Abstract The specification discloses a racking arm having a telescoping boom with a supported end and a free cantilevered end. A pipe gripping head is secured to the cantilevered end of the boom for clamping about elongated members such as pipe sections, drill collars, riser pipes or the like. The supported end of the boom is mounted for pivotal movement about a vertical axis and a motor is provided to selectively rotate the boom about the vertical axis. Hydraulic cylinders are provided to selectively raise and lower the free cantilevered end of the boom. Hydraulic cylinders also are provided to extend and retract the boom to selectively vary the length thereof. In operation, the boom is disposed on a drilling rig with the supported end spaced above the working platform of the drilling rig and the vertical axis spaced away from the well bore axis. The boom may then be employed to move elongated pipe members from various storage positions to the well bore or other areas and vice-versa. The pipe gripper head is normally automatically maintained horizontal during vertical movement of the boom. A first embodiment of the pipe gripper head clamps pipe sections, drill collars and the like for lateral movement while allowing the pipe sections and drill collars to slide vertically along their axes. In a second embodiment of the gripper head, riser pipe having an irregular cross-section may be tightly gripped by the gripper head.
An extendable racker arm assembly comprising: an extendable boom having a supported end pivotable about a vertical axis and having a free end movable upwardly and downwardly, pipe gripper means on said free end of said boom for gripping oil well pipe sections, said boom including an outer housing having first, second and first telescoping sections relatively movable from said housing to extend and retract said boom, the inner of said sections having smaller cross-sections than the outer of said sections, a first fluid cylinder connected between said outer housing and the upper portion of the first outermost section, a second fluid cylinder connected between said first and second sections, a third fluid cylinder connected between said second section and the third innermost section, control means for sequentially applying fluid to said cylinders to control the outward movement of said telescoping sections such that said first outermost section is first extended, said second section is next outwardly extended, and said third innermost section is subsequently outwardly extended, said control means also operative when said boom is fully extended to first retract said third innermost section, then said second section and then said first outermost section in order to provide optimum stability to said boom due to the largest and strongest sections being first extended and last retracted.
Claim 2
Dependent Claim
217 words
An extendable racker arm assembly comprising: an extendable boom having a supported end pivotable about a vertical axis and having a free end movable upwardly and downwardly, pipe gripper means on said free end of said boom for gripping oil well pipe sections, said boom including an outer housing having first, second and first telescoping sections relatively movable from said housing to extend and retract said boom, the inner of said sections having smaller cross-sections than the outer of said sections, a first fluid cylinder connected between said outer housing and the upper portion of the first outermost section, a second fluid cylinder connected between said first and second sections, a third fluid cylinder connected between said second section and the third innermost section, control means for sequentially applying fluid to said cylinders to control the outward movement of said telescoping sections such that said first outermost section is first extended, said second section is next outwardly extended, and said third innermost section is subsequently outwardly extended, said control means also operative when said boom is fully extended to first retract said third innermost section, then said second section and then said first outermost section in order to provide optimum stability to said boom due to the largest and strongest sections being first extended and last retracted.