Define a shuttle valve and its use in OR logic.

Define a shuttle valve and its use in OR logic.

• A. A valve that selects the higher-pressure source from multiple inputs; outputs to the actuator, enabling OR logic.
• B. A valve that blocks flow entirely.
• C. A valve that reduces pressure.
• D. A valve that doubles flow to two outputs.

Answer: (A)

A shuttle valve provides an OR function by letting the actuator be driven from either of two pressure sources. It has two inlet ports and one outlet, with a shuttle (ball or spool) inside that moves toward the higher-pressure side. When one input is pressurized, the shuttle seals off the other inlet and connects that active input to the output, so the actuator receives pressure. If both inputs are pressurized, the higher-pressure source wins, delivering the strongest drive while preventing backflow into the other source. This automatic selection creates OR logic in pneumatics—either input can feed the output to run the actuator. It doesn’t block flow, reduce pressure, or split/double flow to two outputs, which is why the other possibilities don’t fit.

A shuttle valve provides an OR function by letting the actuator be driven from either of two pressure sources. It has two inlet ports and one outlet, with a shuttle (ball or spool) inside that moves toward the higher-pressure side. When one input is pressurized, the shuttle seals off the other inlet and connects that active input to the output, so the actuator receives pressure. If both inputs are pressurized, the higher-pressure source wins, delivering the strongest drive while preventing backflow into the other source. This automatic selection creates OR logic in pneumatics—either input can feed the output to run the actuator. It doesn’t block flow, reduce pressure, or split/double flow to two outputs, which is why the other possibilities don’t fit.