Mining machine with driven disc cutters

1. A mining machine for liberating material from a mine wall, the mining machine comprising:

a frame;

an arm coupled to the frame and including a main portion and a wrist portion, the wrist portion including a first member that is pivotably coupled to the main portion about a first axis and a second member pivotably coupled to the first member about a second axis, the second member including a cutter head, the cutter head having at least one disc cutter for engaging the mine wall, the cutter head defining a leading edge and a trailing edge, the leading edge being adapted to engage the mine wall before the trailing edge engages the mine wall when the wrist portion is pivoted relative to the main portion;

a first actuator for pivoting the first member relative to the main portion, the first actuator including a first end coupled to the main portion and a second end directly coupled to the first member; and

a second actuator for pivoting the second member relative to the first member, the second actuator including a first end coupled to the first member and a second end coupled to the second member,

wherein the combined pivoting of the first member and the second member moves the leading edge through an angle greater than 180 degrees about the first axis.

2. The mining machine of claim 1 , wherein the main portion includes a pair of spaced apart main plates and a support rotatably coupled to and extending between the main plates, the first member being pivotably coupled to the support, the support defining the first axis.

3. A mining machine in accordance with claim 2 wherein the first member includes two spaced apart mounting plates attached to said support, and the second member includes two spaced apart wrist plates, parallel to but spaced radially outward from the mounting plates relative to the first axis, said wrist plates being pivotally attached to the mounting plates by a wrist rod that extends between the wrist plates and through an opening in the mounting plates.

4. A mining machine in accordance with claim 3 wherein an uppermost wrist plate and a lower most wrist plate each include a hook that engages a bar extending between and radially outward from the mounting plates when the second member is fully rotated.

5. A mining machine in accordance with claim 3 wherein the first actuator includes two spaced apart hydraulic cylinders extending between the main portion and the first member so that the mounting plates rotate relative to the main portion, one cylinder being attached to one of the mounting plates on one side of the support, and the other cylinder being attached to the same mounting plate on the other side of the support, so that by extending one cylinder and retracting the other cylinder, the first member pivots relative to the main portion about the support.

6. A mining machine in accordance with claim 3 wherein the second actuator includes a hydraulic cylinder extending between the mounting plates and a wrist rod attached to and extending between the spaced apart wrist plates, the wrist rod being received in and passing through a curved slot in the mounting plates, so that the wrist plates pivot relative to the mounting plates.

7. A mining machine in accordance with claim 6 wherein a cut out in the main portion receives the wrist rod to prevent the main portion from interfering with the wrist rod during pivoting of the wrist portion.

8. A mining machine in accordance with claim 1 wherein the leading edge moves through an angle of about 220 degrees about the first axis.

9. A mining machine in accordance with claim 1 wherein the disc cutter is eccentrically driven.

10. A mining machine in accordance with claim 1 wherein the first actuator and the second actuator are hydraulic cylinders, wherein extension and retraction of the first actuator pivots the first member about the first axis and extension and retraction of the second cylinder pivots the second member about the second axis.

11. A mining machine in accordance with claim 1 wherein the cutter head includes a first disc cutter, a second disc cutter, and a third disc cutter, the first disc cutter being positioned proximate the leading edge of the cutter head, the second disc cutter being positioned proximate the trailing edge, and the third disc cutter being positioned between the first and second disc cutters.

12. A mining machine for liberating material from a mine wall, the mining machine comprising:

an arm including a main portion and a wrist portion, the wrist portion including a first member that is pivotably coupled to the main portion about a first axis and a second member pivotably coupled to the first member about a second axis, the second member including a cutter head, the cutter head having at least one disc cutter for engaging the mine wall;

a first actuator for pivoting the first member relative to the main portion, the first actuator including a first end coupled to the main portion and a second end directly coupled to the first member; and

a second actuator for pivoting the second member relative to the first member, the second actuator including a first end coupled to the first member and a second end coupled to the second member,

wherein the combined pivoting of the first member and the second member through a maximum range of motion moves the cutter head about the first axis between a first point and a second point, the angular distance between the first point and the second point relative to the first axis being more than 180 degrees.

13. A mining machine in accordance with claim 12 wherein the cutter head moves through an angle of about 220 degrees about the first axis.

14. A mining machine in accordance with claim 12 wherein the disc cutter is eccentrically driven.

15. A mining machine in accordance with claim 12 wherein the first actuator and the second actuator are hydraulic cylinders, wherein extension and retraction of the first actuator pivots the first member about the first axis and extension and retraction of the second cylinder pivots the second member about the second axis.

16. A mining machine in accordance with claim 12 wherein the cutter head defines a leading edge and a trailing edge, the leading edge being adapted to engage the mine wall before the trailing edge engages the mine wall when the wrist portion is pivoted relative to the main portion, the leading edge being pivotable through an angle of more than 180 degrees about the first axis.

17. A mining machine in accordance with claim 12 wherein the main portion includes a pair of spaced apart main plates and a support extending between the main plates, the support defining the first axis, and wherein the first member includes a pair of mounting plates pivotably coupled to the support.

18. A mining machine in accordance with claim 17 wherein the mounting plates include a slot, and wherein the second member includes a pair of spaced apart wrist plates parallel to the mounting plates and a wrist rod extending between the wrist plates, the wrist rod being positioned within the slot, wherein the second actuator is coupled between the first member and the wrist rod to move the wrist rod within the slot.

19. A mining machine in accordance with claim 12 wherein the arm further includes a stop engaging the wrist portion when the wrist portion is pivoted to an end of the wrist portion's range of motion.