Mine roof supports
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Aug 13, 1991
Grant Date -
N/A
app pub date -
May 11, 1990
filing date -
May 18, 1989
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Mine roof support comprising a base including a pair of skids, a roof engaging canopy, jacks acting between the base and the canopy, an auxiliary jack connected to the base for lifting or lowering at least part of the base when the support advances and a lost motion arrangement connected between the base and the auxiliary jack for aiding movement of the base and the roof engaging canopy toward each other. The lost motion arrangement is connected to each of the skids by a pivotal connection which permits the front end of one skid to move vertically to a limited extent with respect to the front end of the adjacent skid.
First Claim
Family
International Classification(s)
Cited Art Landscape
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