Mine roof supports
Abstract
Abstract A MINE ROOF SUPPORT COMPRISES TWO UNITS WHICH CAN BE ADVANCED RELATIVE TO EACH OTHER. THE UNITS HAVE PARALLEL ROOF BEAMS EXTENDING IN THE DIRECTION OF ADVANCE, THOSE OF EACH UNIT ALTERATING IN THE BREADTH DIRECTION WITH THOSE OF THE UNIT. EACH UNIT COMPRISES TWO SUB-UNITS, EACH COMPRISING A CROSS BEAM AND SUPPORTING HYDRAULIC LEGS (THE SUB-UNITS BEING CONNCETED ONLY BY THE ROOF BEAMS OF THAT UNIT), AND CAN BE ADVANCED SEPARATELY BY A RAM, THE ROOF BEAMS CAN HAVE CANTILEVER BARS AT THEIR LEADING ENDS AND MEANS FOR RAISING PERMANENT ROOF BARS AT THEIR TRAILING ENDS. AN ANCHOR PLATE CAN BE SUSPENDED IN CRADLE-LIKE MANNER FROM ONE UNIT BY MEANS OF DOUBLE ACTING STAKER PROPS AND BE DISPLACEABLE BY MEANS OF ANOTHER DOOUBLE ACTING RAM.
Inventors
- 👤 Archelaius D Allen
Bibliographic Details
Claims Analysis
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-22 | 1975-05-24 | 1975-11-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-22 | 1979-05-24 | 1979-11-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-22 | 1983-05-24 | 1983-11-23 | $7700.00 | Window Closed / Lapsed |