Non Rising Stem Flanged Gate Valve is also called rotating stem gate valve (also called dark stem wedge gate valve). The valve stem nut is set on the gate. The rotation of the handwheel drives the rotation of the valve stem to lift the gate. Usually there is a trapezoidal thread at the bottom end of the valve stem. The thread on the bottom end of the valve and the guide groove on the disc will rotate the gate. It becomes linear motion, that is, the operating torque is changed to operating thrust.