IPC Subgroup
E21D 15/14 Telescopic props
Introduced: September 1968
Last revised: January 2006
Full Title
Props; Chocks > Telescopic props
Classification Context
- Section:
- FIXED CONSTRUCTIONS
- Class:
- EARTH OR ROCK DRILLING; MINING
- Subclass:
- SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
Related Keywords
TELESCOPIC mineprops
5 direct subcodes
Child Classifications
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- E21D 15/15 Means counteracting entry of dirt; Built-in cleaning devices
- E21D 15/16 with parts held together by positive means, with or without relative sliding movement when the prop is subject to excessive pressure
- E21D 15/28 with parts held relatively to each other by friction or gripping, e.g. using wedges
- E21D 15/44 Hydraulic, pneumatic, or hydraulic-pneumatic props
- E21D 15/46 with load-measuring devices; with alarm devices
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