Steel sleeve, Dnipropetrovsk region.

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A bushing is a detail that facilitates disassembly/assembly of devices and reduces friction between elements rotating during operation. It has a through hole containing various elements necessary for the operation of the unit. Bushings are everywhere, in all modern complex devices: in rolling mills, machine tools, machines, etc.(//tractor-service.com)

Without exception, all the elements that make up the unit play an important role. So, for example, a 25 mm sleeve, which must be bought if it wears out, otherwise the unit simply will not work.
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