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a cylindrical or conical part of a machine, mechanism, or instrument, which has an axial opening into which another part fits. Depending on their purpose, a distinction is made among bearing linings, fastener bushings, adapters, and so on.
A bearing lining is the part of a bushed sliding bearing in which the journal of a shaft or axle rotates. Such a bushing is fitted tightly into the housing portion and is sometimes also held with screws. It is made of antifriction materials (cast iron, bronze, graphite, or plastics), cast iron or steel with a thin layer of antifriction material on the friction surface, or a porous, self-lubricating metal ceramic. The use of bushings in sliding bearings reduces the consumption of costly and usually scarce antifriction materials (tin bronzes and babbitt metal) and simplifies repair by reducing it to the replacement of a worn bushing with a new one.
Fastener bushings secure the inner rings of antifriction bearings and other parts on the cylindrical portions of shafts and axles. They are made in a split form, with a conical outer surface, and are tightened by means of a nut.
An adapter is used to mount a tool with a conical shank in a lathe spindle that has a hole larger than the tool shank.