Note: Descriptions are shown in the official language in which they were submitted.
CA 02311019 2002-O1-11
CROP HEADER WITH DRAPER CANVAS
This invention rE:lates to a header for cutting and transporting a
standing crop and particularly to an arrangement which provides an improved
draper
canvas of the header.
~~ BACKGROUND OF THE INVENTION
Draper headers generally include a header frame, an elongate cutter
bar along a front edge of the frame including a cutter bar beam which carries
a
plurality of knife guards for guiding reciprocating movement of a sickle knife
across a
front edge of the cutter bar. On the header is also mounted a draper assembly
including a first and second draper guide roller each arranged at a respective
end of
the draper assembly spaced apart along the cutter bar with an axis of each
roller
extending substantially at right angles to the cutter bar, a draper canvas
forming a
continuous loop of flexible material wrapped around the rollers so as to
define a front
edge of the canvas adjacent the cutter bar, a rear edge of the canvas spaced
rearwardly of the cutter bar, are upper run of the canvas on top of the roller
and a
lower run of the canvas below the rollers. The cut crop thus falls rearwardly
onto the
upper run of the canvas and is transported longitudinally of the header.
Generally,
between the draper rollers there is provided a support plate assembly for the
upper
run of the draper canvas to prevent sagging.
The header of this type can be used simply for forming a swath in
which case the material is carried to a discharge opening of the header and
deposited therefrom onto the ground. Headers of this type can also be used for
feeding a combine harvester so that the materials are carried to an adapter
member
CA 02311019 2002-O1-11
2
positioned at the discharge opening of the header for carrying the materials
from the
discharge opening into the feeder housing of the combine harvester. Yet
further,
headers of this type can be usE:d for hay conditioners in which the material
from the
discharge opening is carried inl:o crushing rolls. It will be appreciated,
therefore, that
the use of the header is not limited to particular types of agricultural
machine but can
be used with any such machines in which it is necessary to cut a standing crop
and to
transport that crop when cut longitudinally of the header for operation
thereon.
The draper canvas normally comprises a fabric which is coated with a
rubber material which is then vulcanized after forming of the fabric into the
required
shape and after attachment thereto of transverse slats.
An example of a prior art draper of this type is shown in US Patent
5,459,986 of Talbot and Fox issued October 24, 1995 to the present assignee.
One problem with a draper construction of this type is to provide and
effective guiding arrangement for the draper canvas to prevent it from sliding
or
twisting on the rollers forwardly or rearwardly of the cutter bar. While the
above
patent does not show or describe the conventional guiding arrangement for the
draper canvas, in practice, this guide is formed by a bead or rib formed on
the
underside of the canvas that is side facing inwardly which rib runs in a
groove
provided on the rollers.
This arrangement has been used for many years and has been
considered adequate but it has a number of disadvantages examples of which are
as follows.
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3
Firstly, the rib wears rapidly. Secondly the rib is only effective at the
rollers and thus has no guiding effect in the long length between the rollers.
Thirdly
the forces at the roller are very high due to the fact that all of the guiding
effect
occurs at the rollers. Fourthly, if the groove becomes contaminated, the rib
can be
forced out of the groove.
Another problem which has required attention is that of reducing loss
of material from the carrying surface of the canvas by escaping over the front
edge
between the front edge and the cutter bar.
SUMMARY OF THE INVENTION
It is one object of the present invention, therefore, to provide an
improved header which includes an improved and more effective draper canvas.
According to one aspect of the invention there is provided a header for
cutting and transporting a standing crop comprising:
a header frame;
an elongate cutter bar arranged along a front edge of the frame;
a knife mounted on the cutter bar for cutting the standing crop;
a draper assembly mounted on the header frame rearwardly of the
cutter bar such that crop cut by the knife of the cutter bar falls onto the
draper
assembly for transportation longitudinally of the header;
the draper assembly including:
a first and a second draper guide roller each arranged at a respective
end of the draper assembly spaced apart along 'the cutter bar with an axis of
each
guide roller arranged substantially at right angles to the cutter bar;
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4
a draper canvas forming a continuous loop of flexible material wrapped
around the rollers so as to define an upper run of the canvas on top of the
rollers
and a lower run of the canvas (below the rollers, a front edge of the upper
run of the
canvas adjacent the cutter bar, a rear edge of the upper run of the canvas
spaced
rearwardly of the cutter bar, an inner surface of the canvas facing inwardly
and an
outer surface of the canvas facing outwardly such that the outer surface
defines an
upper surface of the upper run for carrying the cut crop thereon;
at least one of the guide rollers being arranged to effect driving of the
canvas in a direction along its length to carry the cut crop therealong;
the cutter bar including a rearwardly facing trailing edge therealong at
the upper run of the draper canvas;
the draper canvas having a front guide bead extending longitudinally
therealong attached to and extending outwardly from the outer surface thereof;
the front guide bead being located rearwardly of the trailing edge of the
cutter bar with a forward side surface of the front guide bead on the upper
surfiace of
the upper run of the canvas.
According to a second aspect of the invention there is provided a
header for cutting and transporting a standing crop comprising:
a header frame;
an elongate cutter' bar arranged along a front edge of the frame;
a knife mounted on the cutter bar for cutting the standing crop;
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a draper assembly mounted on the header frame rearwardly of the
cutter bar such that crop cut by the knife of the cutter bar falls onto the
draper
assembly for transportation longitudinally of the header;
the draper assembly including:
5 a first and a second draper guide roller each arranged at a respective
end of the draper assembly spaced apart along the cutter bar with an axis of
each
guide roller arranged substantially at right angles to the cutter bar;
a draper canvas forming a continuous loop of flexible material wrapped
around the rollers so as to define an upper run of the canvas on top of the
rollers
and a lower run of the canvas below the rollers, a front edge of the upper run
of the
canvas adjacent the cutter bar, a rear edge of the upper run of the canvas
spaced
rearwardly of the cutter bar, an inner surface of the canvas facing inwardly
and an
outer surface of the canvas facing outwardly such that the outer surface
defines an
upper surface of the upper run for carrying the cut crop thereon;
at least one of the guide rollers being arranged to effect driving of the
canvas in a direction along its length to carry the cut crop therealong;
the cutter bar including a rearwardly facing trailing edge therealong at
the upper run of the draper canvas;
the draper canvas having a front guide bead extending longitudinally
therealong attached to and extending outwardly from the outer surface thereof;
the front guide bead being located rearwardly of the trailing edge of the
cutter bar with a forward side surface of the front guide bead on the upper
surface of
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6
the upper run of the canvas in contact with the rearwardly facing trailing
edge of the
cutter bar;
and the front guide bead being located at a position spaced rearwardly
from the front edge of the canvas with the front edge of the upper run of the
canvas
located forwardly of and underneath the rearwardly facing trailing edge of the
cutter
bar.
The term "canvas," as used herein does not imply the use of specific
material for the manufacture of the canvas since this term has become widely
used
as a term identifying the belts or sheets which carry the cut crop in a header
of this
general type.
While the knife uaed with the cutter bar is usually of the sickle knife
type including a plurality of knife guards mounted on the cutter bar, other
types of
knife can also be used.
In some embodiments, the cutter bar itself comprises a channel
shaped member which defines the trailing edge as an integral portion of the
cutter
bar itself. In other embodiments, the cutter bar forms in effect a single bar
carrying
the sickle knife with a separate canvas carrier element in the form of a plate
attached to and carried by the cutter bar. In this latter arrangement, the
trailing edge
can be provided by the edge of the canvas carrier rather than the cutter bar
itself.
However it will be appreciated that in both arrangements the guide bead
engages an
edge which is fixed relative to the cutter bar and thus is guided in position
relative to
the cutter bar as it moves along the cutter bar.
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Preferably the forward side surfiace of the rib is spaced rearwardly from
the front edge of the canvas such that the front edge is located underneath
the
trailing edge of the cutter bar or' canvas carrier.
Preferably there is provided a rear plate adjacent the rear edge of the
upper run of the canvas, wherein the draper canvas has a second guide bead or
rear rib therealong attached to and extending outwardly from the outer surface
thereof, the second guide bead being arranged such that a rear side surface of
the
second guide bead on the upper surface of the upper run of the canvas, as the
canvas moves in its direction of movement, runs in contact with a front edge
of the
rear plate to guide the location of the canvas relative to the rear plate.
Preferably the rear side surface of the second guide bead is spaced
forwardly from the rear edge of the canvas such that the rear edge is located
underneath the front edge of the rear plate.
Preferably the outer surface of the canvas carries a plurality of slats
thereon at spaced positions along the length of the canvas and extending at
right
angles to the guide bead, the slats being formed integrally with the bead so
as to be
connected thereto. Where the draper canvas has a second guide bead or rear rib
therealong attached to and extending outwardly from the outer surface thereof
parallel to and spaced rearwardly from the guide bead, the slats are formed
integrally with both the guide beads so as to be connected thereto.
Preferably the guide bead is continuous along the length of the canvas
and has a series of cut out portions at spaced positions along the length of
the
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canvas such that an outer surface of the guide bead is castelated to form
portions of
reduced height of the bead.
As the guide beads are provided on the outer surface, the inner
surface of the canvas is flat and free from beads.
In the arrangement where the forward surface of the guide bead is
spaced rearwardly from the front edge of the canvas, there is preferably
provided a
front draper support plate defining a substantially horizontal support surface
lying
under the upper run adjacent the front edge thereof and extending therealong
between the first and second guide rollers, the first and second guide rollers
each
having a front end thereof recessed rearwardly of the front edge of the upper
run of
the draper canvas and the support plate having a front edge thereof recessed
rearwardly of the front edge of the upper run of the draper canvas such that
the
upper run of the draper canvas includes a portion thereof at the front edge
which is
cantilevered forwardly of the rollers and of the support plate, the trailing
edge of the
cutter bar extending rearwardly over the upper run of the draper canvas to a
position
rearwardly of the front edge of the upper run of the draper canvas and
forwardly of
the front end of the rollers and of the front edge of the support plate and
engaging
said portion of the draper canvas for forming a seal therewith to inhibit
entry between
the cutter bar and the draper canvas of materials carried by the cut crop.
According to a third aspect of the invention there is provided a draper
canvas for a header having a cutter bar, the canvas comprising an elongate
strip of
flexible material for wrapping around draper guide rollers so as to define an
upper
run of the canvas on top of the rollers and a lower run of the canvas below
the
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9
rollers, a front edge of the upper run of the canvas adjacent the cutter bar,
a rear
edge of the upper run of the canvas spaced rearwardly of the cutter bar, an
inner
surface of the canvas facing inwardly and an outer surface of the canvas
facing
outwardly such that the outer surface defines an upper surface of the upper
run for
~~ carrying the cut crop thereon, the draper canvas having a raised front rib
extending
longitudinally therealong attached to and extending outwardly from the outer
surface
thereof at a position thereon adjacent to but spaced rearwardly from the front
edge
such that an upstanding front side surface of the raised front rib is spaced
rearwardly
from the front edge of the canvas.
According to a fourth aspect of the invention there is provided a draper
canvas for a header having a cutter bar, the canvas comprising an elongate
strip of
flexible material for wrapping around draper guide rollers so as to define an
upper
run of the canvas on top of the rollers and a lower run of the canvas below
the
rollers, a front edge of the upper run of the canvas adjacent the cutter bar,
a rear
edge of the upper run of the canvas spaced rearwardly of the cutter bar, an
inner
surface of the canvas facing inwardly and an outer surface of the canvas
facing
outwardly such that the outer surface defines an upper surface of the upper
run for
carrying the cut crop thereony the draper canvas having a raised front rib
extending
longitudinally therealong attached to and extending outwardly from the outer
surface
thereof at a position thereon at or adjacent to the front edge, the outer
surface
carrying a plurality of slats thereon at spaced positions along the length of
the
canvas and extending at right angles to the front raised rib, the slats being
formed
integrally with the front raised rib so as to be directly connected thereto.
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According to a fifth aspect of the invention there is provided a header
for cutting and transporting a standing crop comprising:
a header frame"
an elongate cutter bar arranged along a front edge of the frame;
a knife mounted on the cutter bar for cutting the standing crop;
a draper assembly mounted on the header frame rearwardly of the
cutter bar such that crop cut by the knife of the cutter bar falls onto the
draper
assembly for transportation longitudinally of the header;
the cutter bar including a trailing edge therealong adjacent the draper
assembly;
the draper assembly including:
a first and a second draper guide roller each arranged at a respective
end of the draper assembly spaced apart along the cutter bar with an axis of
each
guide roller arranged substantially at right angles to the cutter bar;
a draper canvas forming a continuous loop of flexible material wrapped
around the rollers so as to define an upper run of the canvas on top of the
rollers
and a lower run of the canvas below the rollers, a front edge of the upper run
of the
canvas adjacent the cutter bar, a rear edge of the upper run of the canvas
spaced
rearwardly of the cutter bar, an inner surface of the canvas facing inwardly
and an
outer surface of the canvas facing outwardly such that the outer surface
defines an
upper surface of the upper run for carrying the cut crop thereon;
at least one of thE: guide rollers being arranged to effect driving of the
canvas in a direction along its length to carry the cut crop therealong
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the draper canvas having a front raised rib extending longitudinally
therealong attached to and extending outwardly from the outer surface thereof
at a
position thereon adjacent to but spaced rearwardly from the front edge.
According to a sixth aspect of the invention there is provided a header
~~ for cutting and transporting a standing crop comprising:
a header frame;
an elongate cutter bar arranged along a front edge of the frame;
a knife mounted on the cutter bar for cutting the standing crop;
a draper assembly mounted on the header frame rearwardly of the
cutter bar such that crop cut by the knife of the cutter bar falls onto the
draper
assembly for transportation longitudinally of the header;
the cutter bar including a trailing edge therealong adjacent the draper
assembly;
the draper assembly including:
a first and a second draper guide roller each arranged at a respective
end of the draper assembly spaced apart along the cutter bar with an axis of
each
guide roller arranged substantially at right angles to the cutter bar;
a draper canvas forming a continuous loop of flexible material wrapped
around the rollers so as to define an upper run of the canvas on top of the
rollers
and a lower run of the canvas below the rollers, a front edge of the upper run
of the
canvas adjacent the cutter bar, a rear edge of the upper run of the canvas
spaced
rearwardly of the cutter bar, an inner surface of the canvas facing inwardly
and an
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12
outer surface of the canvas facing outwardly such that the outer surface
defines an
upper surface of the upper run for carrying the cut crop thereon;
at least one of the guide rollers being arranged to effect driving of the
canvas in a direction along its length to carry the cut crop therealong;
the draper canvas having a raised front rib extending longitudinally
therealong attached to and extending outwardly from the outer surface thereof;
the outer surface of the canvas having a plurality of slats thereon at
spaced positions along the length of the canvas and extending at right angles
to the
raised front rib;
the slats being formed integrally with the raised front rib so as to be
directly connected thereto.
BRIEF DESCRIPTION OF THE. DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is a top plan view of the front part of a header with the draper
canvas removed to show the underlying elements, the position of the draper
canvas
being shown in dash line.
Figure 2 is a cross sectional view along the lines 2-2 of Figure 1.
Figure 3 is a cross sectional view similar to that of Figure 2 showing
the construction of the draper re~lier.
Figure 4 is a front elevational view of one embodiment of the canvas
only.
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13
Figure 5 is a front elevational view of a second embodiment of the
canvas only.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
~~ DETAILED DESCRIPTION
Only those parts ~of the header which are of importance to the present
invention are shown in the above figures of the present application and the
remaining parts of the header including the frame structure, drives, ground
wheels
and the like are omitted as these will be well known to one skilled in the
art. The
present invention is concerned with the area of co-operation between the front
and
rear edges of the draper with the cutter bar and with the rear header plate
respectively and therefore these elements only are shown in detail.
Many of the figures and much of the following description is taken from
the aforementioned US Patent 5,459,986 of the present assignees since this
shows
the basic construction of the (header and those drawings have been modified to
include the details of the present invention as described hereinafter.
The header therE:fore comprises a frame, one element of which is
indicated at 10 in the form of a beam extending horizontally and forwardly
from a
rear support frame structure (nat shown) to a cutter bar assembly generally
indicated
at 11 for support of that cutter bar assembly. The beam 10 forms one of a
plurality
of such beams arranged at spaced positions along the length of the header
frame so
as to support the cutter bar assembly 11 as an elongate structure across the
front
edge of the header.
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14
The cutter bar comprises a generally C-shaped beam 12 which
provides structural support for the cutter bar with the C-shaped beam being
welded
to the front ends of the forwardly extending beams 10. The C-shape beam 12
includes a top plate portion 13, a bottom plate portion 14 and a forward plate
portion
15 which converges from the top and bottom plate portions toward a front apex
16
forming a forward most point of the beam 12. At the apex 16 is welded a
longitudinally extending bar 17 which forms a support for a plurality of knife
guards
18 only some of which are shown in Figure 1 for convenience of illustration.
The
knife guards are of course of well known construction and their shape is shown
only
schematically. The knife guards carry a sickle knife assembly 20 having a
longitudinally reciprocating bar 21 driving a plurality of triangular knife
blades 22
which sit on the knife guards and reciprocate back and forth across the knife
guards
in a cutting action. Again this construction is well known and therefore
detail is not
necessary.
The cutter bar support beam 12 also carries an elongate angle iron 23
which is welded onto the top plate portion 13 on the underside thereof at the
front
edge thereof with the angle iron extending vertically downwardly and then
forming a
support plate 24 extending forwardly therefrom toward the apex 16.
The draper assembly includes a first draper support roller 30 and a
second draper support roller (not shown). One of these rollers is driven by a
drive
motor (not shown) to effect ratation of the draper in conventional manner. The
draper assembly further includes a draper canvas 32 in the form of a
continuous
loop or band of fabric which is wrapped around the rollers at respective ends
to form
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an upper run 33 of the draper canvas on top of the rollers and a lower run 34
of the
canvas underneath the rollers. The rollers are thus spaced longitudinally of
the
cutter bar and arranged with their axes of rotation parallel and at right
angles to the
cutter bar. The draper canvas thus includes a front edge 35 of the upper run
which
5 is adjacent the cutter bar and a rear edge 36 of the upper run 33 which is
remote
from the cutter bar and spaced rearwardly therefrom thus defining therebetween
a
flat surface of the upper run for transportation of the crop longitudinally of
the
header. The lower run 34 also includes a front edge 37 and a rear edge 38. The
draper canvas includes a plurality of conventional transverse slats 39
(omitted from
10 Figure 1 for convenience of illustration) which assist in carrying the crop
along the
draper canvas. Each edge of 'the draper canvas can include a conventional
folded
seam so as to define a portion of the canvas material which is folded back as
indicated at 40 with that folded back portion being bonded to the canvas by
the
vulcanization effect in the manufacture of the canvas.
15 The upper run of the draper canvas is supported by a support plate
assembly generally indicated at 45 which includes a front plate 46 and
includes a
center plate and rear plates which are not shown for convenience of
illustration. The
front plate 46 includes a horizontal top plate portion 47 lying underneath the
upper
run of the draper canvas adjacent the front edge for supporting that front
edge in
sliding movement across the top surface of that plate portion 47. The support
plate
46 further includes a vertical plate portion 48 which extends downwardly from
a front
edge 49 of the top plate portion 47. At a bottom edge of the vertical plate
portion 48
is provided a lower horizontal plate portion 50 thus forming the front support
plate 46
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into a generally C-shape to provide structural strength so that the support
plate 46 is
essentially self supporting mounted on mounting brackets (not shown).
The rollers are carried on the support plate 46. Further details of the
brackets and support elements are described in the above patent.
The length of the bracket 25 is arranged so that the front edge 49 of
the support plate is spaced rearwardly by a distance T from the front edge 35
of the
upper run of the draper canvas. In addition the front end 65 of the rollers 30
and 31
is spaced rearwardly from the front edge 35 of the upper run of the canvas by
a
distance S which is greater than the distance T. This recessing of the front
edges of
the support plate member and of the rollers provides a portion 70 of the front
edge of
the draper canvas which is cantilevered outwardly beyond the support provided
by
those elements.
The beam 12 of the cutter bar is shaped so that the top plate portion
13 extends rearwardly to a rear edge 71 which overlaps the portion 70. The
rear
edge 71 is located therefore at a position rearwardly of the front edge 35 of
the
draper canvas and in a position forwardly of the front edge 49 of the support
plate
and the front ends 65 of the draper rollers. That portion of the draper canvas
therefore which engages the underside 72 of the top plate portion 13 is
unsupported
on its underside and is therefore free to flex downwardly should it be
depressed
downwardly by the presence of material collecting on the under surface 72. The
top
plate portion 13 of the beam 12 is substantially horizontal that is parallel
to the
generally horizontal surface of the upper run. The co-operation therefore
between
the surface 72 of the upper plate portion 13 and the upper surface of the
draper
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canvas at the portion 70 provides a seal which inhibits the tendency of
materials to
pass between the draper canvas and the cutter bar. This seal therefore
inhibits the
build-up of materials inside the C-shape of the cutter bar and between the
draper
canvas upper run and lower run and around the draper rollers which can of
course
cause damage.
In the conventional arrangement shown in the above patent, although
not shown in the patent, the draper canvas is guided on the draper roller by a
pair of
V grooves in the roller into which projects from the back of the canvas a V-
shaped
guide rib which runs along the inner surface of the canvas along its full
length.
Normally the canvas is guided at each end of the roller by a separate rib.
The present invention provides a modified driving arrangement in
which there is formed on the outside surface of the draper canvas a rib 80
which is
rectangular in cross section and extends along the full length of the canvas
so as to
form a portion projecting upwardly from the upper surface of the upper run and
projecting downwardly from the bottom surface of the lower run. A second guide
rib
81 is provided adjacent the rear edge 36 of the canvas. The rib 80 is formed
with a
front surface 82 which is at right angles to the canvas and extends along the
canvas.
The front surface is thus flat and is arranged adjacent to the rear or
trailing edge 71
of the cutter bar. Similarly the rib 81 includes a rear surface 83 which again
is flat
and at right angles to the canvas so that it abuts a front edge 84 of a rear
plate
assembly 85.
As previously explained, the front surface of the rib is spaced
rearwardly from the front edge of the canvas so that the front portion of the
canvas
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underlies the trailing edge of the cutter bar. Similarly the rear plate
assembly 85
includes a forwardly projecting flange portion 86 which overlies the rear edge
36 of
the upper run of the belt and butts against the surface 83.
The rear plate assembly 85 forms a rear sheet across the width of the
header and that rear sheet is fastened over the frame members 10 by a suitable
fastening arrangements (not shown). The flange 86 projects forwardly from that
rear
sheet and lies in the same plane as the canvas.
The ribs 80 and 81 are shown as of square cross section but it will be
appreciated that the facing edge 82 and 83 forms the important edge of the
structure
so that the remaining surfaces may be of any required shape without affecting
the
operation. The ribs 80 and 81 have a height greater than the thickness of the
abutting plate and preferably lying in the range 0.5 to 1.0 inch.
The spacing between the surfaces 82 and 83 is arranged to be slightly
less than the spacing between the abutting edges 71 and 84 so that there is no
possibility of jamming of the canvas. However front to rear movement of the
canvas
is prevented by the surfaces of the ribs abutting one or other of the surfaces
of the
plates. Thus the forward and rearward movement of the canvas is limited to the
slight clearance defined by the difference in the widths above.
The rib 80 at the front of the canvas also assists in providing an
improved seal since it stands upwardly from the cutter bar and provides a
narrow
gap or lies in abutment with the cutter bar so as to further inhibit the
penetration of
materials between the draper canvas and the cutter bar.
CA 02311019 2002-O1-11
19
The presence of the rib 80 at the front of the canvas also assists in
retaining on the canvas any crop materials including seeds which may tend to
roll
forwardly on the forwardly inclined canvas and thus be lost over the front of
the
cutter bar or between the cutter bar and the canvas. Thus the rib acts as a
dam
tending to retain materials on the canvas so that they are carried with the
canvas to
the discharge location of the header where they can be collected.
The ribs 80 and 81 are formed integrally with the slats 39, that is the
ribs are formed of a strip of rubber or reinforced rubber material which is
applied
onto the canvas surface and attached in place using a vulcanization process so
that
the ribs and the slats are applied simultaneously and thus formed so that the
slats
interconnect with the inside surface of the ribs as an integral structure.
Thus the
slats preferably have a height which is common with the height of the ribs.
As shown in Figure 4, one embodiment of the rib has a constant height
along its full length so that the top surface 88 of the rib is flat and
parallel to the top
surface of the draper. This shape is convenient in that it utilizes the same
strip
material which is utilized for the slats which are similarly shaped.
In the embodiment of Figure 5, however, there is provided a modified
arrangement in which the rib indicated at 80A has a plurality of cut-out
portions 80B
so that the top surface 88A is castelated. In the embodiment shown the cut-out
portions 80B extend over approximately half of the height of the rib so that
there
remains a rib portion raised from the top surface 80C of the canvas itself.
However
in other embodiments, the rib rnay be cut down at each cut out portion so that
its
height is equal to the top of the canvas sheet so that the rib is thus formed
in
CA 02311019 2002-O1-11
separate pieces as opposed to the continuous arrangement shown in Figures 4
and
5. This arrangement is disadvantageous in that it no longer provides the
damming
effect. However the cut-out portions 80B either of full height or of partial
height as
shown assist in allowing the structure to bend around the rollers where
stretching of
5 the rib is necessary to accommodate the differences in diameter. The cut-out
portions further provide an aggressive action on the crop where the shoulders
80D
between each cut out portion and the next adjacent raised or full height
portion
engage the crop to assist in carrying the crop longitudinally of the draper
canvas to
the collection point.
10 While an important aspect of the guide bead or rib at or adjacent the
front edge of the canvas is that it contacts and runs along an edge of the
cutter bar
or fixed relative to the cutter bar, the guiding may be provided by another
element or
may be provided by a contact of the edge of the canvas with a suitable surface
on
the cutter bar and the rib or bead act merely as a dam or barrier to assist in
15 preventing the escape of material at the front edge of the canvas. Thus the
rib acts
to improve the seal between the canvas and the cutter bar and this aspect of
its
operation is important and can be adopted without necessarily using the
guiding
aspect.
Since various modifications can be made in my invention as herein
20 above described, and many apparently widely different embodiments of same
made
within the spirit and scope of the claims without departing from such spirit
and
scope, it is intended that all matter contained in the accompanying
specification shall
be interpreted as illustrative only and not in a limiting sense.
