Which valve type is used in a hydraulic system to change the cylinder's direction of motion?

The valve type that is used in a hydraulic system to change the cylinder's direction of motion is the directional control valve. This type of valve is specifically designed to control the flow path of hydraulic fluid, allowing the operator to select the direction of movement for hydraulic actuators, such as cylinders.

When operating a hydraulic cylinder, it's important to manage how fluid is directed into the cylinder chambers. The directional control valve achieves this by having multiple ports and flow paths. For instance, when engaging one direction, it allows fluid to flow to one side of the cylinder while simultaneously allowing fluid to exit from the other side, which in turn causes the cylinder to extend or retract as desired. Depending on the configuration of the valve, it can perform multiplex functions, controlling multiple cylinders or directions at once.

Other types of valves, like pressure relief valves, primarily focus on protecting the system from overpressure situations; flow control valves regulate the speed of the actuator but do not change its direction; and sequence valves are used to manage the sequencing of operations in a hydraulic system rather than controlling the direction of motion of a cylinder. Thus, the directional control valve is essential for directing hydraulic flow to control the movement effectively.