- All sections
- E - Fixed constructions
- E21D - Shaftstunnelsgallerieslarge underground chambers
- E21D 15/20 - Telescopic props with parts held together by positive means, with or without relative sliding movement when the prop is subject to excessive pressure with pawl, pin, cross-piece, or the like engaging with ratchet teeth, notches, holes, or the like spaced apart at intervals
Patent holdings for IPC class E21D 15/20
Total number of patents in this class: 3
10-year publication summary
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1
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0
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0
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1
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1
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0
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0
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1
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0
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0
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| 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
Principal owners for this class
| Owner |
All patents
|
This class
|
|---|---|---|
| China University of Mining and Technology | 1266 |
2 |
| Ccteg Chinese Institute of Coal Science | 5 |
1 |
| Other owners | 0 |