The unloading valve shares which characteristic with the make-up valve?

• A. They are identical in function
• B. They have the same basic configuration and operation
• C. They are physically adjacent
• D. They are controlled by different systems

Answer: (B)

Both valves are pressure-regulating control devices that share the same basic design and how they work. They use a valve body with a movable element (like a poppet or disk) that seals against a seat and is held closed by a spring or pilot signal. When the control signal or pressure reaches the set point, the element moves, opening the path to allow flow, and it closes again when pressure returns. The unloading function and the makeup function differ in purpose—one relieves or unloads a portion of the system, the other adds makeup fluid—but their underlying configuration and mode of operation are the same.