The machinery and equipment involved is based on the assessment of the thickness of the objects, and is unique in that processing is based on specially-designed box equipment, which preferably holds and moves the objects forwards without shaking them or rubbing their surface in the course of grading. The equipment includes special boxes with one movable side, adjustment device, drive equipment, infeed equipment and the co-ordination of functioning of all these elements in order to achieve the desired aims.

Many types and versions of grading machines for fish and other materials are known which grade the items according to an assessment of their thickness. These include machines with belts or rollers and shaker-graders with several grading channels. Ridge-belt machines also have several grading channels formed of ridgebelt. All the machines have grading channels that are wider at the outlet than at the intake. The belt machine draws the objects forward between two inclined belts which form the channel. The roller machines include two rollers which turn, the items being moved slowly past the rollers by means of friction between the rollers and the objects. The shaker-grader consists of ridges which form gaps, the objects are moved forward between the ridges by shaking. The ridge-belts machine has belts which move the object as a belt conveyor when the gap increases the object falls through.

One type of machine which involves a rotating table is a vaccination apparatus, United States Patent 5,215, 035. On the table are mounted some holders for the fish to be vaccinated. The machine has a basin where fish are placed under an anaesthetic to make it easy to manually transfer them from the basin in to the machine. If the fish is non-breeding the operator can pus a contact on the machine which then will direct the fish to a different outlet.

In addition to the aforementioned grading machines, there are machines which operate in accordance with different principles and are fitted with electronic scales or imaging sensors.

An aim is to provide a box-grading-machine which treats the items to be graded gently, is accurate for living fish, smolt, fry and other organic material and is also able to grade non organic material and is constructed so that it is compact and does not need much working area, is relatively inexpensive and requires little maintenance.

The present invention provides an apparatus for grading sensitive products such as living fish, smolt and fry, comprising an infeed device, boxes for moving and grading the products and devices to control the grading slot, each box is made up of two parts a support-part and an adjustable part, the support-part has one side and two end plates which are bolted to the rotation table and rotate with the central shaft, the adjustable part is a second side of the box and hangs on a pin which is placed in bearings on the support-part of the box and on the end of the pin is a lever arm which is in contact with an adjusting device, the width of the grading slot is controlled by several adjustable guide ways, one guide way for every outlet from the grader when the guide way is lifted the grading slot gets narrower. when the guide way is lowered the width of the grading slot increases.

The infeed device utilizes the natural behaviour of live fish on flat plate which cause the fish to glide on the sloping bottom plate to the slots. The first slot is to ensure that only single layer of fish will be in the spreader part of the in feeding device, the second slot control the flow of fish and orients the fish in a position which is suitable for good grading. The first part og the infeeding device is a receiver with slightly sloping bottom so the fish glide to the first control slot and further to the second slot in the feeding spreader which places the fish in the correct position for grading and in the grading boxes. The fish is lifted up to the receiver either with a dipnet or by pumping.

The machine has a revolving plane to which the grading boxes are fastened and rotate with the central shaft. The outlets are placed in the machine frame under the revolving plane. When the material is to be graded in a few sizes only for instance four sorts the outlets from only half of the machine are needed and then is possible to infeed on two places at the same time and increase the throughput of the machine.

Preferred embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings in which: Figure 1-shows a side view of the equipment designed for grading of live fish, smolt, fry and other objects.

Figure 2-shows a top view of the equipment.

Figure 3-shows a grading box with movable side.

Figure 4-shows a infeeding device.

Figure 5-shows an overview drawing which elaborates on how the different devices work together.

Figure 1 Shows a side-view of the machine. The machine is build on a machine frame (1). In the centre of the frame is pilar bracket (21) and on the top of the pilar is a bearing (13) for the supporting axle (19) and the bracket plate (18), the grading boxes (3) are bolted to the bracket plate and rotate with it. On the top of the supporting axle is a gear wheel (8) which is driven by a motor and pinion wheel (9) The material to be graded is lifted up to the infeeder device (25) and glides through the first slot (24) to the spreader and falls through the second slot (20) to the grading box (3) in a suitable quantity. The adjusting arm (5) is fastened to a pivot (17) which is joined to the movable side (15) of the grading box (3) the adjusting arm (5) glides on an adjusting rim (4), the width of the grading gap depends on how high the adjusting rim is placed, the adjusting rim is moved up or down by the adjusting screw (6) which is placed in a bracket (23) on the bracket holder (22).

Every outlet from the machine has it own adjusting rim which controls the size of the outgoing material, the graded material falls through the gap in the grading box and down a chute (2) to a suitable container.

Figure 2 Shows a top-view of the machine. The items (20), (24) and (25) are on a higher level than the other parts of the drawing. In the middle is the driving shaft (19), the bracket plate (18) is fastened to the shaft and the rotating table (16) and the grading boxes (3) are bolted to the bracket plate. The opposite end of the grading boxes slides on a bearing surface (14). The adjustable side (15) of the grading box is affixed to the pin (17) and the adjusting arm (5) which slides on the adjusting rim (4). Plates (16) cover the gaps between the grading boxes and make up the bottom in the movable part of the machine which is surrounded by bulwarks on the outer side (10) and on the inner side (11).

Figure 3 Shows a grading box and the box parts. The fixed part (3) is bolted to the rotating part of the machine, the movable side (15) is connected to the fixed part through the pivot (17). At the bottom of the grading box is a gap where the material falls through and is sorted by size depending on how wide the gap is. The adjusting arm (5) controls the size of the gap when the arm is lifted or lowered the movable side (15) is turned about the pivot (17) Figure 4.

Shows a in feeding device which are made from three main parts of which the first is the infeeding receiver (25) with sloping bottom (32) so the fish glide to the slot (33) because of the ordinary movement of live fish. The second main part is the spreader and flow control (20).

Between the receiver and the spreader is a control plate (35) which adjust the slot (33) The third main part is the flow control board (26). Between the flow control board and one end of the bottom plate (32) is an adjustable slot (34). The flow control board (34) hangs on taps (27) in slots (30) thus making it possible to control the width of the slot (34) and the width of the canal which leads to the grading box. With use of the adjusting screw (29) and the braced (28) the slot (34) can be finely adjusted. The arrow (31) shows the way the fish glide from the receiver to the grading box. The plate (24) prevent the fish from moving in the wrong direction on the rotating table.

Figure 5 This picture details the workings of the grading system. The grading box (3) and the adjustable box side (15) are the part of the machine where the grading is done. The material is brought into the infeeder (25) and glides trough a slot (33) to the spreader and falls through second slot (34) down to the grading boxes (3). The flow is adjusted with the control panel (26) and the control slots (30) where the control panel is placed. The arrow shows the way the material flows. The movable box side is connected to the pivot (17) which is fastened to an adjusting arm (5). The adjusting arm glides on an adjusting rim (4) and regulates the grading slot at the bottom of the grading box. When the adjusting rim (4) is lifted, the slot narrows, but if the adjusting rim is lowered the slot width increases. The grading boxes are bolted to a bracket dish (18) which rotates together with a central shaft (19).