Wearing rings in a pump serves to

• A. Concentrate wear on an economically replaceable part
• B. Hold the shaft in position
• C. Keep the impeller in place
• D. Wear out rings instead of sleeves

Answer: (A)

Wear rings provide sacrificial, replaceable wear surfaces between the impeller and the pump casing. Their purpose is to absorb the wear so that the more expensive parts—like the impeller and the casing sleeves—are preserved longer. By concentrating wear on these rings, you can simply replace the rings when they wear and restore the intended clearance and efficiency, rather than replacing or rebuilding critical components. The other ideas don’t describe what wear rings do: they aren’t meant to hold the shaft in position or to keep the impeller in place, and while rings wear, the main benefit is their replaceability and protection of more costly parts.