| 摘要 |
A derrick-erection frame hoist consists of paired tubular posts, shoes, crowns, lower and upper ledges, diagonal links, bearing beams and tubes, the upper and the lower blocks of polyspasts. The bearing beams with the lower sections are installed on the surface of earth or on a base with elastic devices that consist of elastic elements placed in the fixed and the movable sections of the body; the fixed ends of the cables of the polyspasts are connected to each other by means of a ring through bypass blocks, guide tubes and elastic elements. |
