摘要:
A mine roof support comprising a floor beam, a roof lever pivotally mounted on the floor beam for engaging the roof, a variable length strut such as a hydraulic jack engaging pivotally between the floor beam and the roof lever at positions spaced from the pivot device and means to adjust the lever pivot on the floor beam to provide at least two separate pivoting positions for the roof lever. The roof lever may carry a roof beam at its free end for engaging the roof.
摘要:
THE INVENTION PROVIDES A SELF-ADVANCING ROOF SUPPORT PRIMARILY FOR MINE WORKINGS IN WHICH A ROOF-ENGAGING SUPERSTRUCTURE CARRIED BY A PLURALITY OF HYDRAULIC PROPS UPSTANDING FROM A BASE INCLUDES LATERALLY SPACED, LONGITUDINALLY EXTENDING, ROOF BARS CONNECTED WITH EACH OTHER BY TRANSVERSELY EXTENDING SPRING STRIP ELEMENTS INCORPORATING ONE OR MORE LOOPED, UNDULATING, OR ARCUATE PORTIONS TO PROVIDE AN EXTENDED LENGTH OF THE STRIP ELEMENT BETWEEN CONNECTIONS TO THE ROOF BARS SUBSTANTIALLY EXCEEDING THE DISTANCE BETWEEN SUCH CONNECTIONS.