CPC Subgroup
E21B 3/02 Surface drives for rotary drilling
Full Title
Rotary drilling > Surface drives for rotary drilling
5 direct subcodes
Child Classifications
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- E21B 3/025 with a to-and-fro rotation of the tool
- E21B 3/03 with an intermittent unidirectional rotation of the tool
- E21B 3/035 with slipping or elastic transmission
- E21B 3/04 Rotary tables