medellager

Medellager is a term used in some engineering contexts to refer to a center bearing, a support bearing positioned near the middle of a shaft. The primary purpose of a medellager is to support radial loads, limit lateral movement, and reduce shaft deflection and vibration in long or high-speed shafts. It often forms part of a multi-bearing arrangement that also includes end bearings.

Design and types are dependent on the application. A medellager can be a plain bearing (sleeve bearing), a rolling-element bearing, or a combination with a flexible mounting to absorb vibrations. Lubrication is an important consideration and may involve grease or oil lubrication with seals, or a sealed-for-life design in some configurations. Mounting arrangements are chosen to accommodate thermal expansion, shaft misalignment, and dynamic loads.

Manufacturing and maintenance considerations include material choice, surface finish, alignment accuracy, and lubrication management. Proper installation aims to minimize preload and misalignment, while maintenance typically involves periodic inspection for wear, leaks, and bearing condition, followed by lubrication or replacement as needed.

Applications and usage vary by industry. Medellager are found in long, high-speed or heavy-duty shafts such as those in power generation turbines, large pumps, conveyor systems, mills, and ship propulsion or industrial drives. In some vehicle drivetrains, a center or mid-shaft bearing serves a similar function to support a long driveshaft and reduce vibrations.

See also: bearing, shaft alignment, tribology.