What is the term for the seal on the ends of a linear ball bushing?

• A. Gland
• B. O-ring
• C. Dust shield
• D. Wiper

Answer: (D)

End seals at the ends of a linear ball bushing are there to keep dirt out and grease in, and the term for that sealing element is a wiper. The wiper is a flexible lip or blade that contact-scrapes the shaft or rail as it moves, removing debris before it can enter the bearing and cause wear. This makes motion smoother and extends life by maintaining lubrication.

Gland is the groove or pocket that holds a seal, not the seal itself. An O-ring is a general-purpose gasket used in many joints, not specifically the end seal of a linear bushing. A dust shield serves to block larger contaminants but doesn’t provide the wiping action at the seal, so it isn’t the end seal term.