| 摘要 |
A dragline comprising a main housing, a bucket hoist mechanism mounted on the housing, a bucket drag mechanism mounted on the main housing, a moving mechanism for moving the main housing over the ground, a boom having upper and lower ends and a rectangular cross-section, the lower end being connected to the main housing, the upper end having thereon a sheave, the boom having a longitudinal axis and including a center section having top and bottom members parallel to the longitudinal axis, the center section having a neutral axis above the longitudinal axis, structure supporting the boom relative to the main housing, a bucket, a hoist rope extending between the bucket and the bucket hoist mechanism and over the sheave for causing vertical movement of the bucket, and a drag rope extending between the bucket and the bucket drag mechanism for causing horizontal movement of the bucket. |
