Handwheel through the handwheel and valve stem threads forward, rewind, enhance or decrease the valve plate connected with the stem, to the opening and closing action .
According to the sealing surface configuration can be divided into wedge gate-type valve and parallel gate-type valve, wedge gate-type valve can be divided into : single -gate type, gate-type double plate and elastic; parallel gate-type valve can be divided into single- gate plate and double plate according to the position of divided threaded stem can be divided into two clear shot valve gate and dark bar .
1, fluid resistance is small, sad sealing surface by the media small brush and erosion .
2, open and close more effort.
3, medium flow unrestricted, non-spoiler, without reducing pressure .
4, simple shape, structure, length short, good manufacturing processes, a wide range.