Stainless sleeve, Dnipropetrovsk region.

Sleeve bearing (sliding bearing) — a sleeve that does not contain intermediate moving elements. A shaft support or other rotating element is placed in a cylindrical bushing with a clearance.

Sliding bearings are divided into:(//tractor-service.com)

dry - periodically lubricated with grease or not lubricated at all. The bushings themselves or only their sliding surfaces are made of bearing metal alloys or synthetic materials (for example: cast iron, bronze, Teflon). Such bushings are used in lightly loaded and less responsible nodes;
air - in which the gap between the shaft and the sleeve is maintained through an air cushion formed by compressed air supplied in the sleeve. Bushings of this type are used in precision equipment, with small radial shaft loads;
oil - part of the sleeve body is filled withoil. During the movement of the shaft, a thin layer of oil (oil film) is formed between the surface of the shaft and the bushing, which is sufficient to support the shaft. Bushing designs depend on the type of plain bearing where it is used. A distinction is made between hydrodynamic sliding bearing bushings, where the oil film is formed independently as a result of hydrodynamic effects occurring in the gap between the bushing and the shaft, and hydrostatic bearings, where oil is supplied under pressure.