Agricultural Machine

Field of the Invention

The present invention relates to an agricultural machine, and in particular to a machine for use in the production and harvesting of root crops.

Background of the Invention

Harvesting of root crops is typically carried out by harvesting machines which harvest multiple rows of root crops. Harvesters can be divided into two groups, those which are trailed and those which are self-propelled. Most trailed potato harvesters are arranged to harvest two rows of potatoes at a time, although single and three row machines are available.

Self-propelled harvesting machines are typically arranged to harvest two to four rows at a time. Legal constraints on the dimensions of vehicles using public roads means that there are no potato harvesters marketed within the European Union having a capacity to harvest more than four rows simultaneously.

There is general trend in farming and in particular root crop growing that the number of growers is decreasing and area of roots an individual grower grows is increasing. As such there is a requirement for increased harvesting capacity.

This requirement has lead to various ways of increasing harvesting capacity. One of these was the development of three row bed systems which may be harvested by suitably configured three row harvesting machines, be they self-propelled or trailed.

More recently, increasing harvester capacity has seen the development of the above- mentioned four row harvesting machines.

The machine sold by the firm Gπmme under the name Techtron is described in published European patent application no EP 1290933. As is explained in EP 1290933, as harvester size increases one of the major design issues is to present a machine which is capable of being transported on the road legally. The harvester described in EP 1290933 includes a particular configuration of elevator which folds into a bunker when the machine is configured for road transport.

Whilst the Gnmme Techtron does allow the harvesting of four rows of potatoes at one time, those rows are of constricted width because of the requirement for the machine to be of a road legal width.

Another aspect of this machine, and others similarly designed is that the position of the chassis members requires the potatoes to be gathered on to a conveyor of narrower width than the total lifting width. Not only does this require an assembly to be located in a soil laden working environment, but also causes potatoes to rub against each other, resulting in damage. Furthermore, the arrangement of the conveyor delivering to the bunker results in at least a proportion of the potatoes being subject to fall heights greater than that which is generally regarded as desirable.

One problem which is associated with self-propelled harvesters generally is the angle at which the cleaning web is mounted on the machine. It is understood that an angle of around 18 degrees to the horizontal is ideal, and in trailed machines web angles of around 18 degrees are typically found.

However, in a self-propelled harvester web angles of upto 28 degrees are common. This is due to the requirement for the web to clear the drive wheels or tracks of the harvester, which are located under the chassis. Such steep web angles result in crop roll back and damage. To overcome this problem operators typically reduce the degree of agitation on the web so that the crop does not roll back. This is a recognised problem.

The harvester described in EP0803178 proposes a solution to this which involves mounting a climbing aid in the form of a conveyor belt above the web to stop the potatoes falling back down the conveyor. Whilst physically preventing potatoes from rolling back down the web, the presence of such a climbing aid may damage potatoes on the web and reduce the agitating effects of the web.

A further problem found in harvesting machines and in particular self-propelled multi-row potato harvesters is a lack of stability. This problem is exacerbated by large bunkers used on self- propelled harvesters.

What is therefore proposed is an improved agricultural machine. When configured as a harvesting machine, and in particular a potato harvester the harvesting machine has significantly increased capacity when compared to those machines currently available.

Further, and again when configured as a harvesting machine, and in particular a potato harvester the harvesting machine is configured such that significantly less damage is caused to potatoes passing through the machine than is the case for self-propelled potato harvesters of the prior art.

The machine of the present invention is significantly more stable than self-propelled potato harvesters of the prior art.

The provision of a bunker which rotates so that the harvested crop may be discharged to either side of the machine has significant advantages in the opening out of a field at the beginning of harvesting operations, and reduces unproductive time running between lands.

Whilst the invention and its background have been described in relation to potato harvesting machines, the invention is not limited to such machines. In fact, a machine of the invention may be configured as a stone and clod separator, or a planter for example.

Summary of the Invention

According to a primary aspect of the invention there is provided an agricultural machine having a working configuration and a transport configuration, wherein in the transport configuration the machine's dimensions are within the legal limits for road transport and in the working configuration the machine may work six root crop rows simultaneously.

According to another aspect of the invention there is provided an agricultural machine having a pair of steerable wheels with an ad _j ustable track width, wherein the track width is ad _j ustable such that in a transport configuration the vehicle may travel along roads legally, and in a working configuration the wheels may span any number of rows between two and six. Advantageously, the track width of each steerable wheel is adjustable independently.

According to another aspect of the invention there is provided an agricultural machine having a pair of steerable wheels with an ad _j ustable track width, and a steering control system wherein the Ackerman angle for the front wheels is generated by the control system.

According to another aspect of the invention there is provided an agricultural machine having at least one pair of wheels mounted on individual wheel mounts and wherein each wheel mount includes an hydraulic actuator. The hydraulic actuators are preferably connected hydraulically such that retraction of one of the hydraulic actuators causes extension of the other hydraulic actuator. The hydraulic actuators may be connected to a source of pressurised fluid and control apparatus to provide adjustable ride height and/or suspension, which may be adjustable, for the machine.

According to another aspect of the invention there is provided an agricultural machine including a chassis and at least one working element, wherein the working element is mounted below the chassis.

According to another aspect of the invention there is provided an agricultural machine in the form of a harvester including a bunker for receiving harvested crop and wherein the bunker is mounted to rotate through 180 degrees to provide for discharge to either side of the said machine. Advantageously, the bunker may be rotated through 90 degrees so that the machine's overall width is within the limit permitted for legal road travel.

According to another aspect of the invention there is provided an agricultural machine including a rear axle assembly attached to a first slew ring mounted on the chassis of the machine and a bunker for receiving harvested crop attached to a second slew ring mounted on the chassis, and wherein the first and second slew rings are substantially aligned axially.

According to another aspect of the invention there is provided an agricultural machine where one or more steering axles are mounted on a freely rotating bogie whereby steering of said axles enables said machine to turn about within its own length. These steering wheels may be controlled to maintain a selected offset in the machine's chassis during work, such control preferably including a computer controller.

According to another aspect of the invention there is provided an agricultural machine comprising a pair of lifting mechanisms each associated with a working element support frame of the agricultural machine, wherein the lifting mechanism causes rotation of the working element support frame between working and transport configurations and wherein the lifting mechanism includes means to generate sideways movement of the working element support frame with respect to the chassis of the agricultural machine. Preferably two such lifting mechanisms are provided for each working element, and are advantageously each disposed towards opposite ends of the working element support frame with which they are associated.

According to another aspect of the invention there is provided an agricultural machine comprising at least one working element support and a means to generate sideways movement

associated therewith, wherein actuation of the said means causes a sideways movement of the said working element support with respect to the chassis.

According to another aspect of the invention there is provided an agricultural machine including a spiral cleaner, wherein at least one part of the said cleaner includes means to generate sideways movement of a product carried on the said cleaner. Preferably, the spiral cleaner includes at least one roller constructed from a compressible material, such as a micro-cellular plastic material.

According to another aspect of the invention there is provided a secondary cleaner including at least one pair of rollers, wherein a first roller of the pair is mounted for rotation in a fixed position and the second roller is mounted for rotation on a mounting means which provides for movement of the second roller towards and/or away from the first roller, and wherein the second roller is driven by a belt or chain drive and wherein the said mounting means mounts the said second roller such that a minimum amount of torque causing the second roller to move towards or away from the first is generated.

According to another aspect of the invention there is provided an agricultural machine configured as a harvesting machine including a pair of crop lifters, a pair of elevators, each associated with a respective crop lifter, and a bunker, wherein each elevator of the pair delivers harvested crop directly into the bunker.

According to another aspect of the invention there is provided an agricultural machine including a chassis and a working element supported on a support frame, which in use is maintained level gravitationally, and the machine further comprises a linkage between the said support frame an a part of the working element, the linkage constraining the working element against sideways movement with respect to the said support frame. The working elements are therefore kept stable both horizontally and vertically stable whilst the main chassis follows field contours.

According to another aspect of the invention there is provided a soil separating apparatus including agitation means, wherein the agitation means includes a high frequency low amplitude agitator, which may include a linear actuator and associated drive means, which drive means may be electronically programmable. The high frequency agitator may be mounted by suspension units. The agitation means may further include a low frequency high amplitude agitator. The agitation means may further include an agitator which generates an intermediate frequency and intermediate amplitude.

According to another aspect of the invention there is provided an agricultural machine including depth sensors for the working elements, which sensors may be ultra-sonic sensors.

According to a further aspect of the invention there is provide an agricultural machine having steering control means which provides for the machine to self steer. The steering control means includes sensors, which may be ultrasonic sensors.,

The ability to self-steer allows the operator to watch the working elements of the machine rather than paying attention to steering the machine. Further the operator's cab is constructed to facilitate this, and preferably includes a seat and controls arranged to swivel between forwards and rearwards facing positions. The floor of the cab may be transparent.

Preferred features of the invention can be found in the description and drawings of this specification.

Embodiments of the invention is described below, and preferred features of the invention can be found in the description. Individual components of the machines or constructions shown in the drawings may in themselves be preferred features of the invention.

Brief Description of the Drawings

In the drawings, which illustrate preferred embodiments of the invention, and are by way of example:

Figure 1 is a side view of a potato harvesting machine according to an aspect of the invention;

Figure 2a is a plan view of the potato harvesting machine illustrated in Figure 1 with the bunker arranged to discharge to one side of the machine;

Figure 2b is a plan view of the potato harvesting machine illustrated in Figure 1 with the bunker arranged to discharge to the other side of the machine;

Figure 2c is a plan view of the potato harvesting machine illustrated in Figure 1 with the bunker arranged in its transport configuration;

Figure 3 is a side view of the lifting share and web of the machine illustrated in Figure 1;

Figure 4 is a schematic representation of a the part of the chassis mounting the slew ring column;

Figure 5a is a plan view of the potato harvesting machine illustrated in Figure 1 configured for road transport;

Figure 5b is a plan view of the potato harvesting machine illustrated in Figure 1 configured for field operation;

Figure 5c is a plan view of the potato harvesting machine illustrated in Figure 5b with the steering apparatus of the machine arranged to execute a turn of minimum radius;

Figure 6 is a schematic representation of the chassis of the potato harvesting machine illustrated in Figure 1;

Figure 8a is a side view of the potato harvesting machine illustrated in Figure 1, with the lifting share and web lifted to an out of work position;

Figure 8b is a side view of the potato harvesting machine illustrated in Figure 1 , with the lifting share and web lowered to an in work position;

Figure 8c is a plan view of the potato harvesting machine illustrated in Figure 1 with the lifting share and web lifted into a transport configuration;

Figure 8d is a plan view of the potato harvesting machine illustrated in Figure 1 with the lifting share and web lowered into a working configuration;

Figure 9a is a schematic representation of a directional roller arrangement;

Figure 9b is an end view of a directional roller of the arrangement illustrated in Figure 9a;

Figure 10a is an end view of a drive assembly for the spiral rollers of a directional roller arrangement as illustrated in Figure 1 ;

Figure 10b is an end view of a drive assembly for the flat rollers of a directional roller arrangement as illustrated in Figure 1 ;

Figure 10c is a schematic representation of the directional roller arrangement illustrated in Figure 9a showing the drive assemblies illustrated in Figures 9a and 9b;

Figure 11 is a side view of a front wheel mount of the potato harvesting machine illustrated in Figure 1 ;

Figure 12 is a schematic illustration of the potato harvesting machine illustrated in Figure 1;

Figure 13a is a schematic illustration of the folding mechanism used in the potato harvesting machine illustrated in Figure 1, with the webs lowered to a working position;

Figure 13b is an end view of the folding mechanism with the first stage in the sequence to lift the webs from their working positions to their raised positions;

Figure 13c is an end view of the folding mechanism part way through the second stage in the sequence to lift the webs from their working positions to their raised positions;

Figure 13d is an end view of the folding mechanism with the second stage of the sequence to lift the webs from their working positions to their raised positions completed and the webs raised to their transport position;

Figure 14a is a detailed illustration of the components of the machine which provide for movement of the webs between their working and transport positions;

Figure 14b illustrates the same components shown in Figure 14a with one of the support frames partially raised; and

Figure 14c illustrates the same components shown in Figure 14a and 14b with both the support frames raised to the transport position.

Detailed Description of the Preferred Embodiments

A harvesting machine of the invention is illustrated in Figure 1, the harvesting machine being configured as a potato harvester 1. The potato harvester 1 includes:

i. a chassis;

ϋ. a pair of front wheel assemblies 2;

in. a rear wheel assembly 5, lv. a steering control system, v. an operator's cab 8 vi. a pair of lifting webs 3, vii. a pair of secondary cleaners 4, viii. alignment and depth control apparatus for digging assemblies lx. fold, cross-level and side shift apparatus for digging assemblies, x. a pair of elevators 6, and xi. a bunker 7.

Chassis

Figure 6 illustrates the chassis 100, which comprises spaced apart elongate side members 101 and a cross-member 102 joining the side members 101 to the front of the chassis. The side members 101 are also joined together by a cross-member 109. To the rear of the chassis 100 and forming a part thereof is a slew ring support frame 103, which comprises spaced apart side members 104 and cross-members 105 extending there between. A slew ring 107 is located in the centre of the rectangle created by the side members 104 and the cross-members 105, and is supported therein by structural members 106 extending from the inside surface of the cross-members and side members 104, 105 to the slew ring to which they are attached (shown in greater detail in Figure 4).

In the corners formed between the elongate elements 101 and the cross-member 102, there are located mounting brackets 110 for the front wheel mounts, which will be described in greater detail with reference to Figures 11 and Figure 12.

It is important to note that the working units are independent of but suspended from the main chassis.

Pair of Front Wheel Assemblies

The front wheel assemblies 2 comprise an arm 210 mounted in mounting brackets 110 of the chassis 100 in order that the arms 210 may be pivoted between the configurations illustrated in Figures 5a and 5b. Suitable actuators, for example hydraulic rams, are provided between the chassis 100 and the arms 210 to change the track width of the front wheels. A wheel suspension assembly (see Figure 11) 212 is attached to each arm 210 by means of an attachment plate 214 with attaches to a slew ring 211 of the arm 210. The whole wheel suspension assembly 212 may therefore be pivoted with respect to the arm 210.

The wheel suspension assembly 212 comprises an upper part 213 to which the plate 214 is attached and a lower part 215 which is attached to the upper part 213 by a pin 218. The lower part 215 mounts a wheel 216. An actuator 219 extends between the upper and lower parts 213, 215. The actuators 219 may be used to raise or lower the whole front end of the machine, or to level the machine.

Whilst the track width of the rear wheels 203 is fixed, the track width of the front wheel assemblies 2 must be adjustable in order to provide for working and transport configurations. For a potato harvesting machine the track width provided by the front wheel assemblies may change between a working configuration of 5.6m and a transport configuration of 1.8m. Each wheel assembly may be moved independently. This function can be used to produce an offset track.

In order to provide for an agricultural machine to traverse rough ground it would typically be provided with one axle in the form of a beam axle, i.e the axle is pivotally mounted to the chassis of the vehicle. In the machine of the present invention the region between the front wheels must be unencumbered.

A beam axle may be provided hydraulically and in the present invention this is achieved by the provision of hydraulic actuators in each front wheel assembly which share a common hydraulic fluid supply. By sharing a common hydraulic fluid supply when one of the front wheels falls the hydraulic actuator associated therewith extends, drawing hydraulic fluid from the common supply, which in turn draws hydraulic fluid from the actuator associated with the other front wheel, causing that wheel to rise. Hence, a beam axle is created without the requirement for a physical beam pivotally mounted on the chassis of the machine. In the machine illustrated in the Figures, the actuators 219, together with a common fluid supply provide the hydraulic beam.

In order to control the working depth of the shares accurately, when in work suspension of the front wheels to attenuate forces exerted on the wheels by the ground is not desirable. However, when the shares are out of work, for example when the machine is being driven between fields, or when executing headland turns, suspension of the front wheels for the purpose of attenuating forces exerted on the wheels by the ground would be desirable. In an arrangement as described above, a degree of attenuation may be provided by including an accumulator, such as a nitrogen over oil accumulator, in the hydraulic circuit. The hydraulic circuit may be configured for the selective engagement and disengagement of suspension by including a valve in the circuit which in one position isolates the accumulator from the hydraulic line connecting the actuators 219 and in another position puts the accumulator in fluid communication with the said hydraulic line. An electronic controller may be provided in order that the machine operator may select appropriate suspension settings.

The ability to raise and lower the machine by means of the actuators 219 may also be useful when negotiating field entrances, which often present steep gradients both up and down, often in close sequence.

Rear Wheel Assembly

The rear wheel assembly 5 comprises a slew ring attachment member 200 which is attached to the slew ring column and walking beams 201 which carry the wheels 203. The walking beams 201 are pivotally mounted on shafts 202 extending from the slew ring attachment member 200. Walking beams are used widely for the mounting of wheels in agricultural machinery applications and will not be described in further detail herein. The wheels 203 are mounted on king pins 204 which provide for pivoting of the wheels with respect to the walking beams 201.

In use steering of the rear wheel assembly 5 is achieved by rotating the drive wheels about their king pins. Due to the mounting of the rear wheel assembly on the slew ring, turning the drive wheels about their king pins causes a change in angle of the whole assembly 5 relative to the longitudinal axis of the harvesting machine. This significantly increases the manoeuvrability of the harvesting machine.

Advantageously, the rear wheel assembly 5 includes a locking means which, when locked, prevents pivoting of the walking beam 201 with respect to the chassis 100. The walking beam may therefore be locked against such movement when the rear axle is turned beyond set limites with respect to the longitudinal centre line of the machine in order to prevent over-turning of the machine.

Further, the rear wheel assembly may include a locking means to lock the slew ring against movement, such a lock being used to prevent rotation of the slew ring during road travel.

Steering Control System

Root crop harvesters are by nature large machines yet it is desirable that they are maneuverable, this has not been sufficiently achieved by machines of the present art.

The steering controller provides for different steering modes; for example, front wheel steering only, rear wheel steering only, front and rear wheel steering.

Whilst such different modes of steering are well known in the field of agricultural machines the addition of a freely rotating rear bogie adds considerably to the ability and complexity of the steering systems.

The harvester of the present invention is very agile. It is steered by front wheels that have the ability to turn through 220 degrees, a rear beam axle with four wheel steering mounted on a slew ring which itself can turn through 180 degrees. Referring now to Figures 1, 5a to 5c, 11 and 12, the harvesting machine 1 is steered by synchronised movement of all the aforementioned assemblies 2, 5.

It will be appreciated that the Ackerman angle must change if the track width of the front wheels is changed. Further the required Ackerman angle also depends upon the position of the rear wheel assembly 5.

Steering of the front and rear wheels is managed by electronic command of hydraulic actuators. The Ackerman angle is generated by a steering controller which includes steering control software and has a number of inputs connectable to transducers which generate the input information necessary to generate the said Ackerman angle. A transducer is located between the arm 210 and the chassis 100 to generate a signal representative of the track width of the front wheels. A further transducer is located between the chassis 100 and the rear wheel assembly 5 to generate a signal representative of the angle of the rear wheel assembly 5 relative to the chassis 100. The transducers may be potentiometers. The Ackerman angle is calculated and continuously updated by the control software according to the signals received from the said transducers.

Control of the steering system may either be directly by the operator or by an electronic self- steer system which is configured to screen out noise produced by crop haulm and weeds, thereby permitting the machine to self-steer along the crop rows.

Operator's Cab

The operator's seat and controls swivel through at least 180 degrees in order that the driver may face forward when transporting the machine and may face rearward when harvesting. By facing rearward the operator has a clear view of those elements of the machine lifting the crop.

Pair of Lifting Webs

The lifting webs 3 are each mounted on a separate sub-chassis beneath the chassis 100. The rear wheel assemblies 5 are mounted behind the webs and cleaner, thus allowing the inclination of the lifting web 3 to be set at the most desirable angle, i.e. in the region of 18 degrees up from the horizontal.

Figures 2a to 2c illustrate the different positions the bunker 7 may occupy.

In Figure 2a, the bunker 7 of the harvester 1 is configured such that bunker discharge elevator 9 discharging to the right of the machine 1 (with the machine travelling in the direction X). In Figure 2b the bunker 7 of the harvester 1 is configured such that the bunker discharge elevator 9 discharges to the left of the machine 1 (with the machine travelling in the direction X). In Figure 2c the bunker 7 is configured for filling thereof with the bunker discharge elevator 9 facing rearward.

The Lifting Web

Figure 3 illustrates the lifting web 3 in greater detail. The lifting web 3 comprises web belt 10 which is supported by rollers Elongate members 17 are located to either side of the web belt 10, the ends of the members 17 being pivotally attached to the side plates 16. The elongate members 17 carry primary and secondary web belt agitators 18 and 19. A tertiary agitator 302 is mounted on a plate 15, which is attached to the frame 120.

The primary agitator provides low frequency, high amplitude agitation and comprises a rocker assembly which includes a shaft 20 to which are attached a plurality of rocker arms 21. The

free ends of each rocker arm 21 are provided with a roller 22. Respective ends of the shaft 20 are mounted in bearings 23. The rocker shaft 18 is rotated reciprocally about the shaft 20 by means of actuators 24, which in the present example are hydraulic actuators, hydraulic fluid being introduced into and removed from causing the rollers 22' and 22 respectively to move towards and away from the web belt 10. The degree of agitation provided by the primary agitator can be adjusted by increasing or decreasing the extent of travel of the actuator and/or increasing or decreasing the frequency of operation of the actuator. In the present invention the flow of power to the actuators is controlled by a programmable electronic device which enables an infinite degree of flexibility, between limits, to be brought to an agitation sequence in terms of frequency, duration and travel. Such agitation sequences may be stored in the programmable electronic device to be at the disposal of the operator to use depending on crop conditions.

The secondary agitator 19 provides agitation of intermediate frequency and amplitude, and comprises a shaft 25 the ends of which are mounted in bearings 30 attached to the lower part of a side plate 31, the side plates 31 being attached to the inner surface of the respective elongate members 17. On the shaft 25 are mounted a plurality of brackets 26 spaced apart longitudinally along the shaft, each bracket 26 carrying a number of rollers 27, three in the present example, which are rotatably mounted on the said bracket 26. As the shaft 25 rotates the rollers repeatedly engage and disengage with the web belt 10. The intensity of agitation achieved by the secondary agitator can be ad _j usted by increasing or decreasing the speed of rotation of the shaft 25. Agitation settings may be stored in the programmable electronic device to be at the disposal of the operator to use depending on crop conditions.

The third agitator provides a high frequency low amplitude agitation. The agitator 302 is mounted via suspension arms 303 on to plates 15, and comprises a variable high frequency agitator 304 suspended in such a way as the vibrations are transmitted to the web thereby causing the fluidisation of remaining soil particles on the web. The high frequency agitator may be driven

hydraulically. Such agitation settings can be stored in the programmable electronic device and are at the disposal of the operator to use depending on crop conditions.

Pair of Secondary Cleaners

Referring still to Figure 3, and to Figures 1 and 10, the lifting webs 3 deliver the harvested product onto the secondary cleaner 4. As can be seen from Figure 1, the secondary cleaner includes four banks 4a, 4b, 4c and 4d of rollers. Each bank comprises two pairs of rollers 32, 33 where the roller 32 includes on its surface a spiral flight and the roller 33 has a smooth surface. Banks of rollers 4a to 4c are identical, with a rollers 32 and 33 of each pair being adjacent each other and the roller 33 of one pair being ad _j acent the roller 32 of the following pair, i.e. the roller 33 of the first pair of rollers of bank 4a is ad _j acent to the roller 32 of the following pair of rollers of bank 4b, and similarly for the bank of rollers 4c.

Their purpose is to further clean the harvested crop, continue movement of the harvested crop towards the elevator 6, and to allow any stones or hard clods of soil to pass between the rollers 32, 33. The manner in which the rollers 32 and 33 are mounted and driven provides for stones and clods to pass between the said rollers.

Referring to Figures 1, 3, 9a and 9b, the configuration of rollers in the bank of rollers 4d differs from that in the banks 4a to 4b in that the roller 33 of one pair of rollers is adjacent a roller 33 of the following pair of rollers. Further, whereas the rollers 32 of the banks of rollers 4a to 4c all rotate in the same direction m and the rollers 33 all rotate in the direction n, in the bank of rollers 4d, the rollers 32 and 33 of the first pair of rollers rotate in the directions m and n respectively, but the rollers 32 and 33 of the second pair rotate in the directions m and n respectively.

The rollers of the bank 4d cause the potatoes to be held between the rollers and transferred sideways following the direction of the spiral flights of the rollers 32.

Referring now to Figures 9a and 9b, spiral flighted roller 32 is shown mounted on a shaft 34 which is substantially square in cross section. On the shaft 34 is mounted a plurality of spiral flighted elements 35, each being made of a resilient material, which in the example is a micro -cellular polyurethane material, such that the material is compressible. It is important that the material is compressible in order that the roller 32 will self-clean and so as to prevent damage to the potatoes. When operating, the action of passage of potatoes and loose clods and stones cause compression of the roller 32.

If a stone or hard clod finds its way into the secondary cleaner 4, it must be able to pass between the rollers 32 and 33.

The drive and mounting arrangements for the rollers 32 and 33 will now be described in greater detail with reference to Figures 10a to 10c, one of the banks of rollers 4a to 4c being illustrated therein. The spiral rollers 32 are driven by drive assembly D _S R which is mounted to one side of the machine, and comprises a conventional belt drive comprising a pulley wheel 42 attached to a drive motor and pulley wheels 43 and 44 attached to the ends of respective shafts 32, with power being delivered from the pulley wheel 42 to the pulley wheels 43 and 44 by a belt 45.

The flat rollers 33 are driven by a similar drive assembly DFR mounted on the other side of the machine. Whilst being similar, the drive assembly DFR is more complex than the D _S R drive assembly. Each flat roller 33 is mounted on a lever 53 which may pivot away from the spiral roller so that the rollers 33 may move away from the spiral rollers 32 to allow clods and stones pass from the machine.

An important aspect of the drive assemblies is that only a small proportion of the torque from the drive belt will be transmitted to the lever 53, which reduces the risk of the rollers 32, 33 being moved apart other than in the presence of a stone or clod. This is achieved by the positioning of the pivot mounting point 55 of the levers 53 in close proximity to the drive belt 39. It can be seen

in Figure 10a that the pivot mounting point 55 lies within the envelope formed by the belt 39 and the pulley wheels.

The plates 53 allow the shaft 33 to swing towards and away from the shaft 32. Resilient means are provide between the plate 43 and the pulley mounting plate 53 in order that pressure may be exerted on the flat roller 33.

In the example illustrated in Figures 10a and 10b the resilient means referred to above comprises a leaf spring 58. One end of the leaf spring 58 is attached to a bracket 49 the position of which may be adjusted by screw 50. The leaf spring 58 passes between the pins 51 and 52 with which it engages.

When a stone or clod is grabbed by adjacent spiral and flat rollers the flat roller 33 moves away from the spiral roller 32 against the force generated by the leaf spring 58, which pivots about pin 51. When the stone or clod has passed between the rollers the force generated by the spring brings the roller back to its working position.

Without departing from the invention the drive arrangements D _S R and DFR may be modified to drive an arrangement of rollers as depicted in Figure 9a.

Secondary separators including a spiral flighted roller and an ad _j acent smooth roller are known in the prior art. Such secondary separators provide for relative movement between the spiral flighted roller and the smooth roller to allow stones or hard clods of soil to pass between the respective rollers. One roller is therefore mounted to swing away from the other roller. In such secondary separators in certain conditions a torque can be generated on the roller mount which causes one roller to swing away from the other due to an excessive build up of material on the roller associated with the scraper without any stone or clod requiring the rollers to move apart. This results

in unnecessary loss of potatoes through the secondary separator. It is therefore desirable to avoid such undesirable relative movement between the rollers.

In the present invention the roller drive arrangement illustrated in Figures 10a and 10b avoids the build up of torque which could result in the roller 33 swinging away from the roller 32.

Alignment and depth control of the digging assemblies

Referring now to Figures 3 and 13a to 13d, the webs 3 are each mounted on a frame 120. The frame 120 supports a share mounting assembly 130 which is movable towards and away from the frame 120. A linkage 230 is provided between the frame 120 and the share mounting assembly 130. The linkage 230 is provided to limit side ways movement of the share mounting assembly 130 with respect to the frame 120. For example, if the machine 1 were following a curved path to lift potatoes from a row, once the share is engaged with the soil the share and hence the share mounting assembly would tend to follow a tangential path to the curve. The linkage 230 comprises a plurality of interconnected rods and levers. The levers 231, 236 are pivotally connected to the frame 120. Rods 233, 234 are pivotally attached to respective ends of the lever 231 by pivot mounts 239, 240. The rod 234 is attached at its other end to a bracket attached to cross-member 131 of the share mounting assembly 130 by a pivot mount 241. The lever 236 is attached to the mounting frame 120 by a pivot mount 237. One end of both rods 233 and 235 is connected to a common pivot mount 238 of the lever 236. The linkage behaves in a similar manner to Watts' linkage, by allowing for movement in only a single plane.

In a potato harvesting machine it is desirable that the share be pushed through the ground as this means that the region to the front of the share is not encumbered by the mounting arrangements for the share. However, when such a force is applied to the share of a potato harvester and the share meets and obstruction the tendency is for the share to dig into the ground too deeply rather than lifting out to clear the obstruction, which is undesirable.

In the harvester of the present invention the share is pushed by the digger assembly side arms. However the connection between the side arms 17 and the share brackets is by way of an actuator 265 mounted at a rearward inclined angle of between 10 and 20 degrees. Should the share hit an obstruction the share will be pushed back and because of the angle of the supporting actuator it will also be lifted up out of the ground. The ease by which this action occurs is adjusted by varying the pressure in the actuator. This actuator is also used for fine depth ad _j ustment.

Accurate control of share depth across the machine is vital both to prevent damage to the crop and minimise unnecessary intake of soil. In this invention this being achieved using depth sensors on each side of the share mounting assembly and controlling the extension of the fine ad _j ustment actuators independently of each other and according to the output of the depth sensor associated with the same side of the share mounting assembly as the respective actuator.

The position of the fine ad _j ustment actuator is monitored by a linear potentiometer which provides the programmable electronic device which controls the depth systems with information which is used to maintain the fine ad _j ustment actuator in a central position by regulating the length of the main digger assembly lift ram 266.

The programmable electronic device allows the operator to change the depth settings on the move and the can store such settings for future use.

Fold, Cross Level and Side-shift of digging assemblies

Referring now to Figures 3, 13a to 13d, in Figure 13a the machine 1 is in its working configuration with the support frames 120 occupying a substantially horizontal plane and the lifting webs 3 lowered. The machine 1 is configured for transport in Figure 13d with the frames occupying a substantially vertical plane. In order to move from the configuration illustrated in Figure 13a to

that illustrated in Figure 13d, the lifting webs 3 are first lifted to the position shown in Figure 13b so that the distance between the support frame 120 and the shares 137 of the lifting web 3 is reduced.

When the machine is in the configuration illustrated in Figure 13b, the lifting webs 3 are rotated from the horizontal plane to the vertical plane. Figure 13c illustrates the machine part way through the sequence to change from a working configuration to a transport configuration. To change the machine from a transport configuration to a working configuration the steps illustrated in Figures 13a to 13d are followed in reverse order.

It will be appreciated from Figures 13a to 13d that there would be interference between the two lifting webs 3 during rotation thereof between the configurations illustrated in Figures 13b and 13c. The invention therefore provides a solution to this problem as illustrated in Figures 14a to 14c.

Referring now to Figures 14a to 14c, the support frames 120 are each supported from one of the side members 101 of the chassis 100 by a linkage 249, preferably two such linkages each disposed towards opposite ends of one of the support frames 120, for example at points a and b in Figure 1. The linkage 249 comprises a bracket 250 which is attached to the side member 101. Attached to the bracket 250 is a lever 251 and a hydraulic actuator 255. The lever 251 is also attached to a bracket 252 which is itself attached to the support frame 120. One end of the hydraulic actuator 255 is attached to the lever 251 by pivot mounting which allows the actuator 255 to pivot with respect to the lever 251. The other end of the actuator 255 is attached to the bracket 250 by a pin 262 which permits pivoting of the actuator about the said pin 262. A second bracket 257 is also attached to the side member 101. One end of an hydraulic actuator 259 is attached to the said bracket 257 by a pin 261, with the other end of the actuator 259 being attached to a bracket 258 by a pin 260. The pins 260, 261 provide for pivoting of the actuator 259 with respect to both the support frame 120 and the side member 101 of the chassis 100.

The function of the linkage 249 is to cause the support frame 120, and hence those components attached to it, to move sideways as the support frame 120 is rotated between the horizontal and vertical positions. Rotation of the support frame 120 is caused by extension or retraction of the actuator 259. Sideways shifting of the support frame 120 during the said rotation is caused by retraction or extension of the hydraulic actuator 255. Looking at Figure 14a at the chassis side member 101 located on the left of the drawings, if the hydraulic actuator 255 is retracted the lever 251 must rotate clockwise, thereby causing the support frame 120 to rotate about the pin 260. When retraction of the actuator 255 is combined with extension of the actuator 259, the effect of retraction of the actuator 255 is to cause sideways movement of the support frame to the left. In addition to the sideways movement generated by the actuator 255 the support frame is rotated about the pin 253 by extension of the actuator 259 as is illustrated in Figure 14b.

In Figure 14c the actuator 255 is extended in order that the support frame 120 lies in a substantially vertical plane.

To move from the configuration shown in Figure 14c to the configuration shown in Figure 14a the sequence of extension and retraction of the actuators 255 and 259 described above is reversed.

The machine includes a suitable hydraulic controller which controls and synchronises the supply of hydraulic fluid to the actuators 255 and 259 to generate the movement described above.

In addition to providing for movement of the support frames 120 between horizontal and vertical orientations, the linkage 249 also provides for side shifting of the support frames 120. When the machine is working across sloping ground there is a danger that the lifting web 3 will become misaligned with the rows of crop to be harvested. This is because the front wheels run between rows of crop to be harvest (one wheel may run between two rows of unharvested crop with the other wheel running between a row of unharvested crop and a row of harvested crop). When operating on

a slope, the support frames are maintained gravitationally level. With the chassis 100 lying substantially parallel to the ground and the support frames being adjusted to be gravitationally level the lifting webs may become misaligned with the rows of crop to be harvested. The linkage 249 may therefore be used to shift the support frame sideways with respect to the chassis 100 to bring the lifting webs into alignment with the rows of crop to be harvested.

Pair of Elevators

As can be seen from Figures 1 and 12, potatoes are delivered to the hopper 160 by a pair of elevators 6, each elevator being fed by one of the secondary cleaners 4. As the hopper 160 fills with potatoes the elevators 6 must be lifted such that the delivery end of the elevator is clear of the heap of potatoes building up in the hopper.

The height of the discharge end of each elevator 6 is controlled independently using suitable apparatus, which is in itself well known in the art. For example, ultra-sound transducers with suitable control software may be used.

Harvesters of the prior art bring the potatoes to a single elevator which then delivers to a hopper. Using a pair of elevators provides threes linked advantages.

Where a single elevator is used, only one heap develops beneath the elevator. As such for a given volume of product unloaded into the hopper the elevator height over the heap will be greater with a single elevator than where a pair of elevators is used over a pair of heaps. Further, the width of the elevator compared to the width of the heap of potatoes building up underneath the elevator is wider for a single elevator than where pair elevators are used, which create a pair of heaps. As such for a single elevator a greater proportion of the potatoes must fall by a greater distance to reach the heap than with a pair of elevators. Furthermore, with a pair of elevators, as the two heaps build up the adjacent edges quickly meet, thereby forming a single heap with two filling points. This results in

the potatoes dropping off the elevators and landing between the heaps falling a smaller distance than those potatoes falling off the elevators at the sides of the elevators adjacent the walls /discharge end of the hopper 160. Filling from two points also allows a greater volume of potatoes to be deposited into the hopper 160 than would be the case for a single elevator, where the maximum volume is limited by the natural angle of repose of the potatoes loaded into the hopper.

The Bunker

A conventional harvester discharges to only one side and therefore if the vehicle into which the crop is to be discharged is not to run over the unharvested crop the vehicle may only drive to one side of the harvester. This means that known harvesting machines may not complete the harvesting of one row or group of rows of crop, turn around on the headland and then proceed to harvest that row or group of rows adjacent the row or group of rows just harvested, as this would result in the discharge elevator being directed towards the unharvested crop. Instead the crop is harvested in lands, resulting in significant wasted time for the harvester traversing headlands.

The bunker is 7 is mounted on the slew ring column 107 by, which allows for the bunker 7 to rotate on the slew ring 107. Rotation of the bunker on the slew ring 107 may be achieved by means of any suitable actuator, which may be a hydraulic ram for example.

As illustrated in Figures 2a to 2c, the bunker may take up one of three positions, namely: a loading position with discharge to the left, a loading position with discharge to the right, or a transport position with the bunker rotated such that its longitudinal axis is in line with the longitudinal axis of the harvesting machine as illustrated in Figure 2c so that the overall width of the machine remains within the legal maximum for road travel. It is possible to lift crop into the bunker when it is in any of these positions and also when moving between these positions.

It should be noted that width of the bunker is constant from front to back and that the outlet simply consists of one end of the bunker being open. The path of harvested crop being discharged from the bunker is therefore unimpeded path, which results in significantly less crop damage than would occur in a bunker where there is a constriction before the bunker outlet.