E21D 23/0056
Mine roof supports for step- by- step movement: with individual advancing shifting
Official title: {with individual advancing shifting devices}
E21D23/0056 (Mine roof supports for step- by- step movement: with individual advancing shifting) appears on 1 US grants and 0 published applications in this corpus.
Search patents in E21D- Granted patents
- 1
- Published applications
- 0
- Assignees
- 1
- Inventors
- 7
- Latest grant
- 31 May 1977
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| Year | Granted patents | Published applications |
|---|---|---|
| 1977 | 1 | 0 |
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