GB/T 2889.7-2026 Plain Bearings—Terms, definitions, classification and symbols —Part 7: Hydrostatic and aerostatic bearings English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
CCS
National Standard of the People's Republic of China
GB/T 2889.7-2026
Plain Bearings - Terms, definitions, classification and symbols - Part 7: Hydrostatic and aerostatic bearings
滑动轴承 术语、定义、分类和符号 第7部分：液体和气体静压轴承
Issue date: 2026-02-27 Implementation date: 2026-09-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Lubrication related terms and definitions
4 Fluid mechanics related terms
5 Hydrostatic bearing construction and classification
6 Fluid supply and control system
7 Operating parameters
8 Bearing static characteristics
9 Bearing dynamic characteristics
Plain bearings — Terms, definitions, classification and symbols — Part 7: Hydrostatic and aerostatic bearings
1 Scope
This document defines the terms and definitions related to hydrostatic liquid bearings and aerostatic bearings.
This document is intended for use by various organizations engaged in the research, manufacture and use of hydrostatic liquid bearings and aerostatic bearings in technical exchanges, preparation of technical documents, formulation of standards, cooperation negotiations, etc. It also serves as a reference for the preparation of relevant teaching materials, books and journals, and for the translation of literature.
2 Normative references
This document has no normative references.
3 Lubrication related terms and definitions
3.1 lubrication
A technique that reduces the friction, wear and degradation of the surfaces of two mutually contacting and relatively moving objects through the action and effect of a lubricant.
[SOURCE: GB/T 2889.3-2020, 3.1.1]
3.2 hydrostatic lubrication
A method of lubrication in which two interacting surfaces, either in relative motion or at rest, are completely separated by high pressure fluid supplied from an external source.
[SOURCE: GB/T 2889.3-2020, 3.2.2.2]
3.2.1 hydrostatic liquid lubrication
A method of lubrication in which two interacting surfaces, either in relative motion or at rest, are completely separated by high pressure liquid supplied from an external pressurizing device.
3.2.2 aerostatic lubrication
A method of lubrication in which two interacting surfaces, either in relative motion or at rest, are completely separated by high pressure gas supplied from an external pressurizing device.
[SOURCE: GB/T 2889.3-2020, 3.2.2.4, modified]
3.3 laminar flow lubrication
A lubrication regime in which the lubricant molecules move steadily and regularly, forming a layered flow.
NOTE: This regime occurs in fluids where viscous forces dominate over inertial forces, or where the Reynolds number is relatively low and the Taylor number is below a critical value.
4 Fluid mechanics related terms
4.1 flow
The motion of a fluid caused by a pressure difference or external force.
4.2 flow rate
The volume or mass of fluid passing through the effective cross section of a flow passage per unit time.
4.2.1 volumetric flow
The volume of fluid passing through the effective cross section of a flow passage per unit time.
4.2.2 mass flow
The mass of fluid passing through the effective cross section of a flow passage per unit time.
4.3 pressure
The force exerted perpendicularly by a fluid per unit area of its confining body.
4.4 differential pressure
The difference in pressure magnitude between any two points in the same flow field.
4.5 fluid density
The mass of fluid per unit volume at a specified temperature and pressure.
4.6 Newtonian fluid
A fluid that obeys Newton's law of viscosity, i.e., the shear stress is proportional to the shear rate.
[SOURCE: GB/T 2889.3-2020, 3.5.3]
4.7 viscosity
A physical quantity measuring the magnitude of fluid viscosity. A volumetric property of a liquid, liquid like or quasi solid material that resists flow, i.e., the internal friction or internal flow resistance exhibited between molecules when subjected to external force and flowing.
4.7.1 dynamic viscosity
absolute viscosity
A measure of the internal friction of a fluid when flowing under a certain shear stress, being the ratio of the shear stress to the shear rate of the fluid.
NOTE: Often expressed as the dynamic viscosity coefficient, or simply viscosity. In the International System of Units, the unit of dynamic viscosity is the pascal second (Pa·s). For practical convenience, the centipoise (1 cP = 1 mPa·s) is commonly used.
4.7.2 kinematic viscosity
At a given temperature, the ratio of the dynamic viscosity of a fluid to its density.
NOTE: In the International System of Units, the unit of kinematic viscosity is the square metre per second (m²/s). Some documents also use the centistoke (cSt), where 1 cSt = 10⁻⁶ m²/s (i.e., 1 cSt = 1 mm²/s).
[SOURCE: GB/T 17446-2024, 3.1.3.35, modified]
4.8 Reynolds number
A dimensionless parameter used to characterize the two flow regimes of a fluid (laminar and turbulent). It is the ratio of inertial forces to viscous forces in the fluid.
4.9 critical Reynolds number
The critical value of fluid velocity corresponding to the transition between laminar and turbulent flow.
4.10 laminar flow
Fluid flow characterized by the orderly sliding of fluid layers past each other.
4.11 turbulent flow
Fluid flow characterized by the random motion of fluid particles.
4.12 compressible fluid
A fluid whose density or volume changes with pressure or temperature.
4.13 incompressible fluid
A fluid whose density or volume does not change with pressure or temperature.
4.14 compressibility rate of fluid
The ratio of the volume change rate of a fluid to the applied pressure change.
NOTE: The compressibility rate of a fluid is the reciprocal of the fluid's bulk modulus of elasticity.
Standard
GB/T 2889.7-2026 Plain Bearings—Terms, definitions, classification and symbols —Part 7: Hydrostatic and aerostatic bearings (English Version)
Standard No.
GB/T 2889.7-2026
Status
valid
Language
English
File Format
PDF
Word Count
12500 words
Price(USD)
375.0
Implemented on
2026-6-1
Delivery
via email in 1~5 business day
Detail of GB/T 2889.7-2026
Standard No.
GB/T 2889.7-2026
English Name
Plain Bearings—Terms, definitions, classification and symbols —Part 7: Hydrostatic and aerostatic bearings
GB/T 2889.7-2026 Plain Bearings—Terms, definitions, classification and symbols —Part 7: Hydrostatic and aerostatic bearings English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
CCS
National Standard of the People's Republic of China
GB/T 2889.7-2026
Plain Bearings - Terms, definitions, classification and symbols - Part 7: Hydrostatic and aerostatic bearings
滑动轴承 术语、定义、分类和符号 第7部分：液体和气体静压轴承
Issue date: 2026-02-27 Implementation date: 2026-09-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Lubrication related terms and definitions
4 Fluid mechanics related terms
5 Hydrostatic bearing construction and classification
6 Fluid supply and control system
7 Operating parameters
8 Bearing static characteristics
9 Bearing dynamic characteristics
Plain bearings — Terms, definitions, classification and symbols — Part 7: Hydrostatic and aerostatic bearings
1 Scope
This document defines the terms and definitions related to hydrostatic liquid bearings and aerostatic bearings.
This document is intended for use by various organizations engaged in the research, manufacture and use of hydrostatic liquid bearings and aerostatic bearings in technical exchanges, preparation of technical documents, formulation of standards, cooperation negotiations, etc. It also serves as a reference for the preparation of relevant teaching materials, books and journals, and for the translation of literature.
2 Normative references
This document has no normative references.
3 Lubrication related terms and definitions
3.1 lubrication
A technique that reduces the friction, wear and degradation of the surfaces of two mutually contacting and relatively moving objects through the action and effect of a lubricant.
[SOURCE: GB/T 2889.3-2020, 3.1.1]
3.2 hydrostatic lubrication
A method of lubrication in which two interacting surfaces, either in relative motion or at rest, are completely separated by high pressure fluid supplied from an external source.
[SOURCE: GB/T 2889.3-2020, 3.2.2.2]
3.2.1 hydrostatic liquid lubrication
A method of lubrication in which two interacting surfaces, either in relative motion or at rest, are completely separated by high pressure liquid supplied from an external pressurizing device.
3.2.2 aerostatic lubrication
A method of lubrication in which two interacting surfaces, either in relative motion or at rest, are completely separated by high pressure gas supplied from an external pressurizing device.
[SOURCE: GB/T 2889.3-2020, 3.2.2.4, modified]
3.3 laminar flow lubrication
A lubrication regime in which the lubricant molecules move steadily and regularly, forming a layered flow.
NOTE: This regime occurs in fluids where viscous forces dominate over inertial forces, or where the Reynolds number is relatively low and the Taylor number is below a critical value.
4 Fluid mechanics related terms
4.1 flow
The motion of a fluid caused by a pressure difference or external force.
4.2 flow rate
The volume or mass of fluid passing through the effective cross section of a flow passage per unit time.
4.2.1 volumetric flow
The volume of fluid passing through the effective cross section of a flow passage per unit time.
4.2.2 mass flow
The mass of fluid passing through the effective cross section of a flow passage per unit time.
4.3 pressure
The force exerted perpendicularly by a fluid per unit area of its confining body.
4.4 differential pressure
The difference in pressure magnitude between any two points in the same flow field.
4.5 fluid density
The mass of fluid per unit volume at a specified temperature and pressure.
4.6 Newtonian fluid
A fluid that obeys Newton's law of viscosity, i.e., the shear stress is proportional to the shear rate.
[SOURCE: GB/T 2889.3-2020, 3.5.3]
4.7 viscosity
A physical quantity measuring the magnitude of fluid viscosity. A volumetric property of a liquid, liquid like or quasi solid material that resists flow, i.e., the internal friction or internal flow resistance exhibited between molecules when subjected to external force and flowing.
4.7.1 dynamic viscosity
absolute viscosity
A measure of the internal friction of a fluid when flowing under a certain shear stress, being the ratio of the shear stress to the shear rate of the fluid.
NOTE: Often expressed as the dynamic viscosity coefficient, or simply viscosity. In the International System of Units, the unit of dynamic viscosity is the pascal second (Pa·s). For practical convenience, the centipoise (1 cP = 1 mPa·s) is commonly used.
4.7.2 kinematic viscosity
At a given temperature, the ratio of the dynamic viscosity of a fluid to its density.
NOTE: In the International System of Units, the unit of kinematic viscosity is the square metre per second (m²/s). Some documents also use the centistoke (cSt), where 1 cSt = 10⁻⁶ m²/s (i.e., 1 cSt = 1 mm²/s).
[SOURCE: GB/T 17446-2024, 3.1.3.35, modified]
4.8 Reynolds number
A dimensionless parameter used to characterize the two flow regimes of a fluid (laminar and turbulent). It is the ratio of inertial forces to viscous forces in the fluid.
4.9 critical Reynolds number
The critical value of fluid velocity corresponding to the transition between laminar and turbulent flow.
4.10 laminar flow
Fluid flow characterized by the orderly sliding of fluid layers past each other.
4.11 turbulent flow
Fluid flow characterized by the random motion of fluid particles.
4.12 compressible fluid
A fluid whose density or volume changes with pressure or temperature.
4.13 incompressible fluid
A fluid whose density or volume does not change with pressure or temperature.
4.14 compressibility rate of fluid
The ratio of the volume change rate of a fluid to the applied pressure change.
NOTE: The compressibility rate of a fluid is the reciprocal of the fluid's bulk modulus of elasticity.
