Hydraulic Control Valve of wheel loader

When controlling the direction of oil flow, hydraulic valves are divided into hydraulic valves and manual valves. Hydraulic directional valve: The hydraulic directional valve is a directional valve that uses the pressure oil of the control oil circuit to change the position of the spool. The operation is more convenient and the starting force is large. However, when the hydraulic control oil flow is large, the reversing shock will be relatively large. Therefore, in order to control the moving speed of the spool, the impact is reduced. Usually a one-way throttling device (damping adjuster) is installed before the hydraulic port. Manual reversing valve: The manual reversing valve is a directional control valve operated by a manual lever. It plays a reverse role (change the direction of fluid flow) and switch (open or cut off fluid flow) in the Hydraulic System.

The pressure control valve is a valve used to control and adjust the hydraulic pressure of the hydraulic system. Common ones are safety valves, pressure reducing valves and sequence valves. Overflow valve Overflow valve is used to set the system working pressure or limit its maximum working pressure through the overflow of the valve port to prevent system overload. The main requirement for the relief valve is that the pressure adjustment range should be large and the pressure adjustment deviation should be small. The pressure swing is small, the action is sensitive, the flow is large, and the noise is small. Pressure reducing valve The pressure reducing valve is a valve that reduces the inlet pressure to a certain required outlet pressure by adjusting, and automatically maintains a stable outlet pressure depending on the energy of the medium itself. The pressure reducing valve is a kind of throttling element whose local resistance can be changed, that is, by changing the throttling area, the flow rate and kinetic energy of the fluid can be changed, thereby causing different pressure losses to achieve the goal. stress reliever. Then rely on the adjustment of the control and regulation system to balance the fluctuations of the pressure behind the valve and the spring force, so that the pressure behind the valve remains constant within a certain error range.

The inlet and outlet pressures of the sequence valve depend on the working conditions of the hydraulic system. When the inlet pressure is lower than the set pressure of the spring, the valve port is closed. When the inlet pressure exceeds the set pressure of the spring, the valve port opens and connects to the oil circuit. The outlet pressure oil does affect the downstream load. The difference between the two is: 1. The relief valve is a pressure control valve that can maintain a constant pressure in front of the valve; 2. The pressure relief valve is a way to throttle the outlet to lower the inlet pressure and keep the outlet pressure constant The pressure control valve; 3. The sequence valve is when the inlet oil pressure reaches the preset value, the valve opens to allow the fluid to flow smoothly. 4. From the perspective of flow control, the hydraulic valve is controlled by changing the flow area of the valve port (local resistance of the throttle valve) or the length of the flow channel. Throttle valves and speed control valves are commonly used.