Crop cutting device, agricultural machine comprising such crop cutting device and knife removal method

1. A crop cutting device comprising:

a crop guiding surface including a plurality of substantially parallel slots extending in a direction of travel of the crop over the guiding surface;

a plurality of knives pivotally mounted below the guiding surface, wherein each knife is aligned with a respective slot and is pivotable about an axis extending substantially perpendicular to the slots between a retracted inoperative position in which it is located below the guiding surface and an extended operative position, wherein at least a cutting edge of the each knife projects above the guiding surface;

an actuating mechanism comprising a plurality of movable operating members, wherein each operating member is associated with a respective one of the plurality of knives and is movable from a first position in which the respective one of the plurality of knives is in its retracted inoperative position to a second position in which the respective one of the plurality of knives is in its extended operative position; and

a lifting mechanism connected to the actuating mechanism for raising at least a part of each knife above the guiding surface while the operating members are in their first position.

2. The crop cutting device according to claim 1 , wherein the lifting mechanism comprises a camshaft arranged below the knives and extending substantially perpendicular to the slots, the camshaft comprising a cam for each knife.

3. The crop cutting device according to claim 2 , wherein at least some of the cams are offset in an angular direction with respect to others of the cams.

4. The crop cutting device according to claim 2 , further comprising at least one actuator connected to the operating members for collectively moving the operating members between their first and second positions, wherein the lifting mechanism is releasably connected to the at least one actuator.

5. The crop cutting device according to claim 4 , wherein the lifting mechanism is connectable to the at least one actuator in two positions, wherein when the lifting mechanism is connected to the at least one actuator in a first position the camshaft is rotatable in a first direction, and when the lifting mechanism is connected to the at least one actuator in a second position the camshaft is rotatable in a second direction opposite to the first direction.

6. The crop cutting device according to claim 2 , wherein the lifting mechanism is spaced apart from the actuating mechanism and each cam acts on a different part of the knife than an associated one of the operating members.

7. The crop cutting device according to claim 1 ,

wherein each operating member includes a spring loaded part which allows the knife to move to its retracted inoperative position while the operating member is in its second position;

wherein the cutting device further comprises a selector mechanism for selectively holding at least the spring loaded part of at least one operating member to maintain the corresponding knife in its retracted inoperative position while the operating member is moved to its second position; and

wherein the selector mechanism includes a rotatable shaft extending substantially perpendicular to the slots and carrying a plurality of substantially parallel cam elements, wherein each cam element is individually mounted on the shaft and is arranged to be moved to a position for blocking a respective spring loaded part upon rotation of the shaft from a non-holding position to a holding position.

8. The crop cutting device according to claim 7 , wherein at least some of the cam elements comprise a plurality of cams spaced apart in peripheral direction of the shaft.

9. The crop cutting device according to claim 8 , wherein each cam has a contact surface extending from the shaft in radial direction and facing the spring loaded part, and an inclined back part.

10. The crop cutting device according to claim 7 , wherein each cam element ( 50 A-F) has a central opening of which the shape and dimensions match the cross-sectional shape and dimensions of the shaft.

11. The crop cutting device according to claim 7 , wherein the shaft is axially movable between a locked position in which the cam elements are aligned with the spring loaded parts and an unlocked position in which the cam elements are offset with respect to the spring loaded parts and in which the shaft can rotate.

12. The crop cutting device according to claim 11 , wherein the shaft is biased to its locked position; and wherein the shaft is arranged to be latched in its locked position when the operating members are not in their first position.

13. An agricultural machine comprising a pickup for collecting a crop and a crop cutting device according to claim 1 arranged downstream of the pickup.

14. A method of removing a knife from a crop cutting device, wherein upon actuation by an operating member of an actuating mechanism the knife is pivotable in a slot between a retracted inoperative position in which it is located below a guiding surface for a crop and an extended operative position in which at least a cutting edge of the knife projects above the guiding surface, the method comprising the steps of:

while the operating member is inoperative, raising at least a part of the knife to a position above the guiding surface by a lifting mechanism connected to the actuating mechanism for raising at least a part of each knife above the guiding surface;

pulling on the raised part to pivot the knife to a release position; and

lifting the knife from the cutting device.

15. The method of claim 14 , wherein the at least a part of the knife is raised by rotating a camshaft to a position in which a cam on the camshaft engages the knife.

16. The method of claim 15 , wherein the cam engages a different part of the knife than the part which is actuated by the operating member.