Folyócsapágyak

Folyócsapágyak, often translated as plain bearings or journal bearings, are a fundamental type of mechanical bearing that reduces friction between moving parts. They work by providing a low-friction surface for a rotating shaft, known as a journal, to rest upon. Unlike rolling-element bearings that use balls or rollers, plain bearings rely on the sliding motion of surfaces.

The simplest form is a sleeve bearing, which is essentially a cylindrical bushing that surrounds the shaft. The bearing surface can be made from various materials, including bronze, Babbitt metal, plastics, or composite materials, chosen based on factors like load, speed, temperature, and lubrication requirements.

Lubrication is crucial for the proper functioning of plain bearings. A fluid film, typically oil or grease, separates the journal and the bearing surface. This fluid film prevents direct metal-to-metal contact, significantly reducing wear and friction. This hydrodynamic lubrication regime is achieved when the shaft's rotation creates sufficient pressure within the lubricant film to support the load. In some cases, hydrostatic lubrication is used, where an external pump supplies pressurized lubricant to the bearing.

Plain bearings are valued for their simplicity, low cost, high load-carrying capacity, and ability to operate in contaminated environments. They are widely used in applications such as automotive engines (crankshaft and connecting rod bearings), pumps, electric motors, and heavy machinery. Their silent operation and shock-absorbing qualities are also advantageous in certain designs.