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Through practical tests, it has been found that steel balls based on different standards could affect tribological performances of the same lubricant, but unfortunately, past researches in the field have been quite inadequate. The aim of this paper, therefore, is conscientiously to study the problem.

The anti‐wear properties of four kinds of lubricants were evaluated by four‐ball tester using two kinds of steel balls based on different standards. The reason for different anti‐wear properties of the same lubricant was also discussed using hardness tester and scanning electron microscope with an energy dispersive spectrometer (SEM/EDS).

It was found that steel balls based on different standards could affect the tribological results for the same lubricant. The reason could lie in the surface chemical composition, surface roughness and hardness of steel balls which originated from the subtle difference of different standards.

The paper shows that, as far as evaluating anti‐wear properties is concerned, steel ball based on AISI Standard Steel No. E‐52100 is a better choice than that based on Chinese standard GB 308.

The purpose of this paper is to present the tribological, anticorrosion and antirust properties of three 2,5-dimercapto-1,3,4-thiadiazole (DMTD) derivatives as water-soluble additives in water–glycol hydraulic fluid.

DMTD derivatives possessing excellent corrosion inhibiting and extreme-pressure (EP) properties have long been used as metal passivators and load-carrying additives in lubricating oils and grease. However, there are seldom literatures about DMTD derivatives as water-soluble lubricant additives as yet. In this work, three DMTD derivatives were synthesized and investigated as water-soluble additives in the water–glycol hydraulic fluid. Their tribological properties were evaluated in detail by four-ball wear test machine and Optimol SRV-IV oscillating friction and wear tester. Meanwhile, their anticorrosion and antirust properties were also investigated by copper strip corrosive tests and antirust tests, respectively. The worn surfaces were analyzed by scanning electron microscope and X-ray photonelectron spectroscope, and the EP, antiwear and friction-reducing mechanisms were primarily proposed.

The synthesized three DMTD derivatives (coded as A, B and C) have excellent solubility in the base liquid of the water–glycol hydraulic fluid. The experimental results demonstrated that all these compounds, especially A, could remarkably improve the EP, antiwear and friction-reducing properties of the base liquid. Furthermore, they all have perfect copper corrosion inhibiting and antirust properties with low adding concentration (< 3 weight per cent) in the base liquid and hence could be used as multifunctional additives in the water–glycol hydraulic fluid.

This research only focused on the synthesized DMTD derivatives. If possible, some other thiadiazole derivatives also should be investigated.

The synthesized DMTD derivatives, especially compound A, can be used as multifunctional water-soluble additives in the water–glycol hydraulic fluid.

In this paper, three DMTD derivatives were synthesized and their tribological behaviors as water-soluble lubricant additives were investigated for the first time. In addition, the EP, antiwear and friction-reducing mechanisms were also put forward.

The National Engineering Laboratory is one of the larger stations of the British Government's Department of Scientific and Industrial Research. Current programmes include theoretical and experimental studies of non‐Newtonian lubricants, the development of new methods of measuring the compressibility of hydraulic fluids, research into the behaviour of oils under hydrostatic tension, and investigations of various aspects of the phenomenon of aeration in hydraulic fluids. The Laboratory's facilities for carrying out sponsored research and testing in this field are briefly described.

THE British Standard 4231 : 1967 “Viscosity Classification for Industrial Liquid Lubricants” together with BS 4475 : 1969 “Specification for Straight Mineral Lubricating Oils” constitute a real step forward for the lubrication world. Not only do they contribute clarity to their respective subjects, they also enable an overall classification of all lubricants and hydraulic fluids based on a common theme to be composed. BS 4231 enables the viscosities of all fluid lubricants including hydraulic media to be identified within one dimensionally rational scale. Though it is specifically for straight mineral oils, BS 4475 suggests a segregation of quality levels appropriate to other than straight oils.

Apart from the basic material properties of liquid lubricants, such as, e.g., the viscosity and density of the hydraulic fluid, it is also important to have information regarding the electrical properties of the fluid used. The latter is closely related to the purpose, type, structure, and conditions of use of a hydraulic system, especially the powertrain design and fluid condition monitoring. The insulating capacity of the hydraulic fluid is important in cases where the electric motor of the pump is immersed in the fluid. In other cases, on the basis of changing the electrical conductive properties of the hydraulic fluid, we can refer its condition, and, on this basis, the degree of degradation.

The paper first highlights the importance of knowing the electrical properties of hydraulic fluids and then aims to compare these properties, such as the breakdown voltage of commonly used hydraulic mineral oils and newer ionic fluids suitable for use as hydraulic fluids.

Knowledge of this property is crucial for the design approach of modern hydraulic compact power packs. In the following, the emphasis is on the more advanced use of known electrical quantities, such as electrical conductivity and the dielectric constant of a liquid.

Based on the changes in these quantities, we have the possibility of real-time monitoring the hydraulic fluid condition, on the basis of which we judge the degree of fluid degradation and its suitability for further use.

Focuses on oleochemicals, a natural alternative to mineral oils for use in liquid lubricants, metal working coolants, quenchants and hydraulic fluids. Natural oil based products generally have many advantages over mineral oils, including lower volatility, better inherent lubricity, higher viscosity index, higher bulk modulus, better fire resistance and better solvency. Details the manufacturing process.

The following is an abstract of a talk presented as part of the Lubrication Engineering Short Course, organized by the American Society of Lubrication Engineers and held at Northwestern University, Evanston, Illinois, in June this year.

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.

The breakdown of laminar flow in the clearance space of a journal is considered, and the point of transition is considered in relation to experiments carried out with ‘bearings’ of large clearance. Experiments involving flow visualization with very large clearance ratios of 0.05 to 0.3 show that the laminar regime gives way to cellular or ring vertices at the critical Reynolds number predicted by G. I. Taylor for concentric cylinders even in the presence of an axial flow and at a rather higher Reynolds number in the case of eccentric cylinders. The effect of the transition on the axial flow between the cylinders is small. The critical speed for transition as deduced by Taylor, is little affected by moderate axial flows and is increased by eccentricity. The effect of critical condition on the axial‐flow characteristics of the bearing system appears to be negligible, again for moderate axial flows. Assuming that the results can be extrapolated to clearances applicable to bearing operation, the main conclusion of this paper is that the breakdown of laminar flow, which is a practical possibility in very high‐speed bearings, is delayed by eccentric operation.

The Presidential Address to the Liverpool Engineering Society by Mr. Farthing (the salient points of which are reproduced in this issue) has particular bearing upon lubrication and especially on young lubrication engineers. Mr. Farthing stressed the very wide field open to young engineers and the difficulties associated with training in order to cover as wide a field as may be necessary. It is usually so important to gain a wide knowledge before one can specialise and this is certainly the case with lubrication engineers. One cannot begin to fully appreciate the intricacies of a lubrication system with all its accessory components lubricating and guarding, for example, a large motive power plant or rolling mill, until one has more than a mere working knowledge of the plant itself, the duties it must perform, how it performs them and the snags that arise which might be overcome by correct lubrication. In view of the fact that lubrication systems are just as important in a textile mill as in a power station or a large brick works, the almost impossible‐to‐achieve‐range of knowledge that would simplify the work of a lubrication engineer is very obvious. Fortunately, lubricating principles apply to most cases and knowing how to apply one's knowledge from basic principles is the key to success in this difficult profession.