| 摘要 |
A multi-stage, well-drilling mast assembly, particularly adapted to mobile drilling platforms, such as drilling vessels, the assembly having a main stage mast and an auxiliary mast, both pivoted to the platform for swinging movements between horizontal and vertical positions. The main stage carries well pipe hoisting equipment, and the auxiliary stage carries rack equipment for vertically storing well pipe, and racker equipment for moving the well pipe between the rack and the center line of the mast assembly. Slings operated by the hoisting equipment swing the stages between horizontal and vertical positions. A low profile and a low center of gravity are achieved when the stages are horizontally disposed. The distribution of the weight of the hoist, the rack, and the rackers between the stages of the mast assembly provides a multi-stage mast assembly in which the individual stages may be conveniently swung between reclined and vertical, well-drilling positions.
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