ISO/TC 123/SC 8 - Calculation methods for plain bearings and their applications

This document specifies a calculation method for oil-lubricated hydrodynamic plain bearings with complete separation of the thrust collar and tilting pad thrust bearing surfaces by a film of lubricant. This document applies to plain thrust bearings with tilting-type sliding blocks (tilting pads), where a wedge-shaped lubrication clearance gap is automatically formed during operation. The ratio of width to length of one pad can be varied in the range B/L = 0,5 to 2. This document is not applicable to heavily loaded tilting pad thrust bearings. NOTE Equivalent calculation procedures exist that enable operating conditions to be estimated and checked against acceptable conditions. The use of them is equally admissible.

This document specifies, in graphic form, characteristic values used in the calculation of oil-lubricated plain journal bearings with drainage grooves.

The aim of this document is to achieve designs of plain bearings that are reliable in operation, by the application of a calculation method for oil-lubricated hydrodynamic plain bearings with complete separation of the thrust collar and plain bearing surfaces by a film of lubricant[1]. This document applies to plain thrust bearings with incorporated wedge and supporting surfaces having any ratio of wedge surface length lwed to length of one pad L. It deals with the value lwed/L = 0,75 as this value represents the optimum ratio[2]. The ratio of width to length of one pad can be varied in the range B/L = 0,5 to 2. The calculation method described in this document can be used for other incorporated gap shapes, e.g. plain thrust bearings with integrated baffle, when for these types the numerical solutions of Reynolds equation are known. The calculation method serves for designing and optimizing plain thrust bearings e.g. for fans, gear units, pumps, turbines, electrical machines, compressors and machine tools. It is limited to steady-state conditions, i.e. load and angular speed of all rotating parts are constant under continuous operating conditions. Dynamic operating conditions are not included.

This document specifies guide values for avoiding damage to thrust-pad bearings in service. The explanation of the symbols as well as examples for calculation are given in ISO 12131-1.

This document specifies the general principles, assumptions and preconditions for the calculation of multi-lobed and tilting-pad journal bearings by means of an easy-to-use calculation procedure based on numerous simplifying assumptions. For a reliable evaluation of the results of this calculation method, it is indispensable to consider the physical implications of these assumptions as well as practical experiences for instance from temperature measurements carried out on real machinery under typical operating conditions. Applied in this sense, this document presents a simple way to predict the approximate performance of plain journal bearings for those unable to access more complex and accurate calculation techniques. The calculation method serves for the design and optimisation of plain bearings, for example in turbines, compressors, generators, electric motors, gears and pumps. It is restricted to steady-state operation, i.e. in continuous operating states the load according to size and direction and the angular velocity of the rotor are constant. Unsteady operating states are not recorded. The stiffness and damping coefficients of the plain journal bearings required for the linear vibration and stability investigations are indicated in ISO/TS 31657-2 and ISO/TS 31657-3.

This document specifies the characteristic values for selected tilting-pad journal bearings with four or five centrally or eccentrically supported tilting pads and with angular spans of pad sliding surfaces of Ω = 80°, 60° and 45°. The functions plotted and listed in table form below are required for the operationally safe design of hydrodynamic tilting-pad journal bearings according to ISO/TS 31657-1. They are based on the presumptions and boundary conditions indicated there and only apply to stationary operating states. The symbols used are explained in ISO/TS 31657-1; calculation examples are also included there. The calculation method described in ISO/TS 31657-1 can also be used for other tilting-pad journal bearing designs, if the numerical solutions of the basic equations are available in the same manner for these designs.

This document specifies the characteristic values for selected two-, three- and four-lobe bearings. The functions plotted and listed in table form below are required for the operationally safe design of hydrodynamic multi-lobed journal bearings according to ISO/TS 31657-1. They are based on the presumptions and boundary conditions indicated there and only apply to stationary operating states. The symbols used are explained in ISO/TS 31657-1; calculation examples are also included there.

This document establishes the permissible operational parameters in terms of guide values for the calculation of selected multi-lobed and tilting-pad journal bearings. In order to attain a sufficient operational safety of multi-lobed and tilting-pad journal bearings by the calculation according to ISO/TS 31657-1, it is necessary for the operational characteristic value hmin to be significantly above the permissible operating parameter hlim,tr and for the permissible operating parameters Tlim and plim not to be exceeded by the calculated operational characteristic values Tmax and pmax. The guide values represent geometrically and technologically founded operational limiting values in the tribological system of plain bearings. They are empirical values that enable sufficient operational safety even in the event of smaller disturbing influences (see ISO/TS 31657-1). The empirical values indicated can be modified for special application areas. NOTE The explanations for the symbols and calculation examples are contained in ISO/TS 31657-1.

This document specifies a calculation procedure for oil-lubricated hydrodynamic plain bearings, with complete separation of the shaft and bearing sliding surfaces by a film of lubricant, used for designing plain bearings that are reliable in operation. It deals with circular cylindrical bearings having angular spans, Ω, of 360°, 180°, 150°, 120°, and 90°, the arc segment being loaded centrally. Their clearance geometry is constant except for negligible deformations resulting from lubricant film pressure and temperature. The calculation procedure serves to provide dimensions and optimize plain bearings in turbines, generators, electric motors, gear units, rolling mills, pumps, and other machines. It is limited to steady-state operation, i.e. under continuously driven operating conditions, with the magnitude and direction of loading as well as the angular speeds of all rotating parts constant. It can also be applied if a full plain bearing is subjected to a constant force rotating at any speed. Dynamic loadings (i.e. those whose magnitude and direction vary with time), such as those that can result from vibration effects and instabilities of rapid-running rotors, are not taken into account. NOTE Equivalent calculation procedures exist that enable operating conditions to be estimated and checked against acceptable conditions. The use of them is equally admissible.

This document specifies empirical permissible values for hlim, Tlim and . The empirical values stated can be modified for certain applications, for example if information supplied by the manufacturer is to be taken into account. The descriptions of the symbols and calculation examples are given in ISO 7902-1.

This document specifies the values of the basic functions used in the calculation procedure for oil-lubricated circular cylindrical hydrodynamic bearings under conditions of full lubrication. The values are given for the assumptions and boundary conditions given in ISO 7902-1. The values necessary for the calculation can be determined from the tables of bearing characteristics, the graphs and from the formulae. The descriptions of the symbols used and calculation examples are given in ISO 7902-1.

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.

This document specifies guide values for the calculation of tilting pad thrust bearings as described in ISO 12130-1. The empirical values given can be modified for specific fields of application. This document is not applicable to heavily loaded tilting pad thrust bearings.

This document specifies a calculation method of oil-lubricated plain journal bearings without drainage grooves under steady-state conditions. It applies to hydrostatic plain journal bearings under steady-state conditions. In this document, only bearings without oil drainage grooves between the recesses are taken into account.

This document lists, in graphic form, characteristic values used in the calculation of oil-lubricated plain bearings without drainage grooves.

ISO 12167-1:2016 applies to hydrostatic plain journal bearings under steady-state conditions. In ISO 12167-1:2016, only bearings with oil drainage grooves between the recesses are taken into account. As compared to bearings without oil drainage grooves, this type needs higher power with the same stiffness behaviour.

ISO 12131-2:2016 specifies functions for thrust pad bearings. It also covers the effect of dynamic viscosity on lubricant film temperature.

ISO 7902-1:2013 specifies a calculation procedure for oil-lubricated hydrodynamic plain bearings, with complete separation of the shaft and bearing sliding surfaces by a film of lubricant, used for designing plain bearings that are reliable in operation. It deals with circular cylindrical bearings having angular spans, Ω, of 360°, 180°, 150°, 120° and 90°, the arc segment being loaded centrally.

ISO 12130-2:2013 specifies the derivation of mathematical functions to be applied when calculating tilting pad thrust bearings.

This part of ISO 12167 lists, in graphic form, characteristic values used in the calculation of oil-lubricated plain journal bearings with drainage grooves.

The aim of ISO 12130 is to achieve designs of plain bearings that are reliable in operation by the application of a calculation method for oil-lubricated hydrodynamic plain bearings with complete separation of the thrust collar and plain bearing surfaces by a film of lubricant. This part of ISO 12130 applies to plain thrust bearings with tilting-type sliding blocks (tilting pads), where a wedgeshaped lubrication clearance gap is automatically formed during operation. The ratio of width to length of one pad can be varied in the range B/L = 0,5 to 2. The calculation method described in this part of ISO 12130 can be used for other gap shapes, e.g. parabolic lubrication clearance gaps, as well as for other types of sliding blocks, e.g. circular sliding blocks, when for these types the numerical solutions of Reynolds' differential equation are present. ISO 12130-2 gives only the characteristic values for the plane wedge-shaped gap; the values are therefore not applicable to tilting pads with axial support. The calculation method serves for designing and optimizing plain thrust bearings e.g. for fans, gear units, pumps, turbines, electric machines, compressors and machine tools. It is limited to steady-state conditions, i.e. load and angular speed of all rotating parts are constant under continuous operating conditions. This part of ISO 12130 is not applicable to heavily loaded tilting pad thrust bearings.

The aim of this part of ISO 12131 is to achieve designs of plain bearings that are reliable in operation, by the application of a calculation method for oil-lubricated hydrodynamic plain bearings with complete separation of the thrust collar and plain bearing surfaces by a film of lubricant [1]. This part of ISO 12131 applies to plain thrust bearings with incorporated wedge and supporting surfaces having any ratio of wedge surface length lwed to length of one pad L. It deals with the value lwed/L = 0,75 as this value represents the optimum ratio [2]. The ratio of width to length of one pad can be varied in the range B/L = 0,5 to 2. The calculation method described in this part of ISO 12131 can be used for other incorporated gap shapes, e.g. plain thrust bearings with integrated baffle, when for these types the numerical solutions of Reynolds' differential equation are known. The calculation method serves for designing and optimizing plain thrust bearings e.g. for fans, gear units, pumps, turbines, electrical machines, compressors and machine tools. It is limited to steady-state conditions, i.e. load and angular speed of all rotating parts are constant under continuous operating conditions. Dynamic operating conditions are not included.

This part of ISO 12131 specifies guide values for avoiding damage to thrust-pad bearings in service. The explanation of the symbols as well as examples for calculation are given in ISO 12131-1.