Bearings allow the compressor pump and motor/engine to run smoothly and reduce friction between moving parts. Bearings can be sealed or open. There are generally two types of bearings found in air compressors, ball bearings and roller bearings. Bearings wear out periodically so If you hear metal grinding, the bearing(s) may need to be replaced.
15-pc Thunderbolt Black Oxide Drill Bit Set
1/4" x 50 Ft Noodle Air Hose with Coupler and Plug