A seal on each end of a linear ball bushing to keep grease in a keep dirt out is called the _______________.

• A. Dust Cap
• B. Gasket
• C. Wiper
• D. Seal Ring

Answer: (C)

The idea being tested is how end seals in a linear ball bushing protect lubrication while blocking contaminants. A wiper is the end-sealing lip that contacts the rail as the carriage moves, doing two jobs at once: it helps keep the grease inside the bushing and it wipes away dirt and dust before it can enter the bearing clearance. That dual function—retaining lubricant and shedding contaminants—is exactly what the description calls for, so this term fits best. A dust cap mainly covers the end to keep large debris out but doesn’t actively wipe contaminants; a gasket is a general seal between surfaces; a seal ring is a broad term that doesn’t specifically describe the wiping action needed here.