Test method for agricultural baler

1. A method for determining an operational condition of a rectangular agricultural baler, said baler comprising a baling chamber equipped with a reciprocating plunger driven by a mechanism comprising a crank shaft and at least one connecting rod, the plunger moving between a fully retracted position and a fully extended position, the baler being further equipped with a load sensor suitable for determining the reaction force on the plunger as said plunger is compressing crops in the baling chamber, the method comprising the following steps:

measuring the reaction force on the plunger or a parameter related to said reaction force, when the plunger is in a position in which it is not exerting a compressive force on the crop material in the baling chamber,

comparing the measured reaction force or the parameter to a predefined reference value, and

deriving from the compared measured reaction force or parameter an assessment of the operational condition;

wherein said measuring step is performed when the plunger is in the fully retracted position.

2. Method according to claim 1 , wherein the steps are performed when the baling chamber is empty.

3. Method according to claim 1 , wherein the steps are performed while the baling chamber is at least partially filled with crop material.

4. Method according to claim 2 , wherein the measuring step is performed when the plunger is in the fully extended position.

5. Method according to claim 1 , wherein the method steps are automatically performed using a control unit.

6. Method according to claim 1 , wherein the load sensor is a pin-shaped load sensor, mounted in a mechanism involving a lever, configured to minimize the effects of transverse or upward vibrations of a gearbox on the sensor.

7. A method for determining an operational condition of a rectangular agricultural baler, said baler comprising a baling chamber equipped with a reciprocating plunger driven by a mechanism comprising a crank shaft and at least one connecting rod, the plunger moving between a fully retracted position and a fully extended position, the baler being further equipped with a load sensor suitable for determining the reaction force on the plunger as said plunger is compressing crops in the baling chamber, the method comprising the following steps:

measuring the reaction force on the plunger or a parameter related to said reaction force, when the plunger is in a position in which it is not exerting a compressive force on the crop material in the baling chamber,

comparing the measured reaction force or the parameter to a predefined reference value, and

deriving from the compared measured reaction force or parameter an assessment of the operational condition;

wherein the method is performed at multiple plunger speeds of the baler, and wherein multiple predefined reference values are applied corresponding to the multiple speeds.

8. A rectangular agricultural baler comprising:

a baling chamber equipped with a reciprocating plunger driven by a mechanism comprising a crank shaft and one or more connecting rod connected to the plunger, the plunger moveable between a fully retracted position and a fully extended position,

a load sensor suitable for determining the reaction force on the plunger as said plunger is compressing crops in the chamber,

a control system configured to measure the reaction force on the plunger or a parameter related to said reaction force, when the plunger is in the fully retracted or the fully extended position, compare the measured reaction force or the parameter to a predefined reference value determined from a previously measured force by the load sensor and derive from the compared measured reaction force or parameter an assessment of an operational condition,

wherein the assessment of the operational condition is a determination of the presence of defects or wear related to at least one of the load sensor, the baling chamber, the plunger, and the driving mechanism of the plunger.

9. A control system for a rectangular baler, said baler comprising a baling chamber equipped with a reciprocating plunger driven by a mechanism comprising a crank shaft and one or more connecting rods, for forming crop material into a rectangular shaped bale, the plunger moving between a fully retracted position and a fully extended position, the baler being further equipped with a load sensor suitable for determining the reaction force on the plunger as said plunger is compressing crops in the baling chamber, the control system comprising:

a control unit configured to:

measure the reaction force on the plunger or a parameter related to said reaction force while the baler is running at a given speed of the crank shaft, when the plunger is in a position in which it is not exerting a compressive force on the crop material in the baling chamber,

select a predefined reference value based on the plunger speed of the baler,

compare the measured reaction force or the parameter to the selected predefined reference value, and

derive from the compared measured reaction force or parameter an assessment of an operational condition.