Agricultural baler and method for removing a plug of crop material stuck in the feeder duct of an agricultural baler

1. A method for removing a plug of crop material stuck in a feeder duct of a baler, the baler comprising:

a bale chamber having an inlet opening formed therein;

a feeder duct communicating with the bale chamber through the inlet opening for charges of crop material to be transferred from the feeder duct into the bale chamber, wherein the feeder duct has an upper end facing generally upwardly and communicating with the inlet opening in the bale chamber and a lower end facing generally in a forward direction;

a plunger reciprocally movable within the bale chamber to compress successive charges of crop material received from the feeder duct to form a bale;

a feeder operable within the feeder duct to accumulate a charge of crop material therein and then stuff that accumulated charge into the bale chamber; and

crop holding fingers provided at the upper end of the feeder duct, that are movable between a crop holding position and a withdrawn position, wherein in the crop holding position the crop holding fingers extend into the feeder duct in the upper end thereof to hold back the crop material while the charge of crop material is being accumulated and in the withdrawn position the crop holding fingers are withdrawn from the upper end of the feeder duct to allow the accumulated charge of crop material to be stuffed into the bale chamber;

wherein the method comprises steps of:

detecting an occurrence of a plugging of the feeder duct, the step of detecting comprising:

measuring a load on the feeder during operation thereof in the feeder duct and

comparing the measured load with a predetermined load that is indicative of the occurrence of the plugging of the feeder duct; and

after detecting the occurrence of the plugging of the feeder duct indicating that a plug of crop material being stuck in the feeder, in a case in which the crop holding fingers are in their crop holding position, moving the crop holding fingers to their withdrawn position and causing the feeder to operate in the feeder duct with the crop holding fingers in their withdrawn position.

2. The method according to claim 1 , wherein the feeder duct has a top wall and a bottom wall extending between the lower end and the upper end of the feeder duct, the top wall providing an upper boundary of the feeder duct and the bottom wall providing a lower boundary of the feeder duct, the method further comprising a step of:

in a case of a plug of crop material being stuck in the feeder duct, in addition to withdrawing the crop holding fingers and before causing the feeder to operate in the feeder duct, increasing a distance between the top wall and the bottom wall of the feeder duct in at least a part of the feeder duct, while leaving the upper boundary provided by the top wall of the feeder duct and the lower boundary provided by the bottom wall of the feeder duct intact.

3. The method according to claim 2 , wherein the part of the feeder duct is where the plugging has occurred, the method further comprising steps of:

additionally increasing the distance between the top wall and the bottom wall of the feeder duct in a part of the feeder duct downstream, as seen in a direction of conveying, of the part of the feeder duct where the plugging has occurred; and

increasing the distance between the top wall and the bottom wall of the feeder duct over substantially a whole length of the downstream part.

4. The method according to claim 2 , wherein the distance between the top wall and the bottom wall of the feeder duct in part of the feeder duct is increased by moving the bottom wall away from the top wall in the part of the feeder duct.