Iron roughneck extension systems

An extension system for an iron roughneck, the iron roughneck comprising an iron roughneck support and a torque wrench and a spinning wrench on the iron roughneck support, the extension system comprising:

• a stem,
• a support column on the stem,
• a mount movably connected to the support column and movable up and down thereon,
• a first linkage with a first linkage first end pivotably connected to the mount and,
• a first linkage second end,
• a second linkage with a second linkage first end pivotably connected to the first linkage second end and a second linkage second end,
• a third linkage with a third linkage first end pivotably connected to the second linkage second end and a third linkage second end pivotably connected to the iron roughneck support,
• raising apparatus connected to the support column for raising and lowering the mount with respect to the support column, powered extension apparatus connected to the mount and to the first linkage, and
• the first linkage, the second linkage, and the third linkage pivotable and movable by the powered extension apparatus to extend the iron roughneck support away from the support column and to retract the iron roughneck toward the support column,
• and wherein the powered extension apparatus for extending the iron roughneck comprises at least one powered piston-cylinder apparatus, and wherein the at least one powered piston-cylinder apparatus comprises a housing, an inner floating piston movable within the housing,
• a shaft extending through the inner floating piston and movable with respect thereto, the shaft having two ends and a shaft piston on one end thereof, the shaft piston movable in the housing, and the shaft having an internal channel through which fluid is flowable from an exterior of the housing into a middle chamber,
• the inner floating piston and the shaft piston dividing an interior of the housing into three chambers including a first end chamber, the middle chamber, and a second end chamber,
• the shaft connected to the first linkage, and
• the shaft piston and the shaft movable by flowing a fluid into the housing to operate the powered extension apparatus at a number of known, discrete positions so that the location of the shaft in the housing may be adjusted to corresponds to the location of the first linkage and to the location of the iron roughneck.