Mining system

A mine roof support comprising first cradle means including a first pair of spaced apart chocks for slidable mounting on a seam floor, a crossbar interconnecting said first pair of chocks and first prop means extending upwardly from said first cradle means and including roof supporting bars for supporting a section of mine roof;

• second cradle means including a second pair of spaced apart chocks for slidable mounting on a seam floor, a web interconnecting said second pair of chocks, and second prop means extending upwardly from said second cradle means for supporting a section of mine roof;
• first coupling means interconnecting said first and second cradle means for moving said first and second cradle means relative to each other and toward or away from a longwall mining face;
• said first chocks and said web being so shaped that said first and second cradle means are slidably interconnected in overlapping relationship with said first and second pairs of chocks parallel to each other;
• third cradle means including third chock means for slidable mounting on a seam floor, and third vertically movable props extending upwardly from said third chock means;
• said third props including roof supporting arms so spaced apart that they are parallel to and between said bars for supporting a section of mine roof;
• second coupling means for releasably interconnecting said second and third cradle means for moving said third cradle means relative to said first and second cradle means and for providing a working passage beneath said third prop means and between said first and second chock means and said third chock means.