Patent ID: 7024806

Claim:
A mining machine including a revolving frame, a boom having two ends, with one end attached to the revolving frame, the boom having a mid point between said two ends, a dipper attached to the end of a handle, a boom point sheave rotatably mounted near the other end of the boom, a hoist rope drum mounted on the revolving frame, a hoist rope that extends from the hoist rope drum along the boom and over the boom point sheave, referred to as the rope span, the middle of the span being referred to as the mid span, said hoist rope being attached to said dipper, and an auxiliary hoist sheave assembly comprising: a sheave support frame, means for mounting the sheave support frame to the boom midpoint, a sheave shaft mounted on said sheave support frame, an upper guide roller shaft mounted on said sheave support frame, spaced apart from but parallel to said sheave shaft, a grooved hoist sheave, rotatably supported by and slidable along the sheave shaft, said hoist sheave being in contact with said hoist rope, and said hoist sheave fleeting side to side along said sheave shaft as the hoist rope follows the hoist drum, and a guide roller rotatably mounted on and slidable along the upper guide roller shaft, said hoist rope being constrained to remain in said hoist sheave by said guide roller.