一、前言 许多采用掩护式支架支护的工作面通常班产原煤高达6000—7000t,每工班产量不低于300t。1986年《煤时代》的统计资料表明:在101个长壁生产工作面中,有96.3％采用掩护式支架进行支护。更准确地说,有64.6％用的是双柱掩护式支架,而有31.7％用的是四柱掩护式支架。一般一个长壁工作面只采用一种类型的机械化支架。但是,在少数的工作面中,由于工作面宽度的增加而更换或补充了其它型号的支架,因此有两种或三种掩护式支架混用的情况。目前最常用的双纽线掩护式支架有以下三种: I. INTRODUCTION Many facers that are supported by shield support usually produce as much as 6000-7000 tons of raw coal, with a production of no less than 300t per shift. Statistics from the 1986 Coal Age show that 96.3% of the 101 long-wall production workplaces are supported by a shield support. More precisely, 64.6% used double-column shields, while 31.7% used four-column shields. In general, only one type of mechanized support is used for a longwall face. However, in a few work surfaces, where two or three different types of shelves are mixed due to the change of face width or the replacement or replacement of other types of brackets. At present, the most commonly used double-line cover type shield has the following three: