CPC Main Group
E21B 4/00 Drives for drilling, used in the borehole
8 direct subcodes
Child Classifications
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- E21B 4/02 Fluid rotary type drives
- E21B 4/04 Electric drives (E21B4/12 takes precedence)
- E21B 4/06 Down-hole impacting means, e.g. hammers (boring rams E21B11/02)
- E21B 4/16 Plural down-hole drives, e.g. for combined percussion and rotary drilling (E21B4/10 takes precedence); Drives for multi-bit drilling units
- E21B 4/18 Anchoring or feeding in the borehole
- E21B 4/20 combined with surface drive (E21B4/10 takes precedence)