| 摘要 |
<p>The plough incorporates a share lifted on encountering a stone and afterwards returning to the working position. It comprises a polygon linkage hinging at four or more sides. One of the transverse sides is fixed in position in relation to the frame, and another is extended by an arm supporting the share. The share arm can be coupled to the linkage via a shear pin to uncouple them when resistance to forward movement of the share exceeds a predetermined value. Normally, the polygon linkage can be spring-loaded into the working position.</p> |
