【正文】 and they are available in standard, onewebback, and immediate forward support (IFS) versions. With the standard system, the wining machine takes a cut or a slice, and the armored face conveyor is pushed over by the hydraulic rams that are fixed to the support units. The support units then are advanced sequentially to the conveyor. With the onewebback system, a support is set back from the conveyor by a device that automatically keeps the leading edge of the support at a fix distance from the conveyor. This allows easy access though the face and employs the standard method of advancing。 這四種類(lèi)型的液壓支架不僅可以用于后退式長(zhǎng)壁回采工作面和前進(jìn)式開(kāi)采工作面，還可以用于標(biāo)準(zhǔn)方式、滯后支護(hù)方式和即時(shí)支護(hù)方式。支架前進(jìn)過(guò)程中，當(dāng)次要支柱降低并通過(guò)活塞推動(dòng)向前移動(dòng)時(shí)，主要支柱使頂梁平衡。擋矸簾由一些矩形的金屬片組成，這 些金屬片的兩端水平連接。頂梁端部的運(yùn) 動(dòng)軌跡，液壓立柱的定位于定向，液壓立柱的數(shù)目，頂梁的幾何形狀，以及其他的可以任意選擇的設(shè)計(jì)方法和理念都可以用專(zhuān)業(yè)術(shù)語(yǔ)詳細(xì)的說(shuō)明。 支撐掩 護(hù)式液壓支架 支撐掩護(hù)式液壓支架結(jié)合了垛式液壓支架和掩護(hù)式液壓支架的特點(diǎn)。 橢圓形：在橢圓形掩護(hù)式液壓支架中，掩護(hù)梁和底座采用這種方式連接，當(dāng)液壓支架的立柱作上升和下降運(yùn)動(dòng)時(shí)，支架頂板的前端沿橢圓形軌跡運(yùn)動(dòng)。 掩護(hù)是液壓支架有很多種類(lèi)。對(duì)于六柱式支架，頂梁在通道的上方鉸接。每根支柱之間有雙作用液壓缸。 基于這個(gè)概念，按照液壓支架發(fā)展進(jìn)化的順序，把液壓支架分為四類(lèi)，即：節(jié)式支架，垛式支架，掩護(hù)式支架和支撐掩護(hù)式支架。 英文原文 Selfadvancing hydraulic powered support Modern longwall mining employs hydraulic powered supports at the face area. The supports not only holds up the roof, pushes the face chain conveyor, and advances itself, but also provides a safe environment for all associated mining activities. Therefore its successful selection and application are the prerequisite for successful longwall mining. Furthermore, due to the large number of units required, the capital invested for the power support usually accounts for more than half of the initial capital for a longwall face. Therefore both from technical and economic points of view, the powered support is a very important piece of equipment in a long wall face. The application of modern powered supports can be traced back to early 1950’s. Since then, following its adoption in every part of the world, there have been countless models design and manufactured in various countries. But unfortunately, there still is no uniform system of classification. A simplified classification is used in this section. Since a powered support consists of four major ponents(i. e. , canopy, caving shield, hydraulic legs and props, and base plate), the ways by which they are interrelated are used for classification. In this respect, two factors are most important: (1) presence or absence of caving shield if a caving shield is included, the support is a “shield” type, otherwise, a frame or a chock。另外，液壓支柱的 安裝方式也很重要，例如，立柱垂直安裝在底座和有掩護(hù)梁的頂梁之間，此時(shí)對(duì)頂板具有最小的支護(hù)效率。先移動(dòng)的是次要裝置，后移動(dòng)的是主要裝置。六柱式垛式支架是為薄煤層設(shè)計(jì)的，兩個(gè)支柱在前，四個(gè)在后，中間是人行走的通道。由于只有液壓立柱的垂直分量 起支護(hù)頂板的作用，掩護(hù)式液壓支架的承載能力隨著采煤高度的變化而變化。另外，當(dāng)降低液壓支柱時(shí)，未支護(hù)面積將會(huì)減少。所以，支撐掩護(hù)式液壓支架具有以上兩者所具有的優(yōu)點(diǎn)。 頂梁端部的運(yùn)動(dòng)軌跡的形式 這是公認(rèn)的最普遍的對(duì)掩護(hù)是液壓支架的分類(lèi)方法。 在大多數(shù)垛式支架中，液壓支柱與頂梁和液壓支柱與底座