Note: Descriptions are shown in the official language in which they were submitted.
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SAW APPARATUS WITH CHAIN STRETCH DETECTION
Field of the Disclosure
[001] The present disclosure relates to a saw apparatus including an endless
cutting chain.
Background of the Disclosure
[002] There are forestry machines that have a forestry head to fell a tree and
to
buck the tree into one or more logs. The head has a saw to perform such sawing
operations.
[003] The endless cutting chain of the saw has broken during sawing causing a
portion of the chain to fly away from the saw area. The chain failures result
from
chain link stretching and direct damage to the chain. Stretching fatigues the
metal
enabling fragment separation from the chain.
[004] It is an object of the present invention to address the foregoing
problems or
at least to provide the public with a useful choice.
[005] Throughout this specification, the word "comprise", or variations
thereof
such as "comprises" or "comprising", will be understood to imply the inclusion
of a
stated element, integer or step, or group of elements integers or steps, but
not the
exclusion of any other element, integer or step, or group of elements,
integers or
steps.
Summary of the Disclosure
[006] According to an aspect of the present disclosure, a saw apparatus
comprises a mount, a chain support attached movably to the mount for movement
relative thereto, a chain driver, an endless cutting chain trained about the
chain
support and the chain driver, a chain tensioner urging the chain support to
move
relative to the mount to tension the chain, and a sensor positioned to sense a
position of the chain support relative to the mount.
[007] According to another aspect of the present disclosure, the saw apparatus
comprises an electronic control system. The sensor is configured to generate a
position signal indicative of the position of the chain support relative to
the mount.
The control system is configured to receive the position signal, and determine
if the
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cutting chain has stretched to a stretch threshold that is dependent on the
position of
the chain support relative to the mount. The control system may be configured
to
activate an alert if the cutting chain has stretched to the stretch threshold.
The saw
apparatus may thus be configured to determine chain stretch during usage of
the
saw apparatus to determine if there is an increased risk of chain breakage.
[008] The above and other features will become apparent from the following
description and the attached drawings.
Brief Description of the Drawings
[009] The detailed description of the drawings refers to the accompanying
figures
in which:
[010] FIG. 1 is a diagrammatic view showing a saw apparatus including, for
example, a forestry head;
[011] FIG. 2 is an elevational view showing the forestry head;
[012] FIG. 3 is a perspective view, with portions broken away, showing a
chain
saw of the forestry head;
[013] FIG. 4 is a perspective view, with portions of the saw broken away;
[014] FIG. 5 is an exploded perspective view showing a chain support of the
saw;
[015] FIG. 6 is an exploded perspective view showing the chain support
exploded
from a swing of the saw;
[016] FIG. 7 is a perspective view showing the chain support assembled to the
swing and a sensor positioned to sense a position of the chain support;
[017] FIG. 8 is a sectional view taken along lines 8-8 of FIG. 7 showing a
first
groove of an arm of the swing;
[018] FIG. 9 is a sectional view taken along lines 9-9 of FIG. 7 showing a
second
groove of the swing arm, and a sensor target embedded within a bar holder;
[019] FIG. 10 is a diagrammatic view showing a control system of the saw
apparatus; and
[020] FIG. 11 is a flow chart showing a control scheme of the saw apparatus.
Detailed Description of the Drawings
[021] Referring to FIG. 1, a saw apparatus 10 may be configured as a forestry
machine that includes, for example, a self-propelled base machine 12, a
forestry
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head 14, a boom assembly 16 attached pivotally to the base machine 12, and a
coupler 17 interconnecting the boom assembly 16 and the head 14. The base
machine 12 may be a track-type machine (FIG. 1) or a wheeled machine, either
of
which may have an operator's station at which a human operator may control the
apparatus 10 and its head 14.
[022] Referring to FIG. 2, the forestry head 14 may be any type of forestry
head
with a saw. In FIG. 2, the forestry head 14 is configured, for example, as a
harvester
head. In such a case, the coupler 17 may be configured in any suitable manner
so
as to suspend the head 14 from an end of the boom assembly 16. For example,
the
coupler 17 may be configured for pivoting of the head 14 between a generally
upright, felling position and a generally prone, processing position, and may
include
a frame 18 attached pivotally to the coupler 17 and a chain saw 20 attached to
the
frame 18 and configured to fell a tree in the harvesting position of the head
14 and to
buck the tree into one or more logs in the processing position of the head 14
(the
chain of chain saw 20 not shown in FIG. 2 for simplification of illustration).
[023] The head 14 may include a number of other features, such as, for
example,
a number of feed wheels 22, a number of delimb arms 24, a front delimb knife
26, a
length-measurement wheel 28, and a topping saw 30. Two of the feed wheels 22
are attached respectively to two feed arms 32 attached pivotally to the frame
18, and
a number of feed wheels 22 (e.g., one) may be attached to the frame 18 such
that its
axis of rotation is fixed relative to the frame 18. Each of the delimb arms 24
and the
delimb knife 26 has a blade for delimbing the tree when the tree is fed past
the arms
24 and knife 26 by the feed wheels 22 during processing. The topping saw 30
may
be used to cut off a small-diameter top portion of the tree to maximize the
value
recovery of the tree (the chain of topping saw 30 not shown for simplification
of
illustration).
[024] Referring to FIGS. 3 and 4, the saw 20 is mounted to a saw housing 32 of
the frame 18. The saw 20 includes an endless cutting chain 34, a chain support
36,
a chain driver 38, and an attachment device 40 attaching the chain 34, the
chain
support 36, and the chain driver 38 to the saw housing 32.
[025] The attachment device 40 includes a saw support ring 42 fastened to the
saw housing 32 with threaded fasteners, a driver support ring 44 fastened to
the saw
support ring 42 with threaded fasteners, a bearing support ring 46 fastened to
the
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driver support ring 44 with threaded fasteners, a bearing 48, and a swing 50.
The
swing 50 includes an arm 52 and an arm support ring 54 to which the arm 52 is
fastened with threaded fasteners. The bearing 48 is positioned between the
bearing
support ring 46 and the arm support ring 54 for rotation of the swing 50, the
chain
support 36 attached to the swing 50, and the chain 34 attached to the chain
support
36 about an axis of rotation 56 of the chain driver 38.
[026] The chain support 36 includes a guide bar 58 and a bar holder 60 holding
the guide bar 58. The chain 34 is trained about the guide bar 58 and the chain
driver
38. The bar holder 60 is attached movably to a mount 62 of the saw apparatus
10
for movement of the bar holder 60 and the guide bar 58 relative to the mount
62.
[027] The mount 62 may be any suitable mount to which the bar holder 60 may be
attached movably. In the illustrated example, the mount 62 includes the base
machine 12, the boom assembly 16, the coupler 17, the frame 18, and the
attachment device 40. In such a case, the bar holder 60 is attached movably to
the
swing 50 for movement of the bar holder 60 and the guide bar 58 relative to
the
swing 50. Exemplarily, the bar holder 60 is attached movably to the arm 52 for
movement of the bar holder 60 and the guide bar 58 relative to the arm 52.
[028] The chain driver 38 includes a hydraulic motor 64 and a sprocket 66. The
sprocket 66 is attached to an output shaft of the motor 64 for rotation about
the
rotation axis 56. The chain 34 is trained about the sprocket 66.
[029] A hydraulic swing cylinder 68 is attached to the arm 52 and the frame 18
therebetween. The cylinder 68 is operable to pivot the swing 50, the chain
support
36, and the chain 34 about the rotation axis 56 between a stowage position
retracted
into the saw housing 32 and a deployed position during a sawing event (e.g.,
felling,
bucking).
[030] Referring to FIGS. 5 and 6, the bar holder 60 includes a first plate
70, a
second plate 72, and a connector 73 connecting the first and second plates 70,
72
therebetween. The connector 73 includes a T-shaped body 74 and a support body
76. The T-shaped body 74 and the support body 76 are positioned between the
first
and second plates 70, 72. The base of the T-shaped body 74 is positioned
against
the first plate 70, and the support body 76 is positioned against the second
plate 72.
The cross member of the T-shaped body 74 merges into the support body 76 such
that the T-shaped portion and the support body 76 cooperate to form an L-
shaped
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body 77. Exemplarily, the plates 70, 72, T-shaped body 74, and support body 76
cooperate to form a monolithic body cut out of a block of material.
(0313 An end portion of the guide bar 58 has two tongues 78 with a slot 80
open at
one end defined between the tongues 78. The guide bar 58 is fitted to the bar
holder
60 such that the base of the T-shaped body 74 is positioned in the slot 80
with the
tongues 78 positioned on either side of the base of the T-shaped body 74 and
between the L-shaped body 77 and the first plate 70, in particular, between
the first
plate 70 and the cross member of the T-shaped body 74 and the support body 76.
Two threaded fasteners 82 fasten respectively the tongues 78 to the first
plate 70,
thereby attaching the guide bar 58 to the bar holder 60. Each fastener 82
includes a
threaded portion that is proximal to the head of the fastener 82 and threaded
to the
first plate 70 and an unthreaded portion that is distal from the head, smaller
in
outside diameter than the threaded portion, and positioned in a respective
unthreaded hole of the tongue 78.
[032] Referring to FIGS. 7 and 8, the bar holder 60 is fitted to the swing
arm 52.
The swing arm 52 has a slot 84 open at a first end thereof. The connector 73,
for
example its L-shaped body 77, is positioned in the slot 84. The arm 52
includes a
first branch 86 and a second branch 88. The slot 84 is defined between the
branches 86, 88. When the connector 73, for example its L-shaped body 77, is
positioned in the slot 84, the first plate 70 and the tongues 78 are
positioned to a
first side of the swing arm 52, and the second plate 72 is positioned to a
second
side of the swing arm 52 opposite to the first side. The first plate 70
overlaps the first
and second branches 86, 88 such that the two tongues 78 are positioned
respectively between the first and second branches 86, 88. The second plate 72
overlaps the first and second branches 86, 88.
[033] Referring to FIG. 4, the saw 20 includes a chain tensioner 90 urging
the bar
holder 60 and the guide bar 58 to move relative to the mount 62 to tension the
chain
34. The chain tensioner 90 is attached to the swing 50 and its arm 52 and
includes,
for example, a piston and a spring urging the piston to extend through an
opening in
an end wall of the slot 84. During operation, the piston is under hydraulic
pressure
that urges the piston to extend through that opening. During replacement of
the
chain 34, the hydraulic pressure is relieved, allowing manual retraction of
the piston
against the spring to facilitate chain removal and subsequent installation of
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chain. Manual pressure on the piston is released so that the spring pre-
tensions the
chain. Hydraulic pressure is then re-introduced to raise the chain tension to
an
operational level.
[034] The chain tension 90 contacts the bar holder 60. The piston of the chain
tensioner 90 contacts the T-shaped body 74 of the bar holder 60 so as to urge
the
bar holder 60 and the guide bar 58 away from the swing 50 and its arm 52,
thereby
tensioning the chain 34.
[035] Referring to FIG. 8, the bar holder 60 is positioned for slidable,
linear
movement in the slot 84 relative to the swing 50 and its arm 52 and thus
relative to
the mount 62 in response to pressure from the chain tensioner 90. The swing 50
is
configured to guide the bar holder 60 and thus the guide bar 58 so as to move
linearly. The connector 73, for example its L-shaped body 77, is positioned
laterally
between the branches 86, 88 for slidable movement against the branches 86, 88.
The branches 86, 88 are positioned transversely between the first and second
plates
70, 72 and between the second plate 72 and the tongues 78.
[036] Referring to FIGS. 8 and 9, the arm 52 of the swing 50 includes a
linear first
groove 92 in the first branch 86 and a linear second groove 94 in the second
branch
88. The second plate 72 overlaps the first and second grooves 92, 94. The bar
holder 60 includes a first post 96 and a second post 98. Each post 96, 98
includes,
for example, a threaded portion that is proximal to the head of the post 96,
98 and
threaded to the second plate 72 and an unthreaded portion that is distal from
the
head and smaller in outside diameter than the threaded portion.
[037] The first post 96 extends through the second plate 72 into the first
groove 92
for linear, slidable movement in and against the first groove 92, as shown,
for
example, in FIG. 8. The threaded portion of the first post 96 is threaded to
the
second plate 72, and the unthreaded portion is positioned in the first groove
92. The
first post 96 can contact the opposite, closed ends of the first groove 92 to
limit travel
of the bar holder 60 and the guide bar 58 relative to the swing 50 and its arm
52.
[038] Referring to FIG. 9, the second post 98 extends through the second plate
72
into the second groove 94 for linear, slidable movement in and against the
second
groove 94. The threaded portion of the second post 98 is threaded to the
second
plate 72, and the unthreaded portion is positioned in the second groove 94.
[039] The bar holder 60 comprises a sensor target 100. The sensor target 100
is
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embedded within the bar holder 60. For example, the sensor target 100 is
embedded within the second plate 72 of the bar holder 60. The second plate 72
includes a hole 109, and the sensor target 100 is positioned and secured
within the
hole 109 (e.g., press fit into the hole 109). If the hole 109 is a through-
hole, filler
material (not shown), e.g., epoxy, may fill the hole 109 above the sensor
target 100,
inhibiting ingress of debris into the hole 109. The sensor target 100 is thus
in
register with the second groove 94 for linear movement along the second groove
94
with the bar holder 60. The sensor target 100 is configured, for example, as a
permanent magnet.
[040] Alternatively, the sensor target 100 may be attached to a tip of the
second
post 98 so as to be mounted thereto. In such a case, the sensor target 100 is
positioned in the second groove 94 for linear movement therein as the bar
holder 60
moves linearly.
[041] Referring to FIGS. 7 and 9, the saw 20 has a sensor 102 positioned to
sense a position of the chain support 36 relative to the mount 62. The sensor
102 is
positioned to sense a position of the bar holder 60 relative to the swing 50
and thus
the mount 62 by use of the sensor target 100 of the bar holder 60. The sensor
102
is configured to generate a position signal indicative of the position of the
sensor
target 100 of the bar holder 60 of the chain support 36 relative to the swing
50 of the
mount 62.
[042] The sensor 102 is configured, for example, as a magnetostrictive linear
position sensor configured to sense linear position. In such a case, the
sensor 102
has an electronics unit 104 and a magnetostrictive sensing element 106 in the
form
of a longitudinal waveguide. The electronics unit 104 is positioned in a
cavity 108 of
the arm 52. The cavity 108 is filled with a filler material (not shown), e.g.,
epoxy,
sufficient to secure the unit 104 in the cavity 108. The sensing element 106
is
positioned in the second groove 94 so as to extend longitudinally therein and
is used
to determine the position of the sensor target 100 along the length of the
sensing
element 106. A dead band 107 is positioned at either end of the sensing
element
106. The second groove 94 is filled with a filler material (not shown), e.g.,
epoxy,
sufficient to secure the sensing element 106 in the second groove 94. The
filler
material may only partially fill the second groove 94, allowing space for the
post 98 to
extend into and move linearly in the second groove 94. In an example, the
sensor
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102 is model C-S-0072-V-P1 available from MTS Systems Corporation, Sensors
Division, in Cary, North Carolina.
[043] In another example, the sensor target 100 may comprise a series of
magnets mounted to the plate 72 of the bar holder 60 (e.g., via a magnet
carrier) and
arranged linearly relative to one another along the linear path of movement of
the bar
holder 60. In the case where the sensor 102 is a magnetostrictive linear
position
sensor, the sensor 102 may be configured to sense the position of those
magnets
with the sensing element 106 (e.g., in the form of a longitudinal waveguide)
and
resolve those measurements into a single voltage output from the electronics
unit
104 indicative of the position of chain support 36, and its bar holder 60,
relative to
the mount 62. Use of the series of linearly arranged magnets promotes accuracy
and error reduction in the position determination. The electronics unit 104
may be
smaller than depicted in the drawings, and the sensing element 106 may be
without
a deadband at each of its opposite ends. The sensor target 100 and the sensor
102
may be mounted respectively to the bar holder 60 and the arm 52 in any
suitable
manner.
[044] Referring to FIG. 10, the saw apparatus 10 includes an electronic
control
system 110. The control system 110 includes one or more electronic
controllers,
each controller including a processor and memory having stored therein
instructions
which, when executed by the processor, causes the processor to perform the
various
operations of the controller. For example, the control system 110 includes a
first
controller 112 on board the head 14 and a second controller 114 on board the
base
machine 12. The controllers 112, 114 are connected to one another via a
communications bus 116 (e.g., a CAN bus). The sensor 102 is coupled
electrically
to the first controller 112. The head 14 has a number of valves 118 arranged,
for
example, in a valve block and coupled electrically to the first controller 112
so as to
be under its control. The valves 118 include, for example, a motor valve
configured
to control operation of the motor 64 and a swing valve configured to control
pivotal
movement of the swing 50.
[045] Referring to FIG. 11, the control system 110 is configured to perform
a
control scheme 210. As part of the control scheme 210, the control system 110
is
configured to receive the position signal and determine if the cutting chain
34 has
stretched to a stretch threshold dependent on the position of the sensor
target 100 of
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the bar holder 60 of the chain support 36 relative to the swing 50 of the
mount 62 in
order to determine if a risk of chain breakage has increased. In an example,
the
control system 110 may be configured to monitor a stretch trend of the chain
34 and
determine if the stretch trend reaches the stretch threshold. In so doing, the
control
system 110 may be configured to determine a predicted stretch indication and
an
actual stretch indication and to determine if the actual stretch indication
exceeds the
predicted stretch indication by at least the stretch threshold. The control
system 110
may activate an alert if the actual stretch indication does exceed the
predicted
stretch indication by at least the stretch threshold. An example of the
control
scheme 210 is shown in FIG. 12.
[046] In step 212 of the control scheme 210, a human operator operates an
operator input device 122 located at the operator's station of the base
machine 12 in
response to which the second controller 114 receives from the operator input
device
122 an operate-saw request signal indicative of a request from the human
operator
to operate the saw 20. In response to the operate-saw request signal, the
second
controller 114 broadcasts an operate-saw request message on the bus 116. The
first controller 112 receives that message and, in response thereto, outputs
control
signals to the two valves 118 responsible respectively for controlling the
motor 64
and the swing cylinder 68 and takes an initial position reading, Po, of the
position of
the sensor target 100 from the sensor 102. The first controller 112 stores
this initial
position reading in its memory so as to begin a historical watch of the
behavior of the
chain 34. Before the control scheme 210 advances to step 214, the first
controller
114 may set a counter variable, n, equal to 1 and a variable Ssum equal to 0.
[047] Step 214 relates to the next time that a human operator operates the
operator input device 122. In step 214, the second controller 114 receives
from the
operator input device 122 the operate-saw request signal indicative of another
request from the human operator to operate the saw 20. In response to that
operate-saw request signal, the second controller 114 broadcasts an operate-
saw
request message on the bus 116. The first controller 112 receives that message
and, in response thereto, outputs control signals to the two valves 118
responsible
respectively for controlling the motor 64 and the swing cylinder 68 and takes
a
position reading, Pn, of the position of the sensor target 100 from the sensor
102. Pn
would be P1 if it is the position reading immediately after Po, or P2 if it is
the position
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reading immediately after P1, and so on. As such, Po and P1 are consecutive
position readings, and Pn and Pn+i are consecutive positions readings. The
control
scheme 210 advances to step 216.
[048] In step 216, the first controller 112 determines an actual stretch
indication,
Sn, indicative of an actual stretch in the length of the chain 34 between Pn
and Po-i.
In an example, the first controller 112 determines the actual stretch
indication
according to the following equation:
= Pt ¨
3_, ________________________________________ (100)
1-71-1 .
In such a case, the actual stretch indication is an actual stretch percentage.
[049] In step 218, the first controller 112 determines if n is greater than
or equal to
2. If yes, the control scheme 210 advances to step 220. If no, the control
scheme
210 advances to step 228 in which the first controller 112 adds one to the
counter n
and then advances back to step 214. Alternatively, in step 218, the first
controller
112 may determine if n is equal to 1, and, if yes, the control scheme 210
advances to
step 228, and, if no, the control scheme 210 advances to step 220.
[050] The control scheme 210 advances to step 220 if the counter is two or
more,
meaning that at least three position readings have been taken from the sensor
102.
In step 220, the first controller 112 determines the sum, Ssum, of all prior
actual
stretch indications, i.e., S1 to Sn..1. The sum does not include the current
actual
stretch indication, Sn. The first controller 112 may determine the sum
according to
the following equation: Ssum = Ssum Sn-i. The control scheme 210 advances to
step 222.
[051] In step 222, the first controller 112 determines a predicted stretch
indication,
SpR. In an example, the predicted stretch indication is the average of all
prior actual
stretch indications, and is determined according to the following equation:
SpR = Ssum /(n-1). The control scheme 210 advances to step 224.
[052] In step 224, the first controller 112 determines if the chain 34 has
stretched
to a stretch threshold, STH. For example, the first controller 112 determines
if the
actual stretch indication exceeds the predicted stretch indication by at least
the
stretch threshold. The first controller 112 does so by determining if the
difference
between the current actual stretch indication and the predicted stretch
indication is
greater than or equal to the stretch threshold according to the following
equation:
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Sn ¨ SpR STH. If no, the control scheme 210 advances to step 228. If yes, the
control scheme 210 advances to step 226. To determine the stretch threshold,
chain
manufacturers may be contacted for an indication of acceptable chain stretch.
The
stretch threshold may be about 1.0% to about 1.5%.
[053] In step 226, the control system 110 activates an alert if the cutting
chain 34
has stretched to the stretch threshold. The first controller 112 broadcasts an
alert
message on the bus 116, and the second controller 114 receives the alert
message.
The second controller 114 outputs a control signal causing an output device
124 to
issue the alert. The alert may be in any suitable form, such as, for example,
a visual
indication, an audible indication, a tactile indication, or any combination
thereof, to
name but a few possibilities. In an example, the output device 124 is a
monitor, and
the alert is a visual alert on the screen of the monitor (e.g., a pop-up).
Illustratively,
the output device 124 is coupled electrically to the second controller 114. In
other
examples, the output device 124 may be coupled electrically directly to the
bus 116.
[054] The alert may remain active until the human operator acknowledges the
alert. For example, in the case where the output device 124 is a monitor and
the
alert is a visual alert on a screen of the monitor, the visual alert may
remain active
until the operator presses a button (e.g., escape button on a keyboard coupled
electrically to the second controller 114 configured as a PC) or other
operator input
device, acknowledging the alert.
[055] In step 228, the first controller 112 adds one to the counter n.
Afterwards,
the control scheme 210 advances back to step 214.
[056] The first controller 112 may store in its memory a number of values. For
example, for historical and evaluation purposes, it may store all of the
position
readings and/or all of the actual stretch percentages, so as to keep a
historical log of
those values ("and/or" means and-or-or). It may also store the stretch
threshold as a
constant, and may store all SSUM and/or SPR values so as to keep a historical
log
of those values or only store them until updated in the next loop of the
control
scheme 210.
[057] In the above example of the control scheme 210, the actual and predicted
stretch indications are stretch percentages. In another example of the control
scheme 210, the actual stretch indication is an actual change in position from
one
position reading to the next position reading, and the predicted stretch
indication is a
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predicted change in position. Change in position may be represented by A, and
the
control scheme 210 may be modified as follows:
step 216 is replaced by An= Pn ¨ Pn-1,
step 220 is replaced by Asum.Asum
step 222 is replaced by APR = sum/(n-1)
step 224 is replaced by An ¨ APR =?- ATH.
[058] In such an example of the control scheme 210, the first controller
112 may
store in its memory all of the position readings and/or all of the actual
changes in
position, so as to keep a historical log of those values. It may also store
the stretch
threshold as a constant, and may store all Asum and/or APR values so as to
keep a
historical log of those values or only store them until updated in the next
loop of the
control scheme 210.
[059] In yet another example, the control scheme 210 may be modified such that
no predicted stretch indication is taken into account, and the actual stretch
indication
is the position reading from the sensor 102. In such a case, the first
controller 112
compares each position reading to a stretch threshold in the form of a
position
threshold. Once the position reading reaches the position threshold, the first
controller 112 signals the second controller 114 to activate the alert. In
such an
example of the control scheme 210, the first controller 112 may store in its
memory
all of the position readings, so as to keep a historical log of those values.
It may also
store the position threshold as a constant.
[060] In another example of the saw apparatus 10, the saw apparatus may be
configured as a hand-held saw apparatus. In that case, the mount may be the
frame
of the hand-held device to which the saw is attached, without a swing. The
chain
support may be attached movably to the frame for movement relative thereto.
The
chain tensioner may urge the chain support to move relative to the frame to
tension
the chain. The sensor may be positioned (e.g., attached to the frame) to sense
a
position of the chain support relative to the frame. Since the saw apparatus
is a
hand-held device, the control system may have a single electronic controller.
[061] The welds, threads, and hydraulic and electrical lines of the
forestry head
have not been shown for simplification of illustration, it being understood
that it would
be well within the skill of one of ordinary skill in the art to provide those
features
without undue experimentation.
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[062] While the disclosure has been illustrated and described in detail in the
drawings and foregoing description, such illustration and description is to be
considered as exemplary and not restrictive in character, it being understood
that
illustrative embodiment(s) have been shown and described and that all changes
and
modifications that come within the spirit of the disclosure are desired to be
protected.
It will be noted that alternative embodiments of the present disclosure may
not
include all of the features described yet still benefit from at least some of
the
advantages of such features. Those of ordinary skill in the art may readily
devise
their own implementations that incorporate one or more of the features of the
present
disclosure and fall within the spirit and scope of the appended claims.
13
