| 摘要 |
A clamp for drill pipes includes an hydraulic motor adapted to drive a gear head which is keyed to a sprocket engaged to a sheave chain. The sprocket and the associated equipment are mounted between two plates which are also provided with an hydraulically operated slide for advancing two rollers. It is these rollers that, by their advancement, enlarge or shorten the effective sheave chain loop, the sheave chain passing over idlers towards the end of two hinged arms or jaws which are conformed to receive the drill pipe. Formed at the end of each jaw are bearing seats each adapted to receive a bearing cap which engages ball bearings in corresponding bearing races supporting the center shaft of two turning sprockets around which the chain is looped. Each of the bearing races includes an enlarged periphery and it is between this periphery and the chain loop that the pipe is engaged. In this manner pipes of various sizes may be clamped on the interior of the jaws and the rotation of the hydraulic motor can then drive the pipe.
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