The HZS type main command constant force rope-retracting gate opening sensor involves pulling out a steel wire rope from inside, which is directly connected to the gate being measured. When the gate is raised or lowered, the steel wire rope drives the measuring wheel coaxial with the encoder to rotate, causing the encoder to synchronize with the gate's movement. This converts the gate's lifting and lowering into the rotation of the encoder shaft, outputting corresponding position information. Simultaneously, it drives the main command shaft to rotate, controlling the upper and lower limits for gate opening and closing, thereby achieving real-time measurement of the gate's displacement while managing its operational limits. Its internal mechanical structure mainly consists of a constant force spring, spring wheel, measuring wheel, wheel shaft, gearbox, cam, limit switch, etc. During the descent process, the gate pulls the spring to reverse wind, driving the mechanical mechanism to rotate. During ascent, the force generated by the reverse-wound spring drives the mechanical rotation and pulls the steel wire rope upward. This sensor features a rational structure, easy installation, strong anti-interference capability, high resolution, large range, long service life, and integrates detection with A/D conversion. It also includes signal tracking and memory functions after power loss. It can be used for long-term detection of displacement in measured components while ensuring stable and reliable performance. It is suitable for measuring and controlling the lifting height of various gates (such as flat gates, radial gates, miter gates, gantry cranes, bridge cranes, etc.). It is an ideal sensor for displacement measurement and control in rivers, lakes, reservoirs, ship locks, hydropower stations, hydrological stations, water treatment plants, and the petrochemical industry.