Square baler

1 . A square baler comprising:

a compression chamber,

a reciprocating plunger configured to compress bale material in the compression chamber to make a square bale, and

a feeding system configured to feed bale material into the compression chamber, the feeding system comprising

a feeding duct having an input end and an output end,

a feeding fork configured to perform a loading stroke to pre-compress bale material in the feeding duct and a feeding stroke to transfer bale material from the feeding duct into the compression chamber, and

a drive mechanism for driving movement of the feeding fork,

wherein the drive mechanism is adjustable to control at least one of a length and a speed of the loading stroke, and

wherein the drive mechanism includes a feeding fork crank and a steering arm crank, the drive mechanism being arranged such that during the loading stroke, the feeding fork crank and a steering arm crank both rotate, and during the feeding stroke, the feeding fork crank rotates and the steering arm crank does not rotate.

2 . A square baler according to claim 1 , wherein the feeding fork crank is connected directly to the feeding fork and the steering arm crank is connected to the feeding fork through a first steering arm, a swing arm mounted on a swing arm pivot, and a second steering arm.

3 . The square baler according to claim 1 , wherein the feeding fork crank and the steering arm crank are driven from an input shaft of the square baler.

4 . The square baler according to claim 3 , wherein the steering arm crank is connected to the input shaft via a clutch mechanism.

5 . The square baler according to claim 1 , wherein the drive mechanism includes a drive adjustment mechanism for adjusting a drive connection between the steering arm crank and the swing arm to control at least one of length and position of at least one of the loading stroke and the feeding stroke.

6 . The square baler according to claim 5 , wherein the drive adjustment mechanism comprises adjustment components for adjusting one or more of:

a length of the first steering arm;

a radial position relative to the steering arm crank of a joint between the first steering arm and the steering arm crank;

a radial position relative to the swing arm pivot of a joint between the first steering arm and the swing arm; and

a circumferential position relative to the swing arm pivot of the joint between the first steering arm and the swing arm.

7 . The square baler according to claim 1 , wherein the drive mechanism is configured to drive the feeding fork at a non-uniform speed.

8 . The square baler according to claim 7 , wherein the drive mechanism is configured to drive the feeding fork faster during the loading stroke than during the feeding stroke.

9 . The square baler according to claim 7 , wherein the drive mechanism includes an asynchronous drive mechanism configured to convert a uniform input speed into a varying output speed.

10 . The square baler according to claim 9 , wherein the asynchronous drive mechanism includes an adjustment mechanism for adjusting the variation in the output speed of the asynchronous drive mechanism.

11 . The square baler according to claim 10 , wherein the asynchronous drive mechanism comprises an offset drive mechanism comprising first and second cranks with offset axes of rotation and a connecting arm that connects the first and second cranks and transmits rotational drive therebetween.

12 . The square baler according to claim 11 , wherein the adjustment mechanism adjusts the offset between the axes of the first and second cranks to adjust the variation in the output speed of the asynchronous drive mechanism.

13 . A square baler comprising:

a compression chamber,

a reciprocating plunger configured to compress bale material in the compression chamber to make a square bale, and

a feeding system configured to feed bale material into the compression chamber, the feeding system comprising

a feeding duct having an input end and an output end,

a feeding fork configured to perform a loading stroke to pre-compress bale material in the feeding duct and a feeding stroke to transfer bale material from the feeding duct into the compression chamber, and

a drive mechanism for driving movement of the feeding fork,

wherein the drive mechanism is adjustable to control at least one of a length and a speed of the loading stroke,

wherein the drive mechanism includes an asynchronous drive mechanism configured to convert a uniform input speed into a varying output speed, and

wherein the asynchronous drive mechanism comprises an offset drive mechanism comprising first and second cranks with offset axes of rotation and a connecting arm that connects the first and second cranks and transmits rotational drive therebetween.

14 . The square baler according to claim 13 , wherein the asynchronous drive mechanism includes an adjustment mechanism for adjusting the variation in the output speed of the asynchronous drive mechanism.

15 . The square baler according to claim 14 , wherein the adjustment mechanism adjusts the offset between the axes of the first and second cranks to adjust the variation in the output speed of the asynchronous drive mechanism.

16 . A square baler comprising:

a compression chamber,

a reciprocating plunger configured to compress bale material in the compression chamber to make a square bale, and

a feeding system configured to feed bale material into the compression chamber, the feeding system comprising

a feeding duct having an input end and an output end,

a feeding fork configured to perform a loading stroke to pre-compress bale material in the feeding duct and a feeding stroke to transfer bale material from the feeding duct into the compression chamber, and

a drive mechanism for driving movement of the feeding fork,

wherein the drive mechanism is adjustable to control at least one of a length and a speed of the loading stroke, and

wherein the drive mechanism comprises a feeding fork crank that is connected directly to a feeding fork and a steering arm crank that is connected to the feeding fork through a first steering arm, a swing arm mounted on a swing arm pivot, and a second steering arm.