Device for mowing crops, comprising a series of mowing units arranged side by side at predetermined distances, each mowing unit comprising a knife holder with at least one knife carrying portion for carrying a mowing knife, and a drive mechanism for each knife holder. The drive mechanism for each knife holder comprises a first drive element comprising a hub portion for carrying the respective knife holder, and a second drive element drivingly engaged with the first drive element to rotatingly drive the knife holder about a vertical axis. In normal operation, the knife holder and the hub portion form a unitary rotatable assembly which, at a position between the knife carrying portion and the hub portion, is provided with a break connection which is effective in a radial direction.
1. A device for mowing crops, comprising a series of mowing units arranged side by side at predetermined distances, each mowing unit comprising a knife holder with at least one knife carrying portion for carrying a mowing knife, and a drive mechanism for each knife holder, wherein the drive mechanism for each knife holder comprises:
a first drive element comprising a hub portion for carrying the respective knife holder, and
a second drive element drivingly engaged with the first drive element to rotatingly drive the knife holder about a vertical axis,
wherein, in normal operation, the knife holder and the hub portion form a unitary rotatable assembly which, at a position between the knife carrying portion and the hub portion, is provided with a break connection which is effective in a radial direction with a plane of breaking having a normal with a radial directional component perpendicular to the axis; and
wherein the break connection-is positioned at a radial outside of the hub portion or radially outwardly thereof.
2. Device according to claim 1 , wherein the break connection is situated in or near the transition between the knife holder and the hub portion.
3. Device according, to claim 2 , wherein the break connection interconnects the knife holder and the hub portion in a radial direction.
4. Device according to claim 1 , wherein the break connection constitutes part of an added body.
5. Device according to claim 4 , wherein the added body is a ring.
6. Device according to claim 5 , wherein the ring does not project above a plate portion of the knife holder.
7. Device according to claim 1 , wherein the break connection is situated at the upper side of the hub portion.
8. Device according to claim 7 , wherein the knife holder forms a plate portion above the hub portion, wherein the break connection is situated flush with the plate portion.
9. Device according to claim 8 , wherein the plate portion is provided with an aperture which is concentric with a drive center line, wherein the hub portion is provided with an upper part which extends into said aperture.
10. Device according to claim 9 , wherein the break connection is situated at the radial outside of the upper part of the hub portion or radially outwardly of the radial outside of the upper part of the hub portion.
11. Device according to claim 9 , wherein the break connection is effective at the edge of the aperture.
12. Device according to claim 11 , wherein the break connection is unitary with one or more centering elements for centering the knife holder relative to the center line.
13. Device according to claim 12 , wherein the one or more centering elements are provided on a pressing element which presses the knife holder vertically against the hub portion, wherein the one or more centering elements are provided with at least one of: one or more of the break connections and one or more with recesses for the one or more break connections.
14. Device according to claim 12 , wherein a plurality of centering elements are present, which are successive in the direction of rotation and which are each provided with one or more breaking elements.
15. Device according to claim 11 , wherein the break connection, by means of breaking elements, extends in a positively locked manner into one or more recesses in the hub portion which centers the knife holder.
16. Device according to claim 11 , wherein the break connection, by means of the breaking elements, extends in a positively locked manner into a centering element for centering the knife holder relative to the center line.
17. Device according to claim 11 , wherein the break connection comprises breaking elements which are unitary with an inner portion of the break connection that is radially located at the inside thereof, to mount the knife holder on the hub portion.
18. Device according to claim 11 , wherein the break connection extends in a positively locked manner into one or more recesses in the edge of the aperture by means of one or more breaking elements.
19. Device according to claim 9 , wherein the break connection comprises breaking elements which are unitary with the edge of the aperture, which breaking elements engage with the upper part of the hub portion.
20. Device according to claim 1 , wherein the break connection is located in the material of the knife holder.
21. Device according to claim 1 , wherein the break connection comprises a weakened portion of material of the hub portion.
22. Device according to claim 21 , wherein the hub portion comprises a hub flange, on which the knife holder is supported, wherein the weakened portion is provided in the material of the hub flange.
23. Device according to claim 21 , wherein the weakened portion interconnects two hub portion parts which are located concentrically with each other and which, after the weakening has collapsed, are located in a manner in which they fit into each other.
24. Device according to claim 21 , wherein the weakened portion comprises a breakaway radial protrusion which is fittingly received in a recess in the knife holder.
25. Device according to claim 21 , wherein the knife holder and the hub portion are provided with first and second edges which engage with each other in a concentric manner relative to the center line and, after the break connection has collapsed, provide each other a guide means for rotation about the center line.
26. Device according to claim 1 , wherein the break connection comprises a weakened portion of the material of the knife holder.
27. Device according to claim 26 , wherein the weakened portion interconnects two knife holder portions which are located concentrically with each other and which, after the weakening has collapsed, are located in a manner in which they fit into each other.
28. Device according to claim 26 , wherein the weakened portion comprises a breakaway radial protrusion which is fittingly received in a recess in the hub portion.
29. Device according to claim 1 , provided with a retaining element to keep or tighten the knife holder or parts thereof in an axial direction against the hub portion, or to prevent the knife holder from leaving the hub portion in an upward direction, wherein the break connection is provided in material of the retaining element.
30. Device according to claim 29 , wherein the break connection is provided in material of the retaining element in the form of a protrusion which fits into a recess in the knife holder.
31. Device according to claim 1 , provided with a retaining element to keep or tighten the knife holder or parts thereof in an axial direction against the hub portion, or to prevent the knife holder from leaving the hub portion in an upward direction, wherein the break connection is provided by means of added breaking elements which fit into recesses in the retaining element and in the knife holder.