ISO 12130-2:2020

Overview

ISO 12130-2:2020 specifies the mathematical functions used to calculate hydrodynamic plain tilting pad thrust bearings under steady‑state conditions. It provides approximate formulae, curves, tables and numerical data - not a full design procedure - for evaluating key performance parameters of oil‑lubricated tilting pad thrust bearings. The standard is explicitly not applicable to heavily loaded tilting pad thrust bearings and is intended to be used with the premises in ISO 12130‑1.

Key topics

ISO 12130‑2 focuses on the derivation and presentation of functions used directly in bearing calculation. Major technical topics include:

• Characteristic load‑carrying capacity (F*) as a function of the relative bearing width (B/L) and relative minimum lubricant film thickness (h_min / C_wed). Curves, tables and approximate formulae (Figure 1, Table 1) are provided.
• Characteristic friction value (f*) expressed versus B/L and h_min / C_wed with supporting formulae and tabulated data (Figure 2, Table 2).
• Relative lubricant flow rates (Q1*, Q3*) for different flow contributions through the bearing, given as functions of B/L and h_min / C_wed (Figures 3–4, Tables 3–4).
• Relative pressure‑centre coordinate / supporting point (a*) in the circumferential direction, with approximate formulae and tabulated values (Figure 5, Table 5). (Note: some formulae have restricted permissible input ranges, e.g. certain a* calculations apply for h_min/C_wed between ~0.333 and 1.)
• Effective dynamic viscosity (η_eff) as a function of effective lubricant film temperature (T_eff), including practical correlations (Vogel type) and guidance on ISO VG and SAE classifications (Figure 6).

The standard supplies constants, approximation coefficients and recommended ranges of validity (e.g., typical application range for h_min/C_wed).

Applications and users

ISO 12130‑2 is intended for engineers and specialists involved in the design, analysis and specification of rotating‑machine thrust bearings:

• Bearing designers and manufacturers who need standardized functions for performance prediction.
• Mechanical and rotating‑equipment design engineers working on turbines, compressors, pumps, marine shafts and power‑generation machinery.
• Tribologists and maintenance engineers performing bearing condition assessment, lubrication studies and thermal‑viscosity calculations.
• Standards committees and software developers creating bearing‑calculation tools.

Practical use cases include estimating load capacity, predicting frictional losses, sizing lubricant flow, locating the pressure centre, and calculating operational viscosity for steady‑state hydrodynamic tilting pad thrust bearings.

Related standards

• ISO 12130‑1 - Calculation of tilting pad thrust bearings (use ISO 12130‑2 functions together with Part 1 premises and definitions).
• ISO documents on viscosity grades (ISO VG) and industry lubricant classifications (SAE) are referenced for viscosity input data.

Keywords: ISO 12130-2, plain bearings, tilting pad thrust bearings, hydrodynamic, bearing calculation, load‑carrying capacity, friction, lubricant flow rate, pressure centre, effective dynamic viscosity.