Engine Scuffing Prevention using Lubricant Additives for High Load Gear Systems

A driveline and transmission fluid composition that achieves low speed wear and scuffing resistance in heavy-duty applications. The composition includes a base oil, zinc dialkyl dithiophosphate, metal-containing detergents, and a low molecular weight diol or triol compound, with the diol or triol compound being present in an amount of 0.01 to 3.5 weight percent. The composition is particularly suited for use in heavy-duty applications such as off-road equipment and construction machinery, where it provides improved wear protection and scuffing resistance in gear and bearing applications.

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Introducing an additive is a practical approach to improve the lubrication performance of base oil in the field of tribology. Herein, a series of sulfoximine derivatives was synthesized and incorporated into base oil A51 as additives. The tribological properties of these lubricants were evaluated at both room and high temperatures, and the result demonstrated that they displayed excellent friction reduction and wear resistance in the friction process under both test conditions. Moreover, the chemical composition of the worn scar surface was inspected using EDS, XPS and TOF-SIMS to explore the lubricating mechanism. It is reasonable to conclude that the synergistic interaction between the aromatic ring scaffolds and elements like N, F, and S facilitated the adsorption of lubricant on the steel block surfaces and forming a tribofilm during the friction process. This tribofilm has a dominant impact on the systems lubrication performance. This research provides novel oil-soluble lubricant additives, offering a facile approach to formulating high-quality lubricants.

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Lubricating compositions for transmissions, axles, tractors, and industrial gears that achieve desired load carrying capacity while improving copper corrosion performance. The compositions include a thiadiazole additive and a specific type of tris-aryl phosphite compound with a particular ratio of para-position to ortho-position substitution. This combination enables the lubricant to meet performance requirements for load carrying capacity while also preventing copper corrosion.

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A lubricating oil composition for various mechanisms in apparatuses, comprising a base oil, zinc dialkyldithiophosphate, and a sarcosine derivative. The composition provides improved lubrication properties, including seizure resistance and wear resistance, while maintaining fuel efficiency. The zinc dialkyldithiophosphate acts as a metal-based detergent and extreme pressure agent, while the sarcosine derivative enhances lubricity and dispersibility. The composition can be used in applications such as engines, transmissions, and hydraulic systems.

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Abstract Enabling gears to withstand loss of lubrication in gearboxes without secondary oil supply systems can reduce weight and space demand and thus fuel consumption. This study investigates the potential of surface and material technologies on the loss of lubrication performance of gears. Thereby, superfinished, coated, and nitrided gears are compared to ground gears. Systematic experiments under loss of lubrication are performed at a back-to-back gear test rig with circumferential speeds of up to 20 m/s and Hertzian pressures in the pitch point of up to 1723 N/mm 2 . Torque loss, pinion bulk temperatures, and tooth flank surface are analyzed. The results show that surface and material technologies can greatly influence frictional behavior and damage initiation of gears operating under loss of lubrication. With the materials and conditions tested, superfinishing yields to accelerated rise of frictional losses and thus scuffing. Coatings lead to significantly enhanced service life under loss of lubrication by friction reduction and scuffing avoidance.

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Solid lubricants are those materials that are used to lubricate mainly in dry circumstances. Its main role is similar to that of oils and greases, which is used to create a continuous and adherent lubricant film on the tribological pair surfaces for minimising friction and wear [1]. These coatings are typically employed in situations where liquid lubricants cannot be used or do not offer expected lubrication, such as in high or cryogenic temperatures, high vacuum, ultrahigh-radiation, reactive environments and in extreme contact pressure conditions [2]. Different types of solid lubricants, including graphite, have been extensively used since the middle of the 20th century [3]. From 1950 onwards, development in aeronautics industries emphasised the research and development of advanced solid lubricants. They can be classed based on their crystalline structure, features, properties, or functions, among other things. Different types of solid lubricant coating are shown in Fig. 1 [1].

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A lubricant composition for driveline and industrial gears that combines two types of viscosity modifiers with optional esters to achieve improved thermal stability, traction performance, and efficiency. The composition comprises a hydrocarbon lubricating base stock and a viscosity modifier composition that includes an olefin polymer and a grafted olefin copolymer. The combination of these viscosity modifiers enables the lubricant to maintain its performance characteristics at lower viscosities, while also providing improved traction and reduced friction.

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Abstract Today, mineral or synthetic oils that are made out of fossil raw materials are the most common lubricants in gear drive applications. Most of them are nonbiodegradable and may pose a risk to the environment. An important step to minimize the risk and the ecological footprint is the use of biodegradable and eco-friendly lubricants. Former research shows the potential of water-based lubricants in gear applications. Therefore, an oil-free, water-based lubricant was developed for this study. The base lubricant contains plant-based thickeners to generate an appropriate viscosity for a sufficient lubricant film thickness in the tooth contact. In experimental investigations, the sliding wear and scuffing performance has been examined under variation of the added polymers and additives. The scuffing tests A/8.3/RT are performed according to DIN ISO 14635-1. The wear test procedure is based on DGMK 377-01. In both scuffing tests with the sample, the failure load stage = 8 was achieved. For case-carburized gears, a medium to high amount of wear can be detected. Additional tests wi... Read More

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In mechanical systems, lubricants play a crucial role in minimizing friction, dissipating heat, and preventing wear. Additives, comprising both organic and inorganic compounds and typically constituting 0.1% to 30% of lubricant volume, are introduced to enhance lubricant performance. This study investigates the influence of various additives on lubricant behaviour and performance, encompassing antifoam agents, corrosion inhibitors, antioxidants, detergents, extreme pressure additives, pour-point depressants, and viscosity index improvers. Friction coefficients were meticulously measured using a pin-on-disk tribometer to assess the Tribological and physical properties of these additives. Surface analysis via SEM provided insights into wear characteristics influenced by the additives. The comprehensive tribological assessment reveals that the incorporation of additives consistently reduces friction and wear across different base oil types. This underscores the critical role of additives in improving lubricant properties, maintaining thermal stability, and forming protective films on su... Read More

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An anti-wear and anti-friction lubricating oil additive comprising malic acid, fatty alcohol, malic acid ester, and maleic acid ester, wherein the additive generates graphite-like carbon structures in situ at the friction contact interface to reduce friction coefficient and wear. The additive can be formulated with malic acid (0.5-20 wt%), fatty alcohol (5-50 wt%), malic acid ester (0.1-80 wt%), and maleic acid ester (0.2-50 wt%). The additive can be prepared by ultrasonication or stirring with a lubricating oil base oil.

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Transmission fluid composition for heavy-duty applications, comprising a base oil, a molybdenum-containing component, a zinc dialkyldithiophosphate, and a calcium detergent. The composition provides bearing pitting protection while meeting the static friction requirements of the Caterpillar TO-4 specification.

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Under high-temperature, high-speed, heavy-duty, and extreme lubrication operating conditions, such as those found in gearboxes of aviation engines and electric vehicles, gear scuffing failure has emerged as a critical issue and a primary technical challenge in the mechanical transmission field. As test methodologies, evaluation criteria, and load-carrying capacities related to gear scuffing are yet to reach full maturity in response to these demanding operating environments, this article examines existing literature on gear scuffing failure and its control, incorporating insights from industry practices and academic studies. The discussion encompasses the development of gear scuffing theories, experimental investigations, and practical applications, ultimately providing an overview of the most recent developments in gear anti-scuffing technologies. The ultimate goal of this work is to elucidate failure mechanisms of gear scuffing and establish effective design approaches for gear anti-scuffing.

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Modern engines are designed for very close contact between shearing planes, which requires high-performance boundary lubrication, delivered by lubricant base oils formulated with an array of additives. Commercial additive packages...

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The objectives of this chapter are to: (i) Define the term lubricants and identify, outline and discuss the principal types of lubricants; (ii) Identify, outline and describe the three typical inorganic compound kinds that could be employed as solid lubricants; (iii) Identify, outline and discuss those significant properties of commercial fluid lubricants; (iv) Identify, outline and discuss the reasons the effectiveness of the lubricating oil deteriorates over time or requires replacement after some time of usage; (v) Outline and discuss the lubricating oil selection and materials for tribological applications; (vi) Define the term additives and outline their roles and functions within lubricants; (vii) Identify, outline and describe the commonly used additives; (viii) Outline and discuss the tribology of rolling elements and applications; and (ix) Analyse, derive and discuss the power absorbed to overcome the viscous resistance due to the lubricating oil's viscosity in rolling bearings, such as journal, foot-step and collar bearings.

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Experimental gear scuffing results were obtained in the FZG test rig for wide ranges of the applied torque, tangential speed, base oil viscosity and bath oil temperature, and for FZG type A and type C gears.A scuffing criterion for gears lubricated with base mineral oils was developed, proposing the existence of gear mass temperatures which are critical for each lubricant (viscosity grade).The scuffing criterion shows very good correlation with experimental results.The dynamic viscosity of the oils at those critical mass temperatures is constant that permits the determination of other critical temperatures for other gear mineral oils without need additional scuffing tests.

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Wear mitigation in gears and rolling bearings lengthens the service life of machines and contributes to the achievement of a more sustainable society. Organic additives form protective films on rubbing steel surfaces of mechanical contacts that can mitigate wear significantly. However, wear prevention requires the design of new additives for lubricants that are environmentally friendly. Molecular simulations are employed to investigate the effect of the base oil on the adsorption, the lubricant adhesion, and structural properties of a promising organic additive (N,N - Bis(4-aminobutyl) oleylamine). Results are compared with oleylamine. They suggest better performances for the promising organic additive. Overall, findings further support the fact that additives with polar head groups with aminoalkyl branches reduce wear efficiently in mechanical contacts.

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This study explored the potential enhancement of lubrication performance by incorporating polydimethylsiloxane (PDMS) powder as a lubricant additive.

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Lubricant additives can effectively enhance the performance and environmental adaptability of lubricants and reduce the energy loss and machine wear caused by friction. Nanomaterials, as important additive materials, have an essential role in the research and development of new lubricants, whose lubrication performances and mechanisms are not only related to their physical and chemical properties, but also influenced by the geometric shape. In this paper, the friction reduction and antiwear performances of nanomaterials as lubricant additives are first reviewed according to the classification of the dimensions, and their lubrication mechanisms and influence rules are revealed. Second, the recent research progress of composite nanomaterials as lubrication additives is introduced, focusing on their synergistic mechanism to improve the lubrication performance further. Finally, we briefly discuss the challenges faced by nanoadditives and provide an outlook on future research. The review expects to provide new ideas for the selection and development of lubricant additives to expand the ap... Read More

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Lubricant is used to decrease wear on two surfaces that come into contact with each other, and additives can aid to improve the lubricant's performance. Engine oil is the lubricant that we use in combustion engines, and ex-ternal additives that are available on the market can be added to the engine oil to improve its performance. The purpose of this study is to see how ex-ternal additives affect the tribological performance of engine lubricants. The performance of three lubricant samples was investigated in this study: commercial engine oil (SAE10W-30), engine oil mixed with friction modifier additives, and engine oil mixed with anti-wear and extreme pressure additives. The mixtures' viscosity, coefficient of friction (COF), and wear scar diameter (WSD) were determined using viscometer, four-ball tester, and high-performance microscope. The findings show that the mixes behave differently than commercial oil. Even though adding additives to engine oil is sup-posed to boost performance, the flash temperature parameter (FTP) deter-mined from WSD, and the frictional behaviour a... Read More

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Lubricants play a critical role in the energy losses of an engine. Several engineering solutions are existing to reduce the frictional and wear losses caused by the lubricant such as ultra-low-viscosity lubricants. With the spread of low-viscosity engine oils like 0W-20 and below, the importance of tribological lubricant additives is increasing. To ensure the necessary protection of the rubbing surfaces against friction and wear, new lubricant additive materials should be researched and investigated. Next to the tribological performance of the additives, their impact on the price is a strong influencing factor. No financial information of the investigated additive materials is available in the current scientific articles and so no rentable decision can be defined which additive worth to invest as an engine oil additive in the future mass production engine oils. This article presents the tribological potential of selected nanoscale ceramic particles (zirconia, cupric oxide and yttria) as lubricant additives and compares them according to their financial impact. According to the result... Read More

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