GB2208994A - Root crop harvester - Google Patents

Abstract

A root crop harvester 10 comprises a horizontally-vibrated stepped primary web 33 feeding material on to horizontally-vibrated secondary web, the vibrating drive for which is derived via an adjustable-amplitude actuator drive 96 including crank wheels 98 driven by a hydraulic motor and connected to the primary web hanger 55. Rod 114 connects between the secondary web hanger 78 and a stud 116 projecting through arcuate slot 118 in hanger 55, the stud being adjustable along the slot to vary the vibration transmitted to the secondary web. The harvester also includes an elevator for delivering crop to a trailer and which is pivotally mounted on the harvester so that it swings in or against the direction of travel of the harvester if it receives an impact. <IMAGE>

Description

ROOT CROP HARVESTER The present invention relates to root crop harvesters within which term is to be included potato harvesters.

Existing designs of potato harvester are subject to various drawbacks and it is an object of the present invention to provide a root crop harvester in which at least some of these drawbacks are either reduced or avoided.

According to the present invention, there is provided a root crop harvester comprising two or more webs, one of which is a primary web and the last of which Is vibrated, and adjustment means for changing the amplitude and/or frequency of the vibrations of at least the last web.

Conveniently, the last web comprises a secondary web and the preceding web comprises either the primary web of the harvester or an intermediate web preceded by the primary web.

Conveniently, the adjustment means Is operable from the driving seat of the harvester (if self-propelled) or from the cab of the towing tractor (if not).

Conveniently, when vibration amplitude is to be adjusted, the adjustment means operates by varying the ratio of the amplitude of the last web to the amplitude of the preceding web.

Preferably, in this last case, the amplitude ratio can be varied (preferably, continuously) between 1:1 and 0:1.

Conveniently, the harvester includes automatic repositioning means adapted to reduce or eliminate any gap which might otherwise occur in operation between the last web and the preceding web when the last web is set by the control means for low or minimal (e.g. zero) vibration.

Alternatively, or additionally, the adjustment means may comprise means for varying the frequency of vibration of the last and preceding webs (both preferably continuously) e.g. from 0 c/s to 3 c/s.

Conveniently, the last web and the preceding web are adapted to be vibrated in directions lying substantially parallel to what, in operation of the harvester, will constitute the respective material-bearing surfaces of the two webs (hereinafter referred to, for brevity, simply as the material-bearing surfaces of the two webs). The resultant vibrations of the webs will hereinafter be referred to as "in-plane" vibrations.

A convenient in-plane drive means for agitating either of the two webs might, for example, be an eccentrically mounted crank pin and connection rod, the effective stroke of which is adjustable.

Alternatively, the last web might be driven from the preceding web by a swinging link and connecting rod assembly whose effective amplitude of movement may be varied e.g. by an electric or other actuator or by a screw adjustment which moves the connecting rod pivot through an arcuate path.

Conveniently, the last web and the preceding web are vibrated in antiphase to one another so as to reduce the overall vibration effects transmitted to the rest of the harvester. However, when an intermediate web is present then, conveniently, the intermediate and secondary webs are vibrated together in anti phase to the primary web. This latter arrangement takes account of the fact that in normal use, the primary web will be carrying the heavier load.

Conveniently, the last web is adapted to be driven with a slower (e.g. 20 slower) conveying speed than the preceding web, this amount being adjustable. By "conveying speed" in this context and elsewhere in this specification, is meant the overall speed of the web concerned i.e. ignoring any in-plane vibrations which might be present.

Conveniently, the primary web conveying speed is controlled from the driving seat of the harvester (if self-propelled) or from the cab of the towing tractor if not.

Conveniently, a double-roller haulm-stripper is fitted at the rear of the last web and/or the preceding web.

Conveniently, to enhance sieving, a fixed or variable step section is included either in the primary web or, where an intermediate web is present, between the primary and the Intermediate webs, if preferred.

Conveniently, some or all of the webs are of a hollow bar construction with two side belts but no centre traction belt.

Alternatively, a centre belt may additionally be fitted and the bars may be hollow or solid.

Conveniently, the primary web inclines upwardly at not more than 15 to the horizontal.

Conveniently, the share assembly of the harvester comprises power-driven double-disc shares delivering rearwards of the front of the primary web to avoid impact damage of the crop at the share-to-web transfer point.

Conveniently, the primary web and share assembly are mounted in a sub-frame which is pivoted to allow lifting of the primary web and share assembly at headlands and/or to allow the inclinations of the primary web and share assembly to be controlled by a depth-monitoring device during operation of the harvester.

Conveniently, the depth-monitoring device comprises a depthcontrol roller designed to run along the bottom of a furrow between ridges.

Conveniently, the harvester includes a delivery conveyor adapted to transfer material received from the last web to an appropriate discharge point.

Preferably, the delivery conveyor is pivotally mounted so that on receiving an impact it is capable of swinging in or against the direction of travel of the harvester over the ground thereby to lessen the likelihood of impact damage to the conveyor. Such impacts might occur, for example, between the delivery conveyor and the front or tailboard of a trailer receiving crop from the delivery conveyor.

Thus in one such arrangement, the delivery conveyor is supported on the rearmost of two transverse subframes the foremost of which is attached by vertical pivots to the preceding section of the harvester at one side of the harvester and to the rearmost sub-frame at the other side of the harvester, a spring or like biassing means being operative to hold the sub-frames against the rear of the harvester in the absence of any disturbing impact forces.

In an alternative arrangement, the distal section of the delivery conveyor is mounted on a sub-frame which is secured to a sub-frame for the preceding section of the conveyor by a pivotal connection the pivot axis of which lies parallel to the material-bearing surface of the conveyor belt at the junction of the two sections.

It is envisaged that the various vibrating web systems outlined above may be of use in a different context to that described above e.g. they might be of use in a static plant and/or with materials other than root crops. Thus in accordance with a second aspect of the Invention a separating conveyor for use in a static plant and/or with materials other than root crops comprises two or more webs one of which is a primary web and the last of which is vibrated, and adjustment means for changing the amplitude and/or frequency of the vibrations of at least the last web.

In particular, but not exclusively, this second aspect of the invention embraces such conveyors when including one or more of the preferred features of the root crop harvester which have been outlined above and/or included in the illustrated embodiments (or described variants of these) e.g. having an intermediate web, varying the amplitude ratio of the final two webs, operating with in-plane vibration etc. etc.

Further, the invention includes any mobile or static machine other than a root crop harvester, when incorporating a conveyor according to the second aspect of the present invention. In this case, however, the conveyor should not include any features from the root crop harvester which are inherently unsuitable in the new context e.g. a share assembly in a static machine, for example.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying simplified and somewhat schematic drawings in which: Figure 1 is a side elevation of a potato harvester in accordance with the invention; Figures la and lb are similar views of the front half and rear half of the same harvester but shown to a larger scale for greater clarity; Figure 2 is a plan view of the same harvester; Figure 3 is a scrap elevational view showing how the vibratory drive is applied to the primary and secondary webs in accordance with a first aspect of the invention; Figure 4 is an enlarged view of part of Figure 3 showing the primary web agitator; Figure 5 shows a modification of the harvester in which an intermediate web is included in accordance with a second aspect of the invention.

Figures 6a - 6d (collectively referred to as "Figure 6") are scrap plan views showing the mounting for a conventional elevator at the rear of the machine; Figure 7 is a side elevation of the elevator of Figure 6; Figure 8 is a simplified perspective view of a new design of delivery elevator shown mounted at the rear end of the harvester; Figure 8a is a detail of the elevator looking along the line A in Figure 8 and drawn to a larger scale; and Figure 8b is a partially-exploded perspective scrap view including that part of the elevator depicted in Figure 8a and drawn to a scale intermediate that of Figures 8 and 8a.

Thus referring now to Figures 1 to 3 of the drawings, a potato harvester 10 according to the present invention comprises a two-row trailed machine having a crop-lifting front section 12 followed by a soil-separating primary web section 14, a crop-conveying secondary web section 16 and a crop-discharge elevator section 18.

At its rear end, the machine is supported on land-wheels 20 which are steerable through a hydraulic linkage (not shown) controlled from the cab of the towing tractor, the rear wheels of which are diagrammatically indicated at 21.

The crop-lifting shares at the front of the machine comprise two inwardly-rotating forwardly-inclined double disc shares 22,23. These have powered digging and scraper discs (not shown) driven from a shaft (not shown) connected to the tractor p.t.o. shaft via multiple vee belts which provide a degree of cushioning. Reference numeral 25 indicates a gear box mounted on the forward end of a first sub-frame 27 which is pivotally mounted at a rear end pivot 29 on a main frame 31 about mid-way along the primary web 33. The web 33 is driven by a hydraulic motor (not shown) whose speed can be varied from a remote control panel in the tractor cab.

It is a design feature of the disc share unit 22,23,25 that a low profile is incorporated to enhance the rearward view of the tractor driver so that he can observe the behaviour of material on the harvester webs.

Secured to the front of the gear box 25 are inclined support arms 35 for a depth control roller 37 which is designed to run centrally between the discs in the furrow between the potatobearing ridges engaged by the disc shares.

At headlands, the disc shares 22,23 and depth control roller 37 can be raised by hydraulic rams 39 acting between a sub-frame bracket 41 and the main frame 31. As these rams extend, they swing the disc assembly and sub-frame about pivot 29 to give about 30 cms clearance under the discs for transport and turning. This new position is shown in broken lines in Figure 1.

The position of the depth control roller 37 can be adjusted in a vertical plane relative to the disc shares (typically from 50 mm below ground level to 50 mm above) by means of a hand screw (not shown) mounted on the housing of gear box 25 to exercise control over the digging depth of the shares. As an alternative to the hand screw, a hydraulic ram (not shown) controlled from the tractor cab or other appropriate point could be used.

Further details of the disc shares 22,23 and the depth control roller 37 may be had from NRDC patent 2118812 and from NRDC patent application 2711791 respectively.

At its front end, the harvester is provided with a pivoted draw-bar 43 which can be slewed to ensure that the harvester runs in line even on side slopes. Drawbar slewing to one side or the other is effected by a hydraulic ram 45 (Figure 2) acting between the draw bar and a main frame bracket 47 and controlled from the tractor cab. Alternative positions illustrated for the drawbar to compensate for an upwards left-to-right slope are shown on Figure 2 in broken line.

In addition to the slewing ram 45, a cab-controlled hydraulic ram (not shown) is also provided for transverse levelling and for levelling of the machine on side slopes.

Turning now to the soil-separating primary web 33, the front and rear support rollers 49,50 for this are arranged on a second sub-frame 52 to give the primary web a gradient of about 15".

This gradient, which is a shallower slope than is currently used in commercially available machines, limits roll-back which could damage the potatoes. Side plates 53 prevent sideways discharge.

The front end of sub-frame 52 Is suspended from the first sub-frame 27 on hangers 54 which are arranged so that various rest positions can be adopted. At its rear end, the sub-frame 52 is suspended on similarly arranged hangers 55 from main frame uprights 56.

In use, both the hangers 54 and 55 are arranged to oscillate about pivots 57 and 58 (Figure 3) through a mean position which is vertical. Other settings of different mean position angles could, however, be arranged e.g. by slotting the hangar top pivot connections to the main frame, to oscillate through a mean position which is normal to the operative run of primary web 33.

Intermediate rollers 60,61 mounted something less than half-way up the sub-frame 52 define an overhanging step section in the material-bearing upper run of the primary web. Although in the illustrated embodiment this step is fixed, it is also feasible in an alternative arrangement (not shown) to have the step moveable (as described, for example, in NRDC Patent 2158738).

At its rear (top) end, after passing round rear roller 50, the primary web 33 wraps round a drive roller 63 which can take the form of toothed sprockets engaging with rubber teeth moulded to the webbing of- the primary belt. The wrap round these sprockets is increased by a further idler roller 65 which may, in an alternative layout, be driven. Idler roller 67 completes the array of web support rollers all of which are mounted on the sub-frame 52.

Mounted on a pivoted bracket 68 underneath the rear (top) end of the primary web 33 and running close to it, are twin haulm stripping rollers 69,70 the second of these rollers being intended to curtail wrapping of haulm around the first.

Reference numeral 71 indicates a manual adjustment for controlling the setting of bracket 68 and the spacing of the haulm-stripping rollers from web 33.

It should be noted that both the haulm-stripping rollers 69,70 are driven anti-clockwise relative to the clockwise rotation of the web rear idler roller and at the same peripheral speed as the web.

The upper end of the primary web 33 all but overhangs the similarly constructed crop-conveying secondary web 72 so as to provide efficient transfer of material from one to the other.

The end support rollers 74,75 for the secondary web are mounted on a third sub-frame 77 (Figure 3) suspended on hangers 78,79 from main-frame uprights 82,83. Reference numerals 80,81 in Figure 3 indicate the pivotal connections between hanger 78 and the upright 82 and sub-frame 77, respectively.

The return run of the secondary web is engaged in analogous fashion to that of the primary web by a drive roller 85 and idler rollers 87,88,89, the arrangement being completed by a second pair of haulm- stripping rollers 91.

As before, all the rollers are mounted on the web' sub-frame (77), and the two haulm-stripping rollers are both driven anti-clockwise relative to the clockwise rotation of the web rear idler roller 75 and at the same peripheral speed as the web.

The transfer region from the primary to the secondary web may be completed by a bank of loosely-hanging fingers (not shown) pivotally mounted on an upright (not shown) from the sub-frame 52 and curling around the top end of the primary web so as to direct into the haulm-stripping rollers 69,70 any haulm present with the potatoes on web 33. The fingers may, for example, be made sufficiently weighty to apply the necessary pressure on the haulm but in var variations, it may be desirable to have the fingers spring-loaded in order that the necessary pressure can be applied. Similar fingers (not shown), can be positioned at the transfer from the secondary web to the delivery elevator.

The secondary web 72 is driven by a chain and sprocket drive (not shown) from the primary web drive shaft but it is possible to alter the surface speed of the secondary web relative to that of the primary by changing the sprockets In the drive - it being generally desirable to have a lower surface speed as the proportion of loose soil etc. to potatoes diminishes. A typicaT web speed for the primary web might be lm/s, for example, while that of the secondary web might lie somewhere in the range 0.6 to 0.8 m/s, depending on conditions.

In accordance with an important operational feature of the machine, both the primary and secondary webs are vibrated in their own planes (independently of the normal running of the webs) by an actuator drive 96.

Basically, the actuator drive 96 comprises two crank-wheels 98 supported side-by-side on main frame uprights and connected to the primary web hanger 55 by a horizontal crank 100.

Typically, the drive to the crank-wheels 98 might comprise a hydraulic motor which can be run at a range of speeds. A typical speed would be 200-220 rpm giving an oscillation frequency of 3.3 hz to the crank 100.

Two ranges of oscillation amplitude for the primary and secondary webs are available by a rotation of up to 180a of a cam plate (not shown) within the crank wheels 98. These ranges may typically be from zero to 35 mm or from 65 mm to 100 mm.

It is to be noted that the haulm-stripping assembly 69,70 moves with the primary web sub-frame as it oscillates to and fro.

As best seen from Figure 4, the crank wheel 98 Is formed with two studs 102,103 projecting through arcuate slots 105,106 of a transfer plate 108. A boss 110 extends from the free face of plate 108 for connection with the crank 100.

In more detail, the studs 102,103 and the slots 105,106 are disposed so as to lie on a circle centred to one side of the crank-wheel rotation axis 112 and the boss 110 is disposed eccentrically of this circle to such a degree as to be co-axial with the crank-wheel rotation axis 112 when the transfer plate 108 has been rotated anti-clockwise to the maximum amount allowed by the slots 105,106 (as shown in Figure 4). Clearly in this latter situation, no reciprocating motion will be imparted to the crank 100 whereas with the plate 108 rotated clockwise to its maximum extent, maximum reciprocation of rod 100 will be achieved.

As well as vibrating the primary web in the desired fashion, typically with an oscillatory movement of 25-35 mm, the actuator drive 96 is also used to vibrate the secondary web, a connection rod 114 being used for this purpose to connect the primary web hanger 55 with the secondary web hanger 78.

As best seen from Figure 3, the rear end of the (or each) connection rod 114 Is pivotally connected to the hanger 78 by a pivot 115 while the front end is secured to a stud 116 via a sllde block (not visible) projecting through an arcuate slot 118 in the hanger casing.

The position of the stud 116 along the slot 118 Is set by a linear electric or hydraulic actuator 121 controlled from the tractor cab. This actuator is housed within the hanger casing and pivotally connected thereto at 122.

Thus to enable varying amounts of vibration to be transmitted to the secondary web as the hanger 55 oscillates about pivot 58, the stroke of the connection rod 114 can be controlled by the actuator 121 to.adjust the height of the stud 116 relative to the hanger pivot point 58.

At the extreme of the stud's upward travel along the slot 118, the stud 116, connection rod 114 and the pivotal connection 115 between the rod 114 and secondary web hanger 78 will all be aligned, with the result that the secondary web sub-frame 77 will be effectively isolated from any vibratory drive from the actuator drive 96.

Although not readily apparent from the drawing, in fact the radius of the slot 118 from pivot point 115 increases towards the top of the slot, so that as the stud 116 is moved to the top of the slot, link 114 pulls hanger 78 and web 72 closer to web 33.

This is arranged to prevent a gap appearing between the webs 33 and 72 when web 33 oscillates and web 72 does not.

At the other extreme of the block's travel, the connection rod 114 will be so disposed as to transmit virtually all of vibratory effect from the actuator drive 96 and both the primary and secondary webs will, to all intents and purposes, be vibrated equally.

Thus, with the stud 116 at its lowest position in the slots 118, an amplitude of, for example, 100 mm or 35 mm might be imparted to the secondary web 72 whilst, as above explained, with the stud at its highest point, a vibration amplitude of 65 mm or practically zero would be obtained at the secondary web thereby, in the latter case, effectively eliminating all horizontal agitation there. Other amplitudes between zero and 100 mm can be imparted by appropriate repositioning of the stud 116 within the slots 118 and, if necessary, rotation of the cam plate referred to earlier within the crank-wheels 98.

Typically, the stud 116 would be set to give maximum agitation to the secondary web for difficult conditions where soil sieving is poor, and to give zero agitation to the secondary web for light soils when the soil cushion has disappeared at the entry point to the secondary web.

Figure 5 shows a modification in which the primary web 33 has been split at 60:61 into a shorter primary web section 200 and an intermediate web section 201. In this arrangement, primary web 200 provides an overhanging step section similar to that formed by rollers 60,61 in the embodiment of Figures 1 to 4.

The support structures for these two web sections are interconnected by a link assembly 202 comprising two equal length hanger.s 203,204, two equal length connecting links 206,207 and a crank link 209 joining together the adjacent ends of the connecting links. These various items are pivotally connected to the main frame 31 at 211,212,213. Elsewhere, as shown, they are pivotally connected either to one another or to the support structures for the primary and intermediate web sections 200,201.

The presence of crank link 209 and the choice of equal length hangers and connecting links ensures that, in operation, the primary and intermediate web sections 200,201 will oscillate by equal amounts in antiphase to one another I.e. when the support structure for web 200 is moving up to the right (as viewed in Figure 5), that for web 201 will be moving down to left, and vice versa.

The secondary web 72 (not shown in Figure 5) is linked with the intermediate web 201 by the same drive assembly as is shown in Figure 3 for the webs 33,72. This means that any oscillation of the secondary web 72 will be in phase with the intermediate web 201.

By dividing the web oscillations in the way above described i.e. with the primary web 200 oscillating in antiphase to both the intermediate and secondary webs 201,72, account is taken of the fact that the effective mass of web 200 will in operation be increased by the greater quantity of soil it Is carrying compared with the essentially produce-carrying webs 201,72. Thus a more effective counterbalancing is achieved than with the first described modification in which the secondary web 72 oscillated in phase with the longer and soil-carrying primary web 33.

At its rear end, the secondary web 72 discharges onto a delivery conveyor or "elevator" 126 The elevator 126 is conveniently a standard commercially available unit, optionally of the type having flights which fold flat at the horizontally disposed portion of the conveyor receiving potatoes from the secondary web but which move to a position approximately normal to the conveyor at its steeply sloping part.

In operation, the elevator 126 will discharge sidewardly of the harvester onto an appropriate trailer (not shown) towed alongside the harvester in conventional manner.

At the other extreme of the block's travel, the connection rod 114 will be so disposed as to transmit virtually all of vibratory effect from the actuator drive 96 and both the primary and secondary webs will, to all intents and purposes, be vibrated equally.

Thus, with the block 120 at Its lowest position in the slots 118, an amplitude of, for example, 35 mm might be imparted to the secondary web 72 whilst, as above explained, with the block at its highest point, a vibration amplitude of practically zero would be obtained at the secondary web thereby effectively eliminating all horizontal agitation there.

Typically, the block 120 would be set to give maximum agitation to the secondary web for difficult conditions where soil sieving is poor, and to give zero agitation to the secondary web for light soils when the soil cushion has disappeared at the entry point to the secondary web.

In circumstances of very heavy conditions or where sandy soil is lost at a very early stage, it may prove necessary to reduce the primary web stroke and increase the secondary web stroke. In a modification of the illustrated design (not shown), this could be arranged by making rod 114 adjustable in length by a central turnbuckle or other means and altering the height of pivot point 115 to bring it in closer proximity to pivot 80, thereby amplifying the effect of the stroke of crank 100.

In another modification (not shown), the hanger 79 extends upwardly beyond pivotal connection 80 and pivot 115 is positioned in this extension. This causes the secondary web to oscillate in opposition to the primary web, so as to combat any surging imbalance in the system in very heavy soils. Appropriate changes in the design of slot 118 will also be required in this instance.

At its rear end, the secondary web 72 discharges onto the elevator 126 as before.

It has been a problem in the past, that elevators have been damaged, often severely, by impact with the front board or tail-board of the trailer when the harvester has temporarily lagged behind the trailer-towing vehicle or vice-versa. This event can seriously disrupt the harvesting operation and repair costs to bent delivery conveyors can be high. The cause of collision is the development of unexpected relative movement between the harvester and the tractor trailer combination. It is usually initiated by the harvester stopping suddenly due to a blockage in which case, unless the trailer tractor driver is constantly vigilant, the trailer tailboard quickly collides with the end of the delivery conveyor.

To alleviate this problem, which can be present in any design of root crop harvester, not just that of the present invention, or possibly in other agricultural machinery as well, the elevator 126 is mounted so as to be able to swing through an arc. This can be in either direction from the position shown in plan view which is at right angles to the harvester chassis and webs.

This co-called "double break-back" facility is achieved by mounting the conveyor in a support cage 128 the front end of which is connected with the rear end upright 83 of the harvester main-frame 31 by what can best be described (when viewed in plan) as a pivoted zig-zag linkage 129 (see Figure 6). By this, is meant a linkage having a string of three elements 130,131,132 pivotally interconnected at 134,135 and the attached rearmost element 130 is attached by a vertical pivot 136 to one back corner edge of the main frame upright 83. When folded flat, as will usually be the case, the linkage will extend from side to side of the main frame 31 as shown in Figure 6a where reference numerals 138,139,140 respectively indicate a distribution chute, a material-retaining wall member and a deflector for the transversely-moving stream of potatoes.

In a variation (not shown), the chute 138 is replaced by a distribution belt. This is supported on two externally driven rollers spaced along the length of the machine and converging towards one another so as to provide the distribution belt with a moving surface the crop-bearing region of which is of approximately the same plan shape and size as that of the chute 188 shown in Figure 6a.

The support rollers for the distribution belt will have to taper in the direction of roller convergence so as to reduce the peripheral speed of the rollers to suit the peripheral dlmension of the belt at that point. In addition, sprockets in the rollers engage with chains secured to the inner surfaces of the belt to prevent axial slip of the belt along the rollers during use.

Preferably, the height of the downstream roller may be adjustable to alter the slope of the belt.

The arrangement is completed by a spring-loaded hook and eye connection 142 of which the tension spring 143 acts between the trailing element 132 and a forward projection 144 from the leading element 130. A dropper pin assembly 146 is used to secure linkage element 130 to the main frame 31.

To better understand the action of this so called "double break-back" linkage 129, reference should be made to the different situations shown in Figure 6 in which the direction of forward motion is from right to left In the drawing. Thus with the linkage 129 in its normal position (Figure 6a), and the elevator extending to what to the driver will be the right-hand side of the harvester, should the elevator impact against the trailer front board, the linkage will open about pivot 134 as shown in Figure 6b so as to minimise the damage to the elevator, the tension spring 143 returning the elevator to its original orientation as normality is restored. If, on the other hand, the elevator impacts against the tailbond of the trailer, then the linkage will open about pivot 135 as shown in Figure 6c and damage to the elevator is once again minimised.For transport, the dropper pin is removed from assembly 146 and the entire linkage 129 (in Its normal collapsed state) is swung outwardly about pivot 136 (as shown in Figure 6d) to the transport position alongside the main body of the harvester. Line 148 in Figure 2 indicates the position of the outer edge of the elevator when in this position.

In practice, there will be sufficient movement at the delivery end of the conveyor to give the tractor driver for the tractor or the harvester an opportunity to stop. If desired, a warning siren and/or flashing light could be fitted to indicate impact.

Typically, as a further safety feature, the elevator swan neck would have a loose link at the attachment point of the adjusting ram to avoid damage to the elevator in the event of the harvester and crop-collecting trailer moving apart and leading to impact of the elevator on the nearside trailer side-board.

Figures 8, 8a and 8b show an alternative break back system in which only the distal section 152 of the delivery conveyor sub-frame is displaced in the event of an impact.

As best seen from Figures 8a and 8b, the sub-frame 154 for section 152 includes a rectangular or square hollow-section crosspiece 156 which is pivotally secured to the corresponding crosspiece 157 of the preceding sub-frame section 159 by a pivot bolt 161. The two crosspieces are spaced apart by rubber bushes 163,164 mounted on the bolt 161. To reduce wear, each bush includes a central brass inlet.

In order to ensure that the two frame sections are correctly aligned, the cross-pieces are further connected together by a shear pin 166. mounted in suitable shearing bushes 168,169. In an alternative design (not shown), a spring-loaded ball detent or the like could be used instead of the shear pin arrangement.

The interface region between adjacent cross-pieces 156,157 is completed by a spring-loaded hydraulic check valve 171 located in the hydraulic circuit for a conveyor belt drive motor (not shown). This valve is held open by a protrusion 173 on the cross-piece 157 when the two sub-frames are in the undisturbed positions shown in Figure 8a. In an alternative version (not shown), the valve assembly 171,173 is replaced by a microswitch and a hydraulic solenoid valve operated by the microswitch.

The conveyor belt, pivot bolt, shear pin and check valve assemblies have all been omitted from Figure 8b in the interests of clarity.

The distal section 152 of the conveyor and the section associated with the sub-frame 159, together form the "swan-neck" section of the conveyor assembly and this is secured to the main section 175 by a horizontal pivot 177 about which the swan-neck section can turn under the control of a hydraulic ram 179 in the usual way.

The inclination of section 175 is controlled by a second hydraulic ram 181 acting between this section and the harvester chassis 183.

The discharge assembly is completed by the delivery conveyor belt 185 adapted at its lower end to receive material from the separating web 16,72.

According to a preferred design, the conveyor belt 185 comprises carrier webs to which cross bars are rivetted at the intervals dictated by flights through which the cross bars pass.

To ensure torsional flexibility, the gaps between adjacent flights are filled by light conveyor belting rather than the closely spaced web rods which are more commonly used in the art.

In operation of the break-back system shown in Figures 8,8a and 8b, collision in either direction (e.g. harvester stopped, trailer continuing or trailer stopped, harvester continuing) will break the shear pin 166 (or spring the detent ball), allowing the end of the delivery conveyor to swing through an angle in the required direction. This angle will be a function of the flexibility of the conveyor belt 185 and the clearances available between the belt at the side plates 187,188 of the sub-frames 154,159. The pivotting movement at the delivery conveyor swan-neck also gives the driver additional time to take emergency action and if it does not make conveyor damage impossible, it should nevertheless reduce the risk of damage.

In order to facilitate the desired slewing action, It is necessary to stop the hydraulic motor driving the conveyor. In the illustrated embodiment, this is achieved by using the hydraulic valve 171 which (as already Indicated) is normally held open by the protrusion 173 but springs into its closed position when pivotting occurs around the pivot bolt 161 and cross-pieces 156 and 157 move away from one another. If desired, a microswitch operated solenoid valve assembly may be used instead of items 171,173, as already described.

After a collision, reinstatement of the impact-protection system is achieved by replacing the shear pin 166 (or by moving the detent ball unit and corresponding indented plate back into register).

Claims (33)

1. A root crop harvester comprising two or more webs, one of which is a primary web and the last of which is vibrated, and adjustment means for changing the amplitude and/or frequency of the vibrations of at least the last web.

2. A harvester as claimed In Claim 1 in which the last web comprises a secondary web and the preceding web comprises the primary web of the harvester.

3. A harvester as claimed in Claim 1 in which the last web comprises a secondary web and the preceding web comprises an intermediate web preceded by the primary web.

4. A harvester as claimed in any preceding claim in which the adjustment means is operable from the driving seat of the harvester (if self-propelled) or from the cab of the towing tractor (if not).

5. A harvester as claimed in any preceding claim when vibration amplitude is to be adjusted and in which the adjustment means operates by varying the ratio of the amplitude of the last web to the amplitude of the preceding web.

6. A harvester as claimed in Claim 5 in which the amplitude ratio can be varied (preferably, continuously) between 1:1 and 0:1.

7. A harvester as claimed in any preceding claim in which the harvester includes automatic repositioning means adapted to reduce or eliminate any gap which might otherwise occur in operation between the last web and the preceding web when the last web is set by the control means for low or minimal (e.g.

zero) vibration.

8. A harvester as claimed in any preceding claim in which the adjustment means comprises means for varying the frequency of vibration of the last and preceding webs (both preferably continuously).

9. A harvester as claimed in any preceding claim in which the last web and the preceding web are adapted to be vibrated in directions lying substantially parallel to the respective material-bearing surfaces of the two webs.

10. A harvester as claimed in Claim 9 in which the drive means for vibrating either of the two webs in said directions comprises an eccentrically mounted crank pin and connection rod, the effective stroke of which is adjustable.

11. A harvester as claimed in Claim 9 in which the last web is driven parallel to its material-bearing surfaces from the preceding web by a swinging link and connecting rod assembly whose effective amplitude of movement may be varied.

12. A harvester as claimed in Claim 11 in which the effective amplitude of the assembly is varied by an electric or other actuator or by a screw adjustment which moves the connecting rod pivot through an arcuate path.

13. A harvester as claimed in any preceding claim in which the last web and the preceding web are vibrated in anti phase to one another so as to reduce the overall vibration effects transmitted to the rest of the harvester.

14. A harvester as claimed in any preceding claim when including the limitations of Claim 3 in which the intermediate andsecondary webs are vibrated together in anti phase to the primary web.

15. A harvester as claimed in any preceding claim in which the last web is adapted to be driven with a slower conveying speed than the preceding web, this amount being adjustable.

16. A harvester as claimed in Claim 15 in which the last web is driven with a 205 slower conveying speed than the preceding web.

17. A harvester as claimed in any preceding claim in which the primary web conveying speed is controlled from the driving seat of the harvester (if self-propelled) or from the cab of the towing tractor if not.

18. A harvester as claimed in any preceding claim in which a double-roller haulm-stripper is fitted at the rear of the last web andlor the preceding web.

19. A harvester as claimed in any preceding claim in which a fixed or variable step section is included either in the primary web or, where an intermediate web is present in accordance with the limitations of Claim 3, optionally between the primary and the intermediate webs.

20. A harvester as claimed in any preceding claim in which some or all of the webs are of a hollow bar construction with two side belts but no centre traction belt.

21. A harvester as claimed in any of Claims 1 to 19 in which some or all of the webs comprise two side belts and a centre belt fitted with bars that are either hollow or solid.

22. A harvester as claimed in any preceding claim in which the primary web inclines upwardly at not more than 15 to the horizontal.

23. A harvester as claimed in any preceding claim in which the share assembly of the harvester comprises power-driven doubledisc shares delivering rearwards of the front of the primary web to avoid impact damage of the crop at the share-to-web transfer point.

24. A harvester as claimed in any preceding claim in which the primary web and share assembly are mounted in a sub-frame which is pivoted to allow lifting of the primary web and share assembly at headlands and/or to allow the inclinations of the primary web and share assembly to be controlled by a depth-monitoring device during operation of the harvester.

25. A harvester as claimed in Claim 24 when including the depth-monitoring device, in which said device comprises a depthcontrol roller designed to run along the bottom of a furrow between ridges.

26. A harvester as claimed in any preceding claim in which the harvester includes a delivery conveyor adapted to transfer material received from the last web to an appropriate discharge point.

27. A harvester as claimed in Claim 26 in which the delivery conveyor is pivotally mounted so that on receiving an impact it is capable of swinging in or against the direction of travel of the harvester over the ground thereby to lessen the likelihood of impact damage to the conveyor.

28. A harvester as claimed in Claim 27 in which the delivery conveyor is supported on the rearmost of two transverse sub-frames the foremost of which is attached by vertical pivots to the preceding section of the harvester at one side of the harvester and to the rearmost sub-frame at the other side of the harvester, a spring or like biassing means being operative to hold the sub-frames against the rear of the harvester in the absence of any disturbing impact forces.

29. A harvester as claimed in Claim 27 in which the distal section of the delivery conveyor is mounted on a sub-frame which is secured to a sub-frame for the preceding section of the conveyor by a pivotal connection the pivot axis of which lies parallel to the material-bearing surface of the conveyor belt at the junction of the two sections.

30. A harvester substantially as hereinbefore described with reference to, and/or as illustrated in, Figures 1, la,lb and 2 or Figures 3 and 4 or Figure 5 or Figures 6 and 7 or Figures 8,8a and 8b of the accompanying drawings.

31. A separating conveyor for use in a static plant and/or with materials other than root crops comprising two or more webs one of which is a primary web and the last of which is vibrated, and adjustment means for changing the amplitude and/or frequency of the vibrations of at least the last web.

32. A separating conveyor as claimed in Claim 31 when including the limitations expressed (in the context of a root crop harvester) in any one or more of Claims 2 to 30, e.g. having an intermediate web, varying the amplitude ratio of the final two webs, operating with in-plane vibration etc. etc.

33. A mobile or static machine other than a root crop harvester, when incorporating a separating conveyor as claimed in Claim 31 or Claim 32.