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US 2012/0148350 A1Published application
Mine prop jack and method of prestressing a mine prop
OwnerKenneth Poulson, Maury Gleaveinventors
Life of this patent
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Abstract
A telescoping mine prop is prestressed by engaging the prop with a jack and thereby telescopically expanding the prop against opposing surfaces of the mine with the jack. Thereafter the prop is locked in position and the jack is disengaged from the prop for use with the expansion of another prop, thereby leaving the mine prop in a prestressed condition.
Claims9
A mine prop prestressing device comprising;
- a jack having means for temporarily attaching it to a telescoping mine prop for expanding said prop into prestressed engagement with opposing surfaces.
A combination mine prop and jack for prestressing the mine prop, comprising:
- a telescopically expandable mine prop having a head plate and a foot plate secured to opposite ends;
- a lock for adjustably locking said prop in an expanded condition;
- an expandable jack post disposed between said head and foot plates for expanding said prop against opposing surfaces to a condition of prestress after engaging said lock and releasing said jack post;
- and
- tie means temporarily tying said jack post to said mine prop.
2 more elements
The method of prestressing a telescoping mine prop comprising;
- engaging said prop with a jack;
- telescopically expanding said prop against opposing surfaces with said jack;
- locking said prop at its expanded position;
- and
- disengaging said jack from said prop for use with the expansion of another prop and thereby leaving said mine prop in a prestressed condition.
2 more elements
Dependencies are inferred from the claim text.