Characteristics and innovation of two-legs shield powerful caving coal hydraulic support for large cutting height face

The paper introduces the current status and developing trend of the two- legs shield powerful caving coal hydraulic support for large mining height face. Wit h the comparison and analysis of the four- legs shield,the two- legs shield has the following advantages: firstly,having stronger supporting forces at the front end of shield a nd better ability for controlling the coal wall slide and roof falling; secondly,the top beam can adjust its position in a larger range and has the stronger ability to adapt to the external load changes and then adjust itself correspondingly; third,easily achieving the automatic control,forth,lower yield load compared with same width of four- leg shiel d. Furthermore,this paper also stated the new achievements of two- legs shield in recent years as follows: first,the ultimate yield load of two- legs shield was increased,sec ond,automatic system was developed ,third,the shield's steel performance was upgraded and then the shield weight was reduced. Finally,it gets the conclusion that the two- legs shield powerful caving coal hydraulic support for large mining height face will become the first choice for the high- seam automatic longwall top coal caving face.