The invention relates to apparatus for removing extraneous matter from a ground crop.

After ground crops, for example potatoes, are removed from the ground using harvesting machines, it is common place to pass the crop over some type of cleaning mechanism in order to remove extraneous matter, such as stones, earth and vegetable matter (other than the crop) from the crop itself.

One such system uses counter rotating rollers to help remove the extraneous matter from the crop as the crop passes over the rollers. However, a problem with this roller system is that matter, such as shaughs or haulm from potatoes, tends to get trapped between the rollers and collects at the end of the rollers where the crop passes off the rollers. This can result in clogging and jamming of the rollers if the trapped matter builds up. This can be a severe problem to the operation of the rollers, especially in geographical areas where there is a relatively high proportion of moisture in the soil. This clogging of the rollers requires the roller cleaning system to be stopped and the extraneous

matter to be manually removed from the ends of the rollers.

One solution at attempting to overcome this problem has been to have the ends of the rollers floating and not fixed at the end at which the crop passes off the rollers . This means that any extraneous matter passes out of the ends of the rollers without clogging or jamming the ends or becoming clogged or jammed in the end fixing of the rollers.

However, this solution has the disadvantage that the rollers are only supported at one end which results in a high degree of flexing of the rollers in use, especially when items such as stones pass through the rollers . This may seriously reduce the life of the rollers and especially the life of the bearings at the fixed end of the rollers, because of the loads exerted on the bearings during flexing of the rollers . In certain cases it may also cause damage to the rollers themselves.

In accordance with the present invention, apparatus for removing extraneous matter from a ground crop comprises an array of adjacent, counter rotating rollers, adapted to pass a ground crop along the rollers as the rollers rotate towards adjacent ends of the rollers; and an array of rotatable members located adjacent the said adjacent ends of the rollers, each rotatable member having an axis of rotation which is transverse to the axes of rotation of the rollers a- i substantially parallel to a plane defined by th- axes of rotation of the rollers.

The term "ground crop" when used herein denotes any crop which grows in the ground such as tubers, roots or

bulbs. Examples of such crops are potatoes, carrots, parsnips, turnips, swedes, sweet potatoes, onions, bulbs and any other similar crops.

Preferably, the plane defined by the axes of the rollers is a substantially horizontal plane.

Preferably, the axes of rotation of the rotatable members are coincident. Typically, the axes of rotation of the rotatable members are substantially orthogonal to the axes of rotation of the rollers.

Preferably, each rotating member may comprise a number of projections which extend in a plane which is substantially orthogonal to the axis of rotation of the member. Preferably, the projections may be flexible or deformable.

Typically, each rotating member may be a wheel and is typically of the type which is commonly referred to as a "star wheel" or a "finger wheel".

Preferably, the tips of the projections define a circle which enters at least a portion of the gap between adjacent rollers. In an example of the invention, the tips may contact the rotating surfaces of the rollers as the rotatable members rotate.

Preferably, the circle defined by the tips intersects a plane defined by the bottom surfaces of the rollers.

Typically, the projections may be plastic, elastomeric, rubber or any other suitable flexible or deformable material.

The projections may be angled so that the tips are

directed in the direction of rotation of the rotatable members. Alternatively, the projections may extend radially from the main body of the rotatable members or may extend such that the tips of the projections are in a direction generally away from the direction of rotation of the rotatable members.

Typically, the ratio of the speed of rotation of the rotatable members to the speed of rotation of the rollers is approximately between 1:1 and 1:10. The rotatable members may rotate at speeds of approximately 100 rpm to 250 rpm and the rollers may rotate at speeds of approximately 300 rpm to 1000 rpm.

An example of apparatus for removing extraneous matter from a ground crop in accordance with the invention will now be described with reference to the accompanying drawings, in which:-

Fig. 1 is a schematic s,ide view of a portion of apparatus for removing extraneous matter from a ground crop; and, Fig. 2 is an end view of a portion of the apparatus shown in Fig. 1.

Figs. 1 and 2 show apparatus for removing extraneous matter from a ground crop, the apparatus comprises a number of rollers 1, 2. The rollers 1 rotate in a clockwise direction and the rollers 2 rotate in an anti-clockwise direction as indicated by the arrows 3, 4 respectively. The rollers 1, 2 are conventional rollers for removing extraneous matter from ground crops and are mounted on a frame and supported at each end by bearings. The rollers 2 have a spiral formation on their surface so that as the rollers 1, 2 rotate, the ground crop is pulled or dragged from the other end

of the rollers to ends 15 of the rollers shown in Figs. 1 and 2, by the spiral formation. The spiral formation is not shown in Figs. 1 and 2 for clarity. The ground crop passes from the rollers 1, 2 over the ends 15 onto a further conveyor or into a container. The rollers 1, 2 are supported at the end 15 by axles 5 which are mounted on bearings on a support member 6. Each of the support members 6 extends downwardly and is attached to the top surface of a cross member 7.

Located in front of the members 6 (as viewed in Fig. 2) is a rotating axle 8 on which a number of star (or finger) wheels 9 are mounted. Each of the star wheels 9 is typically manufactured from a plastic, elastomeric or rubber material such that fingers 10 on the wheel 9 are flexible or deformable. Located between each of the star wheels 9 are spacers 14 which separate the star wheels 9.

As shown in Fig. 1, the axle 8 and wheel 9 rotate in the direction indicated by the arrow 11 and the fingers 10 are angled such that they point towards the direction of rotation of the wheels 9. However, it is possible that the fingers 10 could extend radially from the central axis of rotation of the wheels 9, or could extend in a direction away from the direction of rotation of the wheels 9. Tips 12 of the fingers 10 define a circle and this circle passes across bottom surface 13 of the rollers 1, 2 and the tips 12 rise to approximately the same height as the axles 5 of the rollers 1, 2. It is possible that the position and size of the star wheels 9 may be chosen such that the tips 12 of the fingers 10 contact the rotating surfaces of the rollers 1, 2 as the wheel 9 rotates. This should not cause undue damage to the wheel 9 due to the flexible or deformable nature of the fingers 10.

Typically, the rollers 1, 2 may be driven by a variable drive system, such as a hydraulic variable drive and in normal operation would typically rotate at speeds of between 300 rpm and 1000 rpm. The wheels 9 and axle 8 may be driven by a fixed speed drive system or variable speed drive system and the speed of rotation of the axle 8 and wheels 9 may vary typically, from 100 rpm to approximately 250 rpm.

In use, a ground crop, such as potatoes, would be conveyed onto the rollers 1, 2 and would be conveyed by rotation of the rollers 1, 2 towards the ends 15 of the rollers. The rollers 1, 2 are used to remove extraneous matter from the ground crop and this extraneous matter is extracted by rotation of the rollers and falls out of the mechanism below the rollers 1, 2. However, certain extraneous matter may tend to clog the rollers 1, 2. This is a particular problem with shaughs or haulms which is vegetable matter which tends to collect, in combination with earth or soil, at the ends 15 of the rollers 1, 2. The presence of the rotating star wheels 9 helps to remove any extraneous matter from the ends 15 of the rollers 1, 2 and helps prevent clogging or jamming of the ends 15 of the rollers 1, 2.

In addition, the flexible or deformable nature of the fingers 10 has the advantage that damage to the ground crop is minimised, if the crop contacts the fingers 10.

Modifications and improvements may be made without parting from the scope of the invention.