allows -turntable rotation only when adequate fluid pres-
sure is being received by motor 47. When motor 47 is off
or should a conduit ~ailure occur during its use, brake 51
; is applied-to prohibit further rota-tion of turntable 12.
The operation of the cutting assembly 44 and
boom 32 can be understood with reference -to FIGURES 3, 4,
5 and 6. Inner boom member 33 is telescopically mounted
within outer boom member 34 by use of annular bearing
members 60 and 61. In the preferred embodiment bearing
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members 60 and 61 are fabricated from an ultra-high mole-
cular weigh-t polyethylene material which provides a smoo-th
slidable con-tact surface between boom members 33 and 34.
Bearing member 60 is firmly bonded to outer boom member 34
and has an inner circumferential openlng slightly larger
than the circumference of inner boom member 33. A longi-
-tudinal alignmen-t element 58 at-tached to the outer circum-
ferential surface of inner :boom member 33 mates with a
keyway 59 formed in bearing member 60 in order to maintain
rotational alignment between boom members 33 and 34.
Bearing me~lber 61 is firmly bonded -to the outer circumfer-
ential surface of inner boom member 33 and has an outer
circumferential dimension smaller than the inner circum-
ferential dimension of outer boom member 34. The dimen-
sions of bearings 60 and 61 are sized so that inner boom
member 33 is allowed to move freely wi-thin outer boom
member 34 while maintaining a firm fit between surfaces so
that control of the boom is maintain~d.
Boom retracting and extending movements are
imparted by way of hydraulic motor 43 which is firmly
attached to boom carriage 35. A sprocke-t 62 is attached
to -the end of the shaft of hydraulic mo-tor 43. Sprocket
62 engages a length of chain 63. One end of chain 63 is
firmly affixed to inner boom member 33 a-t poink 64. The
other end of chain 63 is affixed to a high strength cable
65 at connector 66. Cable 65 is threaded through pulley
67 and then connected to inner boom member 33 at point 70.
From -these connections it can be seen that as hydraulic
motor 43 is operated in the direction of boom extension
sprocket 62 will engage chain 63, causing inner boom
member 33 to move outwardly from within ou-ter boom member
34. If hydraulic motor 43 is caused to operate in the
opposite direction inner boom member 33 will be caused to
retract in-to outer boom member 34.
The boom extension and retraction movements are
controlled by an operator from operator's station 26.
However, there is also a mechanically actuated control
which preven-ts the boom from either extending or retract-
ing too far. This mechanical con-trol is provided by
valves 71 mounted on boom carriage 35. One of valves 71
is connected in the conduit supplying ~luid to power -the
forward ro-ta-tion of motor 47 and the other is connec-ted in
the conduit supplying fluid to power the reverse rotation
of motor 47. Each of valves 71 has a pair of arms 72
between which chain 63 is positioned. Chain 63 will move
freely between each pair of arms 72 as the boom is either
extended or retracted. Trip elements 68 are attached to
chain 63 and positioned so that when the boom is either
extended or retracted to the maximum desirable extent one
of the -trip elements will trip one of arms 72, closing the
associated valve 71. This will shut off the flow of
hydraulic fluid to motor 43 in either the forward or the
reverse direction depending upon which of valves 71 is
closed.
Cut-ting assembly 44 is mounted on the end of
inner boom member 33 by means of a mounting cap 73.
Mounting cap 73 fits over the end of inner boom member 33
and may be secured in place in any con~entional manner.
Cutting assembly 44 is secured to mounting plate 78, which
is rotatably secured to end cap 73 about a bolt 74 which,
as seen in FIGURE 6, extends through aligning openings in
mounting cap 73 and mounting plate 78. The cutting assem-
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bly 44 is held in place by spring loaded locking pins 75,which are mounted on moun-ting plate 78. Mounting cap 73
is provided with grooves 77 which mate with locking pins
75 in order to lock cutting assembly 44 in the desired
position. In -the drawing the cutting assembly 44 is shown
locked in a vertical position. The cutting assembly 44
can be rota-ted 90 by releasing the locking pins 75 and
manually ro-tating the cutting assembly 44. Additional
grooves 77 are provided in mounting cap 73 so that locking
pins 75 will lock the cutting assembly 44 in a horizontal
position.
Circular saw 45 is powered by hydraulic motor
46. ~Iydraulic motor 46 is supplied with fluid under
pressure from pump 21 through hydraulic conduit 76 as seen
in FIGURES 3-6. Conduit members 76 travel from pump 21
along the external underside of outer boom member 34 -to
openings 80 where they enter the boom and lie between
. inner boom member 33 and outer boom member 34. Conduit
. members 76 then double back along the internal underside
:~20 of outer boom member 34 and travel through arcuate slot 83
in bearing member 61. They are then threaded through
pulley 81 and travel -the rest o~ the way to mo-tor 46
inside inner boom member 33.
In order to eliminate the possibility that
condui-t members 76 might interfere with boom extension and
retraction movements, conduit members 76 are strung
through a spring loaded pulley 81 which is connected to a
spring rewind 82 which is mounted to the inner surface of
outer boom member 34. During boom extending movements
spring loaded pulley 81 allows conduit members 76 to move
outwardly with inner boom member 33. Thus, the proper
conduit length and tension is always maintained and the
risk of conduit failure is kep-t to a minimum.
In the preferred embodiment of the invention the
cutting efficiency of the tree-trimming apparatus is
grea-tly enhanced by using a high speed motor 46 to drive a
large diameter circular saw ~5. For example, in the
preferred embodiment, motor 46 produces 5000 rpm driving
circular saw 45, which is 18 inches in diameter. This
cor~ination provides a blade -tooth speed of about 265 mph.
This high tooth speed allows even larye diameter limbs to
be cut ~uickly and with ease.
In FIGURES 5 and 6 the position of condui-t
members 76 with respect to inner boom member 33 and outer
boom member 34 can be seen. An arcuate slot 83 is left in
bearing member 61 to allow conduit members 76, chain 63,
and cable 65 to pass freely. FIGURE 6 shows the position
of conduit members 76 inside inner boom member 33. Con-
duit members 76 enter cutting assembly 44 through an
opening 84 in end cap 73.
The operation of the tree-trimming apparatus can
be understood with reference to FIGURE 8, which is a
schematic diagram of the hydraulic circuit used to operate
and control the tree-trimming apparatus. The system is
supplied with fluid under pressure from pump 21, which, in
the preferred embodiment, is a pair of stacked pumps.
Stacked pumps 21 are driven by an internal combustion
engine 22. In the preferred embodiment of the invention
engine 22 is a diesel engine. Hydraulic fluid is supplied
~rom reservoir 90, which is located inside the base of
pedestal 14. Five control elements which are located on
control panel 30 are included in the circuit. These are
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push button 91, and con-trol levers 92, 93, 94, and 95.
Control levers 92-95 control -the various positioning
movements of -the boom by mechanically varying -the position
of a four-way control valve which is associated with each
lever. Their fluid pressure supply is delivered by way of
conduit 96. Conduit 100 returns the fluid to the reser-
voir through filter 101.
Con-trol lever 92 operates cylinder 20 which
varies the degree of tilt of pedestal 14. Fluid is sup-
plied to cylinder and piston 20 by means of conduits 102and 103. In the preferred embodiment, cylinder 20 will
-tilt pedestal 14 up to 20 in either direc-tion. As an
added safety feature, cylinder 20 is provided with load
check valves 104 and 105. Under normal operating condi-
tions fluid will be freely supplied to cylinder 20 through
conduits 102 and 103. However, if for any reason there is
a loss of fluid pressure in either condui-t 102 or 103,
this will be sensed by load check valves 104 and 105 and
they will close and safely keep the tilt pOSitiOIl of the
pedestal stationary.
Control lever 93 controls the operation of
hydraulic motor 47 which powers the rotation of turntable
12. Fluid is supplied to motor 47 through conduits 106
and 110. Hydraulic motor 47 is a reversible motor and
allows the turntable 12 to rotate in either direction.
Flow controls 111 and 112 are provided in conduits 106 and
110 and can be adjus-ted in order to control the response
of motor ~7 to the operation of control lever 93. As an
added safe-ty precaution a spring-loaded pressure off brake
51 is connected between conduits 110 and 106. As pre-
viously discussed, when mo-tor 47 is off or should a pres-
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sure failure occur brake 51 will be applied and the rota-
tion of turntable 12 will automatically stop. This en-
sures that under conditions where a conduit failure occurs
or where the apparatus is used on uneven ground there will
be no ~mcontrollable rotation of turntable 12.
Hydraulic motor 43 which powers the extension
and retraction of boom 32 is opera-ted by control lever 94.
Fluid is supplied to hydraulic mo-tor 43 through conduits
114 and 115. A flow contro;L 116 is provided in conduit
115 and allows the operator to control the response of
motor 43 to control lever 94. Flow control 116 is loca-ted
so that it is within reach of the operator in order to
allow the operator to ad]ust -the response as he is op-
erating the tree-trimming appara-tus. ~echanically
actuated valves 71 are provided in conduits 114 and 115.
As previously discussed, valves 71 are activated by -trip
elements 68 connected to chain 63. By setting the trip
elements in -the proper position on chain 63, the maximum
amount of extension and retraction of the boom can be set.
The boom elevation is controlled by lever 95
which operates cylinder 41. Fluid is supplied to cylinder
41 through conduits 120 and 121. Cylinder 41 is provided
with a load check valve 122 -to ensure safe operation of
the boom. If for any reason load check valve 122 senses a
pressure failure, it will close, keeping the elevation of
the boom stationary. Without this feature, a conduit
failure could cause the boom eleva-tion to drop rapidly,
creating a hazardous situation.
Push button 91 is used to ac-tivate hydraulic
motor 46, which powers circular saw 45. Push button 91 is
connected to stack pumps 21 through conduit 123. A dis-
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charge conduit 124 connects hydraulic motor 46 to reser-
voir 90 through a fluid cooli-ng heat exchanger 125 and a
fil-ter 126. A special flow sensing valve 130 is provided
to ensure -the proper operation and safety of the system.
When push ~utton 91 is on, valve 130 is closed and hydrau-
lic motor 46 receives fluid flow through conduit 131. In
the preferred embodiment circular saw ~5 has a large
diameter, for example, 18 inches. Also, hydraulic motor
46 is a high-speed mo-tor ]providin~ a tooth speed of
approximately 265 miles per hour. The co~ination of high
tooth speed and large saw blade provides a high inertia
for circular saw 45. Consequently, when push bu-tton 91 is
turned off, stopping the supply of fluid from pump 21, the
large intertial force acting on motor 46 from circular saw
45 will cause mo-tor 46 to continue its rotation and cause
it to act like a pump. Flow sensing valve 130 senses the
change of pressure due to the closing of push button 91
and opens the path through conduit 132. This provides a
closed loop -through which motor 46 can harmlessly pump
fluid. If not for the presence of flow sensing valve 130,
the pumping action of motor 46 would cause it to draw a
vacuum in conduit 131 strong enough to cause conduit
failure or damage.
Numerous characteristics and advantages of the
invention have been set for-th in the foregoing descrip-
tion, together with details of the structure and function
of the invention, and the novel features -thereof are
pointed out in the appended claims. The disclosure,
however, is illustrative only, and changes may be made in
detail, especially in matters of shape, size, and arrange-
ment of parts, within the principle of the invention, to
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the full extent extended by the broad general meaning of
the terms in which the appende~ claims are expressed.
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