The gate is mainly composed of three parts:

① The main activity section, used for closing or opening apertures, commonly referred to as a gate, also known as a gate leaf.

② Settled portion

③ Closure Equipment.

Gates are sturdy barriers located at the entrance of city gates, which can be lowered as needed to block the doorway. The castle gate is a gatehouse with an interior space, serving as a strong defense point for the castle. People can reach the gatehouse through a tunnel from the entrance of the gate. In the middle or at both ends of the tunnel, there will be one or more layers of gates. Rolling mechanical mechanisms can lift or lower the gates above the gatehouse for solid protection. The gates themselves are usually heavy wooden or iron栏杆, with defenders and attackers shooting or thrusting from either side of the gates.

We categorize hydraulic gates as follows:

1. Gate types can be categorized based on their operational nature into working gates, maintenance gates, and emergency gates. The working gate, also known as the main gate, can be opened and closed in flowing water. The maintenance gate is installed in front of the working gate. It is used for temporarily blocking water during the maintenance of buildings or working gates, and is typically opened and closed in still water. The emergency gate is often located in front of deep hole working gates, designed to close in flowing water and open in still water when an accident occurs in buildings or equipment; when used as a maintenance gate, it is also referred to as an emergency maintenance gate. Emergency gates that need to be closed urgently within a specified time are called rapid closure gates.

2. If divided by the relative position of the gate top and water level at the time of gate closure, there are overhead gates and submersible slabs.

3. We categorize the gates based on their appearance and shape into flat gates, arc gates, wedge gates, arch gates, spherical gates, and cylindrical gates, among others.

4. Gate leaves are categorized by the material used in manufacturing into steel gates, cast gates, wood gates, reinforced concrete gates, and composite material gates. Sluice gates can be hydraulically automatically opened and closed, known as hydraulic automatic gates. When selecting the type of gate, factors such as its position, size, design head, operating conditions, manufacturing capabilities, and installation technical level in hydraulic structures should be considered. The requirements include good flow conditions during discharge, tight water-sealing, low opening and closing force, simple and flexible operation, and convenient maintenance. Flat gates and arched gates are commonly used gate types.