| 摘要 |
There are hinged caps and base plates on the hydraulically extensible props making up the support frame in a mine. There are rear end swivelling shields, and pressure blocks hinged to the cap and shield so that they run at an angle to the frame centre line, providing cap resistance to displacement. Draw rods (11) are attached at the frame sides, between the cap (3) and shield. These provide for mutual convergence of cap and shield, and determination of the extension length of the pressure blocks (12), and thus the max. interval between cap and shield on each side of the frame. This is effective in spite of relatively unfavourable pressure blocks' position, with props withdrawable into a prescribed position on removal from the roof. |
