Abstract: This invention relates to a lemniscate mining support comprising a foot piece, a roof bar, an anti-fall shield connected between the foot piece and the roof bar, and movable props between the roof bar and the foot piece so as to move the roof bar. The joints connecting the anti-fall shield to the foot piece and the anti-fall shield to the roof bar are positioned so that the anti-fall shield can be positioned at a steep angle, relative to the roof bar so that damage to the anti-fall shield can be minimized while allowing the anti-fall shield to contribute to the support of the roof bar.

Abstract: A generator for dynamic loading of a mine lining simulates an unstable ground structure, such as a "bump" of the formation roof by an explosion of an explosive. The generator /3/ comprises a cylinder /6/ with a piston /7/, the said piston functioning as a percussion member. The bottom of the cylinder /6/ is provided with symmetrical chambers /10/ to place an explosive. The explosive is batched to each of chambers /10/ through holes /8, 9/ made in the flank of the cylinder /6/. Holes /8, 9/ are bored at an angle enabling gravitational filling of the chamber /10/ with an explosive already after initial spragging of the lining section /1/ under test between the floor /2/ and the generator /3/ abutting the roof /5/ of the test-stand. The cylinder /6/ is closed with a limiter /12/ of the stroke of the piston. Between the piston /7/ and the limiter /12/ of its stroke there is a shock-absorbing washer /13/. In the limiter /12/ there are additional holes for release of powder gases.