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1、9-1IntroductionModernlongwallminingemploysself-advancinghydraulicpoweredsupports[1](whichwillsimplybecalledpoweredsupportsinthisbook)atthefacearea.Thesupportsnotonlyholduptheroof,pushthefacechainconveyor（AFC）,andadvancethemselves,butalsoprovideasafeenviro
2、nment[2]forallassociatedminingactivities.Thereforetheirsuccessfulselectionandapplicationaretheprerequisiteforsuccessfullongwallmining.Furthermore,duetothelargenumberofunitsrequired,thecapitalinvestedforthepoweredsupportsusuallyaccountsformorethanhalfofthe
3、initialcapitalforalongwallface.Thereforebothfromtechnicalandeconomicpointsofview,thepoweredsupportsareveryimportantpieceofequipmentinalongwallface.9-2ClassificationofPoweredSupportTheapplicationofmodernpoweredsupportscanbetracedbacktotheearly1950s.Sinceth
4、en,followingtheiradoptionineverypartoftheworld,therehavebeencountlessmodelsdesignedandmanufacturedinvariouscountries.Butunfortunatelytherestillisnouniformsystemofclassification.Inthissectionasimplifiedclassificationisused.Sinceapoweredsupportconsistsoffou
5、rmajorcomponents(i.e.,canopy,cavingshield,hydrauliclegsorprops,andbaseplate),thewaysbywhichtheyareinterrelatedareusedforclassification.Inthisrespect,twofactorsaremostimportant:(1)presenceorabsenceofacavingshield[3]—ifacavingshieldisincluded,thesupportisa“
6、shield”type,otherwiseitisaframeorachock;(2)numberandtypeofarrangingthehydrauliclegs[4]—sincesupportcapacityisgenerallyproportionaltothenumberofhydrauliclegs,itisimportanttospecifythenumberofhydrauliclegsthatasupporthas.Furthermorethewaythehydrauliclegsare
7、installedisimportant;forexample,averticalinstallationbetweenthebaseandthecanopyhasthehighestefficiencyofapplicationwhereasaninclinedinstallationbetweenthebaseandthecavingshieldhastheleastefficiencyinsupportingtheroof.Basedonthisconcept,therearefourtypesof
8、poweredsupports,thoseare,frame[5],chock[6],shield[7],andchockshield[8],inorderofevolutionoftheirdevelopment.However,itmustbenotedthatthetrendoftheirdevelopmentineachtypeissuchthatitbecomeslessdistinguishableintermso
