CPC Subgroup
E21D 15/44 Hydraulic, pneumatic, or hydraulic-pneumatic props
Full Title
Props (in the building art E04G25/00); Chocks > Telescopic props (general means for fixing telescopic parts together ) > Hydraulic, pneumatic, or hydraulic-pneumatic props
2 direct subcodes
Child Classifications
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- E21D 15/45 having closed fluid system, e.g. with built-in pumps or accumulators
Top Applicants
Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT
- HALLIBURTON ENERGY SERVICES GROUP US 27,652
- SAUDI ARABIAN OIL COMPANY SA 7,755
- PETROCHINA COMPANY 7,025
- BAKER HUGHES US 6,589
- SCHLUMBERGER TECHNOLOGY US 6,151
- SINOPEC (CHINA PETROCHEMICAL CORPORATION) 4,443
- SCHLUMBERGER TECHNOLOGY NL 4,255
- CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 3,991
- SERVICES PETROLIERS SCHLUMBERGER FR 3,300
- SCHLUMBERGER CANADA CA 3,086