ISO 4378-3:2017

Overview

ISO 4378-3:2017 - Plain bearings - Terms, definitions, classification and symbols - Part 3: Lubrication is an ISO terminology standard that defines the most commonly used terms and classifications for lubrication of plain bearings. Published by ISO/TC 123 (Plain bearings), this third edition updates and harmonizes vocabulary (adding figures and editorial revisions) to reduce ambiguity in standards, technical literature and engineering practice. The document gives definitions, short forms (where unambiguous), classifications and illustrative figures; self-explanatory terms are listed without formal definitions.

Key topics and requirements

The standard primarily specifies terminology and classification rather than prescribing design parameters. Key technical topics include:

• General definitions: lubrication, method of lubrication.
• Classification by physical state: gas-film, liquid-film, fluid-film, solid-film lubrication.
• Classification by separation mechanism:
  • Hydrodynamic and hydrostatic
  • Aerodynamic and aerostatic
  • Elasto-hydrodynamic (EHL) and variants: hard EHL, soft EHL, micro EHL
  • Boundary, mixed-film (partial-film)
  • Thermo-hydrodynamic (THL) and thermo-elastohydrodynamic (TEHL)
• Flow regimes: laminar, transition (Taylor), turbulent.
• Special conditions: starved lubrication, non-lubrication, oil-free, grease lubrication.
• Methods of lubrication & periodicity:
  • Periodicity: continuous, periodical (including life-time prelubrication)
  • Renewing: recirculating, once-through
  • Application methods: force-feed, mechanical force-feed, dip-feed (oil-bath), drop-feed, ring, hand, splash, oil jet, oil fog/mist, pad, wick, rotaprint, solid-film coating, directed and leading-edge grooved lubrication.
• Notation and short forms: commonly used abbreviations (e.g., EHL, THL, TEHL) where unambiguous.

Practical applications

ISO 4378-3:2017 is a reference for anyone who needs consistent, internationally recognized vocabulary for bearing lubrication. Typical uses:

• Writing unambiguous design and procurement specifications for bearings and lubrication systems.
• Developing maintenance procedures, lubrication schedules and training materials.
• Communicating requirements between OEMs, suppliers and test laboratories.
• Assisting standards writers, technical authors and translators to ensure consistent terminology across documents.

Who should use this standard

• Bearing and tribology engineers
• Lubrication specialists and maintenance managers
• Machine designers and rotating-equipment OEMs
• Standards developers, technical writers and procurement professionals
• Test and inspection laboratories

Related standards

• Other parts of the ISO 4378 series (see ISO website for the full list) and related ISO/IEC terminological resources (ISO Online Browsing Platform, IEC Electropedia) for consistent usage across standards.

Keywords: ISO 4378-3:2017, plain bearings lubrication, lubrication terms, EHL, hydrodynamic lubrication, oil mist, grease lubrication, lubrication classification, lubrication methods.