What component primarily controls the speed of an actuator by restricting flow?

• A. Proportional valve
• B. Needle valve
• C. Check valve
• D. Relief valve

Answer: (B)

Speed of an actuator is governed by how quickly fluid can move into and out of the actuator; throttling the flow increases resistance and slows the movement. A needle valve is designed for fine throttling, with a small, adjustable passage created by the needle and seat. This lets you set the exact flow rate and, therefore, the actuator speed with precision. The proportional valve is used for broader, variable control of flow to achieve different speeds and forces, not primarily by tight flow restriction. A check valve only prevents backflow, and a relief valve protects against overpressure. So, for controlling speed specifically by restricting flow, the needle valve is the best choice.