Note: Descriptions are shown in the official language in which they were submitted.
CA 02839307 2014-01-14
SICKLE CUTTER SYSTEM WITH HOLD-DOWN FINGERS ON ALTERNATE
GUARD FINGERS
This invention relates to a guard assembly for the sickle knife of a crop
cutting apparatus such as a swather or combine harvester.
BACKGROUND OF THE INVENTION
The present invention relates generally to a crop cutting device
comprising a plurality of knife guards arranged to be mounted in spaced
relation
along a cutter bar and projecting forwardly therefrom in transverse alignment;
each
of the guards having an upwardly facing ledger surface with opposed side edges
thereof arranged to provide first and second shearing edges; a sickle bar
mounted in
transversely extending position and being driven for reciprocating movement
relative
to the knife guards; the sickle bar having a plurality of knife blades mounted
thereon
for movement therewith; each of the knife blades having a cutting surface for
passing across the ledger surface of the knife guards and an opposed surface;
each
of the knife blades having two side cutting edges which are beveled from the
opposed surface to the cutting surface to cooperate with the shearing edges of
the
knife guards; the sickle bar being driven to carry the knife blades back and
forth
between the knife guards.
It is well known that many sickle knives of this general type include a
conventional or pointed guard where the guard is formed as an integral element
which includes a base piece attached to the cutter bar and defining the ledger
surface and a nose piece projecting forwardly from the ledger surface in front
of the
front edge of the blade which is generally pointed at a leading end so as to
separate
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the crop to each side of the guard. This nose piece also stands up in front of
the
ledger surface to protect the front edge of the blade and includes a
rearwardly
extending shelf over the ledger surface which forms a slot with the ledger
surface
through which the blade passes. Guards of this type include separate hold down
members between the guards which provide a surface for contacting the cutter
bar
to hold the blades down against the ledger surface.
Pointed guards generally feature a point with a cut slot that the sickle
blades reciprocate in and out of. Various types of hold-down arrangement are
used
to contact the sickle to keep its shearing surface in close contact with the
guard
to ledger as cutting occurs. Usually these are located between the guard
point or at the
rear edge of the sickles. Most are sheet metal and feature easy adjustment
using a
hammer or a simple single point threaded adjustment. By keeping the hold-downs
separate from the guards fewer hold-downs than points may be used to reduce
the
cost and number of adjustments required. Pointed guards have found much favor
in
easier cutting conditions due to the ease of adjustment and superior
performance.
Another form of guard is known as a stub guard which is formed in two
separate pieces including a base piece which carries the ledger surface and a
top
piece which extends over the ledger surface. The pieces are separate and
separately adjustable relative to the cutter bar so that the top piece can
apply
pressure onto the blade to press it onto the ledger surface. The pieces
terminate at a
front edge which is just behind the front edge of the blade so that the front
edge of
the blade is presented to the crop.
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In tough cutting, stub or no-clog guards have found the most favor.
Stub guards use a separate top and bottom guard pieces that spaced slightly
more
than one sickle blade thickness apart create a slot for the blade to operate
in. The
front edge of the blade protrudes slightly past the front tip of the two
guards. This
feature is what originally gave stub-guards their non-clogging self-cleaning
action. A
major improvement in stub guard technology was made when fully adjustable top
hold-down assemblies were introduced. These arrangements allowed the gap to be
controlled much more precisely than previously so that the shearing surface of
the
blade was kept in close contact with the guard ledger surface. This
adjustability
allows the stub top piece to act as a much more effective hold-down than the
hold-
downs found on regular pointed guard systems.
The pointed guard has an advantage of presenting a point to the
incoming crop so that crop is effectively divided around it. This is
especially
advantageous when the sickle blade is at or near the end or start of each
stroke and
a front edge of each blade, which is typically a blunt front edge of a width
of the
order of 0.5 inch, is hidden partially or entirely within the guard slot.
Since the sickle
bar velocity is lowest at or near the end or start of each stroke this gives
the pointed
guard a considerable advantage over the stub guard for most crops.
The guards can be formed as single elements separately mounted on
the guard bar or as double or triple elements connected together side by side
for
common mounting and common adjustment relative to the guard bar. There is no
reason why more elements might be included but this is not typical.
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In some cases the arrangement is of the double sickle type where
each sickle bar is essentially half the length of the cutter bar and the
cutter bars
reciprocate in opposite phase to minimize vibrating mass and vibrations.
Usually the
sickle bars are timed so that they move in opposite directions so that
vibrations
s induced into the cutter bar assembly are minimized.
The sickle knife cutting system has been widely accepted as the most
power efficient system due to the shearing action. However due to speed
restrictions of generally less than 5 to 8 mph ground speed, other systems
such as
rotating flail systems have come into use since these can be operated at much
1.0 higher ground speed of up to 14 mph while maintaining a high cutting
efficiency.
Such rotary systems have however much higher power usage, are limited in width
and provide crop handling difficulties for forming effective swaths for drying
of the
crop.
Cutting crops such as soy beans where the bean pods can be located
15 closely adjacent the ground typically requires low ground speeds of
around 4 to 5
mph to ensure that the crop is cut and fed into the combine harvester without
too
much loss of the pods. Pods can be lost if the cutting action causes some or
too
many of the lowest pods to be left at the stubble or broken up by the cutting
action. It
would be highly desirable to increase cutting speed above the typical range of
4 to 5
20 mph so as to increase this to or above 6 mph.
Cutting crops such as hay or forage crops such as alfalfa or grasses
typically allows higher ground speeds of up to 10 mph since the crop is more
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resistant to a poor or inefficient cutting action. It would be highly
desirable to
increase cutting speed above the typical range of up to 10 mph so as to
increase
this to or above 12 or even 14 mph.
The term "sickle bar" as used herein is intended to refer generally to a
5 structure which supports all of the knife blades at the spaced positions
along its
length and is not intended to be limited to a single continuous element
extending
along the whole length of the structure. Thus the bar may be formed of
different
elements at different parts of the length and may include pieces below and
above
the blades.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a sickle
cutting apparatus comprising:
a plurality of stationary knife guards arranged to be mounted along a
cutter bar;
a sickle bar mounted in transversely extending position and arranged
to be driven for reciprocating movement relative to said knife guards;
the sickle bar having a plurality of knife blades mounted thereon for
movement therewith;
each of the knife blades having a cutting surface for passing across the
knife guards;
each of the knife blades having on first and second sides first and
second side cutting edges;
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each knife guard comprising:
a base portion arranged to be mounted on the cutter bar;
at least one guard finger carried by the base portion so as to
extend forwardly therefrom;
each guard finger having an upwardly facing ledger surface with
opposed side edges thereof arranged to provide first and second shearing edges
which cooperate with said side cutting edges of said knife blades;
the guard fingers being arranged to be mounted at a first
equidistant spacing in a row along the cutter bar;
and a plurality of hold-down members arranged to be mounted along
the cutter bar;
each hold-down member comprising at least one hold-down finger
thereon arranged to extend forwardly from the cutter bar to a position
adjacent the
knife blades in front of the sickle bar;
the hold-down fingers being arranged to be mounted at a second
equidistant spacing in a row along the cutter bar;
wherein the second equidistant spacing of the hold-down fingers is
double that of the first equidistant spacing of the guard fingers;
each hold-down finger being arranged to be located in alignment with
and at a spacing above a respective alternate one of the guard fingers.
Preferably the guard fingers of the second set each include no element
over the knife blade on the ledger surface thereof so that the knife blade on
the
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ledger surface thereof is held down only by the respective guard finger and
the
guard fingers of the first set each include no element over the knife blade on
the
ledger surface thereof so that the knife blade on the ledger surface thereof
is not
held down.
Preferably a length and width of the ledger surfaces of the first set of
guard fingers is equal to a length and width of the ledger surfaces of the
second set
of guard fingers.
In one arrangement each of the guard fingers comprises a pointed
guard finger with a pointed front tip thereof in front of a front tip of the
knife blades
including an upstanding transverse shoulder at a front edge of the ledger
surface.
Preferably there is provided a cutting system including a first plurality
of first stationary knife guards each comprising a stub guard finger with a
front tip
thereof behind a front tip of the knife blades and a second plurality of
second
stationary knife guards each comprising a pointed guard finger with a pointed
front
tip thereof in front of a front tip of the knife blades, the first and second
stationary
knife guards being arranged such that a user can select either the first
stationary
knife guards or the second stationary knife guards to be mounted on the cutter
bar,
the first stationary knife guards, the second stationary knife guards and the
hold
down members are arranged such that the hold down members cooperate with the
first stationary knife guards when selected and with the stationary knife
guards when
selected.
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Preferably the spacing of the hold-down fingers above the respective
one of the second set of guard fingers is adjustable by an adjustment screw at
the
cutter bar which can be preferably operated independently of the other hold-
down
fingers.
Preferably the plurality of hold-down members comprises a plurality of
first hold-down members and a plurality of second hold-down members arranged
to
be mounted alternately along the cutter bar, the first hold-down members
having a
single one of the hold-down fingers thereon and the second hold-down members
having two of the hold-down fingers thereon.
Preferably each knife guard has three fingers mounted on the base
portion and wherein each of the first and second hold-down members is
associated
with a respective one of the knife guards and is arranged to be mounted on the
cutter bar commonly therewith.
Preferably a center line spacing between each guard finger and the
next is equal to 2.0 inches. However the arrangement can be used with other
center
line spacings such as the conventional 3 inch spacing.
Preferably a stroke length of the reciprocating movement of the sickle
bar is equal to the center line spacing between each guard finger and the next
so
that each knife blade is moved between a position aligned with a guard finger
of the
first set and a position aligned with a guard finger of the second set.
Preferably the knife blades are arranged as first and second blades of
a connected pair and the reciprocating movement is arranged such that each
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connected pair is moved in the reciprocating movement between a first position
in
which the first blade of the pair is aligned with a respective hold down
finger and a
second position in which the second blade of the pair is aligned with the
respective
hold down finger.
Preferably at least some of the hold-down members include a hold
down ledge arranged above a rear edge of a base of the knife blade.
In an optional arrangement some of the guard fingers each comprise a
pointed guard finger with a pointed front tip thereof in front of a front tip
of the knife
blades and some of the guard fingers arranged intermediate the pointed guard
1.0 fingers
comprise stub guard fingers with a front tip thereof behind a front tip of the
knife blades.
According to a further independent aspect or important feature of the
invention there is provided a sickle cutting apparatus comprising:
a plurality of stationary knife guards arranged to be mounted along a
cutter bar;
a sickle bar mounted in transversely extending position and arranged
to be driven for reciprocating movement relative to said knife guards;
the sickle bar having a plurality of knife blades mounted thereon for
movement therewith;
each of the knife blades having a base portion mounted on the sickle
bar and at least one blade finger extending forwardly therefrom having a
cutting
surface for passing across the knife guards;
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each of the knife blade fingers having on first and second sides first
and second side cutting edges;
each knife guard comprising:
a base portion arranged to be mounted on the cutter bar;
5 at
least one guard finger carried by the base portion so as to
extend forwardly therefrom;
each guard finger having an upwardly facing ledger surface with
opposed side edges thereof arranged to provide first and second shearing edges
which cooperate with said side cutting edges of said knife blades;
10 and a
plurality of hold-down members arranged to be mounted along
the cutter bar;
each hold-down member comprising at least one hold-down finger
thereon arranged to extend forwardly from the cutter bar to a position
adjacent a
front tip of the knife blade finger;
each hold-down finger being arranged to be located in alignment with
and at a spacing above selected ones of the guard fingers leaving some of the
guard
fingers which have no hold-down finger associated therewith;
wherein at least some of the hold-down members include a hold down
ledge arranged to extend forwardly to a position above a rear edge of the base
portion of the knife blade.
According to a further independent aspect or important feature of the
invention there is provided a sickle cutting apparatus comprising:
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a plurality of stationary knife guards arranged to be mounted along a
cutter bar;
a sickle bar mounted in transversely extending position and arranged
to be driven for reciprocating movement relative to said knife guards;
the sickle bar having a plurality of knife blades mounted thereon for
movement therewith;
each of the knife blades having a cutting surface for passing across the
knife guards;
each of the knife blades having on first and second sides first and
second side cutting edges;
each knife guard comprising a base portion arranged to be mounted on
the cutter bar and a plurality of guard fingers carried by the base portion
and
extending forwardly therefrom;
each guard finger having an upwardly facing ledger surface with
opposed side edges thereof arranged to provide first and second shearing edges
which cooperate with said side cutting edges of said knife blades;
a plurality of hold-down members each comprising at least one hold-
down finger thereon arranged so as to extend forwardly from the cutter bar to
a
position adjacent the knife blades in front of the sickle bar;
the hold down members comprising a plurality of first hold-down
members having a single hold-down finger thereon;
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the hold down members comprising a plurality of second hold-down
members having more than one hold-down finger thereon.
According to a further independent aspect or important feature of the
invention there is provided a sickle cutting apparatus comprising:
a plurality of stationary knife guards arranged to be mounted along a
cutter bar;
a sickle bar mounted in transversely extending position and arranged
to be driven for reciprocating movement relative to said knife guards;
the sickle bar having a plurality of knife blades mounted thereon for
1.0 movement therewith;
each of the knife blades having a cutting surface for passing across the
knife guards;
each of the knife blades having on first and second sides first and
second side cutting edges;
the knife blades being arranged side by side with the first side edge of
each blade and the second side edge of each next adjacent blade converging to
first
apex between the blades and the second side edge of each blade and the first
side
edge of each next adjacent blade converging to second apex between the blades;
the first and second apexes of the blades lying on a common
imaginary line in front of and parallel to the sickle bar such that the first
and second
apexes reciprocate along said imaginary line with said movement of the sickle
bar;
each knife guard comprising:
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a base portion arranged to be mounted on the cutter bar;
at least one guard finger mounted on the base portion so that
the guard fingers are arranged in a row along the cutter bar;
each guard finger having an upwardly facing ledger surface with
opposed first and second side edges thereof arranged to provide first and
second
shearing edges which cooperate with said side cutting edges of said knife
blades;
and a plurality of hold-down members arranged to be mounted along
the cutter bar;
each hold-down member comprising at least one hold-down finger
thereon arranged to extend forwardly from the cutter bar to a position
adjacent the
knife blades in front of the sickle bar;
the ledger surface of each guard finger at the imaginary line having a
width between the first and second side edges thereof which is greater than a
spacing at the imaginary line between the first side edge of the ledger
surface of
each guard finger and the second side edge of the ledger surface of each next
adjacent guard finger;
wherein the first and second side edges of the ledger surfaces of each
of the guard fingers extend to a position behind said imaginary line.
That is the ledger surfaces of each of the guard fingers are free from
any connection each to the next in front of said imaginary line such as a
conventional trash bar.
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In this way the first and second apexes as they reciprocate along said
imaginary line depart from the side edge of the ledger surface of each
respective
guard finger and are free from contact with any support surface of the guard
fingers
until the apexes reach the second side edge of the respective next adjacent
guard
finger.
In order to provide this free space between the guard fingers which
allow the apexes to slide through free space between the ledger surfaces, the
base
member is located behind the sickle bar and each guard finger has no
connection
with a next adjacent guard finger forwardly of the base member. That is there
is no
trash bar on the guard at the location in front of the sickle bar so that the
guard
fingers are preferably cantilevered from the rear base member behind the
sickle bar.
However it may be possible to provide designs which have some interconnecting
support between the fingers in front of the sickle bar but which does not
prevent the
free release of dirt as the apexes of the blades pass across from one finger
to the
next adjacent.
Preferably the ledger surface of each guard finger at the imaginary line
has a width between the first and second side edges thereof which is more than
twice the spacing at the imaginary line between the first side edge of the
ledger
surface of each guard finger and the second side edge of the ledger surface of
each
next adjacent guard finger.
Preferably the spacing at the imaginary line between the first side edge
of the ledger surface of each guard finger and the second side edge of the
ledger
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surface of each next adjacent guard finger is reduced relative to the
conventional
distance so that it is preferably less than 0.75 inch or less than 0.5 inch.
In this way, the ledger surface of each guard finger at the imaginary
line has a width between the first and second side edges thereof which is
greater
5 than a width of the support member.
Where the ledger surfaces has a center to center spacing of less than
3.0 inches and typically of the order of 2.0 inches, the ledger surfaces
preferably has
a width between the first and second side edges thereof which is equal to or
greater
than 1.5 inches.
10 According to a further independent aspect or important feature of
the
invention there is provided a sickle cutting apparatus comprising:
a first plurality of first stationary knife guards each comprising a base
portion arranged to be mounted on a cutter bar and at least one guard finger
carried
by the base portion and extending forwardly therefrom such that the guard
fingers
15 when mounted are arranged at an equidistant spacing in a row along the
cutter bar;
a second plurality of second stationary knife guards each comprising a
base portion arranged to be mounted on the cutter bar and at least one guard
finger
carried by the base portion and extending forwardly therefrom such that the
guard
fingers when mounted are arranged at an equidistant spacing in a row along the
cutter bar;
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the first and second stationary knife guards being arranged such that a
user can select either the first stationary knife guards or the second
stationary knife
guards to be mounted on the cutter bar;
a sickle bar mounted in transversely extending position and arranged
to be driven for reciprocating movement relative to said selected knife
guards;
the sickle bar having a plurality of knife blades mounted thereon for
movement therewith;
each of the knife blades having a cutting surface for passing across the
knife guards;
each of the knife blades having on first and second sides first and
second side cutting edges;
each guard finger of the first and second stationary knife guards having
an upwardly facing ledger surface with opposed side edges thereof arranged to
provide first and second shearing edges which cooperate with said side cutting
edges of said knife blades;
wherein each of the guard fingers of the first stationary knife guards
comprises a stub guard finger with a front tip thereof behind a front tip of
the knife
blades;
wherein each of the guard fingers of the second stationary knife guards
comprises a pointed guard finger with a pointed front tip thereof in front of
a front tip
of the knife blades;
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and a plurality of hold-down members arranged to be mounted along
the cutter bar;
each hold-down member comprising at least one hold-down finger
thereon arranged to extend forwardly from the cutter bar to a position
adjacent the
knife blades in front of the sickle bar for holding down a respective one of
the knife
blades onto the ledger surface of the respective one of the guard fingers;
the first stationary knife guards, the second stationary knife guards and
the hold down members being arranged such that the hold down members
cooperate with the first stationary knife guards when selected for mounting
and with
the second stationary knife guards when selected for mounting.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a top plan view of a part of header showing a portion of the
sickle knife according to a first embodiment of the present invention using a
pointed
guard.
Figure 2 is an isometric view of the part of the header of Figure 1.
Figure 3 is a cross-sectional view along the lines 3-3 of Figure 1.
Figure 4 is a cross-sectional view along the lines 4-4 of Figure 1.
Figure 5 is bottom plan view of a hold-down member for use in the
sickle knife of Figure 1.
Figure 6 is a cross-sectional view along the lines 6-6 of Figure 1.
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Figure 7 is a top plan view of a part of header showing a portion of the
sickle knife according to a first embodiment of the present invention using a
stub
guard.
Figure 8 is a cross-sectional view along the lines 8-8 of Figure 7.
Figure 9 is a top plan view of an alternative arrangement of guard
member where alternate ones of the guard fingers and pointed guard fingers
intermediate two stub guard fingers.
DETAILED DESCRIPTION
In Figures 1 and 2 is shown a first embodiment of a crop cutting device
generally indicated at 10. Only a part of the complete machine is shown since
the
remainder of the machine may vary widely depending upon requirements and since
the construction is of course well known to a person skilled in the art. In
this
embodiment as shown, there is a frame generally indicated at 11 which forms
only
one part of the total frame structure that is the part of the frame that is
relevant to the
present invention.
The cutting device 10 further includes a cutter bar 12 attached to the
frame structure 11. Thus the frame structure 11 in the part as shown comprises
a
guard bar 13 to which is attached a plurality of knife guards 14. The guard
bar 13 is
attached to the frame structure which supports the guard bar in fixed position
across
the front edge of the frame for a cutting action of the crop cutting device on
the
standing crop.
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Each knife guard 14 includes three guard fingers 14A arranged ma
triple guard but guards can be arranged with a single finger, pair of fingers
or triples.
As shown the guard bar forms a triple guard construction with three fingers
where a
series of such guards are mounted on the guard bar 13 at spaced positions
along
The knife guards can comprise a stub guard as shown in Figure 7 but
shown in Figures 1 and 2 each guard finger 14A comprises a pointed guard which
includes a lower portion 15 and an upper portion or hold-down finger 16. These
two
portions are mounted on the guard bar 13 by a mounting arrangement 17
including
15 In the embodiment shown in Figures 7 and 8 the guards are stub
guards so that the noses 20, 22 substantially overlie one another and confine
between them the blades 23 of the sickle bar or knife back 24.
Each pair of guards thus includes two guard elements each defined by
an upper portion or hold-down finger 16 and a lower portion or guard finger 15
and
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to the sickle bar 24. In front of the mounting bar 19 is provided a channel 25
within
which the sickle bar or knife back 24 is mounted for reciprocating movement.
The trash bar may form a continuous bar member extending along the
lower guard portion 15 in front of the bar 24 to prevent any crop reaching
that area.
5 However the trash bar may be formed by any part of the system which
prevents the
crop from moving rearwardly beyond the rear end of the cutting edges of the
blades.
There may be a single sickle bar 24 driven from one end or in some
cases there are two sickle bars driven from opposite ends and meeting in the
middle. The sickle bar or bars 24 are driven by the reciprocating drive (not
shown
io but conventional) such that the bar 24 reciprocates back and forth.
In some cases the bar 24 reciprocates by a distance S1 equal to the
space between the nose of one guard fingers 15 and that of the next along the
guard
bar 13 so that the blades 23 reciprocate from a position with the center line
of the
knife 23 aligned with the center line of the first guard finger to a position
aligned with
is the next guard finger and back to the first. In other cases, the
reciprocation stroke
may be as shown at S2 a multiple of, typically double, the distance between
the
guards so that the knife moves from a first guard finger across a second to a
third
and back to the first. This arrangement reduces the available reciprocation
rate due
to increased acceleration forces but reduces the number of reversals.
20 Each sickle bar comprises the support bar member 24 and the
plurality
of blades indicated at 23. As shown the blades are formed in pairs mounted on
a
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21
common base, but individual blades may be provided or in some cases the blades
may have more than two on the same base.
Each of the blades forms a generally triangular-shaped member which
has a rear end or base 23A bolted to the bar and converges from the rear end
to a
front end 23B. Each of the blades has a top surface 23D and a bottom surface
23E.
Each of the blades has a side edge 23F and a second side edge 23G. The sides
edges are beveled from the top surface down to the bottom surface 23E so that
a
sharp edge is formed at the bottom surface at each of the side edges. The
blades
are also serrated at each cutting edge with grooves extending parallel to the
bars 24
that is at right angles to a center line 23H.
The hold-down finger 16 acts to hold the blades downwardly into
engagement with the top ledger surface 15A of the bottom portion 15. The
bottom
portion 15 has two side edges of the ledger surface 15A as best shown in FIG.
2
with those side edges 15B and 15C acting as side edges of the ledger surface
15A.
Thus the cutting action of the blades occurs between the ledger 15A and the
bottom
surface 23E of the blade as the blade reciprocates from its position at one of
the
guards to its position at the next adjacent one of the guards. In this cutting
action,
therefore, the side edge of the blade moves across the space between the
guards
and enters onto the ledger surface of the next guard in a cutting action
between the
bottom surface of the blade and the top surface of the guard which are
immediately
adjacent and generally in contact or at least closely adjacent to provide a
shearing
action on the crop.
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22
In these guards, the hold-down finger 16 acts to prevent the pair of
blades 23A from moving away from the ledger surface 15A by contacting the
upper
surface 23D of the blade and holding the blade in contact with or closely
adjacent
the ledger surface 15A of the bottom portion where the cutting action occurs.
The
hold-down finger 16 therefore as shown in Figure 1 has side surfaces 16B and
16C
of the bottom surface 16A which are narrower than the ledger surface 15A of
the
bottom portion 15.
The mounting and adjustment arrangements for the bottom portion 15
and the hold-down finger 16 can vary in accordance with a number of different
designs readily available to a person skilled in the art. It suffice to say
that the hold-
down portion 16 is adjustable so that the gap between the bottom surface of
the
hold-down portion and the ledger surface of the bottom portion 15 can be
adjusted to
allow the sliding action of the blades while holding the blades in the
required
position.
The disclosures of the following documents of the present Applicants
may be referred to for details of the construction not provided herein. These
show
various conventional details of the sickle knife system which can be used in
the
arrangement herein but are not described as they are known to persons skilled
in
the art.
US Patent 7,328,565 (Snider) issued February 12 2008;
U.S. Patent 4,894,979 (Lohrentz) issued Jan. 23, 1990
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23
U.S. Patent 4,909,026 (Molzahn) issued Mar. 20, 1990.
U.S. Patent 6,962,040 (Talbot) issued Nov 8, 2005.
US Published application 2013/0192188 (Talbot) published August 1
2013.
In Figure 1, a drive for knife bar 24 can comprise any suitable drive
system known to persons skilled in this art of a type which can generate a
stroke S1
of 2 inches at a drive rate in the range 600 to 1000 rpm. The system can also
be
arranged in an alternative embodiment to drive the stroke S2 of 4 inches in
which
case the reciprocation rate may be lower. The drive system includes an input
from a
ground speed indicator which allows automatic adjusting of the stroke rate of
the
drive system in dependence on ground speed.
Typically each of the knife blades is generally triangular in shape with
straight side edges 23F, 23G. However other shapes of the side edges 23F, 23G
in
plan such as convex or concave can be used. Thus the side edges 23F, 23G
converge to the front apex 23K at an angle of the order of 60 degrees to the
direction of reciprocating movement. The two converging side cutting edges
23F,
23G are beveled from the upper surface 23D to the bottom cutting surface 23E
to
cooperate with the shearing edges of the knife guards. In addition the beveled
side
edges are serrated with grooves running in a direction longitudinal to the
reciprocating direction. In order to maximize the cutting action, the length
of the
CA 02839307 2014-01-14
24
cutting edge is substantially the maximum length extending from the sickle bar
24 at
the rear to a position close to the front apex 23K of the blade.
At the position in the stroke shown in Figure 1 where the center line C
of the knife blades is aligned with the center line C1 of the guard fingers,
the side
cutting edges of the knife blades 23F, 23G substantially directly overlie the
side
edges 15B, 15C of the ledger surface 15A.
Each knife blade has a front point portion in front of the side cutting
edges 23F, 23G which front point portion has side edges converging to the
front
apex 23K, where the apex and the side edges of the front point portion are
shaped
and arranged such that crop material engaging the front point portion, as the
point
portion is moved forwardly in the crop, is shed to one or other side of the
front point
portion for cutting by the side cutting edges and is not pushed forwardly by
the front
point portion 23K.
Thus the preferred construction provides a center line spacing between
each knife blade and the next is of the order of or equal to 2.0 inches, the
radius of
curvature of the front pointed portion at the apex is less than 0.25 inch and
the side
edges of the front portion are arranged relative to a center line of the blade
at an
angle of the order of 20 degrees.
As shown in Figure 1, the width between the centers of the guards is
indicated at Si. This can be the same as the length of the cutting stroke so
that the
blades move from a position aligned with the center line of one guard finger
to that of
the next. However in some embodiments the stroke may be a multiple of the
CA 02839307 2014-01-14
distance D, typically twice, so that the blades move from the first guard
finger to the
third crossing the second. The reversal of the reciprocating action at the
guard
center line ensure that the blades are stationary and therefore carrying out
no cutting
when they are overlying the guard and not at an intermediate location. The
increase
5 of the stroke length to a multiple of the finger reduces the number of times
the
blades are stationary but requires a reduced stroke rate due to the increased
forces
on the drives system.
This distance Si is preferably of the order of 2.0 inches. The fore-aft
length of a blade has traditionally been in the order of 1.75 inches from the
front of
10 the trash bar to the tip of the section, or 2.2 inches from the front
edge of the knife
back to the tip of the section.
It is common practice for sickle blades to have the front edge as a
transverse straight edge in the order of 0.6 inches wide. The wide tip has the
potential for running down crop, thus leaving long uncut stems. In the present
is invention the blade is designed with a pointed tip or front apex 23K,
thus eliminating
the problem.
The guard fingers have the upwardly facing ledger surface 15A with
opposed side edges arranged to provide first and second shearing edges. The
guard fingers have a downwardly facing ground engaging surface 156 shaped and
20 arranged to provide protection for stone engagement as the fingers slide
over the
ground. That is each finger has sufficient strength to avoid breakage when
impacting stones and obstacles causing the cutter bar to rise if the impact is
CA 02839307 2014-01-14
26
sufficient and extends over sufficient number of guard fingers to provide the
lifting
action. This shape of the ground engaging surface is well known to persons
skilled
in the art and includes a longitudinal rib which is generally triangular in
cross-section
on the underside of the upper part containing the ledger surface. The base of
the rib
thus forms an apex which runs over the ground to prevent upward forces from
snapping the guard finger at the ledger surface.
An upstanding transverse shoulder 157 is provided at a front edge of
the ledger surface 15A and extends upwardly to a top surface 158 of the finger
where the shoulder terminates. Thus there is no tang of conventional shape,
that is
no portion of the guard extends rearwardly over the ledger surface 15A from
the
shoulder 157. Above the ledger surface 15A therefore the knife blades of
alternate
ones of the guard fingers are free from confinement by a conventional tang as
used
in a conventional pointed guard or by a cooperating upper guard finger of the
type
used in a stub guard.
A tip portion 159 in front of the ledger surface extends forwardly from
the shoulder 157 and defines a forwardmost generally pointed tip 160 for
engaging
crop in front of the ledger surface 15A.
Each knife guard thus includes a base portion 19 mounted on the
cutter bar 13 by the two longitudinally spaced bolts 18 each of which has a
head 18A
engaging a bottom face of the base portion 19. The knife guard further
includes
three equally spaced guard fingers 15 mounted on the base portion 19 so as to
be
CA 02839307 2014-01-14
27
commonly mounted on the cutter bar at a first equidistant spacing in a row
along the
cutter bar 13.
The guard fingers are arranged also to define a first set and second set
of guard fingers arranged alternately along the cutter bar so that each guard
finger
151 of the first set is located between respective guard fingers 152 of the
second
set. Thus each triple guard defined by three fingers has either two fingers
151 either
side of a finger 152 or has two fingers 152 either side of a finger 151. All
of the
fingers 151 and 152 are identical but as explained hereinafter, the fingers
151 are
left open and have no corresponding hold-down finger, sometimes called an
upper
guard, whereas each of the fingers 152 cooperates with a respective one of the
hold-down fingers 16.
Thus there are provided a plurality of hold-down members 161 and 162
mounted along the cutter bar. Each hold-down member 161, 162 has at least one
hold-down finger 16 thereon extending forwardly from the cutter bar 13 to a
position
adjacent the knife blades at the ledger surfaces 15A in front of the sickle
bar 24.
Thus the hold-down members 161 have a single central finger 16
mounted on a mounting base 163 and the hold-down members 162 have two
separate spaced fingers 16 mounted on a mounting base 163. These are arranged
on the mounting bases so that the hold-down fingers are arranged in a row at a
second equidistant spacing along the cutter bar where the second equidistant
spacing of the hold-down fingers 16 is double that of the first equidistant
spacing of
the guard fingers 15. The result of this is that the hold-down fingers 16 are
arranged
CA 02839307 2014-01-14
28
on the alternate guard fingers 152 leaving the guard fingers 151 open and free
from
a hold-down. Thus each hold-down finger 16 located in alignment with and at a
spacing above a respective one of the second set 152 of guard fingers for
holding
down a respective one of the knife blades 23A onto the ledger surface 15A of
the
respective one of the second set 152 of guard fingers.
As explained previously the guard fingers 151 and 152 are pointed
guards but have no conventional tang over the knife blade on the ledger
surface
thereof which would typically define a slot so that the knife blade 23A on the
ledger
surface 15A thereof is held down only by the respective guard finger 16.
1.0 Thus
the guard fingers 151 of the first set each include no element at
all, that is not a tang and not a hold -down over the knife blade on the
ledger surface
15A so that the knife blade 23A on the ledger surface 15A of the fingers 151
is not
held down at all except for the residual effect of the hold-down finger 16
over the
adjacent guard finger 152.
The guard fingers 151 and 152 are identical in other respects so that
particularly the length and width of the ledger surfaces 15A of the guard
fingers 151
is equal to a length and width of the ledger surfaces of the second set of
guard
fingers.
In Figures 1 to 6, each of the guard fingers comprises a pointed guard
finger with a pointed front tip 159, 160 in front of a front tip 23B of the
knife blades
23A. This pointed guard includes the upstanding transverse shoulder 157 at a
front
edge of the ledger surface 15A. The spacing of the tip 22 of the hold-down
fingers
CA 02839307 2014-01-14
29
16 above the respective one of the second set of guard fingers 152 is
adjustable by
an adjustment screw 40, 41, 42 at the cutter bar 13 independently of the other
hold-
down fingers 16.
Each triple knife guard is associated with a respective one of the hold-
down members 161, 162 and is mounted on the cutter bar 13 commonly therewith
by the pair of bolts 18. The bolts 18 are spaced apart along the cutter bar so
as to
engage into holes through the cutter bar aligned with holes in the base 163 of
the
hold-down member 161 and with corresponding holes in the base member 19 of the
guard member. Similarly the hold-down member 162 is bolted by two bolts 18
onto
in the cutter bar 13 in association with the underlying guard member.
As shown in Figure 3, tightening of the two bolts 18 acts to clamp the
upper surface of the base 19 onto the underside of the cutter bar 13 and to
clamp a
bottom surface 44 of the base member 164 of the double hold-down member 162
onto the top surface of the cutter bar 13. The same arrangement is shown in
Figure
6 respect of the hold-down member 161.
As best shown in Figure 1, the knife blades 23X and 23Y are arranged
as first and second blades of a connected pair mounted on a common base 23Z
carried on the sickle bar 24. These pairs are separately mounted on the bar 24
by a
pair of bolts 23P and 23Q so that each pair of blades can be removed
independently
of the others for replacement. The reciprocating movement of the bar 24 is
arranged
such the blades 23X and 23Y of the connected pair 23Z are moved in the
reciprocating movement between a first position shown in Figure 1 in which the
first
CA 02839307 2014-01-14
blade 23Y is aligned with the specific hold-down finger 16X and a second
position
(not shown) in which the second blade 23Y of the pair 23Z is aligned with the
hold-
down finger 16X. Thus the finger 16X is associated with the pair 23Z and does
not
cooperate with any others of the blade pairs. This situation is of course
repeated
5 along the bar 24 by each of the fingers 16 and the pairs. In this way, in
the event
that a replacement blade pair is inserted into position on the bar 24, for
example due
to a breakage, it sits alongside other pairs which are older and hence are
more worn
and therefore thinner. Each finger 16, when adjusted as explained hereinafter
to set
the spacing with the respective guard finger 15, is associated with a
respective blade
10 pair and can be set in dependence on the thickness of that specific pair
without any
reference to the other blade pairs.
As shown in Figures 1 and 6 the single hold -down members 161
include the single finger also include a hold-down ledge 46 on each side of
the
single finger projecting forwardly from the base portion 163 to a position
above a
15 rear edge of a base of the knife blade. The hold-down ledge 46 covers only
a
narrow strip at the rear of the base of the blade so as to assist in
preventing lifting of
the blade when it is free from the finger 16. The ledge 46 assists in holding
the back
of the knife regardless if the blade is free of a hold-down finger or not.
Because the
hold-down contact area is a long way forward on the blade, the ledges are
provided
zo to hold the back of the knife.
In Figures 1 to 6, the arrangement uses pointed guards with the
pointed portion in front of the tip 23B of the blade. In Figures 7 and 8 the
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31
arrangement uses stub guards 115 with the tip 116 of the guard 115 just behind
the
tip 23B of the blade, as is conventional in stub guards. In both arrangements
the
hold-down fingers 16 have the tip thereof just behind the tip 23B of the
blade.
The stub guards 115 and the pointed guards 15 are arranged such that
a user can select either the stub guards 115 or the pointed guards 15 to be
mounted
on the cutter bar 13 depending on cutting conditions at the choice of the
user. That
is the dimensions of the base portion 19 are identical in both cases to match
with the
holes in the cutter bar and with the bolts 18 therein. Thus the user can
select all
stub guards for cutting so that the blade projects beyond the guard and hold-
down
io fingers in the conventional cutting action.
Alternatively the user can select all
pointed guards if the cutting conditions and the crop to be cut dictate such
guards.
In an optional arrangement shown in Figure 9 some of the guard
fingers each comprise a pointed guard finger 215 with a pointed front tip 216
thereof
arranged to lie in front of a front tip of the knife blades as explained
above, and
is some of the guard fingers arranged intermediate the pointed guard fingers
215
comprise stub guard fingers 315 with a front tip thereof arranged to be behind
a front
tip of the knife blades as described above. In Figure 9 there is shown a guard
having three fingers where two of the fingers 215 are pointed guard fingers
either
side of a stub guard finger 315. In order to create and arrangement in which
the
20 pointed guard fingers alternate with the stub guard fingers there is
provided a
second guard not shown where there are two stub guard fingers wither side of a
CA 02839307 2014-01-14
32
pointed guard finger and the two types are alternated along the cutter bar
mounted
on the bolts 18..
Also the stub guards 115, the pointed guards 15 and the hold-down
members 16 are arranged such that the hold-down members 16 cooperate with the
stub guards 115 when selected and with the pointed guards 15 when selected.
That
is the dimension of the hold-down members is arranged so that they overlie the
ledger surface of both the stub guards when used and with the pointed guards
when
used. Also the pointed guards have no conventional tang so that the ledger
surface
of the pointed guard is presented upwardly to cooperate with the hold-down
finger.
1.0 As best
shown in Figures 4 and 5, the threaded fasteners or bolts 18
have axes 18X lying at spaced positions along an imaginary line 18Y extending
longitudinally of the cutter bar. The hold-down fingers are adjustable on the
cutter
bar to change a settable spacing S between the bottom surface 22A at the tip
22
and the ledge surface 15A of the respective guard finger 15.
In order to provide this adjustment, each of the hold-down fingers 16 is
pivotal relative to the cutter bar about a fulcrum 47 defined by an apex of a
rib 48
extending longitudinally of the cutter bar 13. The rib 48 and its apex 47 are
located
at a position slightly forwardly of the imaginary line 18Y joining the axes
18X.
The pivotal movement is carried out by a respective adjustment screw
40, 41, 12 for individual adjustment of each finger 16 by extension of the
adjustment
screw located on the base portion located rearwardly of the imaginary line
18Y, that
is on the opposite side of the fulcrum from the finger. As shown in Figure 5,
each of
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33
the adjustment screws has a respective hole 41A, 42A in the base portion 164
of the
hold-down member 162.
The base mounting member 164 connects the two hold-down fingers
and defines a bridge 165 between the two hold-down fingers which is shaped to
adjustments of the two fingers. That is the base member 164 including the
bridge
165 and the fingers extending forwardly therefrom forms an integral casting or
forging where the portions 166, 167 of the base member 164 connected to the
fingers 16 are rigid relative to the fingers with the flexibility of the base
member 164
The fulcrum 47 and the adjustment screws 41, 42 are located relative
to the imaginary line 18Y such that the hold-down fingers 16 are adjustable by
extension of the respective adjustment screw to reduce the settable spacing S
without adjustment or loosening of the bolts 18. This is obtained by the fact
that the
imaginary line by a distance less than a radius of the threaded fasteners,
that is the
fulcrum is behind the edge 18Q of the front of the bolts 18. This adjustment
to
reduce the space S as the blades wear obtained by extending the bolts 41, 42
is
obtained because the fulcrum is located such that there may be slight sliding
However the adjustment may be provided from flexing of the hold-down as it is
CA 02839307 2014-01-14
34
easier to flex the hold-downs the small amount required rather than to slide
the
fulcrum.
The fulcrum and where the nut 18N makes contact with the top of the
hold-down should be arranged such that when the nut is tightened it results in
the
hold-down being tight at the back, putting pressure on the adjuster screw as
opposed to causing the finger to put pressure on the knife, in which case the
adjuster screw cannot be used. This is done by having the fulcrum slightly
ahead of
the centerline of the mounting bolt for minimal sliding of the fulcrum, and by
having
the nut contact the top of the hold-down at the center line of the mounting
hole, as
lo provided by the arched shape of the top surface.
Each adjustment screw 40, 41 comprises a bolt with a head 40A
projecting upwardly from a top surface of the hold-down member so that the
head
can be grasped by a wrench for application of a significant adjustment force.
As the hold-down member is an integral member with a bottom surface
including the fulcrum directly contacting the upper surface of the cutter bar
13, there
are no intervening elements which need to be adjusted such as adjustment bars
or
shims.
The bolts 18 each include a nut 18N with a shoulder 18S engaging an
upper surface 168 of the hold-down member and the upper surface 18S is arched
or
convexly curved so as to include a curved surface at least rearwardly of the
imaginary line and preferably on both sides of the common line to allow
rotation of
CA 02839307 2014-01-14
the hold-down member on the shoulder during the extension of the adjustment
screw.
The double hold-down members 162 include therefore two adjustment
screws 41, 42 for individual adjustment of the fingers. The single hold-down
5 members 161 have a single center adjustment screw 40 to adjust the single
finger
so that no flexing of the member 161 is required.
The arrangement described and shown herein, particularly in Figure 7,
has a number of improvements relative to conventional sickle cutting systems.
A
first improvement is obtained by providing a knife blade which is narrower
than
1.0 conventional system so that typically the width W is equal to
approximately 2.0
inches center to center in comparison with the conventional arrangement of 3.0
inches while providing a blade which has a length L greater than conventional
system so that the length from the rear edge of the cutting edge to the tip
23B is
greater than 2.0 inches and typically of the order of or greater than 2.75
inches.
15 This can be further combined with an arrangement in which the width
of the guard at its rear edge 117 is increased so that the width W1 of each
guard
115 at the rear edge 117 is preferably of the order of the maximum width which
can
be obtained while leaving a space W2 at the rear edge 117 between the ledger
surfaces of the order of 0.5 inch or the distance necessary to avoid pinching
of crop
20 stalks between the ledger surfaces.
CA 02839307 2014-01-14
36
Typically, in order to maximize the cutting action, the length of the
cutting edge of each of the knife blades is substantially the maximum length
of the
blade.
The fore-aft length of a blade has traditionally been in the order of 45
MM (1.75 in) from the rearmost cutting location or the rear of the cutting
action, to
the tip of the section, or 55 mm (2.2 in) from the front edge of the knife
back to the
tip of the section. Traditionally this dimension is usually similar to the
length of the
cutting edge.
In this present arrangement, the fore-aft length of the blade is
increased substantially. Thus the length of cutting edge of each sickle blade
from a
rearmost end of the cutting action to a front edge of the blade in the present
invention is greater than 1.75 inches. This can lie in the range 2.2 to 3.0
inches.
This also reduces the angle of inward inclination of the cutting edge
from the typical 30 degrees to an angle less than 20 degrees and typically of
the
order of 15 degrees and in the range 15 to 30 degrees.
Thus in one example the blade has a width of 2.0 inches at the base
and a length from the front of the trash bar to the tip of 2.5 inches.
In view of the increased length of the blade, the fact that the blade
fingers are only in contact with hold-down fingers at alternate guard fingers
and the
increased length at the front point portion, it is highly desirable that the
blade
thickness is increased from the typical value of 2.7 mm (0.106inch) up to a
new
value of the order of 3.68 mm (0.145 inch). Thus a suitable value of the
thickness is
CA 02839307 2014-01-14
37
greater than 0.12 inch and more preferably greater than 0.14 inch. This
provides a
stiffness of the blade which can reduce lifting of the blade at the finger tip
or front
point portion.
The cutting efficiency and therefore stubble length are also affected by
the width W1 of the cutting edge of the knife guard. Generally, the width at
the rear
of the cutting edge on the guard is in the order of 25 mm (1.0 in). In the
arrangement of the present invention that width is substantially increased.
Thus the
width of each guard at the rear end of the cutting edge of each blade is
greater than
1.0 inches. The maximum width W1 of the guard is slightly less than the center
to
center spacing of the blades since it is necessary to leave a gap between the
guards
at the back to prevent pinching the crop and to allow the crop to reach the
back for
the rearmost cutting action. Thus with a blade center to center spacing of 2.0
inches
the width of the guard is slightly less than that of the width of the blade or
roughly 1.5
to 1.9 inches. Thus with a blade of this width, the width of the guards can be
as
much as 1.9 inches and preferably lies in the range 1.2 to 1.9 inches. However
where the blade is greater than 2.0 inches in width, the guard has a width
which is
between 0.5 and 0.1 inches less than the width of the blade.
Thus the arrangement provided herein provides a center line spacing
between each guard finger and the next which is less than 3.0 inches and more
preferably 2.0 inch where a width of each guard at the rear trash bar is
greater than
1.5 inches and preferably 1.75 inches.
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38
As best shown in Figure 7, each blade 123 has a rectangular base 124
and two blade fingers 125, 128 which define between them a rear apex 127 at
the
rearmost end of the cutting side edge of the blade finger. Between each blade
123
and the next is provided a second apex 128 where the side edges of the two
blades
meet. The blades abut side edge to side edge so that the apex 128 has no space
allowing crop to enter behind the apex. The first and second apexes 127, 128
of the
blades lie on a common imaginary line 129 in front of and parallel to the
sickle bar
24 such that the first and second apexes reciprocate along the imaginary line
with
the movement of the sickle bar.
Each knife guard as described before includes the base portion 19
arranged to be mounted on the cutter bar and at least one guard finger 15
mounted
on the base portion so that the guard fingers are arranged in a row along the
cutter
bar presenting the upwardly facing ledger surfaces 15A with opposed first and
second side edges 15B, 15C arranged to provide first and second shearing edges
which cooperate with the side cutting edges of the knife blades.
As set forth above, the ledger surface 15A of each guard finger at the
imaginary line 129 has a width VV1 between the first and second side edges
16B,
15C which is greater than a spacing W2 at the imaginary line 129 between the
first
side edge 15B of the ledger surface 15A of each guard finger and the second
side
edge 150 of the ledger surface of the next adjacent guard finger.
The first and second side edges 156, 15C of the ledger surfaces 15A
of each of the guard fingers extend to a rear end of the side edge at the rear
edge
CA 02839307 2014-01-14
39
117. The rear edges 117 all lie on a common imaginary line 130 at a position
behind
the imaginary line 129.
As shown in Figure 9, the base member 19 of each guard member is
located behind the sickle bar 24 and each guard finger 215, 315 has no
connection
with a next adjacent guard finger forwardly of the base member 19. That is
there is
no trash bar on the guard at the location in front of the sickle bar 24 so
that the
guard fingers 215, 315 are cantilevered from the rear base member 19 behind
the
sickle bar on a plurality of respective forwardly extending parallel support
members
19A, 19B, 19C. The ledger surface 15A of each guard finger at the imaginary
line
130 has a width between the first and second side edges 15B, 15C which is
greater
than the width W3 of the support members.
That is the ledger surfaces 15A of each of the guard fingers 15 are free
from any connection each to the next in front of the imaginary line 129. That
is there
is no conventional trash bar.
In this way the first and second apexes 127, 128 as they reciprocate
along the imaginary line 129 depart from the side edge 15B of the ledger
surface
15A of the guard finger 15 and are free from contact with any support surface
of the
guard fingers until the apexes reach the second side edge 15C of the next
adjacent
guard finger.
Preferably the ledger surface of each guard finger at the imaginary line
has a width between the first and second side edges thereof which is more than
twice the spacing at the imaginary line between the first side edge of the
ledger
CA 02839307 2014-01-14
surface of each guard finger and the second side edge of the ledger surface of
each
next adjacent guard finger.
Thus in an arrangement where the center to center spacing of the
guards is substantially equal to 2.0 inches, the width of the ledger surface
at the
5
imaginary line can lie in the range 1.2 to 1.9 inches. Thus the percentage of
the total
distance between the guards taken up by the width of the ledger surface is
between
60% and 95%. At the preferable width of 1.5 inch, the width of the ledger
surface is
three times the width of the space and the percentage is 75%. These
percentages
can be applied where the center to center spacing is different from the 2.0
inches
3.0 stated.
In such a case, with a center to center spacing of 2.5 inches and a ledger
surface of 2.0 inches thus providing the same preferred spacing of 0.5 inches,
the
percentage is 80%. These widths are significantly greater than the traditional
width
of 1.0 inch guard in a center to center spacing of 3.0 inch where the
percentage of
the ledger surface is only 33%.
15 One
problem which has arisen with the use of wider guards and longer
blades is that there is a tendency for material to collect underneath the
blades and
lift the blade off the ledger surface thus generating a space between the
blade edges
and the ledger surface edges thus reducing the scissor type cutting action. It
has
been found that this effect can be reduced by providing no trash bar joining
the side
20 edges of
the ledger surfaces so that the apex between the blade passes over free
pace as it crosses from one ledger surface to the next and then gets cleaned
or
wiped as it enters onto the next. In addition the tendency of the blade to
lift away
CA 02839307 2014-01-14
41
from the ledger surface is reduced by providing effective hold down action by
the
alternate hold-down fingers while avoiding the presence of the hold-down
fingers
from interfering with the movement of the crop and collecting material away
from the
area of the cutting action.
