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Beyond Similar Appearances: Explore Directional & Pressure-Type Logic Valves’ Secrets
2026-01-17
In hydraulic control systems, the accurate selection of logic valves directly impacts equipment operational efficiency—and valves that look similar in appearance often hide vastly different core functions. Today, we’ll take a close look at two logic valves that seem like "twins" but perform unique roles, guiding you through their difference .
At first glance, these two logic valves are almost same in external appearance. However, their functional orientations are completely distinct. The first is a directional logic valve, which functions similarly to our commonly used large-bore solenoid directional valves, with its core purpose being to control the flow direction of hydraulic oil. A closer inspection of the valve core reveals a unique stepped structure—this design enables hydraulic oil to flow both from port A to port B and in the reverse direction from port B to port A. When hydraulic oil enters through port B, it acts on the stepped part of the valve core, pushing the core upward to open the path from port B to port A. Such directional logic valves are often used to control actuators, such as the extension and retraction of hydraulic cylinders, as well as the start, stop, and direction change of motors. More practically, combining two such cartridge valves allows the creation of a three-position, four-way directional circuit for controlling hydraulic cylinders, adapting to various working conditions.
The other is a pressure-type logic valve. Its valve core has no stepped structure, but there is an inclined small hole reserved on the valve body—this is its key design feature. Pilot oil flows through this inclined hole into the spring chamber above the valve core, which is connected to a relief valve that controls the pressure at this position. When the pressure of the incoming pilot oil exceeds the set value of the relief valve, the pressure pushes the valve core upward, thereby opening the pressure relief channel from port A to port B and achieving pressure overload protection.
Although these two logic valves serve different functions, they both possess the core advantages of the logic valve series—compact structure, strong flow capacity, and high control precision—capable of meeting the rigorous requirements of complex hydraulic systems. For more characteristics of logic valves, feel free to contact us.