GB2172182A - Crop engaging elements, yieldable under an excess load - Google Patents

Abstract

A crop engaging rotor for conveying and/or conditioning or otherwise treating crop comprises support members 12 and a plurality of outwardly extending crop engaging elements 11. Each crop engaging element 11 is made of resilient synthetic plastics material and forms two outwardly extending arms 21 and 22 generally in a V-shape. The element 11 is secured to a flange 14 or 14A of a transverse mounting bar 12 which forms part of the rotor. The arms 21 and 22 are yieldable to move rearwardly under excess load conditions by a rocking movement about the bolt 23 of the element as a whole by means of resilient member 24A or by twisting or lateral bending of the arms. The element 11 is prevented from rotating about the bolt 23 by abutment of the leading edge surfaces of the arms 21 and 22 against the inner surface of the upstanding portion 14A of the member 12, and by abutment of the base of the element 11 against the base flange 14 of the member 12. The arms 21 and 22 are linked by a base portion 80 parallel to the upstanding flange 14A (Fig. 1), or by a base portion 84 perpendicular to the upstanding flange 14A in combination with a strengthening web 80 (Fig. 4, not shown). <IMAGE>

Description

SPECIFICATION Crop engaging device The present invention relates to-a crop engaging device. The invention is concerned in one aspect with apparatus for conditioning of crops especially, but not exclusively, grasses, and is concerned in other applicatioris with pick-up and conveying rotors for collecting cut crop and conveying the same.

Considering firstly the aspect of the present invention concerned with conditioning of crops, it is well known -to treat forage crops such as grasses and legumes in order to assist loss of moisture in the field after cutting prior to storage to provide animal fodder. The -speed at which surface and sap moisture evaporate from the cut crop during field exposure depends inter alia on the physical condition of the crop. The principal barrier to moisture loss is the cuticle and the layer of epicuticular wax-on the crop surface, and it is now common practice in agriculture to mechanically treat the crop in order to damage this barrier.

Such mechanical treatment, which may take the form of crushing, lacerating, bruising, splitting, spiking, bending or scuffing the stems and leaves of the crop, is known as ''conditioning". In our UK Patent No.

1,322,165 there- are described conditioning elements formed in the shape of a V or V and yieldably mounted on a rotor, the elements being yieldable by virtue of being pivotted at their main point of securement to the rotor.

This allows the conditioning elements to yield in operation in contact with stones or other foreign objects found in the crop. However a disadvantage of such free pivotting is that the elements can also yield in response to unusually high crop loads, unless they are heavy and the rotor is rotated at a relatively high speed in order to maintain the conditioning elements in an outwardly extending position by virtue of centrifugal force.

In our later UK Patent and applications Nos.

1493574, 2107963A and 2132462A, there are disclosed conditioning elements which also take the form of a V. The conditioning elements are formed of resilient material and/or are resiliently mounted, so as to be maintained in an outward operative position without the need to rely on centrifugal force, but are yieldable e.g. by pivotting against resilient locating means. Such conditioning means offer many advantages and have found wide acceptance in practice, but are relatively complicated in construction, and expensive to manufacture. Another Patent in the name of the present applicant is GB 204171 B, which shows conditioning elements in the form of brush tufts.

In a US Patent Specification No. 4,021,995 (Hill) there are disclosed conditioning elements which take the form of a U with inciined sides, and which are resiliently mounted.

Again the structure is complicated, and each conditioning element is secured by two bolts passing through the entire rotor assembly.

In one aspect the present invention is concerned with providing crop conditioning elements which can be maintained in an outwardly directed operative position without the need to rely upon centrifugal force, which are yieldable when in contact with foreign material in the crop, and which are relatively simple and inexpensive to manufacture and maintain.

Considering now another aspect of the invention concerned with pick-up rotors for collecting cut crop, and conveying rotors for crop in general, there have been known previously a number of forms of crop conveying rotors having outwardly directed crop conveying elements, commonly known as tines. One form of such crop conveying element is disclosed in German Patent No. 690268 (Lythal) which discloses U-shaped tines for picking up and conveying crop, in which the arms of the U are secured to a rotor by a bolt passing through a bracket which grips the junction of the arms of the U. The bolt also passes through a spring which presses the tine to its normal operating position. In UK Patent No.

198256 (Martin) a similar arrangement is shown in which a U-shaped tine is secured to a rotor by a bolt and spring arrangement. In each case the tine can pivot away from its operating position by compression of the spring. In the German Patent 690268 (Lythal) the retaining bolt is generally at right angles to the main plane of the U-shaped tine. In the the UK Patent 198256 (Martin) the retaining bolt is generally in the same plane as the Ushaped tine. In both arrangements, the coupling is complicated, expensive to produce, and is unsuitable for modern crop conveying and conditioning applications.

According to the present invention in one broad form there is provided a crop engaging device for conveying and/or treating crop, the device comprising support means and, secured to the support means, a plurality of outwardly extending crop engaging elements for engaging crop flowing past, or conveyed by, the device, each crop engaging element comprising a single member shaped to form two outwardly extending arms which diverge from each other in the outward direction and in a plane generally transverse to the direction of intended movement of the arms with or relative to the crop, the said member also being shaped to have a base portion linkingsthe two arms and extending in a plane transverse to the said direction of intended movement of the arms, each element being secured to the support means by an axial fastening means having a principal axis along which it extends through the element and into the support means, the support means and each crop engaging ele ment having cooperating abutment regions such to prevent or inhibit rotation of the crop engaging element away from its required operating position under normal load conditions, but such as to allow the crop engaging element to be yielding under an abnormal load by movement of the crop engaging portion rearwardly in relation to the intended movement of the element with or relative to the crop, the mounting of each element being such that the retaining force in the axial fastening means retaining the element during yielding is predominantly tension along the said axis of the fastening means.

According to the present invention in one aspect there is provided a crop engaging device for conveying and/or treating crop, the device comprising support means and, secured to the support means, a plurality of outwardly extending crop engaging elements for engaging crop flowing past, or conveyed by, the device, each crop engaging element comprising a single member formed of resilient material and shaped to form two outwardly extending arms which diverge from each other in the outward direction and in a plane generally transverse to the direction of intended movement of the arms with or relative to the crop, the said member also being shaped to form a base portion linking the two arms and extending in a plane transverse to the said direction of intended movement of the arms, the said support means comprising a base portion and an upstanding portion fixed relative to the base portion, said upstanding portion extending outwardly from the base portion of the support means towards the region of crop flow, each element base portion being secured to the upstanding portion of the support means by an axial fastening means having a principal axis along which it extends through the upstanding portion of the support means and through the base portion of the element to secure the element thereto, the support means and each crop engaging element having cooperating abutment regions such as to prevent or inhibit rotation of the crop engaging element away from its required operating position under normal load conditions, but such as to allow the crop engaging element to be yielding under an abnormal load by movement of the crop engaging portion rearwardly in relation to the intended movement of the element with or relative to the crop, the mounting of each element being such that the retaining force in the axial fastening means retaining the element during yielding, is predominantly tension along the said axis of the fastening means, both the upstanding portion of the support means and the base portion of the support means being utilised to provide abutment regions of the support means for locating the elements.

Preferably the said base portion of the crop engaging element extends in a plane substantially perpendicular to the direction of the intended movement of the arms with or relative to the crop.

Also preferably the said base portion of the element extends substantially parallel to and abuts against the upstanding portion of the support means, the arrangement being such that during the said yielding movement the crop engaging element tips away from the said upstanding portion of the support means with the said abutting regions'moving apart.

In most preferred forms of the invention the axial fastening means includes resilient biasing means urging the base portion of the crop engaging element against the support means but allowing movement of the element~away from the support means along the direction of the axis of the fastening means to- provide at least in part the said yielding movement.

Conveniently the upstanding portion of the support means is substantially at right angles to the, base portion of the support means.

Also conveniently the said principal axis of the axial fastening means extends perpendicular to the upstanding portion of the support means.

The invention finds particular application where the support means forms a rotor. Conveniently the said principal axis of the axial fastening means extends along a substantially tangential direction relative to the axis of rotation of the rotor.

It is particularly preferred that the said support flange of the support member is arranged to shield the base portion of the crop engaging element by extending in front of the base portion of the crop engaging element relative to the said intended movement of the crop engaging element with or relative to the crop.

Conveniently the element abuts directly against the trailing face of the support flange and is urged against the support flange by a resilient biasing means.

The said-yielding movement may be produced by any one or a combination of different effects for example by pivoting, rocking and/or twisting, but it is preferred that the said yielding movement is produced at least in part by a rocking movement of the element as a whole, e.g. about an axis perpendicular to the axis of the axial fastening means. In other arrangements, or in combination with this arrangement, the said yielding movement may be produced at least in part by bending and/or twisting of the crop engaging portion of the element.

In some arrangements there may be provided a rigid support component positioned against the transverse base portion of the crop engaging element for modifying the yielding charateristics of the element, the axial fastening means passing through the said rigid support component. The rigid support component may comprise a rigid, planar support washer or plate, or a length of channel section.

Conveniently each crop engaging element is secured by a single axial fastening means which may comprise a bolt secured to the support means by a nut and washer arrangement. The axial fastening means may conveniently be provided with resilient biasing means urging the base portion of the crop engaging element against the support member but allowing movement of the element away from the support member along the direction of the axis of the fastening means to provide at least in part the said yielding movement. Thus where for example the fastening means comprises a bolt there may be provided a component of elastomeric material such as rubber, through which the bolt passes, holding the element base portion against the support member but allowing movement of the element as a whole in a rocking movement deforming the block of elastomeric material.

It is an advantage that the said support means can be arranged both to support the crop engaging elements, and also to afford protection against damage by stones and like objects in the crop, the shielding region of the support member being ahead of the element relative to movement between the crop and the element in operation, for the purpose of shielding the base of the element against damage by stones and like foreign matter in the crop.

The invention finds particular but not exclusive application where the said elements are made of resilient material, for example synthetic plastics material, conveniently nylon, or polypropylene.

The crop engaging device finds application either when in the form of a vertical or horizontal rotor for conveying and/or conditioning crop by rotation of the rotor, or when in the form of a stationary device positioned adjacent a crop flow so as to condition crop being propelled past the device by other means.

Where the crop engaging device is in the form of a rotor, the elements may be returned after yielding to their undeflected dispositions by a combination of the yielding arrangements described, aided also by centrifugal force, and where the crop engaging device comprises a stationary device, the elements may be returned to their undeflected dispositions after yielding by means only of the biasing arrangements described.

Crop engaging devices embodying the invention may be provided which are applicable to conditioning, tedding, turning, scoring, fibrillating, threshing or otherwise treating crops.

The present invention provides, at least in preferred embodiments thereof, a number of advantages over previously known crop engaging elements for conveying and/or conditioning crop. Although the crop engaging elements of the invention may be produced from other materials, it is particularly preferred that the elements are made of synthetic plastics material, and the invention affords a particularly simple and inexpensive construction. Such elements of plastics material have the attractions of lightness, cheapness, low risk ofdamaging following machinery if lost, and have a much less complex method of mounting than has been used previously.

In preferred embodiments the invention provides a divergent, two-arm element located and prevented from turning by abutment regions and secured by a single boit and bracket arrangement so that fore and aft movement of the element is possible and the arms themselves can twist or deflect laterally.

There is also provided in accordance with a further aspect of the present invention a crop engaging device for conveying and/or treating crop, the device comprising support means and, secured to the support means, a plurality of outwardly extending crop engaging elements for engaging crop flowing past, or conveyed by, the device, each crop engaging element comprising a single member formed of resilient material and shaped to form two outwardly extending arms which diverge from each other in the outward direction and in a plane generally transverse to the direction of intended movement of the arms with or relative to the crop, the said member also being shaped to form a base portion linking the two arms and a strengthening web extending in a plane substantially perpendicular to the base portion and transverse to the said direction of intended movement of the arms, each element base portion being secured to the support means by an axial fastening means having a principal axis along which it extends through the base portion of the element and into the support means, said principal axis being aligned in a direction extending outwardly from the support means towards the region of crop flow, the support means and each crop engaging element having cooperating abutment regions such as to. prevent or inhibit rotation of the crop engaging element away from its required operating position under normal load conditions, but such as to allow the crop engaging element to be yielding under an abnormal load by movement of the crop engaging portion rearwardly in relation to the intended movement of the element with or relative to the crop, the mounting of each element being such that the retaining force in the axial fastening means retaining the element during yielding is predominantly tension along the said axis of the fastening means.

Various preferred features which have been set out hereinbefore may also be applied (where appropriate)- in connection with this further aspect of the invention, and also in connection with any combination of features of the two aspects.

Embodiments of.the invention will now be described by way of examples with reference to the accompanying drawings in which: Figure 1 is a rear view of a crop engaging element embodying the invention; Figure 1(a) is a side view taken along direction A in Figure 1; Figure 2 is a rear view of an alternative crop engaging element embodying the invention; Figure 2(a) is a side view taken along the direction A in Figure 2; Figure 3 is a perspective view of a crop conditioning and/or conveying rotor having conditioning elements as shown in Figures 2 and 2(a); Figure 4 is a rear view of a further alternative crop engaging element embodying the invention; Figure 4(a) is a side view taken along the direction A in Figure 4; Figure 5 is a perspective view of a crop conditioning and/or conveying rotor having conditioning elements shown in Figures 4 and 4(a);; Figures 6 and 6(a) show in diagrammatic side view and detail perspective respectively, a crop cutting and conditioning apparatus incorporating elements shown in the preceding Figures.

Referring firstly to Figures 1 and 1(a) there is shown a crop engaging element for conveying and/or conditioning crop, indicated generally by the reference 11, and forming one of a plurality of such elements mounted on a rotor having a plurality of transverse support members parallel to the axis of the rotor, of which one is indicated generally by the reference 12.

The support member 12 comprises a right angle section support member having a first, trailing base flange 14 and a second, upstanding, shielding flange 14A, also referred to as a supporting flange.

The crop engaging element 11 comprises a moulded, plastics member having outwardly diverging arms 21 and 22 in the form of flat, strip-like arms of rectangular cross-section.

The arms 21 and 22 are linked by a transverse base portion 80. For example the flat arms 21 and 22 may be of 9 mm thickness, and 40 mm in depth, and each arm being approximately 10 cm in length.

As shown in Figure 1 and 1a, the element 11 is secured to the shielding flange 14A of the support member 12 by a bolt 23 passing through an opening 13 in the flange 14A and through an opening 81 in the element 11. The bolt 23 extends along a principal axis 23A of the bolt. The opening 13 needs to be slightly larger than the diameter of the bolt 23, to allow for the deflection of the bolt. The bolt 23 is secured by a nut 25.

The arms 21 and 22 of the element 11 diverge from each other in the outward direction away from the support member 12.

On the other surface of the transverse base portion 80 is positioned a rubber cone 24A through which the bolt 23 passes, the bolt being provided with a washer 57. The bolt is normally slightly pretensioned against the rub- ber block 24A to hold the element 11 against the flange 14A in the required operating positipn.

In Figure 1(a) the sense of rotation of the crop engaging rotor can be in either direction, but preferably will be such as to move the support member 12 to the left, so that the crop engaging element 11 conveys crop towards the left. Should the element 11 meet with a stone, piece of tramp metal, or like foreign object in the crop, the element 11 is not free to rotate to any great extent about the axis 23A of the fastening bolt 23 but is free to pivot rearwardly by a rocking movement by means of compression of the cone 24A. During such pivoting, the bolt 23 will tilt relative to the support member 12. The rocking movement of the element may be the sole yielding movement of the crop engaging element 11, or there may in addition be some movement of the element 11 due to yielding of the element by virtue of the resilience of the material from which it is made.It is also to be noted that the arms 21 and 22 may be deflected in the plane of Figure 1, that is to say from side to side, in addition to the rearward yielding of the element. Furthermore, the yielding of the element may also be produced by excess load conditions due to a particularly dense portion of crop, in addition to yielding to avoid foreign objects.

Predominantly, the yielding movement of the element 11 will be about an axis transverse to the axis 23A of the bolt 23. The rocking movement of the element 11 will not of course take place about a clearly defined axis, but where the whole element tips rearwardly the movement may be regarded approximately as a pivoting movement about an axis parallel to the member 12. It is to be appreciated that in practice, especially where the element 11 is formed of resilient plastics material, the yielding movement will not be a simple pivoting movement but will include a twisting and deforming of the arms 21 and 22.

It is also to be noted that the rubber block 24A may be replaced by plastics resilient material or by a steel spring.

In Figures 1 and 1(a) the two arms 21 and 22 of the element 11 are joined together immediately behind their leading edges by the base portion or web 80, which has the central hole 81 which is appropriately oversized in relation to the diameter of the mounting bolt 23. At the base the arms of the element are relieved upwardly from front to rear at 82, so that, on rearward deflection of the tips of the element 11, binding at the base is prevented.

As shown, the optional resilient, cone-shaped spring 24A is provided forward of the nut 25 and washer 57-of the mounting bolt 23. The design of the element has the advantage that the relatively thin plastic joining web 80 can bend in response to a sudden tip load experienced by one or both of the arms'21 or 22.

This safety feature is in addition to the arms 21 and 22 themselves being able to twist and/or bend laterally under appropriate load conditions. The additional feature makes it possible to achieve a high degree of safety even if the element 11 is fastened directly to the upstanding flange 14A ofthe mounting bar 12 without the resilient cone 24A. Should it be desired to limit or prevent the plastics web 80 from bending, then the trailing face may be covered by a metal plate- of appropriate size, or a short section of channel may be used which provides a good fit between the two arms 21 and 22.

Figures 2 and 2(a) show a modified element 11 also designed for tangential attachment to the upstanding flange 14A of an angle-section mounting bar 12. The relief at the base of the arms 21 and 22 is carried partly into the joining web 80, which is thicker than in Figures 1 and 1(a). In the-example of Figures 2 and 2(a) the optional resilient, cone-shaped spring 24A is- shown fitted in front of the upstanding flange 14A of the mounting bar 12.

In Figure 3 there is shown a perspective view of a rotor 40 embodying the invention and having an array of conditioning elements 11 as shown in Figures 2 and 2(a) the rotor 40 being an open squirrel-cage type of rotor.

In Figure 3 the- rotor 40 is shown mounted on a frame 60 with a rear housing 61 lifted up from its normal position to show the rotor 40.

Figure 3 is a rear view of the machine. The rotor 40 rotates in such a manner as to lift crop upwardly and rearwardly over the rotor 40, the crop being picked up from the rear of twin cutting rotors, or from multi-disc or other cutters, or from the ground.

With all the conditioner embodiments disclosed, suitable speeds at the tips of the conditioning elements range from 15 to 30 m/s, preferably 20 to 25 m/s. By way of example, the conditioning elements may be mounted to form a rotor of diameter in the range 400 to 600 mm.

In Figures 4 and 4(a) there is shown a modified element 11 designed for radial attachment to the angie-iron mounting bar 12. The optional resilient, cone-shaped spring 24A is located beneath the flange 14 of the mounting bar 12 which supports the base of the element 11. Use has been made of the plastic moulding process to form an optional hexagonal recess 83 in the lower base 84 of the element 11, to accommodate the securing bolt head 23 and to prevent it from turning when tightening or releasing the nut 25. The width of the base portion 84 of the plastics element 11 is so chosen that heavy loads imposed from one side would cause the element 11 to lift on that side.Depending on the operating conditions for which the crop engaging rotor is-intended, the tilting capability can be matched by appropriately selecting the width of the base 84 (overall or by rounding the corners) and by adjusting; the radial tension.

The same possibilities apply to the control of resistence to rearward tilting.

In addition to the main base portion 84 linking the arms 21 and 22, there is provided a strengthening web 80 extending parallel to the flange 14A. If required this web 80 may extend higher into the region between the arms 21 and 22.

Figure 5 shows in a diagrammatic perspective view a rotor incorporating the elements 11 shown in Figures 4 and 4(a), but having a higher web 80.

It should be- noted that many details of the design of the attachment region of a self-supporting plastic element 1-1 may be varied whilst maintaining the principles of the disclosures. For example at the extreme the base region 84 may be a block with or without a hollow, plastics-saving space beneath the seat 83 for the head of the bolt 23.

The embodiments described are suitable where the element is produced by moulding from synthetic plastics material, to produce a relatively rigid, but resilient element, where the inclined arms are self supporting, in that they do not require a metal bracket, or other means, to hold them at the required angle of divergence. The elements are designed to give the required strength, while keeping to a minimum the use of plastics material in the mounting region.

Figure 6 shows diagrammatically in side view a crop conditioning and conveying rotor indicated generally at 40, (which may incorporate any of the elements 11 described hereinbefore) fitted to the rear of a multi-disc mower indicated generally at 41. A pivotable restrictor plate 42 is provided at the front of the rotor 40 on the underside of the hood of the apparatus, and one example 42A. of such a plate is shown in more detail in Figure 6a to have sharp serrations at the upper edge. The restrictor plate 42 forces the crop into the conditioning rotor 40 and also conditions the upper part of the crop layer being drawn into the rotor housing by a scraping action of the teeth. The set clearance between rotor and restrictor plate and the set angle of the restrictor place determine the severity of conditioning; the closer the setting and the more acute the angle the greater becomes the conditioning effect. In an alternative arrangement, the restrictor plate 42 may have mounted thereon an array of conditioning elements 11 of the form described with reference to any of the preceding Figures.

Claims (25)

1. A crop engaging device for conveying and/or treating crop, the device comprising support means and, secured to the support means, a plurality-of outwardly extending crop engaging elements for engaging crop flowing past, or conveyed by, the device, each crop engaging element comprising a single member shaped to. form two outwardly extending arms which diverge from each other in the outward direction and in a plane generally transverse to the direction of intended movement of the arms with or relative to the crop, the said member also being shaped to have a base portion linking the two arms and extending in a plane transverse to the said direction of intended movement of the arms, each element being secured to the support means by an axial fastening means having a principal axis along which it extends through the element and into the support means, the support means and each crop engaging element having cooperating abutment regions such to prevent or inhibit rotation of the crop engaging element away from its required operating position under normal load conditions, but such as to allow the crop engaging element to be yielding under an abnormal load by movement of the crop engaging portion rearwardly in relation to the intended movement of the element with or relative to the crop, the mounting of each element being such that the retaining force in the axial fastening means retaining the element during yielding is predominantly tension along the said axis of the fastening means.

2. A crop engaging device for conveying and/or treating crop, the device comprising support means and, secured to the support means, a plurality of outwardly extending crop engaging elements for engaging crop flowing past, or conveyed by, the device, each crop engaging element comprising a single member formed of resilient material and shaped to form two outwardly extending arms which diverge from each other in the outward direction and in a plane generally transverse to the direction of intended movement of the arms with or relative to the crop, the said member also being shaped to form a base portion linking the two arms and extending in a plane transverse to the said direction of intended movement of the arms, the said support means comprising a base portion and an upstanding portion fixed relative to the base portion, said upstanding portion extending outwardly from the base portion of the support means towards the region of crop flow, each element base portion being secured to the upstanding portion of the support means by an axial fastening means having a principal axis along which it extends through the upstanding portion of the support means and through the base portion of the element to secure the element thereto, the support means and each crop engaging element having cooperating abutment regions such as to prevent or inhibit rotation of the crop engaging element away from its required operating position under normal load conditions, but such as to allow the crop engaging element to be yielding under an abnormal load by movement of the crop engaging portion r arwardly in relation to the intended move ent of the element with or relative to the crop, the mounting of each element being such that the retaining force in the axial fastening means retaining the element during yielding is predominantly tension along the said axis of the fastening means, both the upstanding portion of the support means and the base portion of the support means being utilised to provide abutment regions of the support means for locating the elements.

3. A device according to claim 2 in which the said base portion of the crop engaging element extends in a plane substantially perpendicular to the direction of the intended movement of the arms with or relative to the crop.

4. A device according to claim 2 or 3 in which the said base portion of the element extends substantially parallel to and abuts against the upstanding portion of the support means, the arrangement being such that during the said yielding movement the crop engaging element tips away from the said upstanding portion of the support means with the said abutting regions moving apart.

5. A device according to any of claims 2 to 4 in which the axial fastening means includes resilient biasing means urging the base portion of the crop engaging element against the support means but allowing movement of the element away from the support means along the direction of the axis of the fastening means to provide at least in part the said yielding movement.

6. A device according to any of claims 2 to 5 in which the said crop engaging elements, are made of synthetic plastics material.

7. A device according to claim 6 in which the said synthetic plastics material comprises nylon, polypropylene or polyurethene.

8. A device according to any of claims 2 to 7 in which the upstanding portion of the support means is substantially at right angles to the base portion of the support means.

9. A device according to any of claims 2 to 8 in which the support means forms a rotor.

10. A device according to claim 9 in which the said principal axis of the axial fastening means extends along a substantially tangential direction relative to the axis of rotation of the rotor.

11. A device according to any of claims 2 to 10 in which the said principal axis of the axial fastening means extends perpendicular to the upstanding portion of the support means.

12. Advise according to any of claims 2 to 11 including a rigid support component positioned against the transverse base portion of the crop engaging element for modifying the yielding characteristics of the element, the ax ial fastening means passing through the said rigid support component.

13. A crop engaging device according to any preceding claim, adapted for conditioning grass or other fibrous, fodder crop.

14. A crop engaging device for conveying and/or treating crop, the device comprising support means and, secured to the support means, a plurality of outwardly extending crop engaging elements for engaging crop flowing past, or conveyed by, the device, each crop engaging element comprising a single member formed of resilient material and shaped to form two outwardly extending arms which diverge from each other in the outward direction and in a plane generally transverse to the direction of intended movement of the arms with or relative to the crop, the said member also being shaped to form a base portion linking the two arms and a strengthening web extending in a plane substantially perpendicular to the base portion and transverse to the said direction of intended movement of the arms, each element base portion being secured to the support means by an axial fastening means having a principal axis along which it extends through the base portion of the element and into the support means, said principal axis being aligned in a direction extending outwardly from the support means towards the region of crop flow, the support means and each crop engaging element having cooperating abutment regions such as to prevent or inhibit rotation of the crop engaging element away from its required operating position under normal load conditions, but such as to allow the crop engaging element to be yielding under an abnormal load by movement of the crop engaging portion rearwardly in relation to the intended movement of the element with or relative to the crop, the mounting of each element being such that the retaining force in the axial fastening means retaining the element during yielding is predominantly tension along the said axis of the fastening means.

15. A device according to claim 14 in which the support means comprises a base portion and an upstanding shielding portion fixed relative to the base portion, said upstanding shielding portion extending outwardly from the base portion of the support means towards the region of crop flow and being arranged in front of the base portion of the crop engaging element in relation to the said intended movement of the crop engaging element with or relative to the crop, each element base portion being secured to the base portion of the support means by the axial fastening means which extends through the base portion of the element and into the base portion of the support means to secure the element thereto, each crop engaging element being prevented or inhibited from rotation away from its required operating position under normal load conditions by the effect of co-operating abutment regions of a leading surface of the element and the rear surface of the upstanding 'shielding portion, and by the effect of co-operating abutment regions of the base portion of the element and the base portion of the support means.

16. A device according to claim 14 or 15 in which the axial fastening means includes resilient biasing means urging the base portion of the crop engaging element against the support means but allowing movement of the element away from the support means along the direction of the axis of the fastening means to provide at least in part the said yielding movement.

17. A device according to claim 14, 15 or 16 in which the crop engaging elements are made of synthetic plastics material.

18. A device according to claim 17 in which the said synthetic plastics material comprises nylon, polypropylene or polyurethene.

19. A device according to any of claims 15 to 18 in which the upstanding shielding portion of the support means is substantially at right angles to the base portion of the support means.

20. A device according to any of claims 14 to 19 in which the support means forms a rotor.

21. A device according to claim 20 in which the said principal axis of the axial fastening means extends along a substantially radial direction relative to the axis of rotation of the rotor.

22. A device according to any of claims 14 to 21 in which the said principal axis of the axial fastening means extends perpendicular to the said base portion of the said support means.

23. A device according to any of claims 14 to 22 including a rigid support component positioned against the transverse web for modifying the yielding characteristic of the element.

24. A device according to any of claims 14 to 23, adapted for conditioning grass or other fibrous, fodder crop.

25. A crop engaging device substantially as hereinbefore described with reference to any one or any combination of the accompanying drawings.