This standard specifies the code, technical requirements, inspection rules and markings of internal combustion engine spindles. This standard applies to full-circle main bearings for reciprocating internal combustion engines with a cylinder diameter within 200 mm. The bearing is composed of a bearing body and a thrust ring, or is made of the same bimetallic material by stamping. All products within the above range (except for special design requirements) must comply with the provisions of this standard.