Check valves are used in hydraulics to______.

• A. Control flow
• B. Control speed
• C. Block flow
• D. Control system pressure

Answer: (C)

Check valves act as one-way gates in a hydraulic line. They open to allow fluid to move in the intended direction and immediately close if the flow tries to go the opposite way, effectively blocking backflow. That single function—preventing fluid from returning where it came from—is why this valve is used. It doesn’t set or regulate how much fluid passes (that’s done by flow-control devices) and it doesn’t directly determine system pressure (that’s the job of pressure-control devices). In practice, a check valve helps keep a line from draining or a cylinder from pushing fluid back toward the pump when the pump isn’t supplying flow, preserving the desired direction of flow and protecting components.