EP0199775A1 - Apparatus for treating crop - Google Patents

Abstract

Appareil de conditionnement d'herbe et d'autres cultures fibreuses utilisées comme fourrage, comprenant un châssis mobile et deux rotors agissant de concert (11 et 12) montés en rotation sur des axes parallèles de manière à permettre le passage des végétaux entre les rotors. Un rotor inférieur (11) est monté en rotation sur un axe parallèle au sol pour cueillir et conditionner les végétaux et les transporter vers le haut et à l'arrière au-dessus du rotor, et un deuxième rotor (12) est positionné à un niveau supérieur et à l'avant du rotor inférieur, de manière à comprimer les végétaux contre les bouts pointus d'éléments d'accrochage (10) sur le rotor inférieur (11). Le rotor supérieur (12) peut présenter des nervures de section transversale triangulaire (61), qui peuvent être continues ou en dents de scie sur l'axe du rotor. Dans une variante le rotor supérieur (12) peut avoir des éléments plans (23) dont une partie externe est inclinée par rapport à un plan radial. Le rotor supérieur (12) peut être monté sur des bras de support pivotants (64) à ressort, permettant à l'écartement entre les rotors (11 et 12) de varier en fonction de la charge.Apparatus for conditioning grass and other fibrous crops used as fodder, comprising a movable frame and two concerted rotors (11 and 12) rotatably mounted on parallel axes so as to allow the passage of plants between the rotors. A lower rotor (11) is rotatably mounted on an axis parallel to the ground to pick and condition the plants and transport them up and back above the rotor, and a second rotor (12) is positioned at a upper level and at the front of the lower rotor, so as to compress the plants against the pointed ends of hooking elements (10) on the lower rotor (11). The upper rotor (12) may have ribs of triangular cross section (61), which may be continuous or sawtooth on the axis of the rotor. In a variant, the upper rotor (12) may have planar elements (23) of which an external part is inclined relative to a radial plane. The upper rotor (12) can be mounted on pivoting spring support arms (64), allowing the spacing between the rotors (11 and 12) to vary depending on the load.

Description

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APPARATUS FOR TREATING CROP The present invention relates to apparatus for treating crop, especially, but not exclusively, for conditioning grass and other fibrous fodder crop. Conditioning is a form of crop treatment intended to allow moisture to escape from the crop during wilting, without excessive fragmentation of the crop and without excessive loss of nutrients. It is common practice in agriculture to mechanically treat the crop to effect this conditioning, and such mechanical treatment may take various forms including crushing, lacerating, bruising, splitting, spiking, bending and scuffing the stems or leaves of the crop.

There is at present an increasing trend towards the making of forage crops into silage rather than hay, and the outcome of this is that excessive fragmentation of crop is of less importance, and more severe conditioning can be carried out than has previously been the case. Improved forms of pick-up devices which are now available also mean that greater fragmentation of crop can be tolerated during conditioning.

In some aspects the present invention is concerned with improved apparatus for and methods of conditioning grass and other fibrous fodder crop, in which more severe conditioning is provided than has previously been thought to be acceptable. According to the present invention there is provided apparatus for treating crop comprising two co-operating rotors mounted for rotation about parallel axes for passage of crop between the rotors, at least one rotor comprising a crop treating rotor having a plurality of stiff, outwardly directed crop engaging elements having pointed tips on the outer ends thereof for treating crop, each tip being formed on an outwardly directed projection having side edges converging towards each other in the outward direction, the other rotor also having a plurality of stiff, outwardly directed crop engaging elements, it being arranged that on at least one rotor each crop engaging element has a principal plane transverse to the general direction of crop flow, the arrangement being such that in operation the rotors rotate so that the crop engaging elements of the said other rotor press crop against crop engaging elements on the said one rotor which has the pointed tips for treating the crop. Apparatus according to the invention has particular use where the rotor is mounted on a mobile frame for movement across the ground and the rotor is mounted on the mobile frame with its axis substantially parallel to the ground either in a position such as to pick-up previously cut crop lying on the ground, or in a position such as to receive cut crop from cutting means for cutting crop during movement of the frame over the ground, or from a pick-up device for picking up crop from the ground.

In one preferred arrangement, the apparatus is adapted for conditioning grass or other fibrous fodder crop, and includes a mobile frame for movement across the ground, said one rotor which has the pointed elements being mounted on said frame for rotation about an axis substantially parallel to the ground for picking up and conveying crop, each crop engaging element on said one rotor having a principal plane transverse to the general direction of crop flow, the axis of rotation of the said other rotor being positioned at a higher level than the axis of rotation of the said one rotor, there being provided drive means for driving the said one rotor in rotation in a sense such that the rotor picks up crop and carries crop upwardly and rearwardly over the rotor, and a housing co-operating with the front of the said one rotor and forming with the rotor a crop flow passage between the rotor and the housing. In many preferred forms, the axis of rotation of the said other rotor is positioned forwardly of the axis of rotation of the said one rotor. in accordance with one feature of the invention the said other rotor is mounted on support arms pivottable about an axis parallel to and spaced from the axes of the rotors, to allow the spacing between the two rotors to vary with crop load.

Preferably there may be provided biassing means for biassing the said support arms in a direction such as to urge the two rotors towards each other.

In accordance with one feature, the said other rotor is driven in rotation by rotation of a shaft having an axis lying substantially at the pivot axis of the support arms.

Conveniently the two rotors may be driven in rotation by chains driven by rotation of a single shaft having an axis lying substantially at the pivot axis of the support arms. in accordance with another feature, on the said other rotor each crop engaging element comprises an inner portion having a principal plane transverse to the direction of movement of the element, and an outer portion having a further principal plane transverse to the direction of movement of the element, said further principal plane being inclined to the first principal plane and being inclined to a radial plane passing through the axis and through the element, the two rotors being rotated with a differential peripheral velocity, and with the inclined portion of each element trailing relative to the differential peripheral velocity so that the inclined portion of each element tends to push crop onto the pointed tips of the crop engaging elements on the said one rotor.

In accordance with yet another feature the said other rotor may have around its periphery a number of transverse rib-like portions parallel to its axis, each rib-like portion having an approximately triangular cross-section, the leading and trailing planes of the ribs being¹ so angled that crop is directed into the operating sphere of the said one rotor.

In accordance with a yet further feature the said other rotor may have around its periphery a number of transverse rib-like portions parallel to its axis, each rib-like portion being serrated both in an axial and a circumferential direction, to produce projections each approximately in the shape of a tetrahedron.

In many preferred arrangements the crop engaging elements on both rotors comprise substantially planar elements each having at least one principal plane transverse to the direction of movement of the element, the elements on at least one rotor being serrated to provide the said outwardly directed projections.

It is generally preferred that the crop engaging elements on at least one rotor are formed from thick, stiff, resilient, sheet-like material. It is also generally preferred that the crop engaging elements on at least one rotor are formed from synthetic plastics material.

There may be included in the apparatus drive means for driving the rotors in counter-rotation with different peripheral speeds so as to treat crop by differential peripheral movement between the rotors, or drive means for driving the rotors in co-rotation so as to treat the crop by differential peripheral movement of the rotors. The invention has particular application in a so-called high-speed pick-up apparatus in which the drive means is arranged to drive the said one rotor in rotation at a speed such that at least at the region of first contact between the elements and the crop, the crop engaging elements move faster than the crop being conveyed, and that the rotor accelerates the crop by lifting it against the resistance provided by the housing and releases the crop at least predominantly by centrifugal effect. The invention also has particular advantage where each element on the said one rotor has a principal plane which traverses the general direction of crop flow. In one form such an element comprises a rib-like element extending transversely across the direction of crop flow to a greater extent than it extends outwardly from the support means, and preferably has deep serrations along its outer edge so as to form a plurality of outwardly directed elongate teeth, each said tooth having side edges which converge towards each other in the outward direction. In another form each element comprises a fin-like element extending outwardly from the support means to a greater extent than it extends transversely across the direction of crop flow.

Preferably the crop engaging elements on at least the said one rotor are arranged to be resiliently yieldable, the yielding arrangement having sufficient stiffness for the elements to be capable of returning after yielding to their undeflected dispositions at least predominantly by virtue of the resilience of the yielding arrangement.

The yielding of the crop engaging elements may be due to the resilient nature of the material from which the elements are formed, or may be due to an additional yielding arrangement by pivoting, springing or otherwise, or may be due to a combination of such yielding effects.

The elements may be returned after yielding to their undeflected dispositions by a combination of the yielding arrangement together with centrifugal force. it may be arranged that only one of the rotors has pointed outwardly directed tips, or each of the rotors may have pointed outwardly directed tips on the outer ends of the crop engaging elements thereof.

In some particularly preferred arrangements, the crop engaging elements of each rotor are arranged in elongate formations which traverse the general direction of crop flow, the arrangement being such that in operation the rotors rotate with the outer perimeters of the rotors overlapping and with regular inter-meshing of one or more of the elongate formations of each rotor with one or more elongate formations of the other in such a manner that the crop engaging elements of one rotor press crop into gaps between the elongate formations on the other rotor.

Conveniently one of the rotors may be regarded as a crop treatment rotor and the other rotor can be regarded as a feeding rotor. In one preferred form, each elongate formation on the feeding rotor is formed by a single crop engaging rib-like element, for example which consists of a single sheet of stiff resilient material, conveniently synthetic plastics material. Optionally the distal edge of each crop engaging element on the feeding rotor is serrated or otherwise shaped to assist engagement of crop by the element, but may be plain. In accordance with one particular preferred aspect of the present invention there is provided apparatus for conditioning grass or other fibrous fodder crop, comprising a mobile frame for movement across the ground, and two co-operating rotors mounted for rotation about parallel axes for passage of crop between the rotors for conditioning the crop, one rotor being mounted on said frame for rotation about an axis substantially parallel to the ground for picking up crop and carrying the crop upwardly and rearwardly over the rotor, each crop engaging element on said one rotor having a principal plane transverse to the general direction of crop flow and having pointed tips on the outer ends thereof for treating crop, the other rotor also having a plurality of stiff, outwardly directed crop engaging elements, and the axis of rotation of the said other rotor being positioned at a higher level than the axis of rotation of the said one rotor, in which the said other rotor is mounted on support means pivotable about an axis parallel to and spaced from the axes of the said rotors to allow the spacing between the two rotors to vary with crop load, the said other rotor being driven in rotation by drive means rotating about an axis lying substantially at the pivot axis of the support means.

It is to be appreciated that there are also provided in accordance with the present invention - 10 - various methods of treating crop having the various features set out above with regard to the apparatus according to the invention.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:-

Figure 1 shows diagrammatically in cross-sectional side view apparatus for conveying and conditioning crop which may be arranged to embodying the present invention in some aspects;

Figure 2 is a diagrammatic side view partly in section of a modified form of the apparatus shown in Figure 1, which embodies the invention;

Figure 3 shows in perspective a form of crop pick-up and conditioning rotor which may be used in some of the embodiments of the invention described with reference to the other figures;

Figure 4 shows diagrammatically how two conditioning rotors of the form shown in Figures 1, 2 or 3 may be arranged to interdigitate for conditioning crop;

Figures 5(a) to 5(d) show diagrammatic representations of different modes of interaction of twin rotor conditioning units; Figures 6(a) and 6(b) show diagrammatic side and perspective views of a further crop conditioning apparatus embodying the invention;

Figures 7(a) and 7(b) show diagrammatic side and perspective views of a yet further crop conditioning apparatus embodying the invention; Figures 8(a) and 8(b) show diagrammatic side views of two further alternative forms of conditioning apparatus embodying the invention.

Figure 1 shows in a diagrammatic side view partly in section, apparatus for picking up grass or other fibrous fodder crop from the ground, and conditioning the crop and depositing the conditioned crop back onto the ground. As will be known to those skilled in the art, such a conditioning apparatus commonly consists of a horizontal rotor indicated generally at 11, which is mounted at the rear of a tractor and is moved across the ground 13, and is rotated by drive means (not shown) powered by the pto of the tractor. The rotor 11 is driven in rotation in a sense such as to pick up cut crop from the ground and carry the crop upwardly and rearwardly over the rotor, beneath a housing shown at 15, 16 and 17 (also known as a hood, cowling, or shroud). The housing defines between the rotor and the inner side of the housing a crop flow passage along which the crop is conveyed by the rotor 11. The form of rotor shown is sometimes referred to as a "high-speed" pick-up rotor which consists of a rotor driven at a speed of rotation such that at least at the region where the crop is picked up, the crop engaging elements move faster than the crop during acceleration; that the hood 17 in front of at least part of the rotor above the intake region prevents crop from being thrown forward; and that at the release region 16 the crop is released at least predominantly by the effect of centrifugal force, although the release may be assisted by additional means such as a stripping rotor. The high-speed pick-up rotor accelerates the crop by lifting it against the resistance provided by the front cover or housing 17, usually accelerating the crop through a restriction at the intake region, into a crop flow passage. Typically the rotor may operate at rotational speeds in the range 400 to 900 revs per minute. The rate of rotation is preferably arranged to be such that the circumferential tip velocity of the crop engaging elements on the rotor is in the range 10 to 25 m/s. The form of conveying and conditioning rotor with which the present invention is concerned, is generally of the kind having a plurality of outwardly extending crop engaging elements, each of which has a principal plane which traverses the general direction of crop flow. In the embodiments shown in the specification, the crop engaging elements are indicated generally at - 13 -

10, and each element may have a principal plane lying in a radial plane of the rotor passing through the axis of rotation. Conveniently the crop engaging elements of the rotor may comprise transverse ribs which are deeply serrated, but alternatively the elements may consist of fin-like projections each of which extends outwardly to a greater extent than it extends transverse to the direction of crop flow, with side edges which converge in the outward direction. The hood 15 extends over the rotor 11 and then extends rearwardly at 16 to direct the cut crop rearwardly and downwardly onto the ground. However the crop may in other arrangements be directed to a receptacle or to further crop processing machinery such as the chopping mechanism of a forage harvester. Also, in other embodiments, the rotor 11 may be arranged to pick-up cut crop directly from the rear of a cutting mechanism, for example a drum or disc type cutting mechanism. The crop pick-up and conditioning apparatus includes a second rotor 12 which is mounted to rotate in co-operation with the first rotor 11. In the example shown the second rotor 12 rotates in counter-rotation to the rotor 11 to effect crop conditioning in the overlap region between the two rotors, in addition to the conditioning which takes place due to slip during acceleration of the crop 14 on first contact with rotor 11. In other examples to be described hereinafter, the rotors may rotate in the same sense, or in the opposite sense with different speeds of rotation.

In Figure 2, there is shown an arrangement of two counter-rotating primary and secondary rotors 11 and 12 corresponding generally to those shown in Figure 1 but embodying a feature of the invention. Conveniently, the rotor 11 may be similar to that shown in Figure 3, although any of the other rotors shown in this specification may be used. The rotor 12 may be similar to that shown in Figure 3, but conveniently may have plain, unserrated, outer edges. in Figure 2 the lower rotor 11 is mounted in a fixed position, but the upper rotor 12' is mounted on a spring loaded pivot arm 64 with a corresponding arm (not shown) on the other side of the apparatus. The arms 64 are biassed in a downward direction by a compression spring 65 and may be arranged with the peripheries of the rotors overlapping in normal operation, with the elements on the two rotors intermeshing. Chain drives 66 and 67 drive the rotors in counter- rotation in synchronism. The chain drives to both rotors are from the pivot arm fulcrum so that drive is maintained when the arms pivot. The sense of drive to the upper rotor 12 is reversed by intermeshing gear wheels 68 and 69 on the arm 64, to achieve the required contra-rotation of the rotors 11 and 12. Alternatively at the distal end of the arm 64 the drive to the upper rotor 12 may be produced by the outside of the chain 66, by taking the chain run through additional sprockets (not shown).

In operation the spacing between the two rotors varies with crop load, the upper rotor being able to float upwardly in response to crop flow. It will be appreciated that in some arrangements a similar, pivoted arm, upper rotor may be provided, but may bear against stops so as to only abut the lower rotor perimeter, without intermeshing. In such an arrangement there is no need for synchronisation of the two rotors.

It is to be appreciated that the arrangements shown and discussed with reference to later figures (where the rotors do not overlap, and the rotors are not necessarily driven in synchronism), are applicable in a wide range of other embodiments. For example the rotors may be rotated either in synchronism, when intermeshing, or in non-synchronised counter-rotation, or in co-rotation, when the outer perimeters are merely closely adjacent. Similarly, the arrangement shown in Figure 2 may be operated with the two rotors spaced so that the outer perimeters of the rotors abut or are closely adjacent, but are not overlapping and intermeshing.

There will now be described with reference to Figure 3 an example of a crop engaging element which may be used on a rotor in embodiments of the invention.

In Figure 3, a rotor 11 has transverse rib-like elements 23 mounted on a supporting core 8, and each rib 23 may be mounted by a plurality of bolts 40 passing through resilient washers 41. The ribs 23 are deeply serrated to provide a plurality of outwardly directed teeth, each tooth having side edges converging towards each other in the outward direction. (Where a rotor such as "is shown in Figure 3 is intended to intermesh with another rotor as shown in Figure 5, it is important that the ribs 23 are re-arranged so that the teeth of the ribs are in register with each other around the circumference of the rotor).

Suitable materials for the crop engaging elements 10 of the rotors, are synthetic plastics material such as polyurethene, nylon and polypropylene, although rigid, non-resilient, materials such as sheet-metal may be used, provided that appropriate resilient mounting means are also provided. Figure 4 shows diagrammatically how two rotors as shown in Figure 1, 2 or 3 can be made to inter-mesh to achieve conditioning of crop.

Figures 5(a) to 5(d) show diagrammatically a summary of the modes of operation which are possible with counter-rotating twin-rotor crop conditioning systems. In each case two rotors 11 and 12 carry crop engaging elements 10. Conveniently the crop engaging elements may be ribs, or fins, or any other of the crop engaging elements which are described herein. For convenience, the case will be described where the crop engaging elements 10 are ribs. In Figure 5(a) the ribs 10 are shown to be perfectly aligned along the axis common to both rotors 11 and 12. The effect on crop trapped between two opposing ribs is that it is compressed and consequently bruised. In Figure 5(b) the two rotors are slightly out of phase. If the ribs are parallel sided, then the crop will be sharply bent, stretched and scratched. In Figure 5(c) the ribs on one rotor inter-mesh centrally between pairs of ribs of the other. Treatment will be more gentle than that described in Figures 5(a) and 5(b) above. The essential feature of Figure 5(d) is that the ribs or other conditioning elements are reclined at their tips in the direction of rotation, and this may have advantages, particularly vis a vis Figure 5(a) in respect of the severity of crop treatment and the possibility of foreign objects becoming trapped between opposing ribs; entrapped crop or objects are more likely to cause angular deflection of the ribs or elements.

There will now be described with reference to Figures 6(a) to 8(b), a number of embodiments of the invention which incorporate features generally set out hereinbefore, but in some cases including additions or modifications. The figures to be described are concerned in general with forms of the apparatus in which an upper, feed, rotor presses crop onto a lower, pick-up or conveying rotor, so as to increase the effectiveness Qf the primary, lower rotor', for example achieving conditioning predominantly by a spiking action. In general, in these embodiments, it is not necessary for the rotors to overlap at their outer perimeters, although this may be arranged in some circumstances.

In general, components of the apparatus which correspond to components in previous embodiments, are indicated by like reference numerals.

In Figure 6(a) there is shown a diagramatic side view of apparatus for picking up and conditioning cut crop indicated generally at 14. A first pick-up rotor 11 has outwardly directed serrated ribs 10 (as shown in Figure 6 (b)), and is driven in rotation in the so-called overshot mode so as to pick up cut crop and carry the crop upwardly and rearwardly over the rotor 11. A hood or housing 16 cooperates with the front of the rotor 11, and has an adjustable guide arrangement at the front. second rotor 12 is positioned with its axis of rotation at a higher level than the axis of rotation of the first rotor 11, and at a position forwardly of the rotor 11.

The upper rotor 12 has a number of transverse rib like portions 61 having approximately triangular cross sections. In one preferred form, the upper rotor 12 is rotated in counter rotation with the lower rotor 11 with the outer perimeters of the rotors abutting or closely adjacent. Behind the lower rotor 11 is an optional ground roller 62. Thus Figures 6(a) and (b) show an axially ribbed rotor mounted above a serrated blade, conditioning rotor. The upper rotor 12 is shaped so as to keep the crop flow within the path of the conditioning rotor 11 and to increase crop/rotor interaction. Since the rotors do not overlap, they may be run at different peripheral speeds, or in counter- or co-rotation. When running the rotors in counter rotation, crop conditioning may be enhanced by running the ribbed rotor 12 at a greater or lesser peripheral speed than that of the conditioning rotor 11. In some arrangements, the rotors may be rotated synchronously. and the rotors may be intermeshed with overlapping to improve the interaction.

In the example shown in Figure 6(a) the leading and trailing planes of the ribs on the upper rotor 12 are so angled that crop is directed into the operating sphere of the lower rotor 11 whether the peripheral speed of the upper rotor is faster or slower. In other arrangements, the ribs of the upper rotor need not be symmetrical in cross section. Depending upon relative rotor speed, one or other of the rib planes may be inclined differently, to achieve a particular type of interaction.

The purpose of the optional ground-engaging roller 62 is to enhance operational safety, particularly on undulating land. The roller 62 is to be positioned in a fixed but adjustable relationship to the bottom-dead-centre of the primary conditioning rotor 11. However it should be noted that instead of picking up cut crop from the ground, the primary rotor 11 can also be fitted to receive cut crop directly from a mower beneath or in front. In that case the ground engaging roller 62 is not normally required.

Figures 7(a) and (b) show a modification in which the upper rotor 12 is serrated both in an axial and a circumferential direction, to produce projections each in the shape of a tetrahedron. This arrangement is shown in Figure 7(a) with the outer perimeters of the rotors overlapping, and the two rotors may be intermeshed under any combination of rotor speed and rotor direction, to enhance further the conditioning effects. The secondary rotor 12 in Figures 7(a) and (b) could be of simpler and cheaper construction than shown. For example, the upper rotor 12 could have serrated ribs arranged to interact with the peripherally aligned serrations of the primary rotor 11.

Figure 8(a) shows a similar arrangement to the preceding figures, but in which the upper rotor 12 has axial ribs which in cross section are or have a portion inclined to a radial plane passing through the axis of rotation of the rotor, and the rib. In the preferred arrangement shown, a base portion of each rib 23 is in a substantially radial plane passing through the rib, but an outer portion of each rib is inclined to a radial plane passing through the axis of rotation and through the rib.

In the preferred arrangement, showed in Figure 8 (a), the upper rotor 12 has a greater peripheral speed than, or is synchronous with, the conditioning rotor 11, and is rotated in counter rotation therewith. The ribs 23 act to press the crop onto the conditioning elements 10 on the rotor 11; these may have sharp tips to produce conditioning by a spiking action.

Although in the preceding Figures 6(a) onwards, the preferred directions of rotation for the upper rotor 12 are shown in the figures, or otherwise indicated, it is possible in each case to rotate the upper rotor in co- rotation with the lower rotor. In Figure 8(b) there is shown a modification of the embodiment of the preceding figure, where co-rotation is arranged. The ribs or blades 23 of the upper rotor are then aligned differently, as shown, and this arrangement is suitable where the upper rotor 12 has a peripheral speed significantly less than, or rotates in the same direction as, the conditioning rotor 11. It is to be appreciated that in different arrangements, for co- rotation or counter-rotation, the blades or ribs 23 may be aligned over a range of angles or curvature.

Where a co-rotating system is used, optional bars or ribs may be fitted transversely to the upper rotor housing 16 to generate an additional conditioning effect by increasing the resistance to crop flow and directing the material back into the operating sphere of the upper rotor.

In two preferred forms, the arrangement of Figure 8(a) is operated with the upper rotor rotating at a faster rate than the lower rotor, so that the ribs 23 are angled correctly to push the crop onto the sharp tips of the conditioning elements 10 on the lower rotor 11. In Figure 8(b), when the rotors are rotated in counter rotation, the upper rotor should be rotated at a slower speed than the lower rotor, so that again the ribs 23 are inclined at the correct angle to press crop onto the sharp tips of the ribs 23.

As mentioned previously, the primary and secondary rotors 11 and 12 may be of differing diameter and have differing numbers and spacings o'f elements or rows of crop engaging elements.

Claims

CLAIMS 1. Apparatus for treating crop comprising two co-operating rotors mounted for rotation about parallel axes for passage of crop between the rotors, at least one rotor comprising a crop treating rotor having a plurality of stiff, outwardly directed crop engaging elements having pointed tips on the outer ends thereof for treating crop, each tip being formed on an outwardly directed projection having side edges converging towards each other in the outward direction, the other rotor also having a plurality of stiff, outwardly directed crop engaging elements, it being arranged that on at least one rotor each crop engaging element has a principal plane transverse to the general direction of crop flow, the arrangement being such that in operation the rotors rotate so that the crop engaging elements of the said other rotor press crop against crop engaging elements on the said one rotor which has the pointed tips for treating the crop.

2. Apparatus according to claim 1 adapted for conditioning grass or other fibrous fodder crop, including a mobile frame for movement across the ground, said one rotor which has the pointed elements being mounted on said frame for rotation about an axis substantially parallel to the ground for picking up and conveying crop, each crop engaging element on said one rotor having a principal plane transverse to the general direction of crop flow, the axis of rotation of the said other rotor being positioned at a higher level than the axis of rotation of the said one rotor, there being provided drive means for driving the said one rotor in rotation in a sense such that the rotor picks up crop and carries crop upwardly and rearwardly over the rotor, and a housing co-operating with the front of the said one rotor and forming with the rotor a crop flow passage between the rotor and the housing.

3. Apparatus according to claim 1 or 2 in which the said other rotor is mounted on support arms pivottable about an axis parallel to and spaced from the axes of the rotors, to allow the spacing between the two rotors to vary with crop load.

4. Apparatus according to claim 3 including biassing means for biassing the said support arms in a direction such as to urge the two rotors towards each other.

5. Apparatus according to claim 3 or 4 in which the said other rotor is driven in rotation by rotation of a shaft having an axis lying substantially at the pivot axis of the support arms.

6. Apparatus according to any preceding claim in which on the said other rotor each crop engaging element comprises an inner portion having a principal plane transverse to the direction of movement of the element, and an outer portion having a further principal plane transverse to the direction of movement of the element, said further principal plane being inclined to the first principal plane and being inclined to a radial plane passing through the axis and through the element, the two rotors being rotated with a differential peripheral velocity, and with the inclined portion of each element trailing relative to the differential peripheral velocity so that the inclined portion of each element tends to push crop onto the pointed tips of the crop engaging elements on the said one rotor.

7. Apparatus according to any of claims 1 to 5 in which the said other rotor has around its periphery a number of transverse rib-like portions parallel to its axis, each rib-like portion having an approximately triangular cross-section, the leading and trailing planes of the ribs being so angled that crop is directed into the operating sphere of the said one rotor.

8. Apparatus according to any of claims 1 or 5 in which the said other rotor has around its periphery a number of transverse rib-like portions parallel to its axis, each rib-like portion being serrated both in an axial and a circumferential direction, to produce projections each approximately in the shape of a tetrahedron.

9. Apparatus according to any preceeding claim including drive means for driving the rotors in counter-rotation with different peripheral speeds so as to treat crop by differential peripheral movement between the rotors, or including drive means for driving the rotors in co-rotation so as to treat the crop by differential peripheral movement of the rotors. io. Apparatus for conditioning grass or other fibrous fodder crop, comprising a mobile frame for movement across the ground, and two co-operating rotors mounted for rotation about parallel axes for passage of crop between the rotors for conditioning the crop, one rotor being mounted on said frame for rotation about an axis substantially parallel to the ground for picking up crop and carrying the crop upwardly and rearwardly over the rotor, each crop engaging element on said one rotor having a principal plane transverse to the general direction of crop flow and having pointed tips on the outer ends thereof for treating crop, the other rotor also having a plurality of stiff, outwardly directed crop engaging elements, and the axis of rotation of the said other rotor being positioned at a higher level than the axis of rotation of the said one rotor, in which the said other rotor is mounted on support means pivotable about an axis parallel to and spaced from the axes of the said rotors to allow the spacing between the two rotors to vary with crop load, the said other rotor being driven in rotation by drive means rotating about an axis lying substantially at the pivot axis of the support means.