| 摘要 |
A mine roof support comprising a roof engaging canopy, a floor-engaging means, a pair of shields pivotally secured to the canopy and extending downwardly and rearwardly in side-by-side relation over the floor-engaging means, a quadrilateral linkage securing each shield to the floor-engaging means and extensible strut means for adjusting the height of the canopy so arranged that the canopy may tilt about a transverse horizontal axis and a fore and aft axis to engage the roof, the shields being capable of providing differing height settings to accommodate canopy tilt about the fore and aft axis. |
