Double cylinder system

DETAILED DESCRIPTION The present invention provides a double cylinder, fluid-pressure operated system.
A pair of cylinders are joined together with their respective piston rods extendable in opposite directions.
Each piston rod may be individually extended or retracted.
An alternate form of operation of the double cylinder system involves linking the fluid pressure communication lines leading to the two cylinders so that the piston rods may be operated simultaneously and in combination.
Such combined operation may be such that the piston rods extend simultaneously and retract simultaneously, or such that one piston rod extends while the other retracts.
The paired cylinders may be joined with a second pair of cylinders mutually linked in similar fashion.
The fluid pressure communication lines leading to the two pairs of cylinders may also be joined so that each cylinder pair extends or retracts piston rods at the same time and in the same general direction.
Such a pair of cylinders may be mounted for movement along each leg of a two-legged mast used, for example, in a coiled tubing rig.
The cylinder pairs may be joined by at least one cross-member so that all the cylinders are moved as a unit.
The entire double cylinder system may be suspended from the mast at a point near the top of the mast by a piston rod extending generally upwardly from each cylinder pair.
The downwardly extending piston rods may be lowered and joined to the injector head, or a carriage supporting the injector head.
Operation of the double cylinder system moves the injector head to selected positions along the mast.
The combination of piston rods extendable in either direction from a floating double cylinder assembly provides a stroke length twice that of a conventional piston-cylinder assembly with the same cylinder length.
Thus, the range of movement of the injector head in the referenced copending application may be increased without increasing the length of any one cylinder or piston rod.
The injector head may be readily lowered below the mast hinge point as well as raised, say, two-thirds the length of the mast with the use of a double cylinder system