Under days, removal, in particular for by mountain impact endangered degradation strut

摘要

A hydraulic support for a mine roof, permitting a series of small collapses is equipped with two pistons 2 and 4 dividing each prop into two unequal parts. The lower part 5 is of approximately constant volume over a fixed period of use. It is filled with viscoelastic matter absorbing energy of impacts and vibrations. The upper part 6 of variable volume by virtue of a small-"bleed" exit is filled with a well known water/oil emulsion as a hydraulic fluid. Parts 5, 6 are separated by the floating piston 4. Thus, a sudden shock conveys pressure to the viscoelastic material, which deforms to prevent damage elsewhere in the equipment, and then regains its shape with consequent loss of liquid from space 6. IMAGE