Axial flow rotary separator

In the axial flow rotary separator of a combine harvester spiral propulsion of the crop material mat is achieved through the cooperation of helical guide vanes in the separator casing and rotor fingers free to swing axially. The rotor is eccentrically mounted so that each finger fully engages the mat for only part of each revolution. While in engagement, the fingers maintain the circumferential propulsion of the mat but each finger is free to be carried downstream by the mat under the influence of the guide vanes, deflected from its normal free fully radially extending position. On disengagement from the mat, centrifugal force restores the finger to its fully extended position ready for reengagement of the mat.

CROSS REFERENCES TO RELATED APPLICATIONS 
U.S. Pat. No. 4,574,815 filed simultaneously herewith in the name of West 
et al, entitled ROTOR FOR AN AXIAL FLOW ROTARY SEATOR and assigned to 
the assignee of the invention herein, is directed in a preferred 
embodiment to a tined separator rotor in which the tines are mounted for 
oblique and eccentric rotation with respect to the separator casing axis 
and each tine or finger is individually journalled. To the extent that the 
invention disclosed and claimed in U.S. Pat. No. 4,574,815 is disclosed 
herein, it is done so only for completeness of description of the 
operative environment of the invention claimed herein and thus forms no 
part of the invention claimed herein. 
U.S. Pat. No. 4,611,606 filed simultaneously herewith in the names of Hall 
et al, entitled FEEDING ARRANGEMENT FOR AN AXIAL FLOW ROTARY SEATOR and 
assigned to the assignee of the invention herein, is directed in a 
preferred embodiment to a twin rotor axial flow separator for a combine in 
which threshed material is delivered overshot fashion downwardly towards 
the bite between contra-rotating rotors sharing a common feed casing. To 
the extent that the invention disclosed and claimed in U.S. Pat. No. 
4,611,606 is disclosed herein, it is done so only for completeness of 
description of the operative environment of the invention claimed herein 
and thus forms no part of the invention claimed herein. 
BACKGROUND OF THE INVENTION 
The invention concerns an axial flow rotary separator for a crop harvester 
in which a rotor rotates within an elongated, surrounding casing and more 
particularly, one in which finger-like elements of the rotor 
intermittently engage a mat of crop material while propelling it in a 
generally spiral path within the casing. 
For convenience, crop material engaging elements arranged to penetrate and 
engage a crop material flow only intermittently will often be referred to 
below as "fingers" or "finger-like elements" although, of course, the 
elements may take many forms while still functioning in essentially the 
same way. 
In the discussion which follows, the vehicle for the axial flow rotary 
separator is assumed to be a self-propelled combine harvester as used for 
harvesting a variety of grain and other crops. However, separators of this 
type may of course be used in pull-type combine harvesters as well as in 
stationary threshing and separating operations. 
Although the long history of mechanical threshing and separating of 
agricultural grain crops has been dominated by the conventional 
arrangement of transverse threshing cylinder upstream of a rack or straw 
walkers, there have also been attempts spanning many years to develop 
axial flow rotary separation. In recent years, combine harvesters 
embodying this principal have captured a significant portion of the 
market. Typically their rotors include an upstream threshing portion 
coaxial with a downstream separator portion. The separating operation per 
se is carried out on threshed crop material to separate the remaining 
grain from straw and leaves etc. However, in keeping with common usage, 
the term separator will sometimes be used in this application to describe 
a combination of components including infeed arrangements for a rotor or 
rotors, and discharge provisions in combination with an actual separator 
portion (and an upstream threshing portion if it forms part of the axial 
flow unit). 
Conventional axial flow rotary separators with driven rotors depend for 
axial indexing on sliding motion between crop material and angled surfaces 
within the separator, such as angled blades on the rotor or helical guide 
vanes on the casing or a combination of the two. Crop engaging elements of 
the rotor are carried in fixed relation to the rotor frame and propulsion 
of crop material is not positive. Crop material is deflected axially by 
angled blades or guide vanes but, typically, there is a strong tendency 
for material to ride over the rotor elements and hence, power consuming 
circumferential slippage between rotor and crop material. Overall, there 
are very high friction losses, specific power consumption is high and 
handling of some types of material is unreliable. For example, in damp 
conditions, there may be a tendency to "roping" of the material leading to 
plugging of the separator. 
Nusser (U.S. Pat. No. 4,178,942) has suggested an axial flow rotary 
separator which substitutes more or less randomly oscillating tines for 
the fixed crop engaging elements of conventional rotors and relies 
entirely on helical guide vanes for axial propulsion. However, the 
operating characteristics of Nusser's device are not clear from his 
disclosure. 
The intermittently engaging, positively propelling and obliquely moving 
finger-like crop engaging elements of Witzel's rotor (U.S. Pat. No. 
4,408,618) make guide vanes unnecessary and dramatically cut specific 
power requirement while improving material-handling characteristics and 
maintaining an acceptable level of separating efficiency. There is no 
doubt that Witzel's separator represents an important advance over known 
axial flow rotary separators. However, the embodiments disclosed by Witzel 
are all relatively complex and the potential total cost of using them, 
resulting from the related costs of manufacturing and reliability, may 
make them unattractive. 
SUMMARY OF THE INVENTION 
Accordingly it is an object of the invention to retain, in an axial flow 
rotary separator, material handling and mechanical efficiency advantages 
provided by a rotor whose finger-like elements engage the crop material 
mat only intermittently but which, while in engagement, propel it 
positively (at least circumferentially) while at the same time 
contributing to its axial displacement, but to use a rotor and separator 
casing combination which is inherently lower in cost and more reliable 
than known separators of this type. 
This object may be realized in a separator arrangement in which the 
separator casing has fixed internal helically disposed guide surfaces and 
surrounds a rotor characterized in that at least the radially outward 
portions of its finger-like crop engaging elements are displaceable or 
resiliently yieldable, at least axially, relative to the rotor frame or 
body. The casing shape and the rotor disposition within it are such that, 
as the rotor rotates, each finger approaches and recedes from the casing 
wall. In operation, rotor speeds and material flow rates are normally such 
that, essentially, crop material is maintained, in an annular mat of 
predetermined maximum thickness in contact with the casing wall, so that 
each finger penetrates and propels a mat portion only periodically, 
defining a zone or arc of engagement. Casing helical guide surfaces are 
disposed so that preferably, but not essentially in some portion of the 
zone of engagement, each mat portion is deflected axially downstream, if 
necessary carrying the displaceable finger outward portion downstream with 
it so that it is displaced relative to the rotor frame. Preferably the 
fingers are designed to be easily displaceable, at least axially, offering 
negligible resistance to axial movement of the crop material mat portion. 
The aggregate effect of a plurality of fingers on the rotor cooperating 
with suitably disposed guide surfaces is of course to propel a received 
body of crop material in an annular mat generally in contact with the 
casing spirally downstream. Thus spiral propulsion is achieved essentially 
without two of the power consuming friction components associated with the 
rotors of conventional axial separators. Positive circumferential 
propulsion (and periodic disengagement) eliminates the circumferential 
slippage friction factor. And the axial freedom of the finger tips allows 
the casing guide surfaces to direct crop material downstream without 
generating a related friction component on fixed rotor surfaces. As a 
result, specific power consumption of separators according to the 
invention is much less than that of conventional axial flow separators and 
their mechanical efficiency is comparable to that of separators disclosed 
by Witzel (U.S. Pat. No. 4,408,618) where the intermittently engaging 
fingers are directly driven in oblique orbit and casing guide surfaces may 
be dispensed with. 
A feature of rotors according to the present invention is the "righting" of 
each finger which occurs after disengagement from the crop material mat so 
that it is prepared for reengagement with the mat on the next rotor 
revolution. Compared with '618 Witzel, there is an advantage here, 
especially in operating conditions where, because of overfeeding or 
insufficient mat rotational speed, effective mat depth increases 
sufficiently to increase finger arc of engagement beyond about 180 
degrees. In such conditions, the (passive) rotor of the present invention 
behaves benignly, continuing to propel material at least purely 
circumferentially but also permitting downstream movement if called upon 
(by, say, a guide surface effect). On the other hand, in the same 
conditions, a potentially plugging, or at least efficiency reducing, 
reverse indexing segment is introduced into the arc of engagement of the 
finger driven in fixed oblique orbit as in '618 Witzel. In his principal 
embodiments, (Witzel's net overall indexing effect would of course be zero 
for a 360 degree arc of engagement. But in the embodiment of his FIGS. 22 
and 23, in an overfeeding or underspeed condition, performance would be 
adversely affected by the inability of the folding finger 578 to retract 
sufficiently to clear the crop material mat on the "return stroke.") 
The displaceability of the radially outward portion of each finger relative 
to the rotor frame may also be achieved, for example, by using flexible 
resilient elements fixed to the rotor frame (as in a cylindrical brush) or 
by elements, resilient or stiff, which are pivotably carried by the rotor 
frame. It is essential to the invention that the displaceability of the 
rotor element outer portion include a substantial axial component of 
freedom. This will of course be true of a simple flexible tine of uniform 
cross section. However, in order to retain more positive control of 
material, it is preferable that circumferential yielding be limited. This 
may be achieved by using fixed resilient elements of non-uniform cross 
section which are more flexible in the rotors axial direction than 
circumferentially or, of course, by using elements which are pivoted 
relative to the rotor frame. Preferably the pivot axis of any simply 
mounted pivoting finger is approximately perpendicular to the axis of 
rotation of the rotor and extends approximately circumferentially with 
regard to the rotation of the rotor. Thus the freedom of movement of the 
outer portion of such a finger would be essentially axial or at least an 
arc in a plane parallel to and including the axis of rotation of the 
rotor. 
In a particular embodiment of the invention, rotor elements may be mounted 
in approximately diametrically opposed pairs, rigidly connected and 
sharing a common pivot axis intersecting the rotor axis. With an 
eccentrically mounted rotor, only one end of this double-ended element 
will be active at one time. The downstream axial displacement of the one 
engaged end is accompanied by a corresponding upstream axial displacement 
of the disengaged end preparing it or positioning it for its own 
engagement during the next half revolution of rotation of the rotor. 
It is a feature of the invention that the crop engaging elements, following 
their axially downstream displacement while in engagement with the crop 
material mat, are automatically restored to a fully extended or ready 
position for reengagement. This was referred to above as "righting". The 
restoring or righting means may be simply the resilience of a resilient 
element, centrifugal action in the case of pivoted elements or, in the 
case of the double-ended centrally pivoted element, the restoration is a 
form of automatic indexing derived from the primary function of the 
element. And, of course, the righting of pivoted elements could be 
assisted by a spring. 
Rotor and casing combinations according to the invention may be 
characterized as crop material conveyors with particular material handling 
characteristics deriving from the intermittent engagement of finger-like 
elements with the crop material. These material handling characteristics 
are particularly valuable in the separating portion of a combine harvester 
where separation per se is carried out--the separator casing includes 
grates allowing separated grain to pass outwards through the casing walls 
for collection. However, rotors according to the invention may also be 
used effectively singly or in combination with other similar rotors in the 
feeding, transition and discharge portions of separators or in combination 
with the threshing elements in an axial flow rotor threshing portion of a 
separator.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The invention is embodied in a self-propelled combine harvester, shown 
somewhat schematically in FIG. 1, and particularly in the crop handling 
and processing means of such a harvester. 
The harvester includes a body 10 supported above the ground on powered 
front wheels 12 and steerable rear wheels 14. Other portions of the 
harvester which are collectively generally conventional in nature and 
arrangement include the forward mounted operator station 16, a forward 
header 18 pivotably supported by the body 10 for adjustment of operating 
height and including a gatherer 20 (in this case a corn head) for removing 
crop material from a field, and a feeder house 22 for taking crop material 
from the gatherer 20 and delivering it to a transversely extending 
threshing zone 24. The latter is defined by conventional threshing 
cylinder and concave, 26 and 28, respectively. 
In the threshing zone 24, material is divided into two main streams, one 
consisting principally of threshed grain passing radially outward through 
the bars of the concave 26, and the remaining material, largely straw, 
being discharged circumferentially rearwardly and upwardly to be received 
by what will be named here as the separator 30 and described in detail 
below. 
Reverting to conventional aspects of the harvester, separated material 
passing downwards from the concave 28 and from the separator 30 is 
intercepted by a collecting conveyor 32 and delivered to a cleaning shoe 
34. From the shoe, conventional conveying arrangements (not shown) take 
cleaned grain to a tank 36 to be held temporarily before unloading from 
the combine through an unloading auger assembly 38. Straw discharged from 
the rearward or dowwnstream end of the separtor 30 is received by a straw 
chopper 40. 
Looking now at the separator 30, in more detail and referring particularly 
to FIGS. 2, 3 and 4, crop material carried circumferentially through the 
threshing zone 24 is received and propelled into the separator by a beater 
44 cooperating with an overhead curved guide plate 46. A smooth tubular 
stripper 48 assists in material control. Beater 44, guide plate 46 and 
stripper 48 all extend substantially the full width of the threshing 
cylinder 26. A generally conventional finger bar grate 50 extending 
rearwardly from the downstream end of the concave 28 prevents downward 
passage of straw and other large particles of the crop material mass while 
permitting a certain amount of additional separation and passage of 
threshed grain downwards to the collecting conveyor 32. 
The principal components of the separator 30 are a pair of side-by-side 
parallel rotors, left- and right-hand, 52 and 54 respectively, enclosed in 
a housing or casing 56. Each rotor is a unitary structure but is 
differentiated over its length into rotor infeed, separating and discharge 
portions 52a, 52b, 52c and 54a, 54b, 54c, respectively. For the greater 
portion of their length, the rotors are housed separately, completely 
surrounded by their own cylindrical casings, left- and right-hand, 58 and 
60, respectively, each having its own downstream discharge or outlet 
opening, left- and right-hand 62, 64 respectively. However, in the infeed 
portion of the separator (casing feed portion 66) there is essentially no 
internal division. An infeed chamber 68 of generally rectangular cross 
section with rounded bottom corners is defined by a flat generally 
horizontal floor portion 70 contiguous with generally cylindrical casing 
portions left- and right-hand 72 and 74, respectively, in turn contiguous 
with opposite upright, approximately triangular sidewalls, left- and 
right-hand, 76 and 78 respectively, and a rearwardly and downwardly 
sloping top wall 80. A front wall or bulkhead 82 covers the lower forward 
end of the infeed chamber 68 leaving a rectangular transversely extending 
inlet opening 84 occupied in large part by the beater 44. 
The overall width and height dimensions of the feed casing 66 are somewhat 
greater than the combined overall dimensions of the two cylindrical 
separator casings 58, 60 (which are however, closely spaced). The junction 
between the feed and separator casing portions is made, in its upper half, 
by curved and sloping transition surfaces and in the lower half, by a 
"step". Upper, outer conically formed transitions, left-hand and 
right-hand, 90, 92 respectively, extend between the top wall 80 of the 
feed casing and the sidewalls 76, 78 and connect with the forward edges of 
the separator casings 58, 60. Preferably the arrangement also includes 
upper, inner, conically formed transition members left- and right-hand, 
94, 96 respectively, also connecting with the cylindrical separator 
casings 58, 60 and extending downwards from the feed casing top wall 80 to 
meet each other at a central, rearwardly and downwardly sloping dividing 
edge 98. 
The upright rear wall 100 of the lower portion of the feed casing 66 
includes a central portion 102 between the two separators and outer 
tapering portions left- and right-hand 104, 106, serving as risers for the 
step from the floor of the infeed chamber 68 into the separator casings 
58, 60. 
The separator casings each include a foraminous separator grate left- and 
right-hand 108, 110, respectively, extending the full length of the 
separator portion and occupying its lower half while the upper halves of 
the casing left- and right-hand 112, 114, respectively, are "solid" sheet 
metal. In the casing discharge sections 62, 64, the casings open downwards 
constituting discharge outlets left- and right-hand 116, 118, 
respectively, but each opening includes an outer deflector member left- 
and right-hand 120, 122, respectively, wrapping the lower outer quadrant 
of the separator casing and tapering rearwardly and upwardly. 
In that the separator 30 is symmetrical about a central longitudinal 
vertical plane, it is generally sufficient to describe only one side of 
the separator. Thus, in the following description where possible and 
convenient, only the left-hand components will be described, left- and 
right-hand being as seen by an observer standing behind the machine and 
facing in the direction of forward travel. 
A series of generally helically extending internal guide surfaces span the 
length of the separator casing 56. The general form of these is a vane 
formed of a strip of steel with an outer edge fixed to the inside surface 
of the casing and with the faces of the strip approximately perpendicular 
to the surface. In the feed casing 66, as best seen in FIGS. 3 and 4, a 
front or first feed guide vane 130 comprises floor and lower quadrant 
portions 132, 134, of uniform height and, continuing in the upper outer 
quadrant, an upper portion 136, increasing in width or radial extent so 
that its inner edge 138 remains approximately concentric with the rotor 
52. A second or rear feed vane 140 is similar to the first 130 except that 
its upper quadrant portion 142 extends almost wholly within the separator 
casing 58. 
Within the separator casing 58, the guide vanes are all of similar form but 
a front or first separator guide vane 144 has a helix angle similar to 
that of the feed guide vanes 130, 140 and greater than that of each of the 
series of separator guide vanes 146 spaced through the separator casing 
portion and shorter vanes 147 in the discharge area 62. Taking the form of 
the first separator guide vane 144 as exemplary, it consists of a lower 
portion 148 of uniform height spanning approximately the 1ower 180 degrees 
of the casing (separator grate 108) and an upper quadrant 150 tapering to 
a maximum width at approximately top dead center of the casing so that its 
inner edge 152 remains approximately concentric with the rotor 52. 
Turning now to the structure of the rotors 52, 54 and referring 
particularly to the left-hand rotor 52 as shown in FIG. 7, the rotor frame 
160 extends the full length of the casing 56 and includes front and rear 
coaxial stub shafts 162, 164, respectively on which the rotor is 
supported, offset vertically downwards with respect to the casing. The 
front shaft 162 is journaled in a bearing 166 carried by a transverse 
frame member 168 forming part of a combine body 10. At the rear end of the 
rotors, a rotor drive system 170 supported on a rear transverse frame 
member 171 includes a pair of right angle gear boxes 172, 173, left- and 
right-hand respectively driven by a common input shaft 174 and having 
output shafts left- and right-hand 176, 178, respectively, connected to 
and supporting the rear ends of the rotors at their rear stub shafts 164. 
The drive ratios of the gear boxes 172 are equal so that the two rotors 
52, 54 are driven at equal speeds and with constant timing. 
The frame 160 of the rotor is square in cross section consisting of four 
elongated tubular frame members 180, one at each corner of the square, 
attached to and spaced by a series of spreader plates 182. Each tube 
carries at the downstream end of the rotor an approximately radially 
extending discharge paddle 184. 
Pivotably supported between the tubes 180 of the rotor frame on all four 
sides of the rotor is a series of finger assemblies-infeed finger 
assemblies 186 in the rotor infeed portion 52a and separating finger 
assemblies 187 in the rotor separating portion 52b and extending into the 
discharge portion 52c. In each infeed finger assembly 186 a finger frame 
or base 188 is pivotably supported midway between a pair of adjacent frame 
tubes 180 by a pivot assembly 190 including a conventional low friction 
bearing bushing arrangement, for pivoting about an axis perpendicular to 
the rotor axis of rotation 191. From each finger frame or base 188, first 
and second crop engaging elements in the form of rods or fingers 192 
extend generally radially but diverging somewhat. Each finger has an outer 
crop engaging portion or tip 194. Each finger assembly 186 may pivot 
freely within limits set by a stop pin 196 fixed to the finger frame 188 
and engageable with an adjacent frame tube 180. The range of pivoting is 
indicated in FIG. 10. 
In the separating and discharge portions of the rotor 52b and 52c 
respectively, the structure is the same as in the feed section 52a except 
that each finger 198 with its crop engaging outer portion 200 is somewhat 
shorter. As seen best in FIG. 7, the finger assemblies 186 and 187 are 
arranged in a continuous spiral with respect to the frame 160, the spiral 
preferably being opposite hand from that of a screw conveyor which would 
also convey rearwardly if rotated in the same direction as the rotor. The 
structure of the right-hand rotor 54 is identical but of opposite hand. 
The operation of a conventional combine harvester is well understood and 
the conventional aspects of the present embodiment need not be discussed 
in any great detail. Emphasis will be on the feeding of the separator 30 
and processing, handling and discharge of material from the separator. 
As the combine advances over the field, crop material is gathered and 
delivered to the threshing zone 24 in the usual way. In the threshing 
zone, a significant amount of separation as well as threshing takes place 
with much of the threshed grain passing outwards and downwards through the 
bars of the concave 28. The bulk of material comprising mostly straw and 
chaff but including some, as yet, unseparated grain is discharged 
rearwardly and upwardly from the threshing zone 24 for feeding into the 
separator 30. The stripper roller 48, rotating as indicated by arrow 210 
in FIG. 2, reduces any tendency for material to be carried around or 
recirculated by the threshing cylinder 26 and also provides a live surface 
to assist in conveying and guiding material into engagement by the beater 
44, which, with the help of the guide plate 46 and rotating as indicated 
by arrow 212, propels material overshot fashion rearwardly and downwardly 
into the upper part of the feed chamber 68, towards the rotor feed 
portions 52a, 54a. 
U.S. Pat. No. 4,611,606, also assigned to the assignee of the present 
invention, describes more fully a generic form of this feeding arrangement 
in which crop material is drawn between contra-rotating rotors. The 
present embodiment is characterized by a particular configuration of the 
feed casing 66 including the helical guide surfaces (guide vanes 130, 140) 
in combination with "passive" rotors 52, 54 and a particular delivery 
arrangement (stripper 48, beater 44 and guide plate 46). 
The relative elevation of the beater 44 and the feed casing top wall 80 
above the rotors and the extent of the opposite vertical sidewalls 76, 78 
together provide an unconfined discharge zone for the beater 44 so that 
material leaves the beater cleanly. The downward slope of the feed casing 
top wall 80 and the conically shaped guide surfaces 90, 92, 94 and 96 
immediately begin to guide or assist the crop material downwards into the 
bite 214 between the rotors as it moves rearwardly. The relatively longer 
fingers of the rotor feed portions, 52a, 54a improve the efficiency of the 
rotors in receiving the generally rearward and downward linear flow of 
material propelled from the beater 44 and dividing it and converting the 
flow into contra-rotating annular mats as the material enters the 
separator casings. 
It is the nature of rotors according to the invention that as the rotor 
rotates at normal operating speeds and with the fingers not engaged by a 
crop material mat, the fingers assume their fully extended attitude. In 
the present embodiment this is essentially radial. In the bite 214 between 
the rotors and in the space above it, the initial engagement and 
propulsion of the crop material by the fingers is essentially 
circumferential as the material is carried down through the bite into a 
dividing zone 216 between the rotors and the feed casing floor 70. Now the 
guide vanes 130, 140 begin to influence the direction of the crop material 
deflecting it downstream towards the separator casings. The fingers 192 of 
the rotor being free to pivot offer little resistance to this axial 
propulsion and follow the downstream movement of the material as long as 
they remain in active engagement with it. As seen best in FIG. 2, the feed 
casing guide vanes 130, 140 extend respectively to the inlet of the 
separator casing and, in the case of the second guide vane 140, beyond, so 
that crop material is carried smoothly into the mouth or inlet of the 
separator casing 58 aided by the transitional inner surfaces of the 
conically shaped casing portions 90, 92, 94 and 96. The cooperative action 
of the passive rotor and active casing element with helical guide surfaces 
such as guide vanes is essentially similar whether in the transitional 
environments of the feed and discharge sections of the separator or within 
the axially extending or unchanging conditions of the separator portion 
itself. This cooperative function of the rotor and casing elements will be 
described in more detail below with reference to the separating portion of 
the separator. 
The stepped form of separator casing, permitting the use of longer fingers 
in the rotor feed portion 52a results, of course, in a greater nominal 
diameter of the feed casing 66, at least in the lower portion, compared 
with the separator casing 58. Choosing a vertical or perpendicular 
relative axial step from the feed casing floor 70 up into the separator 
casing 58, as in the present embodiment, permits the greater diameter or 
longer fingers of the rotor feed portion 52a to be maintained throughout 
the length of the feed casing 66. Thus the rotor fingers at the downstream 
end of the rotor feed portion are available to sweep the full length of 
the feed casing floor, minimizing dead space at the critical point of 
entry into the separating casing 58. As can be seen in FIG. 3, the 
effective step 104 diminishes in height with respect to the direction of 
outward and upward movement of the material, so that any material engaged 
by the step is soon freed to continue its downstream movement under the 
influence of the guide vanes. As indicated in FIG. 2, the second feed 
portion guide vane 140 crosses into the separator casing 58 adjacent the 
end of the step 104 at about the level of the rotor axis 191 so that an 
uninterrupted guide surface is available for at least a portion of the 
crop material mat, to ease its entry into the separating casing 58. 
FIGS. 8 and 9 offer a simplified representation of the cooperative function 
of a passive rotor 52b' and separator casing 58' with internal helical 
guide surfaces. The schematic drawings represent a "steady state" 
condition where the rotor is rotating at a constant speed in the direction 
indicated by arrow 217 and the material being processed and conveyed is in 
generally uniform motion, as for example, in an intermediate portion of 
the separator proper away from the end conditions of inlet and outlet or 
discharge. Arrow 218 indicates the downstream direction of material flow. 
The simplification includes representing crop material present in the 
separator as an annular mat 220 with a well-defined inner surface 222. 
Also, only the action of a single finger element 198' pivotably carried by 
a rotor frame 160' in relation to a single guide vane 146' will be 
considered. It is also assumed that the rate of feeding and flow of 
material through the separator, the diameter of the cylinders of 
revolution 224 swept by the rotor finger tips 200', the internal diameter 
(222) of the mat and the offset or eccentricity between the rotor and 
casing (and hence the mat) are such that there are zones of engagement and 
disengagement of the finger 198' with respect to the mat 220, defined by 
the intersections of the respective cylindrical surfaces 222, 224 of the 
mat and the finger tips 200'. In this example, the zone of disengagement 
of the finger is from A to B, somewhat less than 180 degrees. 
Disengaged from the mat 220 and away from the influence of the guide vane 
146', the finger 198', free to pivot only about an axis 226 perpendicular 
to and circumferentially extending with respect to the rotor axis 191', 
assumes a radially extending position under the influence of centrifugal 
force as the rotor rotates, (position 4 in FIGS. 8 and 9). The finger, by 
itself, provides only circumferential propulsion for the mat 220 but soon 
after its engagement with the mat (at B), the crop material portion 
propelled by the finger approaches and comes under the influence of the 
guide vane 146' (position 1 in FIG. 8). Due to the eccentricity, the 
penetration of the mat by the finger and the proximity of the finger to 
the guide vane increase as the finger moves between positions 1 and 2 and 
the axially deflecting influence of the guide vane increasingly dominates 
the centrifugally "righting" effect of the finger so that, carried by the 
crop material mat portion in which it is engaged, the finger is deflected 
axially downstream. (The external force provided by the material mat 
overcomes "righting" tendency of the finger.) This effect continues as the 
rotor carries the finger on from position 2 to 3 but eventually, somewhere 
between positions 3 and 4, the finger effectively becomes disengaged from 
the mat 220 and is free to resume its radially extending position ready, 
as it were, for the next bite or revolution. 
The increased and increasing depth of the guide vane in its upper quadrant 
portion 150' helps to continue the spirally downstream motion of the crop 
material portion now travelling partly under inertia after release by the 
finger. The greater depth of the guide vane helps to continue guiding 
material downstream even though, say loss of speed, causes some falling 
away of the mat from the casing wall while in the zone of disengagement 
AB. This falling away and a certain amount of turbulence may of course 
contribute to efficiency of separation. Preferably, radial clearance 
between fingers and guide vanes, especially in the zone of engagement, 
should be the minimum that practical considerations permit. 
Separators according to the invention, may of course be designed so that 
the respective axial spacings of fingers or finger assemblies in the rotor 
and of guide surfaces in the casing may result in specific axial 
disposition of fingers relative to guide vanes (as is suggested for 
example in FIG. 9). However, in the present embodiment as indicated in the 
drawings, the population of fingers is sufficiently dense or, the fingers 
are sufficiently closely spaced, that they function in aggregate to propel 
the crop material circumferentially, maintaining it in a mat generally in 
contact with the casing whenever rotational speed of the rotor exceeds a 
certain minimum so that the guide vanes are effective to displace the 
material axially regardless of any particular juxtaposition between finger 
and vane. The pivoting of individual fingers responsive to the guide vane 
effect will vary according, among other things, to their proximity or 
disposition relative to a guide vane when in their zone of engagement with 
the crop material mat. However, in normal operation, each finger, during a 
portion of each of its revolutions around the axis of the rotor, is free 
to pivot to follow the crop material mat downstream while maintaining its 
circumferential propulsion while in its principal zone of engagement and 
effectively retracting from the crop material mat outside of the zone of 
engagement, becoming free to regain its radially extending position. 
The separator 30 is designed so that the crop material is long enough in 
contact with the separating grates 108 that separation of the remaining 
grain from the straw mass is virtually completed. 
As seen best in FIG. 5, at least partial guide vanes 147 are continued into 
the discharge portion 62 of the separator. Rotor fingers also extend into 
the discharge portion so that positive axial propulsion extends somewhat 
beyond the separator portion proper to help ensure a smooth flow of 
material through the separator, for efficient separation and avoidance of 
blockages. The discharge casing guide member 120 helps to control the 
downward flow of material for efficient reception by the straw chopper 40. 
The spiral arrangement of finger assemblies on the rotor described above 
makes for smoother operation of the rotor by reducing torque peaks 
compared with a rotor having, say, only two diametrically opposed rows of 
crop engaging elements. "Reversing" the spiral avoids the presentation of 
a "front" to the crop material being handled and reduces the tendency for 
roping by the material, as may occur, when rotor elements are arranged so 
as to create a positive screw conveyor effect. 
As indicated in the drawings, especially FIG. 2, helix angle of the guide 
vanes may be chosen according to their function in the total separator 
system. Here, for example, the feed section guide vanes 130, 140 and the 
first guide vane 144 in the separator section all have a fairly sharp 
angle of about 30 degrees whereas the remainder of the guide vanes 146 in 
the separator section have an angle of about 14 degrees. The sharper angle 
in the feed section and initial portion of the separator section in part 
compensates for the inevitably somewhat less positive control of material 
in the feeding (transition) area when it is being received and divided and 
inserted in the separator casings, compared with the more predictable 
handling characteristics and rate of throughput in the more controlled 
conditions of the separator section where the surrounding casing more 
closely conforms to the rotor. Preferably, feed vane angle is also chosen 
so that material following the vanes will enter the separator within one 
revolution avoiding recirculation and redividing of crop material in the 
feed casing. Overall, the various helix angles chosen may be said to be 
matched to suit functional objectives which include avoidance of material 
buildup or backup in the feed area and, then, within the separator 
portions, to propel the material at an axial speed which suits the 
separation objectives. 
The use of a coordinated positive drive to the two rotors, such as by drive 
system 170, (FIG. 6) makes it possible to time the rotors together to 
optimize or modify, as required, the aggressiveness of their combined 
engagement of incoming material at the bite 214 between the rotors in the 
feed chamber 68. In FIG. 3, the rotors 52, 54 are shown timed 45 degrees 
out of phase, producing a relatively aggressive bite. 
FIGS. 11-16 cover four alternative embodiments of rotors according to the 
invention. That of FIGS. 11 and 12 is similar to the first embodiment 
described above in that each finger element assembly 230 includes a pair 
of fingers 232 free to swing in unison about a common pivot 234. Axially 
extending tubular frame members 236 are held in fixed relationship by 
other frame members (not shown). The finger assemblies 230 are pivotally 
supported by the tubes 236 and each assembly extends through the frame of 
the rotor so that its crop engaging tip portions 238 extend radially 
outwards of the frame tubes 236. Pivots 234 are arranged so that in 
operation, with direction of rotation as shown by the arrow 240, 
circumferential deflection of each finger element assembly 230 is resisted 
by the fingers 232 bearing against the opposite frame tube 236, contacting 
it, as indicated, at 242 in FIG. 11. In this embodiment, the finger pivot 
axis is on the opposite side of the rotor axis from the finger crop 
engaging portion. Therefore, compared with the first embodiment, the swing 
radius for the finger is significantly greater so that its angular 
deflection is less for a given linear axially downstream movement. Using 
the rotor frame to help support or stabilize the fingers (contact 242) is 
a potentially cost reducing simplification. 
FIG. 13 represents another embodiment of the passive rotor, the 
displaceability of the finger 250 in this case resulting from flexibility 
in construction of the finger itself which is rigidly attached cantilever 
fashion to the rotor frame 252 rather than pivoted. Suitable finger 
characteristics may be achieved in a number of ways. For example, FIG. 13 
shows a tapered finger 250 having a base or hinge portion 254 which is 
wider than its crop engaging or tip portion 256. Oriented as shown, this 
element will be relatively resistant to circumferential deflection at its 
tip while permitting necessary deflection in the axial direction when used 
in conjunction with helical guide surfaces. The material of such an 
element may be homogeneous or, as indicated in the drawing, maintaining 
the same "edge-on" orientation with regard to direction of rotation, the 
finger element may consist of a rigid outer portion, for example a steel 
strip of uniform width attached to the rotor frame 202 through or by an 
elastomeric insert providing the desired deflectability. 
FIGS. 14 and 15 represent a fourth embodiment of rotor according to the 
invention in which the finger assembly 260 is double ended in that it 
consists of a pivot frame 262 carrying a pair of approximately 
diametrically opposed fingers 264 each with a crop engaging tip or outer 
portion 266. These assemblies 260 are pivotally carried in a rotor frame 
268 consisting of longitudinal or axial channel members 270 held in fixed 
relationship to each other by other frame members (not shown). The finger 
assemblies 260 are pivotably supported between the channel members 270 by 
suitable pivot hardware 272. In FIG. 15, the disposition of an 
intermediate portion of such a rotor in a separator casing environment is 
indicated "in phantom outline" (casing 274 and guide vane 276). The 
operating or functional cycle for each finger crop engaging tip 266 is 
basically as described above with reference to FIGS. 8 and 9, for the 
"independent" fingers of the first embodiment. However, obviously in this 
embodiment, in each finger assembly 260, each opposite tip 266 is 
responsive to movement of the other tip. The result is that, as indicated 
in FIG. 15, when the first tip is in significant engagement with the crop 
material mat 278, (for example in position 5 in FIG. 15) and has been 
deflected downstream by the mat under the influence of the guide vane 276, 
the opposite tip will have been deflected upstream as indicated at 
position 6 while out of effective engagement with the crop material mat. 
Thus, compared with an independently pivoted "single" finger action, as 
described with reference to FIGS. 8 and 9, there is a preparatory 
"back-swing" and a relatively greater arc of swing is available for the 
engaged phase of finger action. Note, too, that with respect to a 
direction of rotation indicated by arrow 280, the fingers 264 are 
effectively inclined forward even though they are perpendicular to their 
own pivot axis. This finger attitude may be useful in some applications 
but in most the "pure" radial extension shown in FIG. 8 is preferred. 
In the embodiment of FIG. 16, the rotor 282 takes the form of a cylindrical 
"brush" made up of a multiplicity of resilient fingers or bristles 284, 
closely spaced one from another. The separator configuration is again twin 
side-by-side rotor in a casing 286 including a feed portion 288 (only the 
lower portion is shown) and separator portions 290 and 292.