The concealed rod gate valve is also called the rotary rod gate valve (also known as the concealed rod wedge gate valve). Stem nuts are set on the gate plate. Handwheel rotation drives the stem to rotate and lifts the gate plate. Trapezoidal threads are usually found at the bottom of the valve stem. Through the threads at the bottom of the valve and the guide grooves on the disc, the rotary motion is changed into linear motion, that is, the operating torque is changed into the operating thrust.  When opening the valve, when the gate lifting height is equal to 1:1 times of the valve path, the flow passage is completely open, but when running, this position can not be monitored. In practical use, the vertex of the valve stem is used as the sign, that is, the position of the valve stem that is not moving is used as its full open position. In order to consider the locking phenomenon of temperature change, usually open to the vertex position, and then back to 1/2-1 circle, as the position of the full open valve. Therefore, the full open position of the valve is determined by the position of the gate (i.e. stroke).