Method and apparatus for unloading material from a container

1. An unloader for unloading material from a container, the unloader comprising:

an unloader arm movable within the container;

a first chain coupled to the unloader arm and movable to unload material from the container;

a second chain coupled to the unloader arm and positioned to engage material within the container upon movement of the unloader arm;

a sensor located directly on at least one of the unloader arm, the first chain, and the second chain, and configured to directly sense a force on at least one of the unloader arm, the first chain, and the second chain, and to transmit a signal indicative of the force applied to at least one of the unloader arm, the first chain, and the second chain; and

a controller configured to receive the signal from the sensor and to alter an operation of at least one of the unloader arm, the first chain, and the second chain, the alteration based at least partially on the signal received from the sensor.

2. The unloader of claim 1 , wherein the sensor is configured to transmit a signal indicative of a speed with which the unloader arm moves.

3. The unloader of claim 1 , wherein the sensor is configured to transmit a signal indicative of a torque exerted by a motor coupled to the unloader arm.

4. The unloader of claim 1 , wherein the sensor is configured to transmit a signal indicative of a current draw of a motor drivably coupled to the unloader arm.

5. The unloader of claim 1 , wherein the controller alters at least one of the speed with which the unloader arm moves, the speed with which the first chain moves, and the speed with which the second chain moves.

6. The unloader of claim 5 , wherein the controller alters the speed with which the unloader arm moves by transmitting a signal operable to engage a clutch assembly coupled to a cutter arm motor.

7. The unloader of claim 5 , wherein the controller alters at least one of the speed with which the first chain moves and the speed with which the second chain moves by transmitting a signal operable to change the speed of a motor.

8. The unloader of claim 1 , wherein the unloader arm pivots in the container.

9. A method of controlling a rate of material removal from a container, the method comprising:

inputting a desired unloading characteristic into a controller of an unloader, wherein the unloader includes an unloader arm;

starting the unloader;

moving a chain coupled to the unloader arm;

pivoting the unloader arm in an interior space of the container;

engaging material in the interior space of the container with the unloader arm;

detecting a threshold force upon at least one of the chain and the unloader arm by a sensor located directly on at least one of the unloader arm and the chain; and

altering motion of the unloader arm in response to detecting the threshold force.

10. The method of claim 9 , wherein inputting a desired unloading characteristic comprises inputting a desired material delivery rate.

11. The method of claim 9 , wherein detecting a threshold force comprises detecting a threshold current draw of a motor drivably coupled to the unloader arm.

12. The method of claim 9 , wherein detecting a threshold force comprises detecting a torque exerted by a motor coupled to the unloader arm.

13. The method of claim 9 , wherein altering the motion of the unloader arm comprises stopping pivotal movement of the unloader arm.

14. The method of claim 9 , further comprising altering motion of the chain coupled to the unloader arm in response to the recognition of the unloader arm loading characteristic.

15. An unloader for unloading material from a container, the unloader comprising:

an unloader arm movable within a container to engage and move material from the container;

a motor coupled to the unloader arm and operable to advance the unloader arm in material within the container;

a sensor located directly on the unloader arm configured to directly sense a loading characteristic of the unloader arm, and to transmit a first signal indicative of the loading characteristic of the unloader arm; and

a controller in communication with the sensor, the controller configured to respond to the first signal from the sensor by reducing advancement of the unloader arm within the container.

16. The unloader arm of claim 15 , wherein the controller is responsive to the first signal from the sensor by stopping advancement of the unloader arm within the container.

17. The unloader of claim 15 , wherein the sensor is configured to transmit a signal indicative of a torque exerted by the motor drivably coupled to the unloader arm.

18. The unloader of claim 15 , wherein the sensor is configured to transmit a signal indicative of a current draw of the motor.

19. The unloader arm of claim 15 , wherein the controller reduces the advancement of the unloader arm by transmitting a signal to a variable frequency drive electrically coupled to the motor.

20. A method of controlling a rate of material removal from a container, the method comprising:

inputting at least one of a material characteristic and a container characteristic into a controller of an unloader, wherein the unloader includes an unloader arm positioned to remove material from the container;

determining a threshold value based at least partially on at least one of the material characteristic and the container characteristic, wherein the threshold value corresponds to an amount of force transmitted to at least one of the unloader arm and a chain coupled to the unloader arm;

starting the unloader;

moving the chain coupled to the unloader arm;

pivoting the unloader arm in an interior space of the container;

engaging material in the interior space of the container with the unloader arm;

detecting a threshold force upon at least one of the chain and the unloader arm by a sensor located directly on at least one of the unloader arm and the chain;

comparing the threshold force to the threshold value; and

altering motion of the unloader arm in response to comparing the threshold force to the threshold value.

21. The method of claim 20 , wherein determining the threshold value comprises determining a threshold value of at least one of a current draw of a motor and a torque exerted by a motor drivably coupled to the unloader arm.