They work with remote control devices that change the direction, position and speed of a German-made cutting machine that slices back and forth along a 300-metre-wide coalface.
This paper analysis a variety of ventilating systems adopted in the coalface in mining coal of our country by using the method of statistics and compares their advantages and the range available.
本文用统计分析法介绍和分析了我国煤炭开采中，采煤工作面采用的各种通风系统并对比其优点和适用范围。
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Why lose a hard-working 25-year-old for a couple of years when you can train him internally and keep him at the coalface?