US3928981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mine proof support
Assignee: Dowty Mining Equipment Ltd
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Filing: 1974-10-11
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Granted: 1975-12-30
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Expires: 1994-10-11
Abstract
Abstract A roof support for use in a mine comprising, a roof-engaging canopy, a floor-engaging beam, a plurality of variable length struts extending between the floor beam and the canopy, and guide means comprising a first link pivotally connected at one position to the floor beam, a second link pivotally connected at another position to the floor beam spaced from the one position, a third link pivotally connected at spaced positions along its length to the first and second links and an extension fixedly secured to the third link and pivotally connected to the canopy, such that the centre of the pivotal connection to the canopy is limited by the links and the extension to move solely in a fixed path approximately at right angles relative to the plane of the floor beam, the pivotal connection to the canopy being arranged to permit angular tilting movement of the canopy relative to the floor beam about two axes both of which lie parallel to the plane of the canopy and to resist angular movement relative to the floor beam in the plane of the canopy.
Inventors
- 👤 James Eric Parker
- 👤 Nigel Hill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:29
CPC Classifications
E; E21; E21D; E21D23/00; E21D23/04; E21D23/0427; E21D23/0004; E21D23/0034; E21D23/0043
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
213 words
A roof support for use in a mine comprising, a roof-engaging canopy, a floor-engaging beam, a plurality of variable length struts extending between the floor beam and the canopy, and guide means comprising a first link pivotally connected at one position to the floor beam, a second link pivotally connected at another position to the floor beam spaced from the one position, a third link pivotally connected at spaced positions along its length to the first and second links and an extension fixedly secured to the third link and pivotally connected to the canopy, such that the center of the pivotal connection to the canopy is limited by the links and the extension to move solely in a fixed path approximately at right angles relative to the plane of the floor beam, the first link, the third link and its extension being arranged to extend substantially the full width of the support to form a shield and the pivotal connection to the canopy being arranged to permit angular tilting movement of the canopy relative to the floor beam about a longitudinal axis and a transverse axis both of which lie parallel to the plane of the canopy and to resist angular movement relative to the floor beam in the plane of the canopy.
Claim 2
Dependent Claim
213 words
A roof support for use in a mine comprising, a roof-engaging canopy, a floor-engaging beam, a plurality of variable length struts extending between the floor beam and the canopy, and guide means comprising a first link pivotally connected at one position to the floor beam, a second link pivotally connected at another position to the floor beam spaced from the one position, a third link pivotally connected at spaced positions along its length to the first and second links and an extension fixedly secured to the third link and pivotally connected to the canopy, such that the center of the pivotal connection to the canopy is limited by the links and the extension to move solely in a fixed path approximately at right angles relative to the plane of the floor beam, the first link, the third link and its extension being arranged to extend substantially the full width of the support to form a shield and the pivotal connection to the canopy being arranged to permit angular tilting movement of the canopy relative to the floor beam about a longitudinal axis and a transverse axis both of which lie parallel to the plane of the canopy and to resist angular movement relative to the floor beam in the plane of the canopy.
Claim 3
Dependent Claim
61 words
A roof support as claimed in claim 1 wherein the axes of the pivotal connections between the floor beam and the first and second links and between the third link and the first and second links are all substantially parallel to the plane of the floor beam and parallel to one another and transverse to the length of the floor beam.
Claim 4
Dependent Claim
78 words
A mine roof support as claimed in claim 1, wherein the pivotal connection between the canopy and the third link extension comprises a pair of slots in the canopy each substantially at right angles to the plane of the canopy and spaced apart by substantially the width of the canopy, and a pair of co-axial pins on the third link extension for engaging the slots, the axis of the pins being transverse to the length of the canopy.
Claim 5
Dependent Claim
71 words
A roof support as claimed in claim 1 wherein the fixed path for movement of the centre of the pivotal connection of the third link extension to the canopy is such that lowering of the canopy towards the floor beam results in slight forward movement of the canopy in the advancing direction over all or a substantial part of the available range of movement of the canopy towards the floor beam.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |