Apparatus for protecting underground excavations against collapse
Abstract
Abstract AN APPARATUS FOR PROTECTING UNDERGROUND EXCAVATIONS AGAINST COLLAPSE INCLUDES ROOF SUPPORT MEANS, ADVANCING MEANS WHICH ADVANCES LONGITUDINALLY ALONG THE FLOOR OF THE RESPECTIVE EXCAVATION, AND CONNECTING ARANGEMENTS WHICH CONNECT THE ROOF SUPPORT MEANS WITH THE ADVANCING MEANS FOR MOVEMENT OF THE LATTER. UPRIGHT SHIELD MEANS IS ARRANGES SO AS TO TRAIL THE ROOF SUPPORT AND ADVANCING MEANS AND EXTENDS TRANSVERSELY OF THE DIRECTION OF MOVEMENT THEREOF. THE SHIELD MEANS HAS AN UPPER AND A LOWER END PORTION. AT LEAST TWO CYLINDER AND PISTON MEANS ARE PROVIDED EACH HAVING ONE END CONNECTED TO THE ADVANCING MEANS AND ANOTHER END ARTICULATELY CONNECTED TO THE SHIELD MEANS AT THE UPPER AND LOWER END PORTIONS THEREOF. RESPECTIVELY.
Inventors
- 👤 Hans-Joachim Von Hippel
Bibliographic Details
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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) | 1974-02-22 | 1974-08-24 | 1975-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-22 | 1978-08-24 | 1979-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-22 | 1982-08-24 | 1983-02-23 | $7700.00 | Window Closed / Lapsed |