In UDC 621.8 is classed information about various machine elements and installations: bearings, shafts, gears, gearing and other forms of power transmission, materials handling and transfer equipment, cranes, lifts, excavating and dredging equipment, fastening and fixing devices (including screws, bolts and associated tools), and lubrication and lubricants.
Class here information about machine elements, etc. treated generally. If they are treated as parts of specific kinds of machinery, class with the subject, adding the -1/-9 auxiliaries listed under 62.
BS 1000[621.8]:1995 history
2014BS 10008:2014 Evidential weight and legal admissibility of electronic information. Specification
2008BS 10008:2008 Evidential weight and legal admissibility of electronic information – Specification
1995BS 1000[621.8]:1995 Universal Decimal Classification - English full edition - Machine elements - Motive power engineering - Materials handling - Fixings - Lubrication