Search Results for transportation gear oils

This article presents a brief discussion on the main applications for low- and high-viscosity polyalphaolefins (PAOs) and highlights key areas of interest and shows why PAOs are used in these applications. It discusses the physical properties of passenger car motor oils (PCMOs) based on or containing PAOs. The properties include Noack volatility and pour point. The article also discusses the properties and applications of heavy-duty engine oil (HDEO), industrial lubricants, food-grade lubricants, greases, transportation gear oils, compressor oils, hydraulic fluids, and transmission fluids.

Press quenching is a specialized quenching technique that can be utilized during heat treatment to minimize distortion of complex geometrical components by using specialized tooling for generating concentrated forces that constrain the movement of the component in a carefully controlled manner. This article provides a detailed account of the fundamental components of quenching machines, including the upright machine section, control panel, lower die table, tooling, and the base. In addition, it summarizes the critical factors affecting component distortion during press-quenching.

This article is concerned with gear tooth failures influenced by friction, lubrication, and wear, and especially those failure modes that occur in wind-turbine components. It provides a detailed discussion on wear (including adhesion, abrasion, polishing, fretting, and electrical discharge), scuffing, and Hertzian fatigue (including macropitting and micropitting). Details for obtaining high lubricant specific film thickness are presented. The article describes the selection criteria for lubricants, such as oil, grease, adhesive open gear lubricant, and solid lubricants. It discusses the applications of oil and gear lubricants and the types of standardized gear tests. The article presents some recommendations for selecting lubricants and lubricant viscosity for enclosed gear. It provides some examples of failure modes that commonly occur on gears and bearings in wind turbine gearboxes.

The function of lubricants is to control friction and wear in a lubricating system containing machine elements such as gears and bearings. This article discusses the basic properties of lubricants to help scientists and engineers understand the principles behind lubricant selection. It reviews the functions of additives, such as friction modifiers, antiwear additives, viscosity modifiers, corrosion inhibitors, oxidation inhibitors, dispersants, and detergents. The article discusses the physical properties of liquid lubricants and the performance characteristics of lubricants. It describes the most common lubricant categories and provides information on the health and safety aspects of using liquid lubricants. The article concludes with a discussion on the lubricant-application method that plays a vital role in how the lubricant functions.

Gas quenching is one of the standard quenching technologies used in fabricating metallic components. The gas quenching process is usually performed at elevated pressures and is therefore mostly referred to as high-pressure gas quenching (HPGQ). This article presents the physical principles of HPGQ and also presents the equipment for gas quenching. The article describes the three types of gas that are mainly used for HPGQ: nitrogen, helium, and argon. It provides the mathematical model for heat fluxes and temperatures during HPGQ. The article also presents typical industrial applications for HPGQ in addition to equipment process and safety.

This article provides information on the various stages of quenching, sources of distortion, and factors that affect the creation of thermal gradients. It reviews the various determinations of heat-transfer coefficients by the thermal conductivity and diffusivity method, analytical and empirical methods, application of cooling curves, computational fluid dynamics, and the inverse conduction calculation and measurement of parts. Suitable examples are also provided.

This article focuses on lubricants classified as either internal combustion engine or nonengine lubricants, and the lubricant additives. The functional groups of chemically active and inert additives, as well as friction modifiers and other additives, are described in detail. The chemically active additives include dispersants, detergents, antiwear, and extreme-pressure agents, oxidation inhibitors, and rust and corrosion inhibitors. The chemically inert additives include emulsifiers, demulsifiers, pour-point depressants, foam inhibitors, and viscosity improvers. The article also discusses the multifunctional nature of additives and concludes with information on lubricant formulation.

This article provides a discussion on the design, in-process, storage, and in-field problems and their considerations associated with armament corrosion with examples. Design considerations include geometry, material selection, assembly, pretreatment, coatings, and working and storage environments. In-process corrosion concerns include processing locations, in-process storage of parts, time between processing steps, and quality control of each processing step. The article also discusses the analysis of the in-field corrosion of the finished product, including physical environments, repair of corrosion-protective coatings, general corrosion-protection maintenance, and appropriate fixes and procedures that can be implemented by soldiers in-field to stop continued corrosion of armament equipment.

The gas quenching process is usually performed at elevated pressures, and is therefore, mostly referred to as high-pressure gas quenching (HPGQ). This article describes the physical principles of HPGQ; the two main types of equipment used, namely, single-chamber furnaces and cold chambers; and the three gases used, namely, nitrogen, helium, and argon. It also discusses two different groups of fixture materials used, namely, high-nickel-content alloys and carbon-fiber-reinforced carbon materials. The article exemplifies the process of dynamic gas quenching and how core hardness values can be predicted in industrial practices. It also discusses the improvements in distortion control with the application of gas-flow reversing and dynamic gas quenching.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of high-carbon steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the following: torsional fatigue fracture, hydrogen-embrittlement fracture, fatigue crack propagation, and corrosion fatigue of components made from high-carbon steels. The high-carbon steel components include bull gear, drive shaft, power boiler stoker grate, steel wheel, spring wire, suspension spring, automotive engine valve spring, power spring, cantilever-type spring, railroad rail, and seamless drill pipe.

Quenchant agitation can be obtained by circulating quenchant in a quench tank through pumps and impellers. The selection of the agitation method depends on the tank design, type and volume of the quenchant, part design, and the severity of quench required. This article describes flow measurement methods, temperature control, materials handling, and filtration processes during the agitation process. The maintenance of quenching installations is also discussed.

This article provides the basics of overall quench process distortion. It describes the influence of quenching processes on the generation of distortion. Examples for the distortion behavior of different types of components are presented. Then, comparisons between different quenching processes are provided. The article presents some possibilities for minimization of shape changes by the quenching process itself. Several suggestions are given for quenching processes in evaporating fluids. An example is provided for out-of-roundness reduction for rings by well-defined inhomogeneous quenching in a gas nozzle field. Another example shows how intensive and high-speed quenching can help to reduce the bending of shafts with an asymmetrical cross-section. The last example shows the result when external loads and nonsymmetric quenching act together. The article also presents test samples for the judgment about distortion potential arising from heat treatment equipment.

This article focuses on different aspects of wear particle analysis. It discusses the different wear regimes in the wear rate versus time (bathtub) curve. The article explains the essence of condition monitoring and how to properly sample lubricants for condition monitoring. It also discusses in-service lubricant analysis for condition monitoring, focusing on the spectrometric oil analysis program. The article describes the characteristics of wear particles and analytical techniques for characterizing them. It also describes the characteristics of different types of wear particles and the mechanisms by which they are generated. The article concludes with a summary of the major applications of wear particle analysis.

Flame hardening is a heat treating process in which a thin surface shell of a steel part is heated rapidly to a temperature above the critical temperatures of the steel. The versatility of flame-hardening equipment and the wide range of heating conditions obtainable with gas burners, often permit flame hardening to be done by a variety of methods. These include the spot or stationary method, progressive method, spinning method, and the combination progressive-spinning method. This article provides information on fuel gases used in flame hardening and their selection criteria for specific applications. It also discusses operating procedures and control requirements for flame hardening of steel.

Grinding is an extremely complex process that requires the consideration of a number of elements in order to make a reasonably adroit initial selection of a fluid or fluids for a manufacturing plant. In addition, the disposal of grinding wastes must meet the minimum requirements as recommended by the federal Environmental Protection Agency (EPA) and Resource Conservation and Recovery Act (RCRA) regulations. This article explains the selection considerations of such fluids, as well as the applications and environmental issues related to the grinding processes.

Induction heating for hardening of steels has advantages from the standpoint of quenching because parts are individually processed in a controlled manner. This article provides information on the effect of agitation, temperature, hardening, residual stresses, and quenching media, on quenching. It also describes various quenching methods for steel induction heat treating, namely, spray quenching, immersion quenching, self or mass quenching, and forced air quenching. The article also reviews quench system design and quenchants and their maintenance.

This article focuses on failure analyses of aircraft components from a metallurgical and materials engineering standpoint, which considers the interdependence of processing, structure, properties, and performance of materials. It discusses methodologies for conducting aircraft investigations and inspections and emphasizes cases where metallurgical or materials contributions were causal to an accident event. The article highlights how the failure of a component or system can affect the associated systems and the overall aircraft. The case studies in this article provide examples of aircraft component and system-level failures that resulted from various factors, including operational stresses, environmental effects, improper maintenance/inspection/repair, construction and installation issues, manufacturing issues, and inadequate design.

Low-pressure carburizing (LPC) is one of the most popular case-hardening processes and is applied to increase the fatigue limit of dynamically loaded components. It takes place in a pressure range between 5 and 15 mbar (4 and 11 torr) and at temperature range between 870 and 1050 deg C. The LPC process runs in two different types of equipment: single-chamber furnaces and treatment chambers. This article reviews the use of simulation software for prediction of carbon profiles and typical quality control procedures. It describes the physical principles and typical applications of LPC.

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.

This article focuses on the various coatings used on Department of Defense (DoD) systems. These include electroplated coatings; conversion coatings; supplemental oils, waxes, and lubricants; organic paint coatings; and other finishes such as vacuum deposits, mechanical plating, thermal spray coatings, and hot-dip coatings. The article also lists the test requirements and time to failure of the coatings.