Roof support for underground excavations such as coal mines
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United States of America Patent
Stats
-
Jan 12, 1993
Grant Date -
N/A
app pub date -
Sep 26, 1991
filing date -
Sep 26, 1990
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A roof support for the ceilings of excavated spaces underground and particularly for supporting caving edges for pillar recovery in coal mines is described. The roof support has a roof bar connected to a base frame by hydraulically extendable props and by a lemniscate mechanism. The props are articulated to the base frame and to the roof bar. A link of the lemniscate mechanism has a predetermined bending point. Since this link fails when overloaded before the remainder of the apparatus, it is the only element that need be replaced when the apparatus is overloaded. Thus, the device may be economically repaired.
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Cited Art Landscape
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