Patent ID: 8636324

Claim:
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.