There is prior art having to do with top-drive rigs with vertical pipe stacking U.S. Pat. No. 7,021,374 Weatherford ('374), as well as a system designed for snubbing and work-over rigs U.S. Pat. No. 6,158,516 Cudd Pressure Control ('516), and a more general pipe-racking system U.S. Pat. No. 4,042,123 Sheldon et al ('123).
There are, however, significant differences between these systems and this invention.
For instance, '374 Weatherford deals with a top-drive system, and thus has drive equipment which must align with the upper box-end of the tubing in the elevator, inside the drive unit, and the drive unit itself is integrated in the top-end. The similarity ends with the use of hydraulic rains connected to an off-set at the upper end of the bails and to the bails themselves lower down, to effect some vertical displacement. This is not exactly the same as this invention, and takes place in a completely different working environment, although the Weatherford's hydraulic offset device has some similarities, it is effected in a different manner, on a different rig type, with a different drive system.
A block-retracting linkage between a vertical rail offset from the well's centre line and a travelling block is provided in '123 Sheldon, with a number (3) of hydraulic rams which can be actuated to move the block (and any suspended tubulars) off the well's centre line and toward and to a vertical pipe-rack means. This is different from the hydraulic bail/ram system of this invention in that the block in the system of this invention is suspended and not held by a rail-based mechanical setup.
In '516 Cudd, a combination coiled-tubing and rack-back jointed tubing rig is described, but without details of the elevator and racking system. This is relevant in that the type of tubular is commonly seen in pressure-controlled well settings, but Cudd does not disclose a hydraulic-ram bail swing system, and so is merely cited as a reference to similar rig environments in the prior art with rack-back tubular systems.