IPC Subgroup
E21D 17/02 Cantilever extension or similar protecting devices
Introduced: September 1968
Last revised: January 2006
Full Title
Caps for supporting mine roofs > Cantilever extension or similar protecting devices
Classification Context
- Section:
- FIXED CONSTRUCTIONS
- Class:
- EARTH OR ROCK DRILLING; MINING
- Subclass:
- SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
5 direct subcodes
Child Classifications
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- E21D 17/022 Auxiliary devices for temporary support of roof-supporting beams whilst assembling
- E21D 17/03 Brackets for roof-supporting bars
- E21D 17/04 for use in longwall working
- E21D 17/06 for use in drifting galleries
- E21D 17/08 Cap joints for obtaining a coal-face free of pit-props
Top Applicants
Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT
- HALLIBURTON ENERGY SERVICES GROUP US 26,607
- PETROCHINA COMPANY 14,382
- SINOPEC (CHINA PETROCHEMICAL CORPORATION) 10,137
- CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 6,517
- BAKER HUGHES US 6,269
- SCHLUMBERGER TECHNOLOGY US 5,929
- SAUDI ARABIAN OIL COMPANY SA 5,880
- SOUTHWEST PETROLEUM UNIVERSITY 4,477
- CHINA UNIVERSITY OF MINING AND TECHNOLOGY 4,357
- SCHLUMBERGER TECHNOLOGY NL 4,219