Apparatus for feeding the rods or cables (E21B19/22 takes precedence; automatic feed E21B44/02); Apparatus for increasing or decreasing the pressure on the drilling tool; Apparatus for counterbalancing the weight of the rods

Full Title

Handling rods, casings, tubes or the like outside the borehole, e.g. in the derrick; Apparatus for feeding the rods or cables > Apparatus for feeding the rods or cables (E21B19/22 takes precedence; automatic feed E21B44/02); Apparatus for increasing or decreasing the pressure on the drilling tool; Apparatus for counterbalancing the weight of the rods

Child Classifications

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• E21B 19/081 Screw-and-nut feed mechanisms
• E21B 19/083 Cam, rack or like feed mechanisms
• E21B 19/084 with flexible drawing means, e.g. cables
• E21B 19/086 with a fluid-actuated cylinder (E21B19/084, E21B19/087, E21B19/09 take precedence)
• E21B 19/087 by means of a swinging arm
• E21B 19/089 with a spring or an additional weight
• E21B 19/09 specially adapted for drilling underwater formations from a floating support using heave compensators supporting the drill string