There is no way to add lubricant to a _______ bearing.

• A. Sealed
• B. Open
• C. Lubricated
• D. Greased

Answer: (A)

Sealed bearings are designed to retain lubricant and keep contaminants out. The seals create a permanent barrier, so there isn’t a practical path to inject grease or oil after installation. When lubrication is lost in a sealed bearing, the usual approach is to replace the bearing rather than try to add lubricant in service. Open bearings, by contrast, have no permanent seals, so you can access lubrication paths and add grease or oil during maintenance. The terms lubricated or greased describe the current state or design, but they don’t inherently prevent servicing in all cases; still, sealed bearings are the ones you generally cannot top up in the field.