GB2063039A - Combine harvesters - Google Patents

Abstract

A combine harvester comprises a threshing mechanism 17 extending transversely of the machine and has a threshing rotor 18 cooperable with a threshing concave 19 and a separating mechanism 38 having a first and a second separating component (39, 41, respectively) operable to subject the layer of crop material received from the threshing mechanism 17 to a first and second separating action. The first component 39 comprises a separator cylinder 42 cooperable with a separator concave 43 and has a plurality of beater means 47 arranged to impact on the layer of crop material received from the threshing mechanism 17, thus subjecting the material to the first separating action and conveying it to the second component 41. The second component 41 comprises at least one separator rotor 63 cooperable with a separator housing 62 including a separator concave 81. The separator rotor 63 carries at least one separator means 76 which extends generally longitudinally of the rotor 63 and is arranged spirally to convey crop material received from the first separator component (39) around the rotor to one end of the latter whilst subjecting it to the second separating action. <IMAGE>

Description

SPECIFICATION Combine harvesters The present invention relatestocombine harvesters and has particular reference to thethreshing and separating mechanisms of such machines.

In known combine harvesters, grain is threshed and separated in a threshing and separating mechanism and the separated grain, together with the impurities, such as chaff, dust, straw particles, and tailings, is fed to a cleaning mechanism for cleaning. Clean graih is collected below the cleaning mechanism and fed to a grain tank fortemporary storage. The tailings are separated from the clean grain and impurities for reprocessing. This reprocessing either involves recycling the tailings through the threshing and separating mechanism or treating them in a separate tailings rethreshing means.

While the terms grain "straw", and "tailings" are used principally throughout this specification for convenience, it should be understoodthatthese terms are not intended to be limiting. Thus "grain" refers to that part of the crop which is threshed and separated from the discardable part of the crop material which is referred to as "straw". Incompletely threshed ears are referred to as "tailings".

Also, the terms "forward", "rearward", "left", "right", when used in connection with the combine harvester and/or components thereof are determined with reference to the direction of forward operative travel of the combine harvester but should not be construed as limiting.

Recent developments in combine harvesters have led to so-called rotary machines wherein both threshing and separating are accomplished in mechanisms comprising rotary components cooperable with respective stationary threshing and separating concaves and grates. In conventional combine harvesters grain separation is accomplished by straw walkers. In rotary combines the crop material is subjected to a much more aggressive and positive separating action during a relatively prolonged period of time, whereby the efficiency of a rotary combine harvester usually is greater than that of a conventional machine.

Several types of rotary combine harvester have appeared on the market and in one such machine a conventional transversely-extending, threshing mechanism having a threshing cylinder and a cooperable concave is combined with a rotary separating mechanism of a width greater than that of the threshing mechanism and disposed parallel thereto with its ends extending transversely past the respective ends of the threshing mechanism. The rotary separating mechanism operates spirally to convey the crop material received from the threshing mechanism towards each of its ends, whilst submitting the crop to a separating action.

Such a rotary separating mechanism comprises at least one separator rotor rotatable within a rotor housing comprising separator concaves over its entire circumference, except at the top where covers are provided. Rearwardly of the separator housing a deflector member is provided which deflects grain separated in the rear, generally upright, separator concave towards the cleaning mechanism therebelow. This deflector member, together with said concave and a section of the combine harvester chassis form a downwardly facing cavity.

The rotor or rotors comprise crop treating and conveying elements which are disposed at an angle relative to the rotor axis. It has been discovered that these crop treating and conveying elements create air streams around the or each rotor which start centrally below and rearwardly of the or each rotor and move in an upward direction around and over the top of the associated rotor to the front of, and below, the outer section of the rotor. As a result, light particles such as chaff, short straw, etc. are lifted from the cleaning mechanism and sucked into said cavity which is soon filled, whereby the separator concave partially defining said cavity becomes plugged or blocked.

In the separating mechanism described above, the incoming layer of crop material should be divided in two substantially equal portions, each of which is then spirally conveyed from the centre of the separating mechanism to one or other or its ends.

Occasionally tough crops such as wet, green crops with long straw or heavily weed-infested crops cause problems inasfar as the above described division of the crop layer is not accomplished as smoothly and fluently as is desired.

Furthermore, the separating efficiency may vary with varying crops and crop conditions and occasionally this efficiency is not acceptable. This appears to be due to a great extentto the factthat the layer of crop material occasionally does not move smoothly and regularly through the separator mechanism whereby grain separation is hampered.

However, in general, rotary combine harvesters have a substantially increased threshing and separating capacity. This results in much heavier loading of the cleaning mechanism which now frequently appears to have become the limiting factor as regards machine capacity. On conventional combine harvesters, the limiting factor is usually the straw walkers. As regards rotary combine harvesters, there is another factor affecting machine capacity, namely the fact that such machines are found to produce more short straw particles which means an additional loading of the cleaning mechanism.

Increasing the size, such as the width, of the cleaning mechanism has not solved the problem. Indeed, with wide cleaning mechanisms it has been found to be very difficult to produce a substantially constant cleaning air blast transversely thereof and an uneven transverse air blast pattern necessarily results in an inferior operation of the cleaning mechanism.

Also, because of the increased volume of material to be handled in the cleaning mechanisms of rotary combine harvester, it has become necessary to provide cleaning fans of a much greater capacity. This has proven to be difficult to date without making the fan considerably larger. However, it is preferable to avoid larger fans from the standpoint of space availability. Furthermore, the chaffer sieve of conventional cleaning mechanisms easily gets overloaded with the increased volume of material to be cleaned and thus sieve losses under these circums tances soon reach an unacceptable level.

Finally, if no special precautions were taken, mat erial separated in the separating mechanism would fall directly onto the chaffer sieve at a location rearwardly of its leading edge. This may result in increased sieve losses as there is not sufficient time for the grain in this material to be separated from the impurities and to fall through the meshes in the sieve before it is discharged from the rear of the sieve.

The foregoing is only a brief discussion of the major disadvantages of known combine harvesters and other disadvantages will be apparent to those skilled in the art.

The main object of the present invention is to overcome or attenuate one or more of these disadvantages.

According to the present invention there is provided a combine harvester comprising a threshing mechanism extending transversely of the machine and having a threshing cylinder cooperable with a threshing concave to thresh a layer of crop material fed therebetween, and a separating mechanism having a first and a second separating component operable to subjectthe layerofcrop material received from the threshing mechanism to a first and a second separating action, the first component comprising a separator cylinder cooperable with a separator concave means and having a plurality of beater means arranged to impact on the layer of crop material received from the threshing mechanism, thus subjecting the crop material to the first separating action and conveying itto the second component, and the second component comprising at least one separator rotor cooperable with a separator housing including a separator concave, the or each separator rotor having at least one separator means extending generally longitu.dinally thereof and arranged spirally to convey crop material received from the first separator component around the rotor to one end of the latter whilst subjecting it to the second separating action.

Preferably the first and second separator components extend parallel to each other and to the threshing mechanism. The first separator component may have a width substantially equal to that of the threshing mechanism, whilst the second component is wider with the result that its ends extend past the respective ends of the threshing mechanism, the second component being arranged spirally to convey crop material received from the first separator component towards each of its ends.

The beater means of the first separating component may be in the form of tines having flat operative surfaces inclined rearwardly, as seen in the direction of rotation, and arranged to impact on the crop material as it is fed to the further separator component.

The beater tines may further comprise reinforcing side walls and preferably are made of sheet metal.

The beatertines may be arranged in a plurality of rows equiangularly spaced around the cylinder and parallel to the longitudinal axis thereof. The beater tines of adjacent rows may be staggered transversely of the machine.

A straw beater and cooperable beater grate may be disposed between the threshing mechanism and the first separator component for feeding the layer of crop material issuing from the threshing mechanism to the first separator component in a direction per pendicular to the direction of movement of the beates tines at the point where they intercept the crop layer.

The separator housing may comprise a forwardly facing inlet of a width substantially smaller than the width of the housing and an outlet offset relative to the inlet. Preferably, the separator housing is symmetrical relative to the fore-and-aft centreline of the machine and comprises a single central, forwardly facing, inlet and a pair of rearwardly facing outlets towards the respective ends of the housing.

Separatorconcaves are preferably provided between the inlet and the respective ends of the housing on the one hand, and between the outlets on the other hand. A further separator concave may be disposed between the inlet and the outlets over substantiallythe full width of the housing, whilst a cover plate is provided in the upper part of the housing.

Spiral fins may be provided and arranged to extend in opposite directions on both sides of the fore-and-aft centreline of the separator housing on the inside thereof from a location rearwardly of the inlet and at an acute angle of preferably about 25 relative to the direction of rotation. Additional fins may be provided along each side of the inlet, extending spirally outwardly across the lower portion of the separator housing and along the inner sides of the outlets.

Crop layer divider blades may be employed, the blades being disposed in pairs around the circumference of the separator rotor generally atthe centre thereof and oppositely inclined relative to the direction of rotation to define a V having its apex facing in the direction of rotation. Preferably the divider blades define an angle of the order of 55" relative to the longitudinal axis of the rotor The apices of adjacent pairs of crop layer divider blades preferably are staggered transversely of the rotor so as to lie on opposite sides of the fore-and-aft centreline of the rotor. The leading edges of the divider blades of each pair of blades equally may be spaced apart a short distance transversely of the machine.

Radially outwardly extending discharge blades may be provided, the blades extending parallel to the rotor axis at the respective ends of the rotor and in the vicinity of the outlets, and having a length which is less than the width of the outlets.

The separator means preferably extend longitudinally of the separator rotor and comprise separator blades which substantially bridge the space between the crop layer divider blades and the discharge blades and which, like the discharge blades, extend radia lly outwardly from the rotor body. The separator blades are oriented at an acute angle relative to the rotor axis, which angle is preferably of the order of 15 . Each separator blade may be coupled to a corresponding discharge blade and have its leading end closely adjacent the rear end of a corresponding crop layer dividing blade. Alternatively, a further crop conveying blade may be provided bet ween each crop layer divider blade and the associated separator blade at a distance from and parallel to, said crop layer divider blade.In this case, each separator blade has its leading end closely adjacent the rear edge of the associated crop conveying blade.

A combine harvester in accordance with the present invention, together with modifications thereof, will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure lisa diagrammatic side elevation of the combine harvester, Figure 2 shows to a larger scale and in side view the threshing, separating and cleaning components of the combine harvester of Figure 1, Figure 3 is an enlarged view of the components indicated at Ill in Figure 2, Figure 4 is an enlarged view of one end of the component indicated at IV in Figure 2, Figure 5 is a partial schematic development of the component indicated at V in Figure 3, Figure 6 is a sectional view ofthe component of Figure 5 and taken along the lines VI-VI thereof, Figure 7 is a schematic development of the component shown at VII in Figure 3, Figure 8 is a plan view, to a larger scale, of the components indicated at VIII in Figure 2, Figure 9 is a sectional view to a larger scale of the components indicated at IX in Figure 2, Figure 10 is a partial view taken in the direction X of Figure 9, Figure 11 is a partial view taken in the direction XI of Figure 9, Figure 12 is a sectional view to a larger scale showing in greater detail the component indicated at Xll of Figure 2, Figure 13 is a view similarto Figure 3 showing an alternative arrangement, and Figure 14 is a view similar to Figure 9 showing an alternative arrangement of a section of the cleaning device.

With reference to the drawings, particularly Figure 1,the combine harvester, generally indicated at 1, comprises a main chassis 2 supported on a front pair of drive wheels 3 and a rear pair of steerable wheels 4. Supported on the main chassis 2 are an operator's platform 5 with a driver's seat 6 and a steering wheel 7, a grain tank 8, a threshing and separating mechanism indicated generally at 9, a grain cleaning mechanism 11 and an engine (not shown). A conventional header 12 and straw elevator 13 extend forwardly of the main chassis 2 and the header is pivotally secured to the chassis for generally vertical movement which is controlled by extensible hydraulic cylinders 14.

As the combine harvester 1 is propelled forwardly over a field with standing crop, the latter is severed from the stubble by a sickle bar (not shown) on the header 12 whereafter a reel 15 and a header auger 16 convey the cut crop to the straw elevator 13 which supplies itto the threshing and separating mechanism 9. The crop received within the threshing and separating mechanism 9 is threshed, that is to say the crop (which may be wheat, corn, rice, soybeans, rye, grass seed, barley, oats or other similar crops) is rubbed and beaten, whereby the grain, seed or the like, is loosened and separated from the straw, stalks, coils or other discardable part of the crop.

Grain which has been separated from the straw falls onto the grain cleaning mechanism 11 which comprises means to separate chaff and other impurities from the grain and means to separate unthreshed material (known in the art as "tailings").

Cleaned grain is then elevated into the grain tank 8 and the tailings are returned to the threshing and separating mechanism 9 for a repeat threshing action.

The header 12 as described is of the grain type, but clearly other forms of header may be employed, as for example a corn header, depending on the crop to be harvested.

A threshing portion 17 of the threshing and separating mechanism 9 comprises a rotatable threshing cylinder 18 cooperable with a stationary threshing concave 19. The threshing cylinder 18 is composed of a plurality of transversely spaced flanges 21 keyed on a transversely extending shaft 22 rotatably mounted on the main chassis 2. Around their peripheries the flanges 4 support a plurality of conventional rasp bars 23 which extend over a width generally corresponding to the width of the straw elevator 13 and the main chassis 2.

The threshing concave 19 is composed of a number of fore-and-aft extending arcuate main bars 24 (Figure 2) and a plurality of transversely extending threshing bars 25. Furthermore, a plurality of arcuate wires 26 extend at regular intervals in a fore-and-aft direction through apertures in the bars 25 thus defining therewith a mesh for the separation of grain therethrough. The threshing concave 19 extends over an are of about 100" from the bottom of the threshing cylinder 18 in the vicinity of the discharge end of the straw elevator 13 towards the rear of the threshing cylinder generally at the level of the shaft 22 thereof. A stone trap 27 is provided between the discharge end of the straw elevator 13 and the forward edge of the threshing concave 19.

Rearwardly of the threshing mechanism 17, a deflector beater or so-called straw beater 28 (Figure 2) with an associated beater grate 29 is provided.

The straw beater 28 has a smaller diameterthan the threshing cylinder 18 and is arranged above the level of the discharge end of the threshing concave 19.

The straw beater 28 and beater grate 29 have sub stantially the same width as the threshing mechanism 17. The straw beater 28 comprises a generally cylindrical body portion 31 mounted on a transverse shaft 32 with a number of deflector plates 33 supported thereon. The deflector plates 33 extend the full width of the straw beater 28 and are inclined rearwardly relative to the direction of rotation 34 of the beater.

The structure of the grate 29 is similar to that of the threshing concave 19 in that it comprises fore-andaft extending arcuate main bars 35, transversely extending bars 36 and fore-and-aft extending wire 37. The threshing concave 19 is adjustable relative to the threshing cylinder 18, as is the beater grate 29 relative to the straw beater 28. The beater grate 29 spans an arc of about 50 - 60 and is disposed sub stantially horizontally rearwardly of the discharge end of the threshing concave 19.

A separating portion 38 of the threshing and separating mechanism 9 (Figures 2 and 3) comprises a first and a second component generally indicated at 39 and 41, respectively. The first separator com ponent 39 comprises a rotary separator rotor or cylinder 42 which is cooperable with a stationary separator concave 43.

The separator cylinder 42 comprises a plurality of transversely spaced flanges 44 mounted on a shaft 45. A plurality of supporting bars 46 are mounted on the flanges 44 which in turn carry a plurality of beater tines 47 in a manner such that the tines of one supporting bar are staggered transversely relative to the tines of the adjacent supporting bars. The tines 47 are elongate and formed with an active front surface 48 and a pair of reinforcing side flanges 49. The active front surfaces 48 are inclined rearwardly relative to the direction of rotation 51 of the separator cylinder 42 to a degree such that they extend more or less parallel to the direction of movement of the crop issuing from the straw beater 28 and beater grate 29 at the point where the tines 47 intercept that crop.At this point of interception the tines 47 are moving in a downward direction and to this end the shaft 45 is arranged below the level of the shaft 32 of the straw beater 28. The diameter of the separator cylinder 42 substantially corresponds to the diame terofthethreshing cylinder 18 and is thus larger than the diameter of the straw beater 28.

The separator concave 43 extends downwardly and rearwardly from the rear end of the beater grate 29 and wraps around the separator cylinder42 over an arc of about 1209 The separator concave 43 is composed of three sections, indicated respectively at 52, 53 and 54, of different aggression, the most aggressive section 52 being positioned at the forward end and the least aggressive section 54 being positioned atthe rearward end.

The forward concave section 52 comprises, in a manner similarto the threshing concave 19, a number of arcuate fore-and-aft extending bars 55 and a number of transverse bars 56 through which extend arcuate wires 57 which, together with the transverse bars 56, define the mesh ofthe concave section 52.

The middle concave section 53 also comprises arcuate fore-and-aft extending bars 58 but in this section they carry transverse bars 59 in the form of inverted U-shaped members. Arcuate wires 61 extend through apertures in the bars 59 and define therewith the mesh of this concave section.

The rear concave section 54 is formed solely by extensions of the concave wires 61 rearwardly of the rearwardnnosttransverse U-shaped bar 59. This rear concave section 54 is slightly upwardly inclined rela tive to the horizontal with the rear end thereof bent downwardly to form a smooth transition with the next component The width of the separator cyiinder 42 and assocF ated concave 43 corresponds to the width of the threshing mechanism 17 and the straw beater 28 The size of the various components of the threshing mechanism 17, the straw beater 28 and associated grate 29, and the first separator component 39, and the relative positions of these components make it possible to provide separator surfaces (concaves and grate) of a fore-and-aft length exceeding sub stantiallythe fore-and-aft length occupied by said components in the machine.

The second separatorcomponent41 basically comprises a rotor housing 62 with a separator rotor 63 therein (Figures 2 and 3) Both these components have a width substantially exceeding the width of the separator cylinder42. Preferably the rotor housing 62 has a width which is about twice the width of the separator cylinder 42 or slightly less.

The separator rotor 63 comprises a central shaft 64 with a plurality of flanges 65 mounted thereon and on which are secured U-shaped profiles 66 extending the full axial length of the rotor. The U-shaped profiles 66 have flanged radiallyinneredgeswhich are spaced apart and are used to secure the profiles to the respective flanges 65. Six U-shaped profiles 66 are provided and the gaps between adjacent profiles 66 are closed by plates 67 so that at its outer ciwum- ference the rotor body 63 is dodecagonal in shape.

Crop treating and conveying elements 68 are provided on the outer circumference of the rotor body 63 and these components will now be described in more detail.

Figure 5 shows a partial schematical development of the rotor 63 with the various components thereon.

As will be seen from this Figure, the rotor 63 is symmetrical with respect to the fore-and-aft centreline 69 of the machine, except from some minor deviations.

Centrally of the rotor 63, crop layer dividing blades 71 are provided around the rotor body, These blades 71 are arranged i V-shaped pairs with the apices thereof facing in the direction of rotation 72 of the rotor and with adjacent apices staggered to opposite sides of the centreline 69. However, the forward edges 74 of each pair of dividing blades 71 may be spaced apart a short distance transversely of the rotor 63, Parallel to, and at a distance from the blades 71 are provided further crop conveying blades 73 which have the same shape as the blades 71, Thus in total four blades are provided in rows lengthwise of the rotor and as six rows are provided, there is a total of twenty4ourblades, all of which are inclined eta relatively steep angle relative to the rotor axis, All of these blades 71 and 73 have a rounded leading edge 74 as seen in the direction of rotation 72 and a rounded outer edge 75, both of which are welded to a plate member 76 which is secured to the respective plates 67 of the rotor body.The leading edges 74 extend outwardly from the rotor body and are inclined rearwardly relative to the direction of rotation 72, whilstthe outer edges 75 are curved. Seen in the direction ofmovementofthecropmaterial around the rotor, adjacent blades 71 and 74 in each row of blades overlap each other.

Separator blades 76 extend from the rear ends of the srDp convey!ing blades 73 to locaSons shorat of the outer ends of the roto63 and at an angle relative tothe rotoraxiswbich issultttaniliysmallertlran the angle of inclinatn the blades 73. Preferably the separator blades 76 are inclined at an angle of about 15" whilst the blades 73 are inclined at an angle of about 55 relative to the rotor axis. The separator blades 76 are formed of sheet metal and comprise a body 77 extending radially outwardly from the rotor body and having a rearwardly inclined (as seen in the direction of rotation 72) outer edge 78.As best seen in Figure 6, the outer edges 78 are curved to coincide with the outer circumscribing line of the rotor assembly. Due to their length and inclination, the separator blades 76 extend over more than one side of the dodecagonal rotor body. Indeed, the separator blades 76 are attached to the bottom ends of the U-shaped profiles 66 and to adjacent plates 67.

At the associated outer end of the rotor assembly the separator blades 76 are extended to form discharge blades 79 which are oriented parallel to the rotor axis and which extend radially outwardly from the rotor body. The discharge blades 79 are also made of sheet metal and have a radially outwardly extending body with an outer, rearwardly inclined, edge which coincides with the circle circumscribed by the rotor mentioned above.

The rotor housing 62 (Figure 3) is partly composed of separator concaves 81 and partly of cover plates 82 with a central, forwardly facing, inlet 83 and a pair of rearwardly facing outlets 84 at opposite ends of the rotor housing. The inlet 83 has a width substantially corresponding to the width of the separator cylinder 42 and is disposed to receive crop material therefrom. The outlets 84 have a width which is less than half of the width of the inlet 83.

The separator concaves 81 are similar in construction to the separator concave 43 associated with the separator cylinder 42 and comprise arcuate main bars 85, straight transverse bars 86 and arcuate wires 87 extending through the bars 86. At a location rearwardly of the inlet 83, when seen in the direction of rotation 72, and below the rotor assembly 63, the separator concaves 81 extend over the full width of the rotor housing 62 as indicated at 185 in the drawings. Rearwardlythereof, i.e. at the section where the rotor housing extends generally vertically adjacent the rear end ofthe rotor, the separator concaves 81 stop short of the respective ends of the rotor housing 62 to define therewith the outlets 84 mentioned above. This section of the concaves 81 is indicated at 186 in the drawings.Finally, concave sections are also provided between the sides of the inlet 83 and the respective ends of the rotor housing 62 at the forward, upright section thereof as indicated at 187 in Figure 4 of the drawings.

At the rear end of the separator concaves 186, as seen in the direction of rotation 72, a number of transverse concave bars 86 have been omitted and the concave wires 87 inclined towards the opposite ends of the housing 62, thus defining elongate apertures. This section of the concave is indicated at 89 in Figures 3 and 8 of the drawings. It will also be noted, especially from Figures 3 and 8, that the concave wires 87 end short of the adjacent edge of the cover plate 82 and of the forward edge of a shield 94, thus defining therewith an opening which is indicated at 192.

As can best be seen in Figure 4, the separator concave section 185 has flattened sections 188 at respective ends of the rotor, which ser-tions extend forwardly of the separator outlets 84 when seen in the direction of rotation 72. The sections 188 extend generally tangentially to the remainder of the concave 185 at a location forwardly of the outlets 84 and comprise, in common with all the separator concaves, straight transverse bars 86. However, the concave wires 87 are made straight, as opposed to arcuate, and are extended rearwardly of the rearwardmost bars 86 to form a comb structure 189.

The cover plates 82 are arcuate and are disposed above the separator rotor 63 between the section 89 of the separator concaves 81 and the top edge of the inlet 83, being readily removable for easy access to the separator components.

As can best be seen in Figure 7, deflector fins 91 extend at an angle of about 25 relative to the foreand-aft centreline 69 of the machine, spirally around the rotor 63 on the inside of the rotor housing 62.

Three parallel fins 91 are provided at regularly spaced intervals on each side of the centreline 69; the inner two fins have their ends aligned with the lower edge of the inlet 83 at locations between the inlet and the respective ends of the housing 62. The outermost fins 91 have their ends aligned with the top edge of the inlet 83. The middle and outer fins 91 on each side of the centreline 69 have their ends positioned inwardly of the outer ends of the housing 62. The two inner fins 91 define a V with the apex facing in a forward direction and positioned on the centreline 69 of the machine at a location rearwardly of the concave 185. Also the fins 91 partially extend across the separator concaves 81 and across the full width of the cover plate 82.Thus the fins 91 extend across the transverse opening 192 and, to permit removal of the cover plate 82, they are divided at 193 (Figure 8). As can best be seen in Figure 8, the rear ends of the concave wires 87 have the same inclination as the fins 91 and the latter are arranged generally aligned with certain of these wire end portions.

Additional fins 90 (Figure 7) extend at an angle across the concave section 185 from the lower corners of the inlet 83 to a position generally in line with the inner edges of the outlets 84 on the lower portion of the concave section 186. These fins 90 are extended parallel to the centreline 69 alongside the inner sides of the outlets 84 and alongside the edges of the inlet 83.

As is best seen in Figure 2, the circles circumscribed by the various rotatable threshing and separating components are in close relationship to each other Preferably the threshing cylinder 18, the straw beater 28, the separator cylinder 42 and the separator rotor 63 are driven either at the same circumferential speed or at progressively higher speeds.

The rotor housing 62 is arranged in the area above the cleaning mechanism 11 and material separated in the central portion of the housing falls directly onto the cleaning mechanism. Material separated in the outer sections of the rotor housing 62 which extend beyond the sidewalls of the combine harvester is collected separately and conveyed towards, and spread across, the cleaning mechanism 11 in a manner described in more detail in co-pending Patent Application No.80.21667.

A deflector plate 92 is arranged at a distance rear wardly of the upright rear quarter of the rotor hous ing 62 at a location between the outlets 84, the plate being operable to deflect separated crop material downwardly onto the cleaning mechanism 11 there below. The deflector plate 92 is oriented generally vertically and has its lower edge a short distance above the cleaning mechanism 11. The upper edge 93 of the deflector plate 92 stops short of the shield 94 so asto define an air inlet 95 therebetween. The provision of this inlet 95 will be discussed in more detail hereinafter.

The cleaning mechanism 11 extends from below the forward edge of the threshing concave 19 to a location rearwardly of the separating mechanism 38 and has a width substantially corresponding to the width of the threshing mechanism. Thus the ends of the separator rotor 63 and housing 62 extend beyond the respective side edges of the cleaning mechanism 11.

The cleaning mechanism 11 comprises three major components, namely preparation and transporting surfaces, cleaning sieves and a cleaning fan.

The preparation and transporting surfaces are stepped and in use are oscillated so as to prepare the layer of crop material as it is moved to the cleaning sieves. The surfaces in question comprise a forward, an intermediate, and a rear grainpan 101,102, and 103, respectively (Figures 2 and 9).

The first grainpan 101 is conventional in shape and extends generally horizontally or at a slight upward incline between locations below the forward end of the threshing concave 19 and the separator concave 43 associated with the separate cylinder 42, and is thus disposed to receive threshed and separated material from the threshing concave 19, the beater grate 29 and a portion of the separator concave 43.

Material separated in the outer sections of the rotor housing 62, together with tailings, is spread across the grainpan 101 in a manner as described in copending Patent Application No. 80.21667 referred to above. A conventional comb assembly 104 is secured to the discharge end of the forward grain pan 101.

The forward grainpan 101 is suspended adjacent its forward end on a pair of cranks 105 and at its rear end via pivots 106 to an upper cleaning shoe 107.

The upper cleaning shoe 107 basically comprises a rectangular frame with opposed side walls 108, front and reartransverse beams 109 and 111, respectively, and intermediate reinforcing beams 112 which, as seen in Figure 9, also serve to carry certain components. The upper cleaning shoe 107 extends from the discharge end of the forward grainpan 101 to the rearwardmost end of the cleaning mechanism 11.

Adjacent its rearward end, the upper cleaning shoe 107 is movably supported on the chassis at 110 via rocking arms 115 (only schematically shown, with the chassis portion carrying the lower ends of the rocking arms 115 being omitted). The intermediate grainpan 102, the reargrainpan 103, a pre-cleaning sieve 113 and a chaffer sieve 114 are all carried by the upper cleaning shoe 107.

The pre-cleaning sieve 113 extends rearwardly and upwardly at a small angle relative to the horizon tal from a location below and forwardly of the dis charge end of the forward grainpan 101 and comb prises a plurality of angularly adjustable and over lapping louvres which together form a mesh for grain to pass through. At its rear end, the precleaning sieve 113 carries a comb assembly 116 similar to the assembly 104.

Below the pre-cleaning sieve 113, the intermediate grainpan 102 is rocated which terminates short ofthe rear end of the pre-cleaning sieve 113.

The chaffer sieve 114 is generally aligned with the intermediate grainpan 102 and extends rearwardly and upwardly at a small angle relative to the horizontal from a location below the discharge end of the pre-cleaning sieve 113. Between the intermediate grainpan 102 and the chaffer sieve 114 a discharge opening 117 is provided. The chaffer sieve 114 is conventional in shape and comprises a rearward, angularly adjustable, extension 118 (Figure 2). As with the pre-cleaning sieve 113, the chaffer sieve 114 and its extension 118 comprise a plurality of angularly adjustable and overlapping louvres.

The rear grainpan 103 comprises a generally horizontal forward section 119 and a slightly upwardly inclined rear section 121. Both sections 119 and 121 are stepped but the direction of the steps is opposite to that of the front and intermediate grainpans 101 and 102. The rear grainpan 103 extends below the centre portion of the separator housing 62 and above the chaffer sieve 114 and a portion of the precleaning sieve 113. It has a forward discharge end slightly rearwardly of the discharge end of the front grainpan 101.The rear edge of the rear grainpan 103 is positioned below the deflector plate 92 and support arms 122 are attached thereto at one end of their ends, whilst the opposite ends thereof are pivotally mounted on cranks 123 at opposed sides of the cleaning shoe 107.The rear grainpan 103 is also pivotally mounted on further cranks 124 adjacent its forward discharge edge. The cranks 123,124 are generally triangular in shape and each is pivotally mounted at one corner 125 on the associated side wall 108 of the upper cleaning shoe 107. The cranks 123, 124 forming a pair of each side of the cleaning shoe 107 are coupled, together at another corner 127 by a connecting rod 126.

The rear cranks 123 comprise, at their pivotal mounting on the cleaning shoe 107, a stub shaft 128 connected to one end of a link 129, the other end of which is pivotally coupled to a further link 130, which in turn is pivotally attached to a portion of the chassis at 131. Accordingly, as the upper cleaning shoe 107 is oscillated along a curved upwardly and rearwardly directed path 181, (Figure 2) the pivots between the links 129 and 130 are caused to move along arcuate paths 182 around the pivots 131 on the chassis and thus the cranks 123 and the pivots 183 thereon are caused to move along arcuate, upwardly directed paths 184. This movement is transferred to the forward cranks 124 by virtue of the connecting rods 126 and thus the third grainpan 103 is oscillated to throw material in a forward direction.

A lower cleaning shoe 132 is arranged below the upper cleaning shoe 107 and comprises, as is con ventional, a clean grain conveyor floor 133 and a tailings conveyor floor 134 terminating respectively above a clean grain auger 135 and atailings return auger 136. The lower cleaning shoe 132 is arranged to support a lower cleaning sieve 137 so that it has its forward edge forwardly of, and below, the dis charge end of the intermediate grainpan 102 and its rear edge forwardly of, and below, the level of the chaffer sieve extension 118.

The lower cleaning shoe 132 is movably supported on the chassis at 138 (chassis not shown) via rock arms 139 and at 141 (chassis again not shown) via rock arms 142. The rock arms 142 on both sides of the cleaning mechanism 11 are extended above the level of the pivots 141 on the chassis and are pivot ally coupled at 143 to the upper cleaning shoe 107.

The drive means for the cleaning shoes 107, 132 having the grainpans 101, 102, 103 and cleaning sieves 113, 114 coupled thereto or mounted thereon, comprise crank shafts 144 extending between eccen trics 145 on an intermediate shaft 146 and pivots 147 on the lower cleaning shoe 132.

The cleaning fan, which is generally indicated at 151 (Figure 12), is disposed generally below the for ward grainpan 101 and comprises a generally cylin drical fan housing 152 with a pair of opposed air inlets 153. A further air inlet 154 is provided in an upper portion of the housing 152 over the full width thereof. This additional inlet 154 is covered by a per forated shield 158 to keep impurities out of the fan housing 152.

An outlet 155 is provided in the fan housing 152 over the full width thereof and which communicates with a combined outlet structure 159 comprising a main outlet duct 163 and an additional outlet duct 164.

The main outlet duct 163 extends upwardly and rearwardly and faces the underside of the lower sieve 137, the underside of the chaffer sieve 114 and the space between the discharge end of the inter mediate grainpan 102 and the lower sieve 137 as well as the area belowthe lower sieve 137. The main outlet duct 163 comprises a bottom wall 165 which is atangential extension ofthefan housing 152, and a top wall 166 which is oriented generally parallel to the bottom wall 165. The top wall 166 has a forward end 167 spaced from the circumference of the fan 157 and which is rounded so as to extend into a substantially vertical wall 168 which forms part of the additional outlet duct 164.An angularly adjust able baffle 169 is arranged at the forward end 167 of the top wall 166 and is capable of controlling, to some degree, the flow of air through the additional outlet duct 164. A pair of deflector baffles 161, 162 are angularly adjustably mounted in the main outlet duct 163.

The additional outlet duct 164 is confined by the wall section 168 already mentioned and a further wall section 171. The further wall section 171 extends generally parallel to a tangent to the cir cumscribing circle of the fan 157 and has its lower edge closely adjacent that circle and at a distance slightly above the level of the lower end of the wall section 168. The upper portion of the wall section 171 is curved through almost 90 and faces rearwardly and upwardly, being located above the level of the top edge of the other wall section 168 which comprises a sealing strip 172 sealingly engaging the underside of the intermediate grainpan 102. The additional outlet duct 164 is disposed so that its outlet faces the area between the discharge end of the front grainpan 101 and the leading edge of the intermediate grainpan 102.The leading edge of the pre-cleaning sieve 113 is positioned at about the middle of this area.

The additional fan inlet 154 extends from the upper edge of the wall section 171 in the direction of rotation 156 of the fan 157, whereby this additional inlet is located rearwardly of the outlet 155 relative to the direction of rotation 156 ofthe fan.

The fan 157 comprises a central shaft 173 with a number of supporting arms 174 extending generally radially outwardly therefrom and carrying at their outer ends fan blades 175 of special shape. The fan blades 175 are generally concave and are preferably made of sheet metal with a central, generally flat section 176 arranged at a small angle with respect to, and in advance of, the radius of the fan 157, and angled inner and outer portions 177 and 178, respectively, defining with the section 176 the generally concave shape. The outer portions 178 thus are provided at a greater angle relative to, and in advance of, the radius than the central sections 176, and the inner portions 177 are provided at an angle trailing relative to the radius. Thus, so-called "forwardlycurved" fan blades 175 are provided.It will also be understood from what precedes that the cleaning fan 157 is a combination of a so-called "centrifugal fan" and a so-called "cross-flow fan".

In operation, the combine harvester is driven in a field with standing crop and the latter is cut and conveyed by the reel 15 and the header auger 16 to the straw elevator 13. The straw elevator 13 feeds the crop in a layer of more or less even thickness and of a width corresponding to the full width of the elevator to the threshing mechanism 17. The threshing cylinder 18 is rotated at a relatively high speed and the rasp bars 23 strike the crop supplied thereto and entrain it in a rearward direction for passage between the threshing cylinder 18 and the threshing concave 19. Whilst passing therebetween, the crop material is rubbed and beaten whereby the grain kernels are released from the ears. A major percentage of the grain, together with impurities, immediately falls through the mesh of the threshing concave 19 and is thus already separated from the straw.

The straw mat or layer is passed from the threshing cylinder 18 and concave 19 in a rearward and upward direction towards the straw beater 28 which is operative to comb off the layer from the threshing cylinder 18, to deflect it in a rearwardly extending direction between itself and the beater grate 29, and to pass it on to the sepa rato r cyl inder 42 whilst submitting itto some separating action. Indeed a small percentage of grain is separated, together with impurities, through the beater grate 29.

As the straw mat issues from the gap between the straw beater 28 and the beater grate 29 over the full width thereof, it is intercepted by the separator tines 47 of the separating cylinder 42. These tines 42 hit the mat with their leading, active surfaces 48 and thereby deflect the mat in a downward direction between the separator cylinder 42 and the associated concave 43. This beating action on the crop mat and on the remaining grain kernels therein is particularly vigorous due to the orientation ofthe crop mat substantially at a right angle relative to the direction of movement of the tines 47 at the point of interception of the mat by the tines.This results in an abrupt change in the direction of movement of the crop mat with the grain kernels therein and as the grain kernels have a greater specific weightthan the straw particles, and thus also have a greater inertia, the separator tines 47 are operable, especially at the inlet end of the separator mechanism 38, to impel these grain kernels towards the lower regions of the crop layer, and eventually through the separator concave 43, with a high degree of efficiency. This high efficiency is further enhanced by the fact that, on the one hand, the separator tines 47 have a relatively narrow width and, on the other hand, the separator tines 47 on adjacent rows are staggered relative to each other.

Due to the generating line of the separator tines 47 passing closely adjacentthe circle generated by the straw beater plates 33, the separator tines 47 exert an efficient combining action on any material otherwise having a tendency to wrap around the straw beater beyond the discharge end thereof.

The separator tines 47 entrain the crop mat over the full width of the cylinder 42 across the separator concave 43 towards the discharge end thereof whilst submitting itto a continued separating action i.e. a continual urging of the grain kernels towards the lower regions of the crop mat and eventually through the concave. Also, though to a lesser degree, a sustained threshing action is exerted on the crop mat to loosen grain kernels still attached to the ears.

During its movement along the separator concave 43, the crop mat is subjected to a combing action by the separatortines 47 in a manner such thatthe straw, which forms the mat, is oriented generally in a fore-and-aft direction of the machine and spread in a more or less even thickness transversely of the width of the separator mechanism 38. This is very advan tageous with regard to the next step in the process as will be seen.

As the crop mat is conveyed from the separator mechanism 38 through the inlet 83 of the separator mechanism 41, it is intercepted by the crop treating and conveying elements 68 on the rotor 63. At the centre of the rotor 63 the crop layer dividing blades 71 are active to divide the layer, which has a width corresponding to the width of the separator cylinder 42, into two substantially equally portions. As the straw in this layer is already oriented in a generally fore-and-aft direction, as explained above, this divi sion into two portions is easily accomplished. The transverse staggering of the apices of the V's formed by the dividing blades 71 relative to the centreline 69 also helps to accomplish this division without any hesitation in the movement of the crop mat.This was not so in the prior arrangement of British Patent Specification No. 1,460,715 and the improvement achieved is beiieved to result in the first place from the orientation in the fore-and-aft direction of the straw in the separator mechanism 38, and in the second place from the staggering of the blades 71.

The crop layerdividing blades 71 and the crop conveying blades73 urge the two portions of crop mat ourwardly towards the outer line generated by the elements 68 onthe rotor 63, whereby the crop is passed around the rotor against the inside of the rotor housing 62. This is accomplished mainly by the orientation of the blades 71 and 73.

Also the crop layerdividing blades 71 and the crop conveying blades 73, together with the separator blades 76, due to their angled positions relative to the direction of the incoming crop deflect the two portions of the crop mat in respective opposite paths spirally around the rotortowards the end thereof.

The steeper inclination of the blades 71 and 73, relative to the separator blades 76, is also necessary to change the crop from a generally fore-and-aft direction of movementto the spiral movement and once the spiral movement has been initiated, the lesser inclination of the separator blades 76 is enough to sustain that movement. The spiral movement is also induced by the stationary spiral fins 91.

In operation, the movement of the crop is more or less aligned with the direction of the stationary fins 91, and thus, when this direction is projected on the development of the rotor as shown in Figure 5 at 191, it will be seen that in this direction adjacent blades 71,73 in each row of blades overlap each other. Also, as seen in the same direction, adjacent separator blades 76 overlap each other. This overlapping prevents crop material from becoming trapped in the "pockets" formed between the adjacent blades 71,73 and adjacent 76 which would otherwise interrupt the spiral movement described.

From the inlet 83 crop material is conveyed generally rearwardly across the middle section of the separator concave 185 between the additional fins 90, whereafter it is led in opposite spiral paths in outward directions across the upright concave section 186 but still between the opposed additional fins 90. The crop layers thereafter further move spirally across the cover 82 from an area between the fins 96 towards an area outside these fins 90 on the concave sections 187. Thus the crop layers now are moved ip the areas between the opposed rotor ends and the sides of the inlet 83. The crop finally passes for a second time over the lower separator concave 185, but this time at the outer sections thereof which are located between the respective rotor ends and the additional fins 90, whereafterthe layers are dis charged through the outlets 84 onto the ground.

Thus, it will be appreciated thatthe crop layers loop or pass around the rotor 63 about 1 times and that the loop sections are neatly separated from each other by the additional fins 90.

At the ends of the rotor the discharge blades 79 extend parallel to the rotor axis as no further axial movement should be induced into the crop, these blades serving to discharge the straw from the separator mechanism 41. It will be seen from Figure 7 of the drawings that the discharge blades 79 are shorter than the width of the outlets 84 and that they are positioned in the vicinity of the outer sections of the outlets 84 which means that the separator blades 76 partially overlap the outlets. Tests have shown that this is the most advantageous combination.

Also, as can be seen from Figure 7, the outlets 84 have a width which is less than half the width of the inlet 83 and thus the two portions of the crop mat entering the separator mechanism 41 should be consolidated into a narrower width during their movement spirally around the rotor so as to be able to pass through the outlets without difficulty. This is mainly accomplished by the steeper angle of the blades 71, 73 relative to the centreline 69. This is advantageous for the reason that thereby the crop layers move past the side edges of the inlet 83 without any hesitation at the point where the first loops or passes around the rotor 63 are completed.

Tests have also shown that the crop conveying blades 73 can be omitted with the two portions of the crop mat or layer entering the inlet 83 still being deflected sufficiently quickly into the spiral paths 191 as required using only the crop layer dividing blades 71 and the stationary fins 91.

As the crop material is moved spirally around the rotor 63 from the housing inlet 83 to the outlets 84, the outer edges 75 and 78 of the crop layer dividing and crop layer transporting blades 71,73, and the separator blades 76, respectively, rub on the crop mat and rub it across the separator concaves 81, whereby the crop is subjected to a further and final sustained grain separating action. Grain kernels separated by this rubbing action, and under influence of the centrifugal forces acting thereon, move through the concaves 81. Grain separated in the central portion of the mechanism 41 falls directly onto the rear grainpan 103, whilst grain separated in the end sections of the mechanism 41 is collected and conveyed to the front grainpan 101 by mechanisms shown and described in more details in the copending Patent Application No.79.23774.

As the separator rotor 63 is rotated in the direction 72, the fan blades 7.1,73,76 and 79 cause air blasts directed from a location centrally and rearwardly of the separator mechanism 41, around the rotor 63 and mainly within the housing 62 towards the opposed ends of the separator mechanism and forwardly thereof. If no special precautions were taken, these air blasts would create a suction in the area above the third grainpan 103 rearwardly of, and below, the separator mechanism 41, whereby dust, straw particles, chaff, etc. would be sucked into the cavity between the separator concave 186 and the deflector plate 92. After a short period of time the cavity would be filled completely and thus the separator concave 186 would get plugged or blocked so that the separating surface would be diminished which in turn would result in a reduced separating efficiency.

The opening 95 is provided between the deflector plate 92 and the top shield 94, i.e. substantially at the upper portion of the cavity between the concave 186 and the plate 92, where the build up of chaff, etc.

occurs and the plugging has a tendency to start when nothing is provided to counteract it. The opening 95 is provided at a substantial height above the cleaning mechanism 11 and at a location where grain kernels separated through the concave 186 have no tendency to pass therethrough. The air blasts referred to above create a suction through the opening 95 and thus chaff, etc. is no longer lifted from the cleaning mechanism 11, which means that plugging of the concave 186 is avoided. Thus the provision of the opening 95 avoids one of the problems encountered in known machines.

If no special precautions were taken in connection with the concave section 89, there would be a tendency for this section to plug with crop material, whereby the separating efficiency would be reduced.

This fact has been revealed by experiments and apparently is due to the fact that in this area of the concave the transverse bars normally provided have a wrong orientation as they tend to impede the fall under gravity of the crop material. Indeed, in this concave section the transverse concave bars normally have their flat sides extending generally horizontally or even slightly upwardly inclined as seen from the inside of the separator housing 62. Thus any crop material falling thereon has a tendency to stay there. This is particularly true for straw particles.

This drawback is clearly interrelated with the drawback of the above described cavity getting filled with chaff, etc. and for which a separate solution has already been described.

The solution provided to the problem of an easily blocked concave section 89 is that of removing the transverse separator bars 86 in the section 89 although this does not totally solve the problem.

This is because although straw can no longer hook around the transverse bars since they are absent in this concave area, it has been experienced that, when a number of bars 86 are omitted, there is a tendency for long straw stalks to stick through the elongate slots between the concave wires 87 in the section 89 and to strike the shield 94 and to crumple as a result. These crumpled stalks now tend to hook around the concave wires 87, hanging partly inside and partly outside the housing 62. When this occurs, complete plugging soon follows. To prevent this, the opening or free space 192 is provided between the ends of the concave wires 87 and the adjacent edge of the cover plate 82 to allow the separator rotor 63 to strip off any crumpled or other stalks from the ends of the concave wires 87 and to draw them back into the separator housing 62. Thus the separator mechanism 41 has a self-cleaning effect in the concave area 89. The air blasts mentioned above and which appear mainly in the central portion of the separator mechanism 41 help in moving crumpled straw back in the rotor housing so that the plugging is avoided, whereby the separating efficiency is kept exceptionally high.

Having described the threshing and separating functions ofthe machine in some detail, the cleaning function will now be reviewed. When the cleaning mechanism 11 is in operation, the fan 157 is rotated in the direction 156 and the cleaning shoes 107 and 132, with the elements attached thereto, are oscil lated. The lower cleaning shoe 132 is oscillated back-and-forth along a generally rearwardly and slightly upwardly extending path 181. The upper cleaning shoe 107 is oscillated in substantially the same direction but with a phase displacement of 1800. The third grainpan 103, by virtue of its pivotal mounting on the upper cleaning shoe 107 and its drive received therefrom in the manner described above, is caused to oscillate back-and-forth along a generally forwardly and upwardly directed path.

Cleaning air blasts are directed through the outlet ducts 163,164 of the fan housing 152.

Material separated through the threshing concave 19, the beater grate 29, the portion of the separator concave 43 associated with the separator cylinder 42, and through the concave sections at the opposed ends of the separator mechanism 41 falls directly onto the grainpan 101 which, especially on large capacity combines, may be relatively thick. In addition, rethreshed tailings may be added thereto as is shown and described in co-pending PatentApplication No. 79.23773. Material separated in the central portion of the separator mechanism 41 and in the rear portion of the mechanism 39 falls directly onto the rear grainpan 103.By virtue of the oscillatory movements in generally opposite directions of the grainpans 101 and 103, material thereon is gradually moved towards the respective discharge ends thereof whilst allowing the heavier grain kernels to "sink" to the lower portions of the layers of material and thus allowing the lighter chaff, straw, dust and other lightweight impurities to rise to the top.

As the layers of crop material drop off the discharge ends of the grainpans 101 and 103, they are fluffed out by the comb assembly 104 and thereafter subjected to a strong air blast from the fan outlet duct 164 astheyfall towards the pre-cleaning sieve 113. Thus a major percentage of lightweight impurities (chaff, dust, straw, etc.) immediately becomes airborne and is moved in the direction of the discharge end of the cleaning mechanism 11.

Directing an air blast onto and though a fluffed out layer of material during its fall is much more effective for cleaning purposes than when the same air blast is directed onto and through a layer which is positioned on top of a cleaning sieve. It should also be remarked that the layers of crop material issuing from both grainpans 101 and 103 are not discharged the one on top of the other, but rather the one rearwardly of the other. Thus, an even fluffier mass of crop material is obtained. Also, at this point in the machine, there is no great risk for a strong air blast to blow grain kernels out of the machine giving rise to increased grain losses. Accordingly, a strong air blast may be applied and hence a good pre-cleaning operation accomplished.

A layer of crop material of already reduced thickness thus falls on to the pre-cleaning sieve 113, the mesh of which is adapted to the kind of crop being handled. A cleaning air blast is directed from below and through the pre-cleaning sieve 113 as well as through the area between that sieve and the inter mediate grain pan 102 therebelow. As the layer is moved across the sieve 113 towards its discharge end, grain which has been cleaned to a great extent, falls through the pre-cleaning sieve 113 and across said air blast onto the intermediate grain pan 102 and is conveyed therefrom directly to the lower sieve 137 ofthe main cleaning mechanism formed by the lower sieve and the chaffer sieve 114 thereabove.As the grain falls from the intermediate grain pan 102 to the lower sieve 137, it is again subjected to a clean ing air blast which this time issues from the main fan outlet duct 163. It will be noted here that grain sepa rated through the pre-cleaning sieve 113 bypasses the chaffer sieve 114.

The remainder of the layer of crop material on the pre-cleaning sieve 113 is fluffed up again as it falls through the comb assembly 116 onto the chaffer sieve 114. Again a cleaning air blast, issuing from the additional outlet duct 164 is directed onto this layer during its fall and the profile 112 at the rear end of the pre-cleaning sieve 113 is so shaped and oriented so as to direct some cleaning air on the underside of the comb assembly 116. A further percentage of impurities thus becomes airborne and, together with the impurities coming from the stage above, carried out of the machine.

Even though the total capacity of the machine, and hence also of the entire cleaning mechanism 11, is very high, the loading of the chaffer sieve 114 has been reduced substantially and thus the efficiency thereof has been increased accordingly. Indeed a large percentage of impurities is already separated before the layer of crop material reaches the chaffer sieve 114, on the one hand, whilst on the other hand, a large percentage of partially cleaned grain is directed from the intermediate grainpan 102 directly onto the lower sieve 137, thus bypassing the chaffer sieve 114. Due to this reduced loading of the chaffer sieve 114, the layer of crop material thereon is more easily passed through by the cleaning air blast without any undue risks of losses occurring and thus all impurities easily become airborne and discharged.

The main cleaning device, that is the chaffer sieve 114 together with the lower sieve 137 and the associated fan outlet duct 163, operate in a generally conventional manner. A cleaning air blast is directed through the areas below both sieves 114 and 137 as well as through those sieves from below. In this way, the remaining impurities become airborne and are blown out of the machine whilst cleaned grain falls through the sieves and through the cleaning air blasts onto the clean grain conveyor floor 133 which conveys the cleaned grain to the clean grain auger 135 fortransportto the grain tank 8.

Tailings which are too large to fall through the chaffer sieve 114 are conveyed to the sieve extension 118 where they either fall through the larger apertures or through the comb assembly attached thereto. Tailings are collected on the tailings conveyor floor 134 which conveys them to the tailings return auger 136 for recycling and reprocessing.

The cleaning fan 151 operates partially as a centrifugal fan and partially as a cross flow fan. The fan blades 175 are operable to draw air in not only through the opposed end inlets 153 as in conventional contrifugal fans, but also through the transverse inlet 154 as in conventional cross flow fans.

This has become possible due to the special design of the fan blades 175 which are concave and which basically are oriented at a sharp angle in advance of the radius of the fan. As a result, the cleaning air blast is distributed very evenly transversely of the cleaning mechanism 11 even when a relatively wide cleaning fan is employed. An even transverse air pattern is an absolute requirement for a highly efficient cleaning device and to achieve this virtually irrespective of the width of the fan means a cleaning mechanism of increased width, compared with known machines can be employed. Also the volume of the cleaning air produced by the fan is substantially increased, whereby again higher capacities are obtainable.

The major percentage of cleaning air expelled from the fan housing through the main outlet duct 163 whilst the remainder is directed through the additional outlet duct 164. The proportion of cleaning air issuing from both outlet ducts 163 and 164 is adjustable by the angularly adjustable baffles 161, 162 and 169 and thus cleaning air blasts can be directed at will where needed.

It will be seen that a high capacity threshing mechanism is combined with a high capacity separating mechanism. The high capacity separating mechanism is obtained mainly by the combination of the separator cylinder and cooperable concave on the one hand and the separator rotor and associated housing on the other hand. Separation in the first component to a great extent is based on the separator tines impacting on the kernels whilst separation in the latter component results to a great extent from the sustained centrifugal forces to which the grain kernels are subjected. Nevertheless, a smooth flow of crop through the machine is obtained. This is partially due to the fact that the separator cylinder reorientates the straw in the layer prior to the layer dividing blades 71 actually dividing the layer in two portions.Furthermore, a spiral movement of the two crop portions to the discharge ends is positively induced as described above.

Problems with airturbulences created by the separator rotor causing components of the rotor housing to plug have been overcome in a very simple manner.

High capacity threshing and separating mechanisms necessarily require high capacity cleaning devices, especially on rotary combine harvesters which are known to load more heavily the cleaning mechanisms with short straw than the so-called conventional combine harvesters. First of all, the rear grain pan shields the cleaning mechanism from the separating mechanism so that grain separated in the latter cannot fall directly on the cleaning sieves rearwardly of the leading end thereof. Instead, this material is conveniently conveyed to a more forward location of the cleaning device in a direction opposite to the direction of flow through the remainder of the cleaning mechanism.

It will be apparent to those skilled in the art that various modifications of the embodiment of Figures 1 to 12 can be made. For example, the deflector plate 92 and the shield 94 with the air inlet 95 therebetween defining the open ended cavity may be arranged in a different manner as shown in Figure 13. In the arrangement of Figure 3, it may happen that grain kernels separated through the upper section of the separator concave 186 are projected through the air inlet 95 whereby they are not deflected by the deflector plate 92 towards the cleaning mechanism 11 therebelow. In the arrangement according to Figure 13, the shield 94 is more in the form of a hood with a rear and lower edge 201 disposed forwardly and below the upper edge 202 of the deflector plate 92.Thus the air inlet 95 is now disposed generally vertical, or even slightly downwardly inclined, as seen in the forward direction, as opposed to generally horizontal in Figure 3. Grain kernels, which are projected generally radially away from the upper section of the separator concave portion 186, are thus prevented from being projected through the air inlet 95, and hence are deflected by the concave shield 94 and the deflector plate 92 to the cleaning mechanism therebelow.

Also the drive and suspension means for the third grainpan 103 may be different from the drive and suspension means shown in Figures 2 and 9. In one such alternative arrangement shown in Figure 14 the rear rock arm 115, the link 129 and the further link 130 on each side of the machine may be replaced by a single link 203 which is rigidly coupled at pivot 125 to the associated crank 123 in a manner defining, with the crank 123, an angle preferably of the order of 90". The crank 123 and link 203 on each side of the machine are disposed so that the pivot 125 is positioned at one side of the vertical plane passing through the pivot 131 and the pivot 183 is positioned on the opposite side of that plate. Preferably each link 203 is positioned parallel to the rock arms 142 and its length corresponds to the distance between the pivots 141 and 143 of the rock arms.

As is shown in Figure 14, the connecting rods 126 may be omitted. This is possible and practical only provided in all operating positions the pivotal couplings between the cranks 123 and further cranks 124, on the one hand, and the grainpan 103, on the other hand, are sufficiently spaced from the dead centreline relative to the pivots 125. Preferably, the cranks 123, 124, are inclined upwardly in a rearward direction from the pivots 125, have the same length, and extend parallel to each other.

Alternatively the further cranks 124 may be replaced by cranks which are pivotally coupled at one end to the grainpan 103 and at the other end to the chassis 2. Preferably, in this arrangement, these cranks extend parallel to the imaginary straight line between the pivots 183 and 131 at the rear of the grain pan 103 and have a length which corresponds to the distance between said pivots.

In still a further alternative, the connecting rods 126 may be omitted and the further cranks 124 and upper halves of the rock arms 142 may be firmly coupled together in a manner to form supporting and drive means which are congruous to the structures formed by the links 203 and cranks 123 of Figure 14.

Other aspects of the illustrated embodiments are described and claimed in co-pending Patent Applications 8036274, 8036275, 8036301, 8036302, 8036303 and 8036304.

Claims (120)

1. A combine harvester comprising a threshing mechanism extending transversely of the machine and having a threshing cylinder cooperable with a threshing concave to thresh a layer of crop material fed therebetween, and a separating mechanism having a first and a second separating component operable to subject the layer of crop material received from the threshing mechanism to a first and a second separating action, the first component comprising a separator cylinder cooperable with separator concave means and having a plurality of beater means arranged to impact on the layer of crop material received from the threshing mechanism, thus subjecting the crop material to the first separating action and conveying it to the second component, and the second component comprising at least one separator rotor cooperable with a separator housing including a separator concave, the or each separator rotor having at least one separator means extending generally logitudinallythereof and arranged spirally to convey crop material received from the first separator component around the rotor to one end of the latter whilst subjecting itto the second separating action.

2. A combine harvester according to claim 1, wherein the first and second components of the separating mechanism extend parallel to the threshing mechanism.

3. A combine harvester according to claim 2, wherein the first component of the separating mechanism has a width substantially equal to the width of the threshing mechanism, and wherein the second component of the separating mechanism has a width greater than that of the threshing mechanism with its ends extending transversely past the respective ends of the threshing mechanism and is arranged spirally to convey crop material received from the first separating component towards each of its ends whilst subjecting the crop material to the second separating action.

4. A combine harvester according to any of the preceding claims, wherein the beater means of the first component of the separating mechanism are in the form of tines each having a flat operative surface inclined rearwardly, as seen in the direction of rotation of the separator cylinder, and arranged to impact on the crop material fed thereto.

5. A combine harvester according to claim 4, wherein the separator cylinder is provided with a plurality of rows of beater tines, the rows being equiangularly spaced around the periphery of the cylinder.

6. A combine harvester according to claim 5, wherein the rows of beater tines extend parallel to the longitudinal axis of the separator cylinder.

7. A combine harvester according to claim 5 or 6, wherein the beater tines of each row are staggered relative to the tines of adjacent rows.

8. A combine harvester according to any of claims 4 to 7, wherein each beatertine is formed from sheet metal and comprises a pair of opposed side walls in addition to said rearwardly inclined operative surface.

9. Acombine harvester according to any of the preceding claims and further comprising a straw beater cooperable with a beater grate and disposed between the threshing mechanism and the separating mechanism, the straw beater being operable to convey crop material issuing from the threshing mechanism to the first component of the separator mechanism in a direction generally perpendicular to the direction of movement of the beater means of said first component at the point where the beater means intercept the crop material.

10. Acombine harvester according to any of the preceding claims, wherein the separator housing comprises a forwardly facing inlet, of a width smaller than that of the housing, for receiving crop material from the first component of the separating mechanism, and an outlet offset relative to said inlet.

11. A combine harvester according to claim 10, wherein the inlet is disposed centrally of the housing, and two outlets are provided which face rearwardly and are disposed towards respective ends of the housing such that each is offset transversely of the machine relative to the inlet.

12. Acombine harvester according to claim 11, wherein generally vertical separator concaves extend between the respective ends of the separator housing and the inlet, and between the two outlets.

13. A combine harvester according to claim 11 or 12, wherein the lower part of the separator housing comprises a further separator concave and the upper part comprises a cover plate.

14. Acombine harvester according to claim 10, wherein the separator housing comprises an inlet which is substantially rectangular and of a width substantially equal to that of the threshing mechanism.

15. A combine harvester according to any of the claims 10 to 14 and further comprising fins extending spirally in opposite directions on both sides of the fore-and-aft centreline of the separator housing on the inside thereof from a location rearwardly of the inlet, as seen in the direction of rotation of the separator rotor, and at an acute angle relative to said direction of rotation.

16. A combine harvester according to claim 15, wherein said angle is of the order of 25".

17. A combine harvester according to claim 15 or 16, wherein a pluralityofequispaced and parallel fins are provided on each side of said centreline.

18. Acombine harvester according to claim 17, wherein the fins closest to said centreline on respective sides of the latter together form a V with the apex facing in a direction opposite to the direction of rotation of the separator rotor.

19. Acombine harvester according to claim 17 or 18, wherein three fins are provided on each side of said centreline, the forward ends thereof being positioned on a line extending transversely of the machine.

20. A combine harvester according to claim 19, wherein the inner pair of fins on each side of said centreline have rear ends aligned with the lower edge of the inlet at locations between the inlet and the respective ends of the separator housing.

21. A combine harvester according to claim 19 or 20, wherein the outer pair of fins on each side of said centreline terminate short of the adjacent end of the separator housing by a similar amount.

22. Acombine harvester according to claim 21, wherein the outer fin on each side of said centreline terminates in alignment with the top edge of the inlet at a location between the inlet and the adjacent end of the separator housing.

23. Acombine harvester according to anyofthe claims 11 to 22, wherein additional fins extend along respective sides of the inlet, extending spirally outwardly across the lower portion of the separator housing and along the inner sides of the outlets.

24. Acombine harvester according to anyofthe claims 10 to 23, wherein the separator rotor comprises generally mid-way along its length crop layer divider blades disposed in pairs around the circumference of the rotor, the blades of each pair being oppositely inclined to define a V having its apex facing in the direction of rotation of the rotor.

25. A combine harvester according to claim 24, wherein the crop layer divider blades are disposed at angles of the order of 55 relative to the longitudinal axis of the rotor.

26. Acombine harvester according to claim 24 or 25, wherein the apices of the V's formed by adjacent pairs of crop layer divider blades are staggered transversely of the machine so as to lie on opposite sides of the fore-and-aft centreline of the rotor.

27. Acombine harvester according to any of the claims 24 to 26, wherein the leading edges, as seen in the direction of rotation of the rotor, of each pair of crop layer dividing blades are spaced apart transversely of the machine.

28. A combine harvester according to any of the claims 24 to 27, wherein six pairs of crop layer divider blades are provided around the circumference ofthe rotor.

29. Acombine harvester according to any of the claims 11 to 28, wherein the separator rotor comprises discharge blades disposed at respective ends of the rotor and extending generally radially outwardly from the circumference of the rotor and parallel to the longitudinal axis of the rotor.

30. Acombine harvester according to claim 29, wherein the discharge blades have a length less than the width of the outlets in the separator housing.

31. A combine harvester according to claim 29 or 30, wherein six discharge blades are provided around the circumference of the rotor at each end of the latter.

32. A combine harvester according to any of the claims 29 to 31 when appended to any of the claims 24 to 28, wherein the separator means extending generally longitudinally of the separator rotor comprise separator blades substantially bridging the space between the crop layer dividing blades and the discharge blades.

33. Acombine harvester according to claim 32, wherein the separator blades project generally radially outwardly and extend from the vicinity of the crop layer dividing blades to the vicinity of the discharge blades at an angle relative to the longitudinal axis of the rotor and in a rearward direction as seen in the direction of rotation.

34. Acombine harvester according to claim 33, wherein said angle is of the order of 150.

35. A combine harvester according to claim 33 or 34, when appended to any of claims 28 and 31, wherein six separator blades are provided around the circumference of the rotor at each side of the fore-and-aft centreline thereof.

36. A combine harvester according to claim 35, wherein each separator blade is coupled to a corresponding discharge blade.

37. A combine harvester according to any of claims 32 to 36, wherein the separator blades and discharge blades are formed of sheet metal and comprise a generally radially outwardly extending body and an outer edge directed rearwardly as seen in the direction of rotation.

38. A combine harvester according to any of the claims 32 to 37, wherein each separator blade has its leading end closely adjacent the rear end of the corresponding crop layer dividing blade.

39. A combine harvester according to any of claims 32 to 37 and furthercomprising an additional crop conveying blade between each crop layer dividing blade and the associated separator blade at a distance from, and parallel to, the crop layer dividing blade.

40. Acombine harvester according to claim 39, wherein each separator blade has its leading end closely adjacent the rear end of the corresponding crop layer conveying blade.

41. A combine harvester according to any of claims 24 to 40, wherein each crop layer dividing blade comprises an outwardly and rearwardly inclined edge, as seen in the direction of rotation, and an outer slightly arcuate edge generally coincident with the outer circle circumscribed by the separator rotor on rotation thereof.

42. A combine harvester according to claim 39 or 40, wherein each crop conveying blade comprises an outwardly and rearwardly inclined leading edge, as seen in the direction of rotation, and an outer slightly arcuate edge generally coincident with the outer circle circumscribed by the separator rotor on rotation thereof.

43. A combine harvester according to any of the claims 39, 40 and 42, wherein each crop layer dividing blade and the adjacent crop conveying blade overlap each other when seen in the direction of the spiral movement of crop material around the rotor.

44. A combine harvester according to any of the preceding claims and further comprising a cleaning device disposed below the separating mechanism, means defining, in conjunction with a separator concave of the separator housing, an open ended cavity having its open end facing the cleaning device and operable to guide grain separated through the separator concave to the cleaning device, and an air inlet in said means at an upper portion thereof.

45. A combine harvester accordingto claim 44, wherein said means comprise a deflector spaced from the concave, with a lower edge spaced above the cleaning device.

46. A combine harvester according to claim 45, wherein the separator concave and the deflector defining said cavity are both oriented generally vertically.

47. A combine harvester according to claim 45 or 46, wherein the top of the cavity is formed by a shield member, and wherein the air inlet is provided between the shield member and the deflector.

48. A combine harvester according to any of claims 44 to 47, wherein the air inlet is generally elongate and flat and extends generally parallel to the longitudinal axis of the separator housing.

49. A combine harvester according to any of the claims 44 to 48, when appended to claim 11, wherein the cavity has a width substantially equal to the width of the cleaning mechanism and is disposed vertically thereabove and between the outlets at the respective ends of the separator housing.

50. A combine harvester according to any of the preceding claims wherein, as seen in the direction of rotation of the separating rotor, the separator concave means terminate short of the remainder of the separator housing, thus defining therewith an opening downstream of the separator concave.

51. Acombine harvester according to claim 50, wherein the opening between the separator concave and the remainder of the separator housing has a dimension in the direction of rotation of the separator rotor of the order of 4 cms.

52. Acombine harvester according to claim 50 or 51, wherein the separator concave comprises a plurality of spaced bars which extend generally transversely of the machine, and a plurality of spaced, arcuate wires which extend generally in the direction of rotation of the separator rotor, the bars and the wires together defining a mesh through which separated crop material may pass.

53. A combine harvester according to any of the claims 50 to 52, wherein the opening between the separator concave and the remainder of the separator housing is situated above the longitudinal axis of the separator rotor and at an angle relative to the horizontal plane passing through that axis of the order of 400.

54. A combine harvester according to claim 52, wherein the rear portion of the separator concave, as seen in the direction of rotation of the rotor, is void of said bars.

55. Acombine harvester according to claim 54, wherein the rear portion of the separator concave which is void of bars comprises a plurality of wire sections which extend generally in the direction of rotation of the separator rotor and thus define open ended, elongate apertures facing generally in the direction of rotation of the separator rotor.

56. A combine harvester according to claim 65, wherein the wire sections terminate short of said remainder of the separator housing, thus defining therewith said opening.

57. A combine harvester according to any of claims 54 to 56, wherein the rear portion of the separator concave which is void of bars has a dimension, in the direction of rotation of the separator rotor, of the order of 13 cms.

58. A combine harvester according to any of claims 55 to 57, wherein the wire sections are inclined generally in the direction of said spiral movement of the crop material,

59. A combine harvester according to claim 58, when appended to claim 11, wherein the wire sections are inclined in opposite directions towards the respective ends of the housing.

60. A combine harvester according to claim 59, wherein the centre pairofwire sections define a V with the apex facing in a direction opposite to the direction of rotation of the separator rotor.

61. A combine harvester according to claim 59 or 60, when appended to any of claims 15 to 23, wherein the spiral fins extend across the separator concave, the remainder of the separator housing, and across the opening therebetween.

62. Acombine harvester according to claim 61, wherein the spiral fins extend generally in the same directions as the wire sections.

63. A combine harvester according to claim 62, wherein sections of the spiral fins are aligned with corresponding wire sections.

64. Acombine harvester according to claim 63, when appended to any of claims 61 to 62, wherein the cover plate is removably mounted, and wherein the spiral fins are divided at the location of the opening between the separator concave and the remainder of the separator housing to facilitate removal and replacement of the cover plate.

65. A combine harvester according to any of the claims 59 to 64, wherein the opening between the separator concave and the remainder of the separator housing extends over substantially the full width of the housing between said outlets at the opposite ends thereof.

66. A combine harvester according to any of claims 50 to 65, wherein the air inlet is disposed in the vicinity of the opening in the separator housing between the separator concave thereof and the remainder of the housing.

67. A combine harvester according to claim 44, and any claim appended thereto, wherein the cleaning device comprises a grainpan adapted to receive threshed and separated grain from the threshing and separating mechanism and progressively to convey the threshed and separated grain towards a discharge end of the grainpan, sieve means disposed to receive threshed and separated grain from the grainpan and comprising at least a chaffer sieve having a receiving end at a level below the level of the discharge end of the grainpan, fan means operable to direct a cleaning air blast to the sieve means to clean grain therein, a pre-cieaning sieve disposed between the grainpan and the chaffer sieve and having a receiving end below the grainpan discharge end, and further fan means operable to direct a cleaning air blast on the grain falling between the grainpan discharge end and the receiving end of the pre-cleaning sieve.

68. A combine harvester according to claim 67, wherein the pre-cleaning sieve has a discharge end disposed above the receiving end of the chaffer sieve.

69. A combine harvester according to claim 67 or 68, wherein the grainpan, the pre-cleaning sieve and the chaffer sieve are disposed the one generally behind the other, and wherein the pre-cleaning sieve and the chaffer sieve are inclined upwardly and rearwardly of the machine.

70. A combine harvester according to any of claims 67 to 69, wherein a comb assembly is provided at the discharge end of the grainpan.

71. Acombine harvester according to any of claims 67 to 70, wherein a comb assembly is provided at the discharge end of the pre-cleaning sieve.

72. A combine harvester according to any of claims 67 to 71, wherein the pre-cleaning sieve comprises a plurality of angulariy, adjustable louvres.

73. A combine harvester according to any of claims 67 to 72, comprising a further grainpan disposed substantially vertically below the pre-cleaning sieve.

74. A combine harvester according to claim 73, wherein the further grainpan has a discharge end spaced from the receiving end of the chaffer sieve thus defining therewith a discharge opening, the arrangement being such that grain received from the pre-cleaning sieve on the further grainpan is conveyed through the discharge opening, there bypassing the chaffer sieve.

75. A combine harvester according to claim 73 or 74, wherein the further grainpan has a stepped surface and is inclined upwardly as seen in the rearward direction of the machine.

76. A combine harvester according to any of preceding claims 67 to 75, wherein the further fan means direct the cleaning air blast partially from below through the pre-cleaning sieve and through the space therebelow.

77. A combine harvester according to any of claims 67 to 76, wherein the grain pan, the precleaning sieve and the chaffer sieve are, in use, oscillated in unison.

78. Acombine harvester according to claim 77, wherein the pre-cleaning sieve and chaffer sieve are mounted in a common subframe coupled to the grainpan.

79. A combine harvester according to claim 77, when appended to any of the claims 73 to 76, wherein the further grainpan is oscillated in unison with the grain pan, the pre-cleaning sieve and the chaffer sieve.

80. Acombine harvester according to claim 78, when appended to any of the claims 73 to 76, wherein the further grainpan is mounted on the subframe.

81. A combine harvester according to any of claims 67 to 80, wherein the sieve means further comprise a further sieve disposed generally beneath the chaffer sieve and with one end below and forwardly of the discharge end of the pre-cleaning sieve.

82. Acombine harvester according to claim 81, when appended to any of the claims 73 to 76,79 and 80, wherein the further sieve has one end generally beneath the discharge end of the further grainpan, the arrangement being such that grain received on the further grain pan from the pre-cleaning sieve is passed to the further sieve, thus by-passing the chaffer sieve.

83. A combine harvester according to claim 82, wherein the fan means which are operable to direct a cleaning air blast to the sieve means are disposed so as to direct at least a portion of the air blast to the transition between the further grainpan and the further sieve.

84. A combine harvester according to any of claims 81 to 83, wherein the further sieve is, in use, oscillated oppositely to the oscillatory movement of the chaffer sieve and the pre-cleaning sieve.

85. A combine harvester according to any of claims 81 to 84, wherein the fan means which are operable to direct a cleaning air blast to the sieve means are disposed to direct the air blast from below through the chaffer sieve and the further sieve, and through the respective areas therebelow.

86. Acombine harvester according to any of claims 67 to 85 and further comprising a cleaning fan structure having a fan housing and a fan mounted therein, the fan housing comprising a generally cylindrical body with a pair of opposed end walls and extending transversely of the machine, an air inlet provided in each wall, and a further air inlet and an air outlet provided in the cylindrical body.

87. A combine harvester according to claim 86, wherein the air inlet in the end walls are disposed generally coaxially with the fan.

88. A combine harvester according to claim 86 or 87, wherein the further air inlet extends substantially across the full width of the fan housing and has a generally rectangular shape.

89. A combine harvester according to claim 88, wherein the air outlet extends substantially across the full width of the fan housing, and wherein the further inlet and the outlet are provided the one closely adjacent the other in the circumference of the fan housing.

90. A combine harvester according to claim 89, wherein the further air inlet and outlet together extend over an arc of the order of 1800 of the cylindrical body of the fan housing.

91. A combine harvester according to any of claims 86 to 90, wherein the further air inlet is provided substantially in an upper portion of the fan housing.

92. A combine harvester according to any of claims 86 to 91, wherein the further air inlet is covered by a perforated shield.

93. A combine harvester according to any of claims 86 to 92, wherein the fan means and further fan means are formed by a main and an additional outlet duct, respectively, which both communicate with said air outlet.

94. A combine harvester according to claim 93, wherein the main and additional outlet ducts extend at an angle relative to each other.

95. A combine harvester according to claim 93 or 94, wherein the main outlet duct and the additional outlet duct each have a first wall extending substantially tangentially to the cylindrical body of the fan housing, the two first walls being spaced apart, and a second wall spaced from the first wall, the two second walls being connected together at a location spaced from the circle circumscribed by the fan.

96. A combine harvester according to claim 95, wherein the additional outlet duct is formed with a bend.

97. A combine harvester according to claim 96, wherein the additional outlet duct has a bend of the order of 90".

98. A combine harvester according to any of claims 95 to 97, wherein the further air inlet is provided between the first wall of the additional outlet duct and a point on the circumference of the cylin drical body of the fan housing disposed rearwardly of said first wall, when seen in the direction of rotation of the fan.

99. A combine harvester according to any of claims 93 to 98, wherein an angularly adjustable baffle is provided generally between the main outlet duct and the additional outlet duct and is operable generally to throttle one outlet duct in favour of the other.

100. A combine harvester according to any of claims 88 to 99, wherein the fan comprises a plurality of generally concave fan blades, with the concave surfaces facing in the direction of rotation of the fan.

101. Acombine harvester according to claim 100, wherein the fan blades are of the forwardly-curved type.

102. A combine harvester according to claim 100 or 101, wherein the fan blades comprise three generally flat sections, a first central section disposed at an acute angle in advance of the fan radius, and angled inner and outer sections defining with said first section the generally concave shape.

103. Acombine harvester according to any of claims 67 to 102, wherein the sieve means is oscillated along a first path, and further comprising an additional grainpan above the sieve means, the additional grainpan receiving oscillatory movement from the sieve means via first linkage means, the first linkage means being pivotally attached at a first point to the additional grain pan, at a second point to the sieve means and at a third point to a component of the machine relative to which the sieve means is movable, the arrangement being such that the oscillatory movement of the sieve means along the first path causes the additional grainpan to oscillate along a different path so as to convey crop material received thereon in a direction generally opposite to the direction of movement of crop material on the sieve means.

104. Acombine harvester according to claim 103, wherein the additional grainpan comprises a first, generally horizontally extending, section and a further upwardly and rearwardly inclined section, the surface of both sections being stepped in a manner progressively to convey crop material received thereon in a forward direction of the machine.

105. A combine harvester according to claim 104, wherein the grainpan and additional grain pan have oppositely oriented discharge ends, the one being disposed in the vicinity of the other.

106. A combine harvester according to any of claims 103 to 105, wherein the additional grain pan is provided between the sieve means and at least a portion of the separating mechanism to shield the sieve means from said portion of the separating mechanism.

107. A combine harvester according to any of the claims 103 to 106, wherein the additional grainpan is movably mounted on said machine component via second linkage means.

108. Acombine harvester according to anyofthe claims 103 to 107, wherein the additional grainpan is movably mounted on the sieve means via third link ages.

109. A combine harvester according to any of the claims 103 to 107, wherein the first linkage means also support the additional grainpan on the sieve means.

110. Acombine harvester according to anyofthe claims 103 to 107 and 109, wherein the first linkage means also movably supports the sieve means on said machine component.

111. A combine harvester according to claim 110, wherein the first linkage means comprise a first arm extending between the first and second pivot points and rigidly coupled at an angle to a further arm which extends between the second pivot point and the third pivot point.

112. A combine harvester according to any of claims 103 to 111,wherein identical linkage means are provided at each side of the sieve means and the associated additional grain pan.

113. A combine harvester according to claim 109, wherein the additional grain pan is also movably suspended on said machine component by additional linkage means pivotally coupled at one end to the additional grainpan and at the other end to said machine component.

114. A combine harvester according to claim 110, wherein a pair of additional linkage means are provided, one at each side of the additional grainpan.

115. Acombine harvester according to claim 113 or 114, wherein the linkage means and the additional linkage means are provided adjacent the rearward and forward ends, respectively, of the additional grainpan.

116. A combine harvester according to any of the claims 103 to 106, wherein the linkage means comprise a first arm extending between the first and second pivot points and rigidly coupled at an angle to one end of a further arm, the further arm being pivotally coupled at its other end to a link which itself is pivotally connected at the third pivot point to said machine component, the arrangement being such that the further arm and the link define an angle therebetween.

117. A combine harvester according to claim 116, wherein the additional grainpan is further movably suspended on the sieve means by additional linkage means pivotably coupled atone end to the additional grain pan and at the other end to the sieve means.

118. Acombine harvester according to claim 117 and further comprising a connecting rod pivotally connecting the first linkage means to the additional linkage means in a manner such that oscillatory movementofthe linkage means is imparted to the additional linkage means.

119. Acombine harvester according to claim 118, wherein identical linkage means and additional linkage means are provided at each side of the sieve means and the associated grainpan.

120. A combine harvester substantially as herein particularly described with reference to Figures 1 to 12, or as modified by Figure 13 or Figure 14, of the accompanying drawings.