US3565488A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Devices for breaking down hard or rocky materials
Assignee: WM Park and Co Forgemasters Ltd
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Filing: 1969-01-17
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Granted: 1971-02-23
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Expires: 1989-01-17
Abstract
Abstract A HYDRAULIC PISTON AND CYLINDER DEVICE FOR BREAKING HARD OR ROCKY MATERIAL BY DRIVING A WEDGE INTO A HOLE IN SAID MATERIAL, IS CARRIED BY A MANDREL INSERTABLE INTO SAID HOLE AND HAVING MEANS WHEREBY IT IS EXPANDED, BY OPERATION OF THE PISTON AND CYLINDER DEVICE, SO AS TO BECOME SELF-HOLDING IN SAID HOLE AND FORM AN ANCHORAGE FOR THE DEVICE WHEN THE LATTER APPLIES A FORCE TO THE WEDGE TO DRIVE IT INTO THE HOLE.
Inventors
- 👤 Donald T Walsh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:40
CPC Classifications
E; E21; E21C; E21C37/00; E21C37/04
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
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 |