GB2081566A

GB2081566A - Crop cutting and conditioning

Info

Publication number: GB2081566A
Application number: GB8124023A
Authority: GB
Original assignee: National Research Development Corp UK; National Research Development Corp of India
Current assignee: National Research Development Corp UK; National Research Development Corp of India
Priority date: 1980-08-14
Filing date: 1981-08-06
Publication date: 1982-02-24
Also published as: GB2081566B

Abstract

A crop cutting and conditioning apparatus has two vertical axis rotary drum cutters 13, each having an upper rotor with a crop conveying surface 19 and a lower rotor carrying knives 21. Gears drive the upper and lower rotors at different peripheral velocities. The lower rotor has an annular rim 18 having an upper surface shaped to continue the outline of the conveying surface 19. The knives 21 protrude outwardly from beneath the rim 18 and rotate with the rim. A wiper brush mounted on the conveying surface 19 projects outwardly over the rim 18 for lifting and transferring crop to the surface 19. The upper rotor has conditioning brushes 35 for conveying crop and conditioning crop by relative movement between the brushes and the crop. The envelope of brush tips on the rotor may be conical. The population of brush elements may vary with rotor height. The conditioning brushes may be mounted on the conveying surface 19. The upper and lower rotors may be rotated in opposite senses to effect at least partial shear cutting. <IMAGE>

Description

SPECIFICATION Apparatus for conditioning crop The present invention relates to apparatus for the conditioning of crops especially, but not exclusively, grasses, and is concerned in some respects with apparatus for cutting and conditioning crop.

In some aspects the present invention is concerned with improved arrangements of combinations of crop conditioning devices with crop cutting devices. In other aspects, the present invention is concerned with improvements in crop conditioning devices themselves.

Modern crop cutting devices are usually mowers of the rotary type which sever the crop by impact, using free swinging knives attached near the periphery of discs which may be used alone (disc mowers), or which may form lower skirts of vertical drums which assist in conveying the cut crop towards the rear of the machine (drum mowers). In each case the discs which support the knives serve to convey the cut crop to the rear. Knife tip speeds have to be in the broad range of 70 to 90 metres per second, to ensure clean cutting in most crops and conditions, where impact is used. At these speeds it has been found that the power requirement for conveying the crop by the discs is very considerable. In some aspects the invention is concerned with reducing the power requirement for cutting the crop and/or for conveying the cut crop.

In some aspects the present invention is concerned with improved arrangements of combinations of crop conditioning devices with crop cutting devices. Such a device is shown in a previously published US Patent No. 3977165 (Klinner et al) which shows a form of drum cutter in which the main upper drum rotor is driven at a different rate of rotation from a lower rotor which carries the cutting knives of the cutting device. In this arrangement, conditioning devices are provided on the upper surface ofthe crop conveying skirt of the upper drum rotor which is rotated at a different rate of rotation from the cutting knives. In practice a problem arises with such an arrangement in that it is difficult to maintain the correct close vertical clearance of the two rotary components, especially when the disc diameter is large and foreign objects are present on the surface of the field.In some aspects the present invention seeks to provide a rotary cutting apparatus of an improved and simplified nature having regard to the drum cutters described in this US patent specification.

In other aspects, the present invention is directed towards means for conditioning crops. Forage crops such as grasses which are surplus to immediate requirements are usually cut and field-dried to provide animal fodder, particularly hay or silage, for the feeding of animals when fresh forage crops are not available. In temperate, especially maritime climates, the crops are at risk between cutting and harvesting (i.e. the field exposure time) because the adverse effects of light and rain and micro-organism activity can produce appreuiable nutrient and dry matter losses. Accordingly, it is important to minimize the field exposure time to reduce the risk of such losses. However, the crops cannot be harvested until they have dried to a sufficiently high dry matter content for safe storage as animal fodder.In the case of hay, a dry matter content of about 80% is usually required.

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 two 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, bending or scuffing the stem and leaves of the crop, is known as "conditioning". A variety of conditioning devices have been used or proposed, for example as in UK Patents Nos. 588439 (Chilton), 662303 (Goodall), 1303970 (Bucher Guyer), US Patent No.3977165 (Klinner et al) and PCT published application No. PCT/GB79/00053-publication No.

WO 79/00863 (BSRAE). The earlier of the devices described in these publications would often cause undesirable deep tissue damage to the crop resulting in high dry matter and nutrient losses, and were also unsatisfactory when attempts were made to condition a wide swath of crop, as the complexity and weight of machines increased considerably with width. The form of conditioning described in the last of the specifications set out above has allowed considerable progress to be made in producing acceptable conditioning with a light and relatively inexpensive conditioning device, and the present invention is concerned in some aspects, although not exclusively, with improvements in relation to the form of conditioning described and claimed in the said PCT patent application.

Another factor which affects the amount of time the crop lies in the field after cutting is the number of passes required to cut and condition the crop. In some cases the crop requires three or more passes, including cutting, conditioning the crop after it has fallen to the ground, and finally tedding to restructure the swath so that it maintains a fast drying rate.

Many proposals have been made in the past for reducing the number of passes by combining cutting and conditioning in a single machine, such combined machines are described, inter alia, in the PCT application numbered above. In another aspect, the present invention is particularly concerned, although not exclusively, with apparatus for carrying out in a single pass the cutting and conditioning operation.

In this connection the present invention is concerned in its main aspects with cutting and/or conditioning crop by rotary movement about a vertical axis. Such cutting and conditioning by rotary movement about a vertical axis is known in itself, for example in the UK Patent No. 1303970 (Bucher Guyer), US Patent No.3977165 (Klinner et al) and PCT application No.

PCT/GB79/00053 (BSRAE) mentioned above. In the UK Specification No. 1303970 (Bucher Guyer) the conditioning rotor is described, inter alia, as a vertical "squirrel-cage" type of rotor rotating behind a vertical axis drum mower, whereas in the US Patent No.3977165 (Klinner) the conditioning devices are described as conditioning elements mounted on the upper surface of the crop conveying skirt of a vertical axis drum mower. The PCT application No.

PCT/GB79/00053 (BSRAE) mentions the possibility of two counter-rotated brushes fitted vertically so as to cover the opening between the drum oftwodrum mowers to give a simple swath-forming arranged ment. The brushes are described as being cylindrical or conical.

In accordance with a first aspect of the present invention, there is provided crop cutting and conditioning apparatus comprising one or more crop cutting devices for cutting crop by rotary motion about a vertical axis, the or each crop cutting device comprising a first rotor and a second rotor, the first and second rotors being mounted for rotation about a common vertical axis, the first rotor including cutting means for cutting crop by rotation of the first rotor, and the second rotor comprising a crop conditioning device for engaging crop and for conditioning the crop, and drive means for driving the first and second rotors in rotation at different peripheral velocities such as to effect cutting of crop by the cutting means and conditioning of crop by the conditioning device, in which the conditioning device comprises a brush-like structure having a multiplicity of stiff resilient elongate conditioning elements for conditioning the crop by a spiking and/or stiff brushing action consisting predominantly of surface damage to the crop, the elements being yieldable in response to engagement with the crop and being yieldable at least predominantly by bending of the elements along at least part of the crop engaging portions of the lengths thereof, and the elements being sufficiently stiff to return to their undeflected dispositions when free from engagement with the crop at least predominantly by virtue of the stiffness of the elements.

Hereinafter, where reference is made to a "crop cutting and conditioning apparatus as hereinbefore defined" there is meant a crop cutting and conditioning apparatus comprising one or more crop cutting devices for cutting crop by rotary motion about a vertical axis, the or each crop cutting device comprising a first rotor and a second rotor, the first and second rotors being mounted for rotation about a common vertical axis, the first rotor including cutting means for cutting crop by rotation of the first rotor, and the second rotor comprising a crop conveying and conditioning device for engaging crop for the purpose of conveying it and for conditioning the crop by relative movement between the conditioning device and the crop engaged thereby, and drive means for driving the first and second rotors in rotation at different peripheral velocities such as to effect cutting of crop by the cutting means and conditioning of crop by the conditioning means.

By the term different angular velocities is meant that the first and second rotors of each cutting device are rotated with different angular rates of rotation and/or in different directions of rotation.

Where reference is made to the elements being sufficiently stiff to return to their undeflected dispositions at least predominantly by virtue of the stiffness of the elements, it is to be appreciated that the base of an element may be secured to a support member of the conditioning device by a mounting which has itself a degree of resilience, for example by being clamped to a support member by clamping means including resilient material. Such a resilient mounting may contribute to the return of an element to its undeflected disposition, but it is a feature of the conditioning device set out above that the elements are sufficiently stiff to return to their undeflected dispositions predominantly by virtue of the stiffness of the elements.Where, as will be described hereinafter, the elements are mounted in tufts with a plurality of elements set closely together, it will be appreciated that adjacent elements will assist each other in the return to an undeflected disposition when free from engagement with crop, but again it will be appreciated that this return is effected predominantly by virtue of the stiffness of the elements.

Similarly the return of the elements to their unde flected dispositions may be assisted by the effects of centrifugal force, but again the elements are returned predominantly by virtue of the stiffness of the elements.

In any of the arrangements above, there may be provided the feature that the second rotor of each cutting device provides a crop conveying surface (conveniently an outwardly extending and downwardly inclined crop conveying surface) for conveying cut crop to the rear of the apparatus, and there is provided on the crop conveying surface at least one conditioning device comprising a straight or curved linear array of conditioning elements upstanding from the crop conveying surface, the array being aligned at least approximately along a direction which, when viewed from above, is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the crop conditioning device and is inclined to the horizontal.

Preferably the said array extends at least substantially over the whole of the width of the crop conveying surface from the outer to the inner edge thereof.

Also preferably the said angle is chosen to be such as to inhibit excessive scattering of cut crop and to assist inward movement of cut crop through a gap formed between two adjacent cutting devices, so as to form a suitable swath for drying.

Preferably the said angle is such that the outer end of the array trails the said radial vertical plane, and the angle formed with the radius is greater than 3d9 preferably in the range of 500 to 700, most preferably about 60".

Preferably the angle the upstanding array makes with the horizontal plane is such that its upper edges or tips are trailing the base in the direction of rotor rotation. Preferably the angle to the horizontal is between 30 and 700, most preferably 45"to 60".

In any of the arrangements above, there may be provided the feature that each second rotor includes or consists of a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the second rotor, the envelope of the outer tips of the condition- ing elements having a shape such that over at least a part of the height of the second rotor the radius of the envelope decreases with increase of height of the second rotor.

Preferably the shape of the envelope is such as to achieve height-related differential conditioning of crop in which crop is more severely conditioned by the lower portions of the second rotor than by the upper portions.

In any of the arrangements above, there may be provided the feature that the second rotor includes or consists of a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the second rotor, the said conditioning elements comprising elongate elements secured in groups distributed around the second rotor, the elements of each group being aligned along a direction which when viewed from above is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the second rotor.

Preferably the second rotor is arranged so that the said angle is adjustable.

Also preferably the said angle is such that the outer ends of the elongate elements trail the said radius, and the angle formed is preferably in the range of 20 to 60".

In any of the arrangements above, there may be provided the feature that the second rotor of each cutting device includes or consists of a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the said second rotor, the population of conditioning elements being arranged to decrease with increasing height of the second rotor.

Preferably the non-uniformity of the conditioning elements is arranged to be such as to produce height-related differential conditioning of crop in which crop is conditioned with greater severity by lower parts of the said second rotor than by upper parts.

In accordance with a second independent aspect of the invention, there is provided crop cutting and conditioning apparatus as hereinbefore defined in which the second rotor of the or each cutting device provides a crop conveying surface for conveying cut crop to the rear of the apparatus, and there is provided on the crop conveying surface at least one conditioning device comprising a straight or curved linear array of conditioning elements upstanding from the crop conveying surface, the array being aligned at least approximately along a direction which, when viewed from above, is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the crop conditioning device.

In accordance with a third independent aspect of the present invention, there is provided crop cutting and conditioning apparatus as herein before defined in which the second rotor includes or consists of a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the second rotor, the envelope of the outer tips of the conditioning elements having a shape such that over at least a part of the height of the second rotor the radius of the envelope decreases with increase in height of the second rotor.

In accordance with a fourth independent aspect of the invention, there is provided a crop cutting and conditioning apparatus as hereinbefore defined in which the second rotor includes or consists of a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the second rotor, the said conditioning elements comprising elongate elements secured in groups distributed around the second rotor, the elements of each group being aligned along a direction which when viewed from above is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the second rotor.

In accordance with a fifth independent aspect of the invention, there is provided a crop cutting and conditioning device as hereinbefore defined in which the second rotor of the or each cutting device includes or consists of a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the second rotor, the population of conditioning elements being arranged to vary with height of the second rotor, e.g.

to decrease with increasing height of the second rotor.

In any of the arrangements above, there may be provided the feature that the second rotor provides a crop conveying surface for conveying cut crop to the rear of the apparatus by rotation of the second rotor, and in which the first rotor has an upper surface or surfaces positioned adjacent to the crop conveying surface of the second rotor, the or each said upper surface having at least a part thereof shaped to continue the general outline of the crop conveying surface of the second rotor at least at the transition region between the said upper surface and of the said crop conveying surface, the cutting means being arranged to protrude outwardly from the said upper surface or surfaces of the second rotor.

In any of the arrangements above, there may be provided the feature that the second rotor provides a crop conveying surface for conveying cut crop to the rear of the apparatus by rotation of the second rotor, and in which the first rotor extends outwardly beyond the perimeter of the crop conveying surface of the second rotor, and the second rotor includes one or more resilient wiper devices projecting outwardly beyond the perimeter of the crop conveying surface over at least part of the outer region of the first rotor, for engaging, lifting or transferring crop from the first rotor to the crop conveying surface of the second rotor or otherwise engaging crop.

In any of the arrangements above, there may be provided the feature that the drive means is arranged to drive the first and second rotors in rotation in opposite sense in such a manner that the cutting by the cutting means is at least in part shear cutting effected by the action of the two rotors in opposite directions on the crop, the effect being particularly applicable when a wiper device or devices extend from the second rotor outwardly over the cutting path of the cutting means.

In accordance with a sixth independent aspect of the invention, a crop conditioning apparatus comprises a pair of crop conditioning rotors each mounted for rotation about a vertical axis with the vertical axes spaced aparttransversely relative to an intended direction of forward travel of the apparatus, and drive means for driving the rotors in counter rotation in such a manner that crop is passed between the rotors from the front to the rear of the apparatus and is conditioned by relative movement between the conditioning rotors and the crop engaged thereby, in which each conditioning rotor comprises a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the conditioning rotor, the envelope of the outer tips of the conditioning elements having a shape such that over at least a part of the height of the conditioning rotor the radius of the envelope decreases with increase of height of the conditioning rotor.

In accordance with a seventh independent aspect of the invention a crop conditioning apparatus comprises a pair of crop conditioning rotors each mounted for rotation about a vertical axis with the vertical axes spaced apart transversely relative to an intended direction of forward travel of the apparatus, and drive means for driving the rotors in counter rotation in such a manner that crop is passed between the rotors from the front to rear of the apparatus and the crop is conditioned by relative movement between the conditioning rotors and the crop engaged thereby, in which each crop conditioning rotor comprises a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the conditioning rotor, the said conditioning elements com prising elongate elements secured in groups distri buted around the conditioning rotor, the elements of each group being aligned along a direction which when viewed from above is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the conditioning rotor.

In accordance with an eighth independent aspect of the invention a crop conditioning apparatus comprises a pair of crop conditioning rotors each mounted for rotation about a vertical axis with the vertical axes spaced apart transversely relative to an intended direction of forward travel of the apparatus, and drive means for driving the rotors in counter rotation in such a manner that crop is passed between the rotors from the front to rear of the apparatus and the crop is conditioned by relative movement between the conditioning rotors and the crop engaged thereby, in which each conditioning rotor comprises a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis ofthe conditioning rotor, the population of conditioning elements being arranged to vary with height of the rotor, e.g. to decrease with increase in height of the conditioning rotor.

In any of the cutting arrangements above, there may be provided a first cutting feature that the first rotor includes cutting means for cutting crop by rotation of the first rotor, and the second rotor provides a crop conveying surface for conveying cut crop to the rear of the apparatus by rotation of the second rotor, and there being drive means for driving the first and second rotors in rotation at different peripheral velocities such as to effect cutting of crop by the cutting means and conveying of crop by the conveying surface.

Also in any of the cutting arrangements above, there may be provided a second cutting feature that the first rotor includes cutting means for cutting crop by rotation of the first rotor, and the second rotor provides a crop conveying surface for conveying cut crop to the rear of the apparatus by rotation of the second rotor, and there is provided drive means for driving the first and second rotors in rotation at different peripheral velocities such as to effect cutting of crop by the cutting means and conveying of crop by the conveying surface, in which the first rotor extends outwardly beyond the perimeter of the crop conveying surface of the second rotor and the second rotor includes one or more resilient wiper devices projecting outwardly beyond the perimeter of the crop conveying surface.

Further in any of the cutting arrangements above, there may be provided a third cutting feature that the first rotor includes cutting means for cutting crop by rotation of the first rotor, and the second rotor comprises crop conveying means for conveying cut crop to the rear of the apparatus by rotation of the second rotor, and there is provided drive means for driving the first and second rotors in rotation in opposite sense in such a mannerthatthe cutting by the cutting means is at least in part shear cutting effected by the action ofthetwo rotors in opposite directions on the crop, the effect being particularly applicable when a wiper device or devices extend from the second rotor outwardly over the cutting path of the cutting means.

There will now be described a number of preferred features which may be provided in accordance with the conditioning device which has been referred to in various arrangements.

In connection with all those aspects of the invention set out above in which a crop cutting and conditioning apparatus has crop cutting devices with first and second rotors, there is provided in accordance with another general aspect of the invention a modification in which the first and second rotors of each cutting device are replaced by a single rotor which provides both the conditioning device and the cutting means, so that in such an aspect the crop conditioning device and the cutting means are driven in rotation at the same speed.

Conveniently the conditioning elements may be arranged in a brush of conventional form, that is to say in which groups of elements are mounted together in tufts, and the positions of the tips of the elements are to at least some extent random. However other forms of brush will be readily apparent, and in particular the brush may comprise elements which are disposed in a regular, non-random, pattern.

It is preferred that the conditioning elements are sufficiently stiff to penetrate a stream of crop, and it is also preferred that the elements condition the crop by an action which consists predominantly of surface abrasion of the crop. It is further preferred that the elements are yieldable by bending substantially along the whole of the free lengths thereof.

In one form, the tips of the elements may be distributed substantially uniformly and the population of the elements at the tips may lie in the range 1 to 20 elements per sq. cm, preferably in the range 3 to 16 elements per-sq. cm. In another form the elements may be arranged in spaced apart tufts of elements and the population of the elements in each tuft at the tips may lie in the range 1 to 20 elements per sq. cm, preferably in the range 3 to 16 elements per sq. cm.

Conveniently each tuft may be formed of one or more lengths of element material doubled over and secured within a protective, resilient retaining sleeve or tube to a supporting base in the region of the fold of the doubled over element length or lengths.

Conveniently each element or group of elements in a tuft may be supported and protected at the base thereof by a sleeve of resilient material.

In general terms, the conditioning elements may be of the form described in the published P.C.T.

patent application No. PCT/GB79/00053.

With reference to the crop cutting and condition ing devices referred to above as described in U.S.

Patent No. 3977165 (Klinner et al), the present invention represents in a number of aspects improvements over the devices previously described. Work at the National Institute of Agricultural Engineering at Wrest Park, Silsoe, Bedford, England in the late 1960s had shown that the knife carrying discs of rotary mowers, both of the drum and disc type, could be fitted with conditioning attachments in such a way that their mowing performances was not impaired and the action of the attachments imparted to the crop a conditioning treatment simultaneous with the cutting. The effectiveness of the various attachments, all made of steel, was good, but there were two serious disadvantages. Firstly, a significant percentage of crop was too severely treated so that dry matter losses would become rather high.Secondly, any stones or other heavy objects which were picked up by the mower were projected at times in a hazardous manner. The arrangement shown in Figure 24 of U.S. Specification No.3977165 was intended to attempt two overcome these difficulties by providing a slower rate of rotation of the upper drum rotor than the lower knife carrying disc.However, from the engineering point of view, it is difficult to construct a rotary mower (particularly of large diameter disc type as used in modern drum mowers) in such a way that in the hostile environment of typical grass fields, the small clearance between the upper and lower discs and the pivoted knives is maintained, and the step which cut crop has to climb onto the conveying surface does not constitute so great an obstacle that the power requirement of the machine is drastically increased.In preferred arrangements of the present invention, it is possible to provide rotary mowers on which the cutting knives are driven at the optimum speed for impact cutting, i.e. between approximately 70 and 95 mls, but the crop conveying discs are driven at a very much lower speed, so that resilient conditioning devices attached to them will neither fragment the crop excessively nor propel foreign objects dangerously. Furthermore, and most importantly, the risk of collision between metal components can be arranged to be minimal.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-section showing from the front the outer half of a twin unit, two-speed crop cutting apparatus for use in an embodiment of the invention, and generally of the drum mower kind; Figure 2 is a front view partly in cross-section of a modified form of the crop cutting apparatus of Fig urge 1 ; Figure 3 is a diagrammatic perspective view of the general layout of a crop cutting apparatus for use in an embodiment of the present invention as shown in the preceding Figures; Figures 4 and 5 are front and plan diagrammatic representations respectively of a modification of a crop cutting apparatus of the form shown in the preceding Figures; Figures 6, and 6(a); 7 and 7(a); and 7(b); and 7(c); are diagrammatic front and plan views respectively of a further modification of the crop cutting apparatus shown in the preceding Figures, in which a lower rotor includes discrete projecting portions; Figure 8 and 8(a) show a side cross-section and plan view respectively of a crop cutting apparatus suitable for use in connection with the crop cutting apparatus shown in the preceding Figures; Figure 9 is a diagrammatic side view of crop cutting and conditioning apparatus embodying the invention in which an array of conditioning elements is provided on an upper rotor of a crop cutting device; Figure 10 and 10(a) show diagrammatic perspective views of a crop cutting and conditioning device embodying the invention; Figure 11 is a diagrammatic perspective view of a modification of the crop cutting and conditioning device shown in Figs 10 and 10(a);; Figures 12, and 12(a) are diagrammatic front, and plan views respectively of a crop conditioning device embodying the invention for use in a crop cutting and conditioning apparatus; Figures 13, 14(a) (b) and (c), 15, and 16 and 16(a) show various diagrammatic front, plan, and perspective view of modifications of the crop conditioning device shown in Figures 12 and 12(a); and Figures 17,17(a), 18,18(a) and (18(b) showdiagrammatic front views and plan views respectively of a crop cutting and conditioning apparatus in which there are mounted on an upper rotor of the conditioning device, groups of conditioning elements arranged in various configurations and forms.

Figure 1 is a cross-section showing from the front the outer half of a twin unit, two-speed crop cutting apparatus embodying the invention and generally of the drum mower kind. From a transverse drive shaft 11 a centre spindle 12 of the drum cutter indicated generally at 13 is driven by means of two bevel gears 14. At its base the spindle 12 runs in a thrust bearing 15 and has attached to it a skid disc 16 which is freely rotatable in known manner. Above the skid disc 16 there is fixedly attached to the spindle 12 a support disc 17 which constitutes a first, lower rotor of the cutting device and which carries a narrowfrusto- conical rim 18 which may for example be 50 mm wide.The shape ofthe rim 18 is such that its sloping upper surface is a continuation ofthe shape of a crop conveying skirt 19 attached to the base ofthe central drum 20 of the cutting device 13. Pivoted knives 21 are attached to the underside ofthe narrow rim 18 in such a way that upon meeting an obstruction each knife can swing through 3609 The knife carrying rim 18 is entirely smooth on its crop facing surface and may for example be coated with polytetraf- luoroethylene or other durable low friction material.

At the position of each knife 21 recesses in the disc 17 allow the knife to pivot underneath the rim 18, through 3609 upon striking an obstruction on the ground.

The drum 20, skirt 19 and intemal supporting webs 22 constitute a second, upper rotor which is mounted by bearings 23 and 24 on The central spik dle 12, and is driven from the transverse shaft 11 at the top by a second pair of bevel gears 25 and through a gearwheel 26 and internal gear ring 27.

The speed at which the upper rotor 1920, is driven may for example be 20 mls at the circumference of the crop conveying skirt 19, but may in other cases be in the range 10 most40 mls. As shown in Figure 1 bythetwo arrows, both the knife carrying rim 18 and the crop conveying skirt 19 rotate in the same direction, namelytowardsthe rearonthe inner side of the cutting device 13 which facestowards the other cutting device (not shown). Thus in convent tional mannerthe crop is gathered inwardly between the two cutting devices and transferred rearwardly to form a swath.Thus on the second cutting device (not shown) the rotating components revolve in the opposite direction so that the crop is conveyed to the rear through the central space between the adjacent devices.

Figure 2 is a front view partly in cross-section of a modified form of the crop cutting apparatus of Fig ure 1, and in this and other embodiments corres ponding elements are indicated by like reference numerals. In this modification the bevel gears 14 and 25 are so arranged that the knife carrying rim 18 rotates in the opposite direction to the direction of rotation ofthe crop conveying skirt 19.

With regard to the gearing shown in Figures 1 and 2, it will be appreciated that alternative ways of achieving the differential drive may be provided, such as planetary gearing.

It is not essential.thatthe cutting rotor rotates more quickly than the conveying and conditioning rotor. If a method is used which achieves the desired crop cutting at lower speeds than the lowest effec tive conditioning speeds of, say, 15 mls, then the ratio ofthe speeds between cutting and conditioning components may be reversed.

Figure 3 is a diagrammatic perspective view ofthe general layout of crop cutting apparatus embodying the invention in the form shown in Figure 1 or Figure 2, but with the attachments 28 attached to the upper surfaces of the crop conveying skirts 19. The attach ments 28 are support bars intended for mounting crop conveying and/or conditioning elements to be described and shown hereinafter. The two crop cut ting devices are indicated generally at 13 and 13' and are shown as supported from an overhead frame 29 suitable for attachment to the three point linkage of a tractor.

Figures4and Sare front and plan diagrammatic representations respectively of a modification of the crop cutting apparatus of the form shown in the preceding figures, and again corresponding elements are indicated by the like reference numerals. Figure 4 shows the skid disc 16 at the base ofthe cutting device, and a disc 17 which carries the outer rim 18 and knives 21.

Figure 5 shows how the knife carrying rim 18 8 is attached to the support disc 17 by means of spaced apart angled brackets 33. This method of construction ensures that any material which may enter through the gap between the knife carrying rim 18 and the crop conveying skirt 19 can leave again through the gaps between brackets 33 under the influence of centrifugal forces. The plan view in Figure 5 shows how the pivoted knives 21 can rotate through 3609 between the brackets 33.

Figures 6 and 6(a) are diagrammatic front and plan views respectively of a further modification of the crop cutting apparatus shown in the preceding figures, in which the lower support dise 17 consists of a dished pressing from which smaller discs have been cut as indicated at 17' to save weight To provide locating and mounting means for the knives 21, part-moon shaped plates 18 are welded to an upstanding rim 17" which is also recessed at the top to allow each knife to swing through a full 3600, on impact with a heavy object. In this modification, the projections 18'fulfill a similar function to the rim 18 in the preceding figures, and as shown in Figure 6, the shape of each projection 18' is such as to continue the shape ofthe upper surface ofthe crop conveying skirt 19.In a modified version shown in Figures 7 and 7it), each plate is in the form of a ramp acting to lift cut crop towards the conveying surface 19 of the upper rotor.

Although it is preferred that the knives 21 are mounted beneath the projections 18 orthe rim 18, it is to be appreciated that the knives could be mounted on top of the projections 18' or rim 18.

Furthermore, the knives could be fixedly or semirigidly mounted without pivotting.

The embodiments of Figs Sand 7 give the advan tage that the overlap zone between two adjacent, counter rotating and synchronously driven cutting units can be made greaterthan is possible with plain disc units. As a result the "mane" of long stubble so often left in difficult crops and conditions by rotary mowers is avoided.

It should be understood that the shape of the ramp-like protrusions in Figures 6,6(a), 7 and 7(a) can be varied; the most preferred shape is the leading half of a part-moon, as in Figure 6(a).

In Figure 7(b) there is shown in plan view an alternative form of the rotor 17 for supporting the knives 21, although in Figure 7{b) the knives are omitted.

Figure 7(c) is a cross-section along the lines A-A in Figure 7(b), and shows one of the knives 21, and also the relationship of the rotor 17 to the conveying rotor surface 19. Thus in general it will be appreciated that the cutting knives can be attached to upturned or downturned spoke-like extensions of a lower rotor of small centre diameter, in such a way that the upper surface of each knife lies approximately in the continuation plane of the crop conveying surface of the upper rotor.

Figures 8 and 8(a) show a side cross-section and plan view respectively of an apparatus embodying the present invention and suitable for use in connection with the crop cutting apparatus shown in the preceding figures. Figure 8 shows a wiper device 34 in the form of a tuft of resilient crop conditioning elements (also referred to as filaments) 35 formed for example of synthetic plastics material. The tuft 34 is bolted onto the crop conveying skirt 19 in such a way that it is supported on two sides by a shallow bracket 36 to prevent the tuft from turning under the influence of centrifugal force or load applied to its tip. In the plan view of Figure 8(a), the tuft 34 is shown to be orientated in such a way that, relative to a radius of the crop conveying skirt 19, the tips of the elements 35 are trailing.It is also shown that the elements 35 overhang the knife carrying rim 18 and may extend over the cutting path so that, relative to a radius of the crop conveying skirt 19, the tips of the elements 35 are trailing. It is also shown that the elements 35 overhang the knife carrying rim 18 and may extend over the cutting path of the cutting knives 21. The number of wiping tufts 34 fitted near the perimeter of the crop conveying skirt 19 may be varied from two per disc to several times the number of cutting knives.

The wiper element of Figures 8 and 8(a) overhanging the cutting rim is not primarily for conditioning the crop; it also serves the purpose of engaging, lifting or assisting crop on to the conveying skirt and prevents repeated contact of crop with the cutting knives. Optionally it can intrude into the cutting zone. The degree of resilience and its construction can vary.

Figure 9 is a diagrammatic side view of a crop cutting and conditioning apparatus embodying the invention and is particularly concerned with a linear array 37 of crop conditioning elements 35 which are provided on the crop conveying skirt 19 of a crop cutting and conditioning device 13. Figure 9 shows a knife carrying rim 18 of the form described with reference to the previous figures, and also shows a tuft 34 protruding out over the rim 18. The rim wiping tuft 34 is shown to be followed by an attachment to the crop conveying skirt 19 which consists of a rearwardly leaning bracket plate 38 to which are attached on tbe upwardly inclined trailing face thereof a series of tufts 39 of synthetic plastics conditioning elements 35 similar to the elements described with reference to Figure 8(a).The conditioning elements of the embodiments described with reference to Figures 8 onwards of the present description may conveniently be of any of the forms described in published pending PCTApplication No.

PCT/TB79/00053 - Pubication No. W079/00863. It is an object of the attachment shown in Figure 9 as a whole to drive itself under the cut crop, forcing the crop upwards so that it is scratched and abraded by the tufts of plastics material during acceleration. To maintain the drum unit of the cutting device 13 in balance in operation, two attachments 38 are normally required, although alternatively a counterweight may be fitted on the opposite side of the crop conveying skirt 19 and this may be appropriate on a relatively small diameter cutting device. Preferably the multi tuft attachment 37 is fitted at an angle to a radial vertical plane of the vertical axis of the cutting device 13 so that the outer end of the attachment 37 leads the radius.The angle which the attachment 38 makes with a radial vertical plane of the vertical axis of the cutting device 13 (when viewed from above) determines whether the crop is scattered at the rear of the mower or whether it is formed into a distinct swath. In the trailing mode, the greater the enclosed angle between the radius and the attachment, the neaterthe swath will be, up to an optimum position. By way of example the scattering effect often persists at angles of up to about 30" but at around 60 a distinct swath is formed in most crops.

In Figure 9 the inclination of the crop conveying skirt 19 has been accentuated by the base of the attachment 38 being tapered down towards the rim. This configuration makes it more difficult for the crop to move towards the centre of the crop conveying skirt 19, and conditioning is largely confined to the lower crop regions.

Figures 10 and 10(a) are a diagrammatic perspective view of a further embodiment of a crop conditioning device embodying the invention, in this case where conditioning elements are provided on bars 43 positioned to extend between the outer edge of the conveying skirts 19, and the upper part of the drum 20. The bars are arranged in the general form of a conical "squirrel cage" arrangement, and represent a further movement of the conditioning elements from the positions shown in Figure 9, so as to by lying at an even steeper angle to the plane of the conveying skirt. The conditioning bars are so fitted that they connect the upper surface of the crop conveying skirt 19 with the underside of an upper ring 44 attached to the top of the drum 20.In Figures 10 and 11, brush tufts 45 are shown set substantially horizontally, whilst in Figure 11 which shows a modification the tufts 45 are inclined downwardly in the outward direction. In Figure 10 the lower parts of the bars lead the upper parts, relative to the rotation of the rotors, forming a helical arrangement in order to give a lifting effect to the crop. The lowermost conditioning elements may be made of sheet plastic and may overhang the cutting rim 18.

The crop conditioning unit need not necessarily be of open cage construction, but can consist of a solid cone or drum to which fins for conditioning or for mounting the conditioning elements can be attached.

Figures 12, and 12(a) are diagrammatic side and plan views respectively of a further embodiment of a crop conditioning device embodying the invention, in this case where conditioning elements are provided on bars 43 positioned to extend between the outer edge of the conveying skirts 19, and the upper part ofthe cutting device 13 at the upper end of the central spindle. The bars are arranged in the general form of a conical "squirrel cage" arrangement. The conditioning bars are so fitted that they connect the upper surface ofthe crop conveying skirt 19 with the underside of an upper sealing ring 44 attached to the top of the cutting device 13. In Figure 12, brush tufts 45 are shown set substantially horizontally.

The crop conditioning unit need not necessarily be of open cage construction, but can consist of a solid cone to which fins for conditioning or for mounting conditioning elements can be attached.

In Figures 13 to 15 there is shown a further modification of conditioning apparatus, and in this figure mounting bars 50 for conditioning elements 35 are shown to be vertical and to form a skeleton cylinder or squirrel cage. Alternatively the mounting bars 50 may be provided as ribs on a solid cylinder (not shown). The purpose of the embodiment shown in Figures 13 to 75 is to treat the crop before it has time to fall with head ends forwards, and so ensure that the conditioning effect is spread over a much greater length of crop than is possible with conditioning attachments which slope towards the rotor axis at the top.In some conditions, for example when the crop is leaning or laid, or when the conditioning elements are set so that they sweep a vertical plane marginally ahead of the tips of the cutting knives, a particular severe conditioning effect may be obtained, because then the crop is not yet free to move under the impact of the conditioning devices.

The situation when the conditioning elements 35 operate in advance of the cutting knives is indicated in Figure 14(a). When conditioning elements are mounted radially, then the treated crop is scattered over a wide strip at the rear of the mower. This effect may be minimised by angling the carrying bars 50 and conditioning elements 35 so that the tips of the elements are trailing. This latter situation is shown in plan view in Figure 14(b). Since the angle of the conditioning elements 35 relative to a radial vertical plane of the main axis of rotation determines the spreading effect and also the severity of treatment, it is desirable to facilitate adjustment of this angle in conformity with prevailing conditions and desired swath structure.In Figure 14(c) there is shown an adjusting system indicated generally at 51, which requires the mounting bars 50 to be pivoted at the top and bottom at pivot 52 and to carry at either or both ends of each bar 50 a lug 53 which can be swivelled and fixed in any one of a series of holes 54.

The most appropriate of angles has been found to be from 0 to 600 angle to the radial, the angle being in such a sense thatthe conditioning elements trail relative to the radius of rotation.

In Figure j6 mounting bars 55 are shown to be attached at their base at right angles to a crop conveying skirt or disc 56. Towards the top, the bars 55 converge towards the axis of the mower unit 13. This embodiment has the advantage that the lowermost conditioning elements 35 sweep the knife carrying rim 18 and the working zone or cutting path of the knives 21 parallel to the direction of inclination of the skirt 19 and rim 18. In orderto ensure rigidityofthe intermediate knife supporting disc 17, gusset fins or pressed ribs 57 are provided radially along spokes of the disc 17. In Figure 16(a) knives 21 are shown to be attached halfway between adjacent spokes so that the knives can swing freely through 360" on impact with a heavy object.Figures 17 and 17(a) show a modification in which ramps 18' are provided to lift cut crop towards the conditioning rotor.

Considering generally some of the advantages which may be obtained from the invention as embodied in the structures described, one principal advantage is that there can be provided resilient conditioning elements or devices which may be attached to components which rotate substantially more slowly about an axis than the knives which cut the crop. Amongst other advantages is that there may be provided a conditioning rotor on which the angle of the conditioning elements is adjustable relative to a radial vertical plane of the axis about which conditioning elements are rotated, so that crop may be treated at different levels of severity and may either be spread or arranged in distinct swaths.In some arrangements there may be advantage derived in respect of better cutting performance by arranging that the cutting knives and resilient wiper elements counter rotate in the same vertical plane giving the effect that crop stems are held more positively by the resilient elements at the moment of impact with the knives. Thus in some arrangements a lower rotor carrying cutting elements may be rotated about a vertical axis in one sense, while an upper rotor carrying conditioning elements may be rotated about the same vertical axis but in the opposite sense.

Returning now to specific embodiments shown in the drawings, Figures 18, 18(a) and 18(b) show a diagrammatic front view and plan view respectively of a crop cutting and conditioning apparatus comprising a lower rotor consisting of the knife supporting disc 17 as shown in previous figures, and an upper rotor consisting of a framework of supporting discs 58 and 59 interconnected by mounting bars 60.

In the embodiment of Figures 17 and 17(a) there is provided no upper crop conveying skirt of the kind shown at 19 in previous embodiments. Otherwise the upper and lower rotors are mounted for rotation on the spindle 12 generally in accordance with the arrangements shown in preceding figures. The bevel gear drives 14 and 25 for the supporting disc 17 and the conditioning rotor framework 58,59 and 60 are in this embodiment housed in a main beam housing 61, where lubrication can be easily arranged. The conditioning rotor, which is indicated generally at 62 and which constitutes the aforementioned upper rotor, comprises the framework 58, 59 and 60 as described, and conditioning devices 34 attached td the mounting bars 60, the conditioning devices comprising conditioning elements 35 of the kind generally described hereinbefore. The conditioning rotor, built around the spindle 12, can be of open construction or may consist of a solid cylinder with ribs for conditioning or for attaching the conditioning tufts. The advantage of a "squirrel cage" arrangement of bars, as shown, is that the bars 60 may be angled (optionally), as shown in Fig 18(a) or 18(b), to vary the severity of treatment and the swath formation. The advantage of a solid cylinder with fins (not shown) is that simply by removing the conditioning means the machine can be used for mowing alone. In that event an upstanding circular rib indicated at 63 on the knife carrying disc 17 just in front of the fins or mounting bars of the crop conditioning rotor, prevents crop from creeping under the cylinder and wrapping around the central spindle.

It is a particular feature of the embodiment shown in Figure 17 that the population density of the tufts of conditioning elements is varied vertically along the mounting bars 60, as shown. This is intended to cause more severe conditioning to the lower parts of the crop stems than to the upper parts. The distribution of tufts and the population density of the tufts on a conditioning rotor is one way of controlling the distribution and severity of crop treatment.

Brief reference will now be made to some of the preceding figures and to various features thereof.

With regard to the gearing shown in Figures 1, 2 and 3, it will be appreciated that alternative ways of achieving the differential drive may be provided, such as planetary gearing.

The two mower embodiments with protrusions emanating from the rim give the advantage that the overlap zone between two adjacent, counter rotating and synchronously driven cutting units can be made greaterthan is possible with plain disc units. As a result the "mane" of long stubble so often left in difficult crops and conditions by rotary mowers is avoided.

The wiper element of Figures 8 and 8(a) overhanging the cutting rim is not primarily for conditioning the crop; it serves the purpose of assisting crop on to the conveying skirt and prevents repeated contact with the cutting knives. Optionally it can intrude into the cutting zone. The degree of resilience and its construction can vary and can include pivotally mounted metal plates.

It is to be appreciated that in the embodiments shown, it is not essential that the cutting rotor rotates more quickly than the conveying and the conditioning rotor. If a method of cutting is used which achieves the desired results at lower speeds than the lowest effective conditioning speeds of, say, 15 m/s, then the ratio of the speed differential between cutting and conditioning components may be reversed.

Returning to consideration of general aspects of the embodiments described hereinbefore, it is to be appreciated that the conditioning elements may, in generality, be of alternative construction, for example by being resiliently mounted metal spokes, or shaped fins. It should also be appreciated that the aspects of the invention set out above may be utilised with an under-driven disc mower as well as with a top driven drum mower. Alternatively the cutting discs may be driven from below and the crop conveying skirts or conditioning rotor from the opposite end.

Finally, in accordance with a further general aspect of the present invention, advantage may be obtained in some circumstances by providing, eg by removing the knives, a crop conditioning apparatus having conditioning means embodying a particular aspect of the present invention as set out before, in which the conditioning means is mounted for rotation about an axis or axes spaced from the axis or axes of the cutting means. Indeed in some forms the invention may provide conditioning apparatus for conditioning previously cut crop, there being provided no cutting means associated with the conditioning means.

Claims

1. Crop cutting and conditioning apparatus comprising one or more crop cutting devices for cutting crop by rotary motion about a vertical axis, the or each crop cutting device comprising a first rotor and a second rotor, the first and second rotors being mounted for rotation about a common vertical axis, the first rotor including cutting means for cutting crop by rotation of the first rotor, and the second rotor providing a crop conditioning device for engaging crop and for conditioning the crop and drive means for driving the first and second rotors in rotation at different peripheral velocities such as to effect cutting of crop by the cutting means and conditioning of crop by the conditioning device, in which the conditioning device comprises a brush-like structure having a multiplicity of stiff resilient elongate conditioning elements for conditioning the crop by a spiking and/or stiff brushing action consisting predominantly of surface damage to the crop, the elements being yieldable in response to engagement with the crop and being yieldable at least predominantly by bending of the elements along at least part of the crop engaging portions of the lengths thereof, and the elements being sufficiently stiff to return to their undeflected dispositions when free from engagement with the crop at least predominantly by virtue of the stiffness of the elements.

2. Apparatus according to Claim 1 in which the second rotor of each conditioning device provides a crop conveying surface for conveying cut crop to the rear of the apparatus, and there is provided on the crop conveying surface at least one conditioning device comprising a straight or curved linear array of conditioning elements upstanding from the crop conveying surface, the array being aligned at least approximately along a direction which, when viewed from above, is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the crop conditioning devices and is inclined to the horizontal.

3. Apparatus according to Claim 2 in which the said array extends at least substantially over the whole of the width of the crop conveying surface from the outerto the inner edge thereof.

4. Apparatus according to Claim 2 or3 in which angles of inclination are chosen to be such as to inhibit excessive scattering of cut crop and to assist movement of cut crop through a gap formed between two adjacent cutting devices, so as to form a suitable swath for drying.

5. Apparatus according to any preceding Claim in which the second rotor includes or consists of a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the second rotor, the envelope of the outer tips of the conditioning elements having a shape such that over at least part ofthe height of the second rotor the radius ofthe envelope decreases with increase of height of the second rotor.

6. Apparatus according to Claim 7 in which the shape of the envelope is such as to achieve height related differential conditioning of crop in which crop is more severely conditioned by the lower portions of the second rotor than by the upper portions.

7. Apparatus according to any preceding Claim in which the second rotor includes or consists of a conditioning device comprising a plurality of condi tioning elements directed outwardly from the said vertical axis of the second rotor, the said condition ing elements comprising elongate elements secured in groups distributed around the second rotor, the elements of each group being aligned along a direc tion which when viewed from above is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the second rotor.

8. Apparatus according to Claim 7 in which the second rotor is arranged so that the said angle is adjustable.

9. Apparatus according to Claim 7 or 8 in which the said angle is such that the outer ends of the elongate elements trail the said radius, and the angle formed is in the range 200 to 600.

10. Apparatus according to any preceding Claims in which the second rotor of each cutting device includes or consists of a conditioning device com prising a plurality of conditioning elements directed outwardly from the said vertical axis of the said sec ond rotor, the population of conditioning elements being arranged to decrease with increasing height of the second rotor.

11. Apparatus according to Claim 10 in which the non-uniformity of the conditioning elements is arranged to be such as to produce height-related dif ferential conditioning of crop in which crop is coni ditioned with greater severity by lower parts ofthe said second rotor than by upper parts.

12. A crop cutting and conditioning apparatus as hereinbefore defined in which the second rotor of the or each cutting device provides a crop conveying surface for conveying cut crop to the rear of the apparatus, and there is provided on the crop conveying surface at least one conditioning device comprising a straight or curved linear array of conditioning elements upstanding from the crop conveying surface, the array being aligned at least approximately along a direction which, when viewed from above, is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the crop conditioning device.

13. A crop cutting and conditioning apparatus as hereinbefore defined in which the second rotor includes or consists of a conditioning device com prising a plurality of conditioning elements directed outwardly from the said vertical axis of the second rotor, the envelope of the outer tips of the conditior ing elements having a shape such that over at least a part of the height of the second rotor the radius of the envelope decreases with increase of height of the second rotor.

14. A crop cutting and conditioning apparatus as hereinbefore defined in which the second rotor includes or consists of a conditioning device com prising a plurality of conditioning elements directed outwardly from the said vertical axis of the second rotor, the said conditioning elements comprising elongate elements secured in groups distributed around the second rotor, the elements of each group being aligned along a direction which when viewed from above is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the second rotor.

15. A crop cutting and conditioning device as hereinbefore defined in which the second rotor of each cutting device includes or consists of a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis ofthe second rotor, the population of conditioning elements being arranged to vary with height of the second rotor.

16. Apparatus according to any preceding Claim in which the second rotor provides a crop conveying surface for conveying cut crop to the rear of the apparatus by rotation of the second rotor, and in which the first rotor extends outwardly beyond the perimeter of the crop conveying surface of the second rotor, and the second rotor includes one or more resilient wiper devices projecting outwardly beyond the perimeter of the crop conveying surface over at least part of the outer region of the first rotor, for lifting and transferring crop from the first rotor to the crop conveying surface ofthe second rotor.

17. Apparatus according to any preceding Claim in which the drive means is arranged to drive the first and second rotors in rotation in opposite senses in such a manner that the cutting by the cutting means is at least in part shear cutting effected by the action of the two rotors in opposite directions on the crop.

18. Crop conditioning apparatus comprising a pair of crop conditioning rotors each mounted for rotation about a vertical axis with the vertical axes spaced apart transversely relative to an intended direction of forward travel of the apparatus, and drive means for driving the rotors in counter rotation in such a manner that crop is passed between the rotors from the front to the rear of the apparatus and is conditioned by relative movement between the conditioning rotors and the crop engaged thereby, in which each conditioning rotor comprises a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis ofthe conditioning rotor, the envelope of the outer tips ofthe conditioning elements having a shape such that over at least part of the height of the conditioning rotor the radius of the envelope decreases with increase of height ofthe conditioning rotor.

19. Crop conditioning apparatus comprising a pair of crop conditioning rotors each mounted for rotation about a vertical axis with the vertical axes spaced apart transversely relative to an intended direction of forward travel of the apparatus, and drive means for driving the rotors in counter rotation in such a manner that crop is passed between the rotors from the front to rear of the apparatus and the crop is conditioned by relative movement between the conditioning rotors and the crop engaged thereby, in which each crop conditioning rotor comprises a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the conditioning rotor, the said conditioning elements comprising elongate elements secured in groups dsitributed around the conditioning rotor, the elements of each group being aligned along a direction which when viewed from above is inclined at an angle of inclination to a radial vertical plane of the said vertical axis of the conditioning rotor.

20. Crop conditioning apparatus comprising a pair of crop conditioning rotors each mounted for rotation about a vertical axis with the vertical axes spaced apart transversely relative to an intended direction of forward travel of the apparatus, and drive means for driving the rotors in counter rotation in such a manner that crop is passed between the rotors from the front to rear of the apparatus and the crop is conditioned by relative movement between the conditioning rotors and the crop engaged thereby, in which each conditioning rotor comprises a conditioning device comprising a plurality of conditioning elements directed outwardly from the said vertical axis of the conditioning rotor, the population of conditioning elements being arranged to vary with, height of the conditioning rotor.

21. Crop cutting and conditioning apparatus as hereinbefore described with reference to any one or any combination of the accompanying drawings.

22. Crop conditioning apparatus as hereinbefore described with reference to any one or any combination of the accompanying drawings.