ISO 12130-2:2020

Plain bearings - Hydrodynamic plain tilting pad thrust bearings under steady-state conditions - Part 2: Functions for calculation of tilting pad thrust bearings

This document specifies the derivation of mathematical functions to be applied when calculating tilting pad thrust bearings. This document is not applicable to heavily loaded tilting pad thrust bearings.

Paliers lisses — Butées hydrodynamiques à patins oscillants fonctionnant en régime stationnaire — Partie 2: Fonctions pour le calcul des butées à patins oscillants

General Information

• Status: Published
• Publication Date: 19-Feb-2020
• ICS: 21.100.10 - Plain bearings
• Technical Committee: ISO/TC 123/SC 8 - Calculation methods for plain bearings and their applications
• Drafting Committee: ISO/TC 123/SC 8 - Calculation methods for plain bearings and their applications
• Current Stage: 9092 - International Standard to be revised
• Start Date: 03-Nov-2025
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 12130-2:2013 - Plain bearings - Hydrodynamic plain tilting pad thrust bearings under steady-state conditions - Part 2: Functions for calculation of tilting pad thrust bearings
• Effective Date: 23-Apr-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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 12130-2
Third edition
2020-02
Plain bearings — Hydrodynamic plain
tilting pad thrust bearings under
steady-state conditions —
Part 2:
Functions for calculation of tilting pad
thrust bearings
Paliers lisses — Butées hydrodynamiques à patins oscillants
fonctionnant en régime stationnaire —
Partie 2: Fonctions pour le calcul des butées à patins oscillants
Reference number
©
ISO 2020
© ISO 2020
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Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Functions for the tilting pad thrust bearing . 1
4.1 General . 1
4.2 Characteristic value of load-carrying capacity . 1
4.3 Characteristic value of friction . 3
4.4 Relative lubricant flow rate . 5
4.5 Relative pressure centre coordinate or tilting pad supporting point . 8
5 Effective dynamic viscosity of the lubricant .10
Bibliography .12
Foreword
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 123, Plain bearings, Subcommittee SC 8,
Calculation methods for plain bearings and their applications.
This third edition cancels and replaces the second edition (ISO 12130-2:2013), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— adjustment to ISO/IEC Directives, Part 2:2018;
— correction of typographical errors.
A list of all parts in the ISO 12130 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

Introduction
The functions of the following type are necessary for the calculation of oil-lubricated tilting pad thrust
bearings in accordance with ISO 12130-1, assuming hydrodynamic conditions with full lubrication.
They are based on the premises and boundary conditions specified therein. The values necessary for
the calculation can be determined by means of the given formulae as well as from diagrams and tables.
The formulae are approximations of the numerically determined values traced as curves in accordance
with Reference [2]. The explanation of the symbols and examples for the calculation are included in
ISO 12130-1.
On account of the premises laid down in ISO 12130-1:2001, Clause 3, g) and k), the following definitions
*
are not applicable to the calculation of thrust bearings with centrally supported tilting pads ( a = 0,5),
F
which, under the premises indicated therein, have no hydrodynamic load-carrying capacity. For the
determination of the characteristic values of such bearings, it is necessary to consider at least the
deformations of the tilting pads which occur during operation. For example, References [3] and [4] can
be compared.
INTERNATIONAL STANDARD ISO 12130-2:2020(E)
Plain bearings — Hydrodynamic plain tilting pad thrust
bearings under steady-state conditions —
Part 2:
Functions for calculation of tilting pad thrust bearings
1 Scope
This document specifies the derivation of mathematical functions to be applied when calculating tilting
pad thrust bearings.
This document is not applicable to heavily loaded tilting pad thrust bearings.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Functions for the tilting pad thrust bearing
4.1 General
An explanation of the symbols is given in ISO 12130-1.
4.2 Characteristic value of load-carrying capacity
The characteristic value of load-carrying capacity, F* is defined as a function of the relative bearing
width, B/L, and the relative minimum lubricant film thickness, h /C .
min wed
By substituting Formulae (2) to (5) into Formula (1), the approximate curves in Figure 1 are obtained
h
min
(range of application: 02,  ≤≤ 2 ).
C
wed
   
  1 1
** *
AB +−1  + CC 1 −
   
 
 h  1 + hC hC hC
( ) 2
   
min min wed min wed min wed
*  
F =5  × ln  − ×
 
 
h
C hC
  min
wed min wed  1 
1 +  2×
 
1 + a
 
C
  BL
wed
 
(1)
   
h h
 
minmin
   
12 −+
2  
C C
     
h h wedw ed 
 
10  
 
minmin
 
a =  ×+    + (2)
   
C C h 1 + hC
     ( ) 
 
 h   wedwed min min wed 
 
min
12  12 + × ln −2
   
12 +
   
C hC
C   wed  min wed 
 
wed  
 
2 3
B B B
     
*
A =− ,1 168 60 , 329 45×  +×0, 222 67  − 00, 046 51×  (3)
     
L L L
     
2 3
B B B
     
*
B =−0, 100 95+× ,0 197 43  −× ,0 131 36  + 0, 028 703×  (4)
     
 L   L   L 
2 3
B B B
     
...