| 摘要 |
This invention relates to a mine prop. The prop consists of a timber pole which is cut adjacent one of its ends and over a portion of its length to provide an axially positioned core of reduced cross-section relatively to the uncut portion of the pole, timber on the outside of the cut and at least one hoop of yieldable material surrounding the pole over the core and the timer on the outside of it to restrain expansion of the cone and outer timber in a direction transverse to the pole axis when the prop is reduced in length under a compressive load in its axial direction. |
