What is Bush bearing?
A plain bearing, also known as a bushing, is a mechanical element used to reduce friction between rotating shafts and stationary support members. Typically, a bushing relies on soft metal or plastic and an oil film to support the rotating shaft on the hardened shaft journal. Plain bearings are used primarily in machinery that has a rotating or a sliding shaft component. Also called a journal bearing, sleeve bearings, or sliding bearings, plain bearings have no rolling elements. Some are made of relatively soft metal, such as Babbit, to protect the shaft journals. They are made of other materials as well, depending on the application and load requirements. Other bushings may be used for alignment jigs in drilling operations.
How does a plain bearing work?
Rolling-element bearings utilize balls (ball bearings) or cylindrical rollers (roller or “needle” bearings). These elements are contained with bearing rings or “races”, where they facilitate motion with little resistance to sliding. Ball bearings, the most common type, can accommodate both radial and axial loads.
However, rolling element bearings are subject to failure modes such as brinelling, when the race is deformed by the rolling element due to load or the balls deform if they are overloaded, false brinelling, due to repeated loads under static conditions, as well as wear due to insufficient lubrication with oscillatory movements. Designed for heavier loads, cylindrical roller bearings have greater contact with the races, spreading the load over a larger area. However, they are not well suited for applications involving thrust loads.
Applications of plain bearings?
Due to their versatile properties, plain bearings are used successfully in almost all industrial sectors.
Plain bearings are used as:
.Radial bearings for bearing forces perpendicular to the central shaft axis
.Axial bearings in direction to shaft center axis
.Floating bearings for free longitudinal displacement
.Locating bearing for absorbing transverse and longitudinal forces
.and in other designs.
plain bearing vs ball bearing?
A roller bearing is a cylindrical unit that is used to provide low-friction movement for a bushing or bearing block. A ball bearing is a spherical unit that accomplishes the same objective as a roller bearing. The real difference has to do with the contact surface between the bearing and the rail. For ball bearings (assuming a perfectly spherical bearing and no deformation), the contact surface is just a single point. Even once deformation is accounted for, the amount of surface where the ball is contacting the rail is limited. This creates an inherent strength limit for the balls. Roller bearings on the other hand, have an entire line of contact. This greatly increases the rigidity, stability, and maximum load capacity of the system.