E21D 21/02
Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
Official title: having means for indicating tension (screwed connections specially modified for indicating tensile load F16B31/02)
E21D21/02 (Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection) appears on 52 US grants and 42 published applications in this corpus.
Search patents in E21D- Granted patents
- 52
- Published applications
- 42
- Assignees
- 43
- Inventors
- 146
- Latest grant
- 12 Aug 2025
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1977 | 2 | 0 |
| 1978 | 0 | 0 |
| 1979 | 0 | 0 |
| 1980 | 0 | 0 |
| 1981 | 1 | 0 |
| 1982 | 5 | 0 |
| 1983 | 1 | 0 |
| 1984 | 2 | 0 |
| 1985 | 0 | 0 |
| 1986 | 0 | 0 |
| 1987 | 1 | 0 |
| 1988 | 0 | 0 |
| 1989 | 0 | 0 |
| 1990 | 1 | 0 |
| 1991 | 0 | 0 |
| 1992 | 1 | 0 |
| 1993 | 2 | 0 |
| 1994 | 0 | 0 |
| 1995 | 1 | 0 |
| 1996 | 2 | 0 |
| 1997 | 0 | 0 |
| 1998 | 2 | 0 |
| 1999 | 2 | 0 |
| 2000 | 1 | 0 |
| 2001 | 1 | 0 |
| 2002 | 0 | 0 |
| 2003 | 0 | 0 |
| 2004 | 1 | 1 |
| 2005 | 0 | 1 |
| 2006 | 1 | 2 |
| 2007 | 0 | 1 |
| 2008 | 1 | 1 |
| 2009 | 0 | 0 |
| 2010 | 0 | 2 |
| 2011 | 2 | 1 |
| 2012 | 1 | 1 |
| 2013 | 0 | 1 |
| 2014 | 2 | 2 |
| 2015 | 0 | 2 |
| 2016 | 1 | 0 |
| 2017 | 3 | 3 |
| 2018 | 0 | 2 |
| 2019 | 3 | 2 |
| 2020 | 1 | 2 |
| 2021 | 1 | 0 |
| 2022 | 1 | 6 |
| 2023 | 2 | 5 |
| 2024 | 3 | 3 |
| 2025 | 4 | 1 |
| 2026 | 0 | 3 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Recent patents
- Tension indicator for a rock bolt12 Aug 2025US 12,385,396 B2Sandvik Mining and Construction Australia Pty Ltd
- Determining residual tension in threaded fasteners22 Jul 2025US 12,366,493 B2Predictant LLC
- Rock bolt assembly having an indicator15 Apr 2025US 12,276,195 B2Rocbolt Technologies (Pty) Ltd.
- Visual indicator for correct torsion of a rock bolt21 Jan 2025US 12,203,372 B2Sandvik Mining and Construction Australia Pty Ltd
- Methods and systems for ultrasonic rock bolt condition monitoring12 Nov 2024US 12,140,032 B2National Research Council of Canada
- "stress-displacement" intelligent early warning method for roof disaster23 Jul 2026US 2026/0210250 A1Guizhou University
- A displacement measuring device for installation in a rock hole26 Mar 2026US 2026/0085610 A1Innovative Mining Products (Pty) Ltd
- Adapter for rock or building anchor system5 Mar 2026US 2026/0063036 A1MontanuniversitäT Leoben
- Determining residual tension in threaded fasteners9 Oct 2025US 2025/0314546 A1Predictant LLC
- Rock anchor comprising sensor for measuring mechanical stress4 Jul 2024US 2024/0218793 A1
Most cited
By later US patents
- Tension gauge32US 4,322,193 A1982
- Cable attachable device to monitor roof loads or provide a yieldable support or a rigid roof support fixture29US 5,253,960 A1993
- Mine roof bolt assembly25US 4,347,020 ABirmingham Bolt Company · 1982
- Tensionable cable bolt with mixing assembly25US 5,919,006 AJennmar Corporation · 1999
- Tension indicator21US 4,047,463 AEaton Corporation · 1977