Patent US3309880A successfully refreshed from Google Patents.
US3309880A
Expired / Lapsed
US
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Mining apparatus
Assignee: Dowty Mining Equipment Ltd
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Filing: 1964-07-21
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Granted: 1967-03-21
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Expires: 1984-07-21
Abstract
No abstract record available.
Inventors
- 👤 Potts Michael Charles
- 👤 Pawling Frank
- 👤 Bolton Douglas Herbert Hewlett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:38
CPC Classifications
E; E21; E21D; E21D23/00; E21D23/16
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
164 words
MINING APPARATUS INCLUDING A SERIES OF ADVANCEABLE ROOF SUPPORTS, A GUIDE MEANS FOR A CUTTING MACHINE, AT LEAST SOME OF THE ROOF SUPPORTS HAVING A FLUID-PRESSUREOPERATED JACK MEANS OPERABLE TO APPLY AN ADVANCING FORCE TO THE GUIDE MEANS, MEANS FOR ADVANCING EACH ROOF SUPPORT, AT LEAST ONE FLUID-PRESSURE-OPERATED PROP INCORPORATED IN EACH ROOF SUPPORT AND OPERABLE TO SET THE ROOF SUPPORT AGAINST THE MINE ROOF, OR TO RELEASE THE SAME PREPARATORY TO ITS ADVANCE, A CONTROL VALVE ASSEMBLY OPERATIVELY CONNECTED WITH EACH ROOF SUPPORT AND OPERABLE TO CONTROL THE SUPPLY OF FLUID UNDER PRESSURE TO SAID PROP, AND ALSO OPERABLE TO CONTROL THE SUPPLY OF SUCH FLUID TO SAID JACK MEANS, TO CAUSE THE ROOF SUPPORT TO UNDERGO AND ADVANCING OPERATION FOLLOWING RELEASE OF SAID PROP, MEANS FOR SENDING A FLUID-PRESSURE SIGNAL FROM EACH ROOF SUPPORT TO THE CONTROL VALVE ASSEMBLY OF THE NEXT ROOF SUPPORT TO ACTUATE THE LATTER, AT LEAST SOME OF THE ROOF SUPPORTS INCLUDING SENSING MEANS RESPONSIVE TO THE AMOUNT
Claim 2
Dependent Claim
164 words
MINING APPARATUS INCLUDING A SERIES OF ADVANCEABLE ROOF SUPPORTS, A GUIDE MEANS FOR A CUTTING MACHINE, AT LEAST SOME OF THE ROOF SUPPORTS HAVING A FLUID-PRESSUREOPERATED JACK MEANS OPERABLE TO APPLY AN ADVANCING FORCE TO THE GUIDE MEANS, MEANS FOR ADVANCING EACH ROOF SUPPORT, AT LEAST ONE FLUID-PRESSURE-OPERATED PROP INCORPORATED IN EACH ROOF SUPPORT AND OPERABLE TO SET THE ROOF SUPPORT AGAINST THE MINE ROOF, OR TO RELEASE THE SAME PREPARATORY TO ITS ADVANCE, A CONTROL VALVE ASSEMBLY OPERATIVELY CONNECTED WITH EACH ROOF SUPPORT AND OPERABLE TO CONTROL THE SUPPLY OF FLUID UNDER PRESSURE TO SAID PROP, AND ALSO OPERABLE TO CONTROL THE SUPPLY OF SUCH FLUID TO SAID JACK MEANS, TO CAUSE THE ROOF SUPPORT TO UNDERGO AND ADVANCING OPERATION FOLLOWING RELEASE OF SAID PROP, MEANS FOR SENDING A FLUID-PRESSURE SIGNAL FROM EACH ROOF SUPPORT TO THE CONTROL VALVE ASSEMBLY OF THE NEXT ROOF SUPPORT TO ACTUATE THE LATTER, AT LEAST SOME OF THE ROOF SUPPORTS INCLUDING SENSING MEANS RESPONSIVE TO THE AMOUNT
References Cited (Backward Citations)
US3207041A
Cited
US3241654A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1970-03-20 | 1970-09-19 | 1971-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1974-03-20 | 1974-09-19 | 1975-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1978-03-20 | 1978-09-19 | 1979-03-21 | $7700.00 | Window Closed / Lapsed |