| 摘要 |
1487702 Advancing mine roof supports GEWERKSCHAFT EISENHUTTE WESTFALIA 2 Jan 1975 [3 Jan 1974] 56/75 Heading E1P In a mine roof support having a goaf shield 14 articulated to a roof bar 15 and a floor plate 10, the gap between the shield and the rear of the roof bar is closed by a telescopically interfitting cover 24 fixed to the roof bar. The cover may be made of sheet metal and take the form of a three sided box having a central slit to allow passage of a cable 33 connecting the roof bar with a fixed point 34 on the floor plate. The support is also provided with two, articulated props 20, on advancing jack 23, a ram 17 for adjusting the roof bar relative to the roof and a rear shield 11. |
