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This paper seeks to investigate the influence of chemical structure of ester basestock (trimethylolpropane pelargonate) on the viscosity characteristics of formulations obtained and the operating mechanism of two widely used viscosity index improvers – poly(butadiene‐styrene) and poly(alkyl methacrylate).

Oil formulations of trimethylolpropane pelargonate and poly(butadiene‐styrene)/poly(alkyl methacrylate) as viscosity index improvers are prepared. Their kinematic viscosity at different temperatures is measured. Relative, intrinsic and characteristic viscosities are calculated from the experimental data.

The thickening ability of linear polymers from butadiene‐styrene and alkyl methacrylate in a synthetic oil of ester type (trimethylolpropane pelargonate) is clarified. The conformation of these polymers is studied. Results of comparative tests about the influence of the type of polymer and solvent on characteristic and intrinsic viscosity are presented. It has been established that with the increasing of temperature the quality of used synthetic oil decreased and the characteristic viscosity decreased for both polymers. At lower temperatures the intermolecular interaction between the polymeric macromolecules becomes bigger than their interaction with the molecules of solvent. Molecule associates have been possibly formed at low temperature. These associates increase the viscosity of solutions and this increase is bigger at low temperatures in comparison with high temperatures.

Viscosity index improvement of poly(butadiene‐styrene) and poly(alkyl methacrylate) is determined. The information about concentrations and viscosity is of practical interest.

The combination of these synthetic basestock and viscosity index improvers is a new one. The data obtained may have value for the oil production.

A brief review of the conditions to which a crankcase oil is subjected during engine operation is given prior to a consideration of the relevance of the current SAE J300 viscosity classification to the needs of today's engines. Regarding the high‐temperature part, it is concluded that the current classification based on the low‐shear‐rate kinematic viscosity at 100°C provides a useful guide to oil consumption and a convenient means of evaluating used oils; it is, however, unsatisfactory as a guide to the fuel consumption and journal‐bearing performance of polymer‐containing oils. Whilst modification of J300 to include high‐shear‐rate viscosity limits could provide a classification relevant to the fuel consumption of such oils, knowledge of the complicated effects of both elasticity and viscosity on load‐bearing capacity, although increasing, is currently incomplete and it will be some years yet before J300 could be usefully modified to provide a guide to the rheological performance of oils in automotive journal bearings.

Oleochemicals can be made from the components of renewable animal, marine and vegetable oils and fats. This oleochemical group of products is a large one, comprising fatty acids, glycerol and numerous derivatives of these including fatty alcohols, fatty esters, and nitrogen‐, phosphorus‐and sulphur‐containing materials. Polyoxyalkylated end products from the above, from heavy metal and water‐soluble soaps, epoxidised chemicals, polymer components, and the quarternary ammonium compounds are found. The oleochemicals of interest to the lubricants manufacturer are those which function in some specific manner. Anti‐corrosive, anti‐oxidant, anti‐squawk, anti‐stick, anti‐sludge, anti‐wear detergent, dispersant and oiliness agents, pour point depressants and viscosity modifying materials, are examples.

To study and estimate changes of various properties upon use of engine oil by different methods.Design/methodology/approach – By viscosity measurement, pH measurement, Fourier transform infra‐red spectroscopic analysis and UV‐Visible (Ultraviolet and visible rays) spectroscopic analysis.Findings – Some specific changes in additives of the oil upon use could be traced.Practical implications – Correct choice for additives for a particular use may enhance the oil life and also protect the engine from damage.Originality/value – The findings may be important to the lube oil producers and the users.

In this study, an attempt is made to show the linkage between the oil additive and journal bearing the running conditions such as temperature, load, speed, etc. in effecting lubricating. It is well known that öne of the roles of additives is to form protective layer to reduce friction coeffıcient in lubricated contacts.

The tests were performed at three different loads, and eight speeds. The tests were carried out for three different commercial additives that are concentration ratio of 3 per cent.

The test results of the experimental coeffıcient of friction were graphically presented. The highest reduction in the friction coeffıcient was obtained at high temperature (100°C) in the tests than room temperature (25°C) tests.

In this study, effects of commercial oil additives on the friction coefficîent in the journal bearing under statically loaded have been studied experimentally at 25 and 100°C temperatures.

Lubricating oils find applications in engines, industrial uses, greases and automotive transmissions. The majör uses of these oils are in engines (55 per cent), industry (27 per cent), processes (9 per cent), greases (5 per cent) and automotive transmissions (4 per cent). Lubricants perform a variety of functions in automotive application. One of the important functions is to reduce friction and wear in movîng machinery.

Generally, by adding additives to engine oil the lower friction coeffıcient were observed comparison engine oil both at 25 and 100°C temperatures. But, the smallest friction coefficient was obtained in the tests at 100°C comparison with the tests at 25°C in the additive addition to engine oil tests.

ADDITIVES today are important ingredients in lubricating compositions whose efficiency they enhance by an improvement in certain desired characteristics. The inclusion of such substances in lubricating mixtures has therefore occupied the attention of both the engineer and chemist.

A series of articles dealing, in as simple a way as possible, with the basic facts of lubrication, lubricants, their selection and prescription, specification, application, and testing. This series is primarily intended for students, engineering personnel who may be unfamiliar with certain aspects and others who, one way or another, are interested in this important subject.

To anyone concerned with the use of lubricants the word “additive” is nowadays commonplace, but just what an additive is or what is meant by additive treatment is not so widely understood. Any attempt at a simple explanation would undoubtedly err on the side of understatement and leave a lot unexplained but some form of definition is necessary as a basis from which to work.

This paper aims to investigate the effect of plugging of holes on the static performance characteristics of a constant flow valve compensated hole‐entry hybrid journal bearing system operating with Newtonian and non‐Newtonian lubricants. The analysis considers the generalized Reynolds equation governing the flow of lubricant having variable viscosity in the clearance space and equation of flow of lubricant through constant flow valve restrictor. The non‐Newtonian lubricant is assumed to follow the power law. The performance characteristics are computed for the two values of power law index (n=1.0 and 0.566). The computed results indicate that the blockage of holes during operation will not be the likely causes for the imminent failure of a well‐designed non‐recessed hole‐entry hybrid journal bearing.

Finite element method has been used to solve generalized Reynolds equation governing the flow of lubricant having variable viscosity in the clearance space and equation of flow of lubricant through constant flow valve restrictor.

The computed results indicate that the blockage of holes during operation will not be the likely causes for the imminent failure of a well‐designed non‐recessed hole‐entry hybrid journal bearing. The bearing configuration with plugged holes provides sufficient fluid film thickness and low power requirement as less lubricant is required to be pumped in the bearing.

To the best of the author's knowledge, no study which considers the influence of plugging of holes on the static performance characteristics of a constant flow valve compensated hole‐entry hybrid journal bearing system operating with Newtonian and non‐Newtonian lubricant is yet available in the literature.

This paper aims to describe the theoretical study concerning the effect of non‐linear behavior of the lubricant on the performance of symmetric constant flow valve compensated hole‐entry hybrid journal bearing. The bearing performance characteristics have been computed for various values of non‐linearity factor, land width ratio, aspect ratio and external load.

The analysis considers the generalized Reynolds equation governing the flow of lubricant having variable viscosity in the clearance space and equation of flow of lubricant through constant flow valve restrictor. The non‐Newtonian lubricant is assumed to follow the cubic shear stress law.

The study indicates that for generation of accurate bearing characteristics data, the inclusion of non‐linear effects of lubricant in the analysis is essential.

The performance characteristics in terms of minimum fluid‐film thickness, fluid‐film stiffness and damping coefficients, critical mass and threshold speed for a wide range of values of the non‐linearity factor and external load are presented. The results presented are expected to be quite useful to bearing designers.