This article describes the characteristics of three types of gas bearings, such as aerostatic bearing, precision aerodynamic bearing (PAB), and compliant aerodynamic bearing (CAB). It discusses the applications for aerostatic bearings and advantages in lubricating a bearing with a compressible gas. The article also describes the different types of aerostatic bearings, such as annular thrust bearings and orifice-compensated journal bearings. It presents a discussion on load capacity and stiffness, friction and power loss, and stability and damping of the aerostatic bearings. The article provides a discussion on the types of PAB and CAB. The types include spiral groove annular thrust bearings, cylindrical journal bearings, three-sector journal bearings, tilting-pad journal bearings, and helical-grooved journal bearings. The types of CAB include foil bearings and pressurized-membrane bearings. The article concludes with a description of factors that influence materials selection for gas-lubricated bearings.

Bearings are usually provided where a specific spatial relationship (alignment) must be maintained between the parts or where a force is to be transmitted from one part to the other. This article introduces the general types and configuration of sliding bearings, bearing materials, and the practical aspects and solutions in the friction, lubrication, and wear mitigation of sliding bearings. The lubrication of bearings includes thick-film lubrication, thin-film lubrication, and boundary lubrication. The article concludes with a discussion on the effects of material elasticity on the lubrication of bearings.

A mechanical part, which supports the moving part, is termed a mechanical bearing and can be classified into rolling (ball or roller) bearings and sliding bearings. This article discusses the failures of sliding bearings. It first describes the geometry of sliding bearings, next provides an overview of bearing materials, and then presents the various lubrication mechanisms: hydrostatic, hydrodynamic, boundary lubrication, elastohydrodynamic, and squeeze-film lubrication. The article describes the effect of debris and contaminant particles in bearings. The steps involved in failure analysis of sliding bearings are also covered. Finally, the article discusses wear-damage mechanisms from the standpoint of bearing design.

This article provides an overview of two major classes of bearings: rolling bearings and sliding, or plain, bearings. It reviews the experimental data resulted from testing of rolling and sliding bearing materials with illustration. The article presents a table that summarizes rolling contact fatigue test methods that ASTM published in STP 771. It also describes the role of lubrication in the bearings.

Because of the tough engineering environment of the railroad industry, fatigue is a primary mode of failure. The increased competitiveness in the industry has led to increased loads, reducing the safety factor with respect to fatigue life. Therefore, the existence of corrosion pitting and manufacturing defects has become more important. This article presents case histories that are intended as an overview of the unique types of failures encountered in the freight railroad industry. The discussion covers failures of axle journals, bearings, wheels, couplers, rails and rail welds, and track equipment.

This article discusses the classification of sliding bearings and describes the major groups of soft metal bearing materials: babbitts, copper-lead bearing alloys, bronze, and aluminum alloys. It provides a discussion on the methods for fluid-film lubrication in bearings. The article presents the variables of interest for a rotating shaft and the load-carrying capacity and surface roughness of bearings. Grooves and depressions are often provided in bearing surfaces to supply or feed lubricant to the load-carrying regions. The article explains the effect of contaminants in bearings and presents the steps for failure analysis of sliding bearings. It also reviews the factors responsible for bearing failure with examples.

Horizontal centrifugal casting is used to cast parts having an axis of revolution. This article discusses the operations of three types of horizontal casting machine: the flanged shaft machine, the horizontal roller-type machine, and the double-face plate machine. It provides information on expendable and permanent molds used for centrifugal casting. The parameters and operations of the horizontal centrifugal casting process, including pouring and solidification, as well as the applications are described.

Rolling-element bearings, also called rolling bearings and antifriction bearings, tend to have very low friction characteristics compared to plain bearings or simple sliding bearings. This article discusses the types of rolling-element bearings, namely, ball bearings and roller bearings. It provides information on the bearing component materials. The article describes the lubrication requirements and lubrication methods, namely, elastohydrodynamic lubrication and grease lubrication. It reviews the adjustment factors influencing fatigue life of the bearing. The article also provides information on bearing load ratings, standard bearing geometries, rolling bearing friction factors, and wear and its control methods. It concludes with a discussion on damage modes of bearings.

Tribology is the study of friction, lubrication, and wear. It is a multidisciplinary subject covering the mechanics of contacting surfaces, their roughness characteristics, lubrication, and material behavior under normal load as well as in traction. This article focuses on well-established and widely accepted analytical methods and design and analysis charts for dealing with some of the issues in the area of engine and power train tribology. It provides a discussion on lubricant rheology and the prediction of lubricating film thickness. The article reviews the frictional power loss in piston-cylinder conjunctions, engine bearings, and transmission and differential gearing systems.

A sliding bearing (plain bearing) is a machine element designed to transmit loads or reaction forces to a shaft that rotates relative to the bearing. This article discusses the properties of bearing materials. It provides information on bearing material systems: single-metal systems, bimetal systems, and trimetal systems. The article describes the designations, nominal compositions, mechanical properties, and applications of various sliding bearing alloys: tin-base alloys, lead-base alloys, copper-base alloys, aluminum-base alloys, silver-base alloys, zinc-base alloys, additional metallic materials, nonmetallic materials. It describes casting processes, powder metallurgy processes, and electroplating processes. The article also discusses the selection criteria for bearing materials.

A sliding bearing (plain bearing) is a machine element designed to transmit loads or reaction forces to a shaft that rotates relative to the bearing. This article explains the role of wear damage mechanisms in the design and selection of bearing materials, and its relationship with bearing material properties. Sliding bearings are commonly classified by terms that describe their application; they also are classified according to material construction, as single-metal, bimetal, or trimetal sliding bearings. The article further provides detailed tabular data on the designation and composition of the following types of bearing materials: tin-base alloys, lead-base alloys, copper-base alloys, and aluminum-base alloys. It also briefly discusses the following types of bearing materials: zinc-base alloys, silver-base alloys, gray cast irons, cemented carbides, and nonmetallic bearing materials.

Induction heat treatment is a common method for hardening and tempering of crankshafts, which are necessary components in almost every internal combustion engine for cars, trucks, and machinery, as well as pumps, compressors, and other devices. Similar to crankshafts, camshafts also belong to the same group of the critical engine/powertrain components. This article focuses on induction technologies used for surface hardening and tempering of automotive crankshafts, and provides general information on U-shaped inductors with crankshaft rotation and clamshell or split inductors without crankshaft rotation and their pros and cons. It also describes the effect of post-heat-treatment processes in crankshafts. The article concludes with a discussion on induction hardening of camshafts that focuses on those used in automobiles and truck engines.

This article focuses on friction, lubrication, and wear of internal combustion engine parts, improvements in which provide important gains in energy efficiency, performance, and longevity of the internal combustion (IC) engine systems. It discusses the types, component materials, and Friction and Wear Control of IC engine. The article explains the process of friction reduction by surface textures or coatings. It provides information on surface hardening of iron and steel, which is commonly employed for engine and powertrain components such as crankshafts, cams, and cylinder liners. The article also discusses advanced surface engineering technologies, such as diamondlike carbon coatings and surface texture technology. Information on thermal-spray methods that have led to improvements in engine components is also provided. The article describes IC engine-components wear, namely, piston assembly wear, valvetrain wear, cylinder-bore wear, and engine bearing wear. It concludes with information on inlet valve and seat wear of IC engine.

In addition to failures in shafts, this article discusses failures in connecting rods, which translate rotary motion to linear motion (and conversely), and in piston rods, which translate the action of fluid power to linear motion. It begins by discussing the origins of fracture. Next, the article describes the background information about the shaft used for examination. Then, it focuses on various failures in shafts, namely bending fatigue, torsional fatigue, axial fatigue, contact fatigue, wear, brittle fracture, and ductile fracture. Further, the article discusses the effects of distortion and corrosion on shafts. Finally, it discusses the types of stress raisers and the influence of changes in shaft diameter.

Lapping is the lower-pressure, lower-speed, and lower-power application of the use of fixed abrasives. This article begins with a discussion on the process capabilities of lapping and reviews the selection of abrasive and vehicle for lapping. It describes the methods of lapping outer cylindrical surfaces, namely, ring lapping, machine lapping between plates, centerless roll lapping with loose abrasives, and centerless lapping with bonded abrasives. In addition, the article discusses the methods employed for lapping of outer surfaces of piston rings, crankshafts, inner cylindrical surfaces, flat surfaces, end surfaces, spherical surfaces, balls, spring like parts, and gears. It also reviews the problems in flat and end lapping. The article concludes information on the use of lapping in accelerated wearing-in process for matching and aligning components of bearing assemblies.

This article is dedicated to the fields of mechanical engineering and machine design. It also intends to give a nonexhaustive view of the preventive side of the failure analysis of rolling-element bearings (REBs) and of some of the developments in terms of materials and surface engineering. The article presents the nomenclature, numbering systems, and worldwide market of REBs as well as provides description of REBs as high-tech machine components. It discusses heat treatments, performance, and properties of bearing materials. The processes involved in the examination of failed bearings are also explained. Finally, the article discusses in detail the characteristics and prevention of the various types of failures of REBs: wear, fretting, corrosion, plastic flow, rolling-contact fatigue, and damage. The article includes an Appendix, which lists REB-related abbreviations, association websites, and ISO standards.

This article provides a brief introduction to lubrication as a method to reduce friction between two surfaces. It discusses the surface characteristics of parts and explores how lubrication helps separate two contacting surfaces and thereby decreases the coefficient of friction. The article details the classifications of lubrication regimes, namely, boundary, mixed, hydrodynamic, and elastohydrodynamic lubrications. It discusses the various types of lubricant materials and additives, including liquid lubricants, solid lubricants, gaseous lubricants, greases, green lubricants, and nanomaterials. The article also reviews the properties of lubricants. It describes the tribological evaluation of lubricants, including stribeck test, four-ball test, block-on-ring test, pin-in-vee test, and reciprocating motion test.