Patent classifications
E
FIXED CONSTRUCTIONS
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E21
EARTH OR ROCK DRILLING; MINING
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E21B
EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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31/00
Fishing for or freeing objects in boreholes or wells
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E21B31/107
using impact means for releasing stuck parts, e.g. jars
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E21B31/113
hydraulically-operated
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E21B31/1135
Jars with a hydraulic impedance mechanism, i.e. a restriction, for initially delaying escape of a restraining fluid
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