CA2920644A1 - A device for separating feed for livestock - Google Patents

Abstract

A device for the loosening of forage, in particular silage from a silo. The device is provided with a grabber provided with grabber shells of which the edges facing towards each other are provided with cutting elements. The grabber shells are movable between a closed position and an opened position, wherein the cutting elements are positioned at an angle with the vertical. This angle is in the range of -25 to 25 degrees, preferably -15 to 15 degrees with the vertical.

Description

CA Patent Application Agent Ref: 13137/00001

2

3 TECHNICAL FIELD

4 [0001] The invention relates to a device for separating feed for livestock, in particular compacted forage such as silage in a silo, or bales.

7 [0002] Silage is collected layer by layer into a silo and compacted, for example by riding over 8 it with a tractor. By compacting, the feed is protected against environmental factors, such as 9 oxygen, and storage becomes possible for a longer period of time. The silage is typically dissected into blocks which can then be used in a supply bunker or feed kitchen. Also, the feed 11 can be separated at the spot, such as, for example, is known from EP 2 232 982 A. However, 12 this is labor intensive and non-computerized labor wherein usually more is loosened than 13 necessary. An excess of loosened forage spoils quickly and cannot be stored for a long period 14 of time.
[0003] From WO 2013/157931 a feed kitchen is known with a grabber for grabbing loose 16 forage. Possibly present silage would first have to be cut loose from the silo and have to be 17 released after which it could be picked up by the grabber. Once loosened silage is perishable.

19 [0004] In an example embodiment, there is a device with which compacted forage can be detached and dosed in a simple, efficient, and preferably automated manner.
21 [0005] In an example embodiment, a device is provided for the loosening of forage, which 22 apparatus comprises a grabber which is provided with grabber shells of which the edges that 23 are facing towards each other are provided with cutting elements. The grabber shells can be 24 moved between a closed position and an opened position, wherein the cutting elements are arranged at an angle with the vertical, which angle lies in the range of -25 to 25 degrees, 26 preferably -15 to 15 degrees with the vertical.

22870561.2 CA Patent Application Agent Ref: 13137/00001 1 [0006] With such a device, it is possible to detach silage quickly and efficiently from above. In 2 the opened position of the grabber, the cutting elements are at an advantageous angle of 3 intersection with the upper surface of the silage. As a result, the silage can for instance directly 4 be cut loose from the silo, and be dosed without having to be cut loose in blocks first. Because this intermediate step can be beaten, time and costs can be saved. The grabber is capable of 6 penetrating to a desired depth of cut in the silage, after which the grabber may be closed. This 7 enables the removal of an accurately metered amount of feed.
8 [0007] The grabber may, for example, be movable in a first horizontal direction, along one or 9 more beams which are moveable along a guideway in a second horizontal direction. As a result, the full range of a silo or feed kitchen can be covered. The guideway may thereby be provided 11 with flanges for the provision of a vertical reaction force on the beams when the cutting 12 elements of the grabber are pressed into the silage. As a result, a considerably larger cutting 13 force may be exerted.
14 [0008] The beams may for example be supported by columns, wherein the girders and the columns are moveable as a whole along said guideway.
16 [0009] The apparatus may be provided with, for example, at least two parallel walls, each of 17 which is provided with a guiding rail on which one or more of the columns rest and along which 18 the respective columns are movable. For example, the guiding rail may be arranged on the 19 upper edge of the associated wall. The silage may be collected between the walls and be compacted there.
21 [0010] In an exemplary embodiment, one of the guiding rails may cooperate without play with 22 rollers that support columns on the respective guiding rail. The guiding rail may for example be 23 an l-profile, in which the columns are supported by a first roller with a horizontal axis that runs 24 over an upper surface of the I-section, and two lateral, vertical rollers that run on both sides of the I-profile over the side faces of the profile. In order to prevent jamming of the beams, the 26 other guiding rails may comprise a profile that incorporates rollers with clearance in horizontal 27 and vertical direction. Such a profile may for example consist of a C-profile in which at least one 28 roller that is attached to the respective column is rollably accommodated with play. The upper 22870561.2 CA Patent Application Agent Ref: 13137/00001 1 flange of the C-profile herein prevents the roller can be moved up too much, in particular, during 2 the cutting, whereby an upward force is exerted on the grabber and the beams.
3 [0011] For collecting the amount of forage loosened by the grabber, the device may be 4 provided with one of more collector bins. The collector bin may for example be suspended to one or more columns on one of the walls and be movable along with the columns.
Because the 6 collector bin moves along with the columns, the grabber needs to be moved, after taking a bite, 7 only via the beams, while the columns will remain at their places. The displacement of the 8 columns over the wall parts will in practice be more gradual than the displacement of the 9 grabber via the beams. For limiting the displacement of the grabber via the beams, the collector bin is preferably positioned as central as possible.
11 [0012] The collector bin may for example be suspended on an outer side of the device or in 12 an empty interspace between two parallel partitioning walls of the device.
13 [0013] If the device is used for a silo with several silo slots, the device may comprise three or 14 more of said parallel walls. These walls then comprise two outer walls and one or more inner walls, by which the longitudinal sides of all silo slots are bordered. Next to each inner wall a 16 parallel auxiliary wall may be positioned. Between the respective inner wall and the auxiliary 17 wall that is positioned next to it an interspace is present, in which for example a collector bin 18 may be accommodated that is movable along with the columns. Preferably, the collecting tray 19 can be moved vertically, for example along the columns standing on the respective wall, between a lower receiving position and an upper position in which it is possible to empty the bin.
21 In order to be able to empty the bin, the bottom of the collector bin may be arranged as a 22 conveyor belt that may is capable of discharging the forage via a discharge opening in a wall of 23 the collector bin, for example to a loading platform of a trolley or a feeding robot.
24 [0014] The collector bin may for example be provided with one or more mixing means, such as a rotatably drivable mixing auger. The drive of the mixing unit may thereby be controlled by a 26 control unit that activates the mixing member as soon as the amount of collected forage 27 exceeds a minimum value.

22870561.2 CA Patent Application Agent Ref: 13137/00001 1 [0015] The grabber may include one or more sensors for determining the amount of forage 2 cut-loose. These sensors may, for example, be weight sensors or volume sensors, such as 3 sensors for the measurement of the cutting depth, after which the separated volume may be 4 calculated on the basis of the pre-known distance between the cutting edges in the opened position of the grabber and the length of the cutting edges. When the grabber cuts loose a part 6 of the forage, the cutting depth and the cutting width may be determined by a computer, and the 7 separated volume may be calculated, assuming a fixed cutting length (=
the distance between 8 the cutting edges when the grabber is fully opened). Preferably, this does not happen at a first 9 bite of the grabber, because the upper face of the silage is then still irregular and may contain pits and holes. In a second or further bite, the removed strip has a more or less uniform 11 thickness so that the volume may be easily determined. When both the volume and the weight 12 have been determined, the specific gravity of the computer may be calculated. Then, the 13 computer can always easily calculate the desired cutting depth and cutting width of a next bite 14 that are needed in order to achieve a certain final weight.
[0016] If the grabber is driven by electric motors, it becomes possible to measure the 16 horizontal and the vertical movements of the grabber accurately by the number of revolutions of 17 the rotors of the electric motors, with the aid of a suitable sensor or tachometer. In this manner, 18 it becomes possible to determine, for example, the cutting depth and the cutting width (the width 19 of the bite that is to be taken off in the direction along the cutting edges) accurately.
[0017] In a specific example embodiment, each inner wall may carry a front column and a 21 rear column, wherein the front columns support a front beam and the rear columns support a 22 rear beam, and wherein the grabber includes a frame, that is movable along the front and rear 23 beam. The two columns supported by one and the same wall may thereby be connected at the 24 bottom side by means of a coupling beam to which an auxiliary motor is provided that drives the movement of the columns along the guideway by means of a transmission.
26 [0018] The cutting edges of the grabber shells may, for example, consist of straight knives, 27 serrated knives, cutting edges and / or point-shaped blades engaging in one another. The 28 cutting edges may, for example, further be provided with a drive for moving back and forth the 29 cutting elements in connection with the closing of the grabber. The reciprocating cutting elements may be, for example, saw segments. The back and forth movable cutting elements will 22870561.2 CA Patent Application Agent Ref: 13137/00001 1 typically be moved in a direction parallel to the longitudinal direction of the cutting edge. For 2 example, a row of movable cutting teeth may be moved back and forth with respect to a row of 3 fixed cutting teeth, wherein both rows of cutting teeth overlap each other. In a particular 4 embodiment, the cutting elements comprise a fixed knife with a row of cutting teeth, and a knife that is movable back and forth and has a row of cutting teeth, wherein the two rows of cutting 6 teeth overlap each other, and wherein the cutting teeth of the fixed knife protrude with respect to 7 the cutting teeth of the moving knife. At the closing of the grabber the long teeth of the fixed 8 knife will push aside any stones or other hard objects possibly present, as a result of which the 9 moving cutting teeth of the moving knife are shielded and the risk of damage is reduced.
[0019] The grabber shells may be arranged with edges that are vertical and connecting to 11 each other, in the closed position. These edges may also be provided with cutting edges, such 12 as knives, serrated edges, or saw segments that may optionally be driven for a reciprocating 13 cutting or sawing movement.
14 [0020] In order to obtain a substantially straight cutting plane, the grabber may be made so that the grabber shells can be moved upwards through a slotted guideway during the closing of 16 the grabber. The cutting edges of the grabber may thereby be moved in a substantially straight 17 horizontal line towards each other during the closing. This allows flat slices of forage to be cut 18 loose, whose volume can be properly determined by presetting the cutting depth and cutting 19 width.
[0021] The grabber may further comprise a frame with a horizontal sliding or roller guideway 21 along which the grabber shells are freely moveable. As a result, the grabber is self-locating in 22 situations where the upper surface of the stock of silage is not flat:
if one of the grabber shells in 23 the opened position of the grabber experiences a cutting resistance earlier than the other 24 grabber shell does, the grabber shell will move sideward until the second grabber shell also experiences cutting resistance. After this, the grabber may be closed further.
26 [0022] The frame of the grabber may comprise an upper sub frame, that is movable forth and 27 back via the beams, and a lower sub frame, that may be moved up and down relative to the 28 upper sub frame, for example by means of a scissor construction.

5 22870561.2 CA Patent Application Agent Ref: 13137/00001 1 [0023] If desired, the grabber may be rotatable about a vertical axis, for example, over an 2 angular range of 180 degrees.
3 [0024] If the grabber is moveable downwards at an angle of at least 75 degrees with the floor, 4 the grabber is also suitable for detaching silage from bales or blocks.
[0025] The device may further also be provided with a control unit arranged to at least

6 partially close the grabber and to re-open it one or more times during grabbing, for example

7 after reaching a maximum cutting pressure. As a result, the silage at the location of the cutting

8 line is loosened so that the knives are allowed to cut the silage more easily and with less back

9 pressure.
[0026] The device may for example be used at a silo, for example a silo having one or more 11 silo slots positioned next to each other. However, the device is also suitable for use in a covered 12 feed kitchen where the silage has been put down in pre-cut blocks.

14 [0027] The invention will be explained in more detail with reference to the example embodiments shown in the drawings.
16 [0028] Figure 1: shows, in perspective, a preferred embodiment of a device according to the 17 invention;
18 [0029] Figure 2: shows a grabber of the apparatus of Figure 1 in opened position;
19 [0030] Figure 3: shows the grabber of Figure 2 in closed position;
[0031] Figure 4: shows the guideway of a column in relation to a silo wall of the device of 21 Figure 1;
22 [0032] Figure 5: shows the guideway over a second or further wall;
23 [0033] Figure 6 shows an alternative guideway;
24 [0034] Figure 7: shows a perspective top view of the grabber;

22870561.2 CA Patent Application Agent Ref: 13137/00001 1 [0035] Figure 8: shows an alternative embodiment of a device according to the invention;
2 [0036] Figure 9: shows another possible embodiment of the grabber;
3 [0037] Figure 10: shows a a front view of a cutting edge of the grabber;
4 [0038] Figure 11: shows a side view of the cutting edge of Figure 10.
DETAILED DESCRIPTION
6 [0039] Figure 1 shows a silo 1 with four silo slots la, lb, lc, ld of which one is filled with 7 silage 2 in the drawing. In the exemplary embodiment of Figure 1, the silo is provided with a 8 device 3 with a number of parallel walls bordering the silo slots: two outer walls 4, three load-9 bearing inner walls 5 that allow columns 6 to rest upon them, and three non-load-bearing auxiliary walls 7 each positioned next to an inner wall 5.
11 [0040] The load-bearing inner walls 5 and the outer walls 4 are provided at the upper side 12 with a guideway 8 along which the columns 6 are movable back and forth in a first horizontal 13 direction A that coincides with the longitudinal direction of the respective wall 5. Each load-14 bearing wall 5 carries a front column 6a and a rear column 6b. The front columns 6a jointly carry a front beam 9a. The rear columns 6b jointly carry a rear beam 9b. At both ends, the two 16 parallel beams 9a, 9b, are coupled by means of a coupling beam 11, which is centrally 17 supported by a single column 6c which in turn is supported by the guideway 8 at the upper side 18 of the respective outer wall 4.
19 [0041] The device 3 further comprises a grabber 13 having a frame 14 suspended from the beams 9a, 9b, and that is movable along these beams 9a, 9b in a second horizontal direction B, 21 which is substantially perpendicular to the first horizontal movement direction A of the columns 22 6. The grabber 13 thus may be moved in the direction A as well as in the direction B and may 23 thus be moved over the entire range of the silo 1.
24 [0042] Between each carrying inner wall 5 and the auxiliary wall 7 positioned next to it, an intermediate space 16 is present. In one of the intermediate spaces 16, a collector bin 17 is 26 positioned in which the forage that has been loosened by the grabber 13 may be collected. The 27 collecting bin 17 is vertically movable between a low position, in which it is located in the 22870561.2 CA Patent Application Agent Ref: 13137/00001 1 intermediate space 16 between the two walls 5, 7, and an upper position, as shown in Figure 1.
2 In this upper position, it is possible to empty the tray 17 in a conveyor trolley 19. The collector 3 bin 17 may be provided to this end with a bottom consisting of a conveyor belt 15 which 4 discharges the forage into the collector bin 17 via an opening in the wall of the collector bin 17 into the conveyor trolley 19. After the collector bin 17 is emptied, it is moved downwardly again 6 in the intermediate space 16, so that it becomes possible again to place the grabber 13 above 7 the collector tray 17 in order to load new amounts of feed into the collector bin 17.
8 [0043] Figure 2 shows the grabber 13 in the opened position. The grabber 13 comprises two 9 identical, symmetrically arranged grabber shells 21 with cutting edges 22 that point downward in the opened position and that abut closingly against each other in the closed position (Figure 3).
11 In the opened position, the cutting edges may be at an angle al, resp.
a2 with the vertical of, for 12 example, -15 to 15 degrees.
13 [0044] In the closed position (Fig. 3), the grabber shells 21 also have vertical, mutually 14 adjoining edges 23, that are also provided with cutting edges. The grabber shells 21 are each suspended in a hinging manner by means of a hinge 24, to a suspension plate 26 that is carried 16 by a guiding plate 28 of the frame 14. The suspension plate 26 may move up and down over a 17 short distance with respect to a guiding plate 28 via a vertical slotted guideway 29. Both grabber 18 shells 21 are guided via a curved slide guideway 31, in such a manner that the cutting edges 22 19 perform a substantially straight, horizontal movement during the closing and the opening of the grabber 13, such that it becomes possible to cut loose a substantially straight slice of silage.
21 [0045] The drive 13 of the grabber (not shown) may comprise, for example electric motors, 22 hydraulic cylinders, or similar drives that are common for grabbers. If the drive consists of 23 electric motors, it may be provided with a tachometer so that the cutting depth can be tracked 24 accurately. Optionally, the grabber may also be provided with one or more distance sensors or 3D cameras for tracking the cutting depth. Another alternative is shown in Figure 9, in which a 26 grabber is shown which is provided with a spacer 55 that may be set at the desired length. As 27 soon as this touches the silage 2, the desired cutting depth has been reached.
28 [0046] The frame 14 includes an upper sub frame 14a that is movable along the girders 9a, 29 9b and a lower sub frame 14b that is suspended to the upper sub frame 14a by means of a 22870561.2 CA Patent Application Agent Ref: 13137/00001 1 scissoring frame 32. Through folding in and out of the scissoring frame 32, the lower sub frame 2 is movable up and down along with the grabber 13. The scissoring frame 32 may be rotatably 3 attached to the upper part frame 4a by means of a vertical axis of rotation 40 so that the grabber 4 13 is rotatable around its vertical axis, for example, over an angular range of 180 degrees, as shown in Figure 7.
6 [0047] The lower sub frame 4b includes two horizontal rails 30, to which the hanger plate 26 7 is suspended by means of rollers (not shown). This enables the grabber 13 to be moved freely 8 back and forth along the rails 30 between two stops 25. The two stops 25 are located at the 9 same distance from the center line of the grabber 13. When the grabber 13 is in opened position, the grabber 13 simultaneously abuts to both stops 25. As a result thereof, the grabber 11 13 is always suspended on the frame 4 in a centered manner.
12 [0048] If the top layer of the silage is not flat, the one grabber shell 21 will come into contact 13 with silage earlier than the other grabber shell 21 than when the grabber 13 is closed. As a 14 result, the grabber 13 will move aside during the closing further until the second grabber shell also meets the silage. This causes both grabber shells to be loaded simultaneously and evenly, 16 as a result of which the generation of pry and bending moments is reduced. When the grabber 17 13 opens again above the collector bin, the grabber 13 is re-centered again by means of the 18 stops 25, so that no forage falls outside the collector bin.
19 [0049] Figure 4 shows in cross-section a column support on one of the walls 4 or 5. Here, the guiding rail 8 comprises an I-profile 43 that is fastened at an upper edge of the wall 4, 5 by 21 means of clamps 37, and extends in the displacement direction A. A first roller 41 with a 22 horizontal axis 41a rests on an upper surface of the I-profile 43. On both sides of the I-profile 43 23 two rollers 42 with vertical axes 42a are provided. The three rollers 41, 42 are placed around the 24 I-profile free of play or with little play, in such a manner that the column 6 is movable on the I-profile 43 only by allowing the simultaneous rolling of all three of the rollers 41, 42.
26 [0050] In order to prevent jamming, the other walls 4, 5 are provided with a different 27 guideway. This guideway is shown in Figure 5. The guiding rail 8 comprises a C-profile 44 with 28 two downwardly diverging flanges between which the upper edge of the wall 4, 5 is clamped.
29 Other attachments may also be applied. In the cavity surrounded by the C-profile, a roller 33 is 22870561.2 CA Patent Application Agent Ref: 13137/00001 I accommodated that is connected to the column 6 with play and that is drivable by an auxiliary 2 motor 35 via a transmission 34.
3 [0051] When the grabber 13 is pressed into a stock of silage, a reaction force will press the 4 grabber 13 with the beams 9a, 9b and the columns 6 upward. However, the C-profile 44 prevents that the roller 33 can be moved upwards and as a result provides a counterforce via 6 the column and the beams 9a, 9b and the column 6 with the beams and the grabber 13. As a 7 result, it becomes possible to press the grabber 13 into the silage with a larger force.
8 [0052] Figure 6 shows an alternative for the guideway of Figure 5. Here, the roller 33 runs in 9 an L-profile 46 instead of a C-profile. The desired reaction force which has to prevent that the column 6 during grabbing of the wall 4, 5 is lifted off, is generated here by means of a ledge 47 11 on the underside of the L-profile 46 and a flange 48 disposed below 48 this which is connected 12 to the impeller 33.
13 [0053] Figure 8 shows an alternative embodiment of a device according to the invention. This 14 device 51 does not include a collector bin, but, instead thereof, a conveyor belt 52 which forms the bottom of the space between one of the walls 5 and the auxiliary wall 7 placed next thereto.
16 At the front side of the device 51 the conveyor belt 52 runs obliquely upwards over a portion 53 17 to terminate in a raised horizontal end 54. A collecting car may be driven under the horizontal 18 part 54, after which the conveyor belt may be activated to load forage that has been collected 19 on the conveyor belt 52, into the collecting car.
[0054] Figures 10 and 11 show an example of cutting elements that are suited for application 21 at the grabber 13 at the cutting edges 22, 23. The cutting elements 56 are mounted in recesses 22 57 at the ends of the edges 22, 23 of the grabber shells 21 and comprise a static bottom knife 23 58 and a movable upper knife 59. Both knifes 58, 59 are provided with cutting teeth 60, 61, 24 wherein the cutting teeth 60 of the lower blade 58 protrude by a distance d above the cutting teeth 61 of the moving knife 59. When the grabber 13 closes, the longer teeth of the static knife 26 will push away stones or other hard elements that are possibly present.
Thus the moving knives 27 59 obtain an additional protection, so that the risk of damaging the moving blades by stones in 28 the silage material is reduced significantly.
22870561.2 CA Patent Application Agent Ref: 13137/00001 1 [0055] The moving knife 59 may be moved forth and back during the closing of the grabber 2 13 in a direction that is parallel to the cutting edge, in the direction C in the figure.

22870561.2 ,

Claims (29)

1. A device for separating feed for livestock, comprising a grabber with grabber shells of which the edges facing towards each other are provided with cutting elements, which grabber shells are movable between a closed position and an opened position, wherein the cutting elements are at an angle with the vertical, which angle lies in the range of -25 to 25 degrees, preferably -15 to 15 degrees with the vertical.

2. The device according to claim 1, wherein the grabber is movable in a first horizontal direction, along one or more beams which are moveable along a guideway in a second horizontal direction.

3 The device according to claim 2, characterized in that the guideway is provided with flanges for the provision of a vertical reaction force on the beams when the cutting elements of the grabber are pressed into the forage.

4. The device according to claim 3, wherein the beams are supported by columns, and wherein the beams and the columns as a whole are moveable along said guideway.

5. The device according to claim 4, comprising at least two parallel walls, which each carry a guiding rail which forms the guideway along which the respective columns are moveable.

6. The device according to claim 5, wherein each guiding rail forms the upper edge of the associated wall.

7. The device according to claim 5 or 6, wherein one of the guiding rails cooperates without play with rollers which support columns on the respective guiding rail and wherein the remaining guiding rails comprise a profile that accommodates rollers with play in horizontal and vertical direction, for example a C-profile in which at least one of the rollers that is fastened to the respective column is rollably accommodated with play.

8. The device according to any one of the claims 4-7, provided with at least one collector bin which is suspended from one or more columns on one of the walls and is movable together with the columns.

9. The device according to claim 8, wherein the collector bin is suspended from an outer side of the device.

10. The device according to any one of claims 5, 6 or 7, comprising three or more of said parallel walls, comprising two outer walls and one or more inner walls, wherein next to each inner wall a parallel auxiliary wall is provided and wherein in an intermediate space between each inner wall and the associated auxiliary wall a collector bin is provided that is movable with the columns.

11. The device according to any one of claims 8, 9 or 10, wherein the collector bin can be moved vertically between a lower receiving position and an upper position in which emptying the collector bin is possible

12. The device according to any one of claims 8, 9, 10 or 11, wherein the collector bin is provided with one or more mixing devices, such as a rotatably drivable mixing auger.

13. The device according to claim 12, wherein the collector bin comprises one or more sensors for determining the amount of forage collected in the collector bin.

14. The device according to claim 13, wherein the drive of the mixing unit is controlled by a control unit which activates the mixing device as soon as the amount of collected forage exceeds a minimum value.

15. The device according to claim 13 or 14, wherein the sensors in the grabber comprise one or more weight sensors and wherein the device is provided with means for the determination of the cutting depth and with a computer for the calculation of the volume of forage that has been separated by the grabber.

16. The device according to claim 15, provided with a control unit which is arranged to determine, after the grabber has released a bite of silage the specific gravity of the silage on the basis of the weight measured by the weighing sensors and the calculated volume of the bite of silage and for the determination of the desired volume of a next bite of silage to be taken by the grabber.

17. The device according to claim 16, wherein the control unit is set up to determine the specific gravity only of a second or further bite of silage by the grabber.

18 The device according to any one of the preceding claims 5-14, wherein each inner wall carries a front and a rear column, wherein the front columns support a front beam and the rear columns support a rear beam, wherein the grabber comprises a frame which is movable along the front and rear beam.

19. The device according to claim 18, wherein the two columns supported by one and the same wall are connected at the bottom side by a means of a coupling beam to which an auxiliary motor is provided which drives the movement of the columns along the guideway.

20. The device according to any one of the preceding claims, wherein the cutting elements comprise straight knives, knurled, saw segments and / or interlocking point-shaped knives.

21. The device according to claim 20, provided with a drive for moving back and forth of the cutting elements or cutting segments upon closing of the grabber.

22. The device according to claim 21, wherein the cutting elements comprise a fixed knife with a row of cutting teeth, and a knife movable forth and back with a row of cutting teeth, wherein the two rows of cutting teeth overlap each other, and wherein the cutting teeth of the fixed knife protrude with respect to the cutting teeth of the moving knife.

23. The device according to any one of the preceding claims, wherein the grabber shells are moved upwards via a slotted guideway during the closing of the grabber.

24. The device according to claim 23, wherein the cutting edges of the grabber are moved in a substantially straight horizontal line towards each other during the closing.

25. The device according to any one of the preceding claims, wherein the grabber comprises a frame with a horizontal sliding or roller guideway along which the grabber shells are freely moveable

26. The device according to any one of the preceding claims, wherein the grabber is rotatable about a vertical axis, for example, over an angular range of 180 degrees.

27. The device according to any one of the preceding claims, wherein the grabber is moveable downwards at an angle of at least 75 degrees with the floor.

28. The device according to any one of the preceding claims, comprising a control unit arranged to close the grabber at least partially and to open it again one or more times during the grabbing, for example, after reaching a maximum cutting force.

29. Silo provided with a device according to any one of the preceding claims.