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The Nordic marketplace, and in particular the Swedish market, is a sizeable part of the world market for environmentally adapted lubricants (EALs). The largest segment, by far, is EAL hydraulic fluids for mobile hydraulics, and chain saw oils for the environmentally adapted forestry operations (mainly) by the international Swedish and, until recently, Finnish forestry companies. In this paper, some of the important parameters influencing the size and development direction are analysed. These include market regulatory factors, eco‐labels, OEM‐issued standards/specifications, end‐user demands and the market volume development for the period 1999‐2001. The spread of EALs to other forestry markets, Norway and the Baltic States, is also covered.

THE TERM “synthetic lubricant” has been adopted to designate a variety of fluids, derived from sources other than mineral oils, which have been developed by the technologist in order to satisfy the extreme conditions under which present‐day machinery has to operate : for example, high or low temperatures, or both, often with high bearing loads, and sometimes under conditions which demand resistance to ignition. Although, in fact, modern petroleum oils are prepared to such stringent specifications, and by such carefully controlled processes, that they are almost equally as “tailor‐made”, it is their comparatively limited temperature range that largely brought about the development of the so‐called synthetic product.

HYDRAULIC POWER and control is being applied more and more widely in industry and is finding both general and specialised uses. Generally, hydraulics could be just another item in the designer's toolchest—another way of applying power and of exercising control. In the specialist fields hydraulics is being used as the force transmitting element in complex closed loop control systems and where the very nature of a fluid medium is to be used with advantage.

WHETHER it delivers lubricant to working surfaces or conveys a column of fluid transmitting mechanical thrust, a flexible hose unit becomes a potential weak link if its performance falls short in any way of that of the remainder of the installation of which it is an integral part. A weak oil seal not up to its job impairs the fluid conductor systems. That much might seem obvious but, with increasing application of hydraulics in industry, and with heat and pressure conditions far more severe now than a couple of decades ago, new standards of reliability in fluid conductors and seals have become mandatory.

THE EARLIER APPLICATIONS of hydraulic power used only water as a medium (the word itself is derived from the Greek words hydros (water) and aulos (pipe)), but subsequent developments have resulted in the term hydraulics being applied to any system arrangement whereby a fluid or even a semi‐fluid is used as a means of transmitting power or movement.

Environmental protection regulations are becoming increasingly strict. Using water instead of a hydraulic mineral or biodegradable oil in power‐control hydraulic systems is a very positive step towards complying with these regulations. Since water hydraulics has many specifics, primarily related to lower viscosity and lubricity of water compared to oil, which greatly affects the leakage, and even more the friction and wear in these systems, a dedicated test rig is required for performing research with the real‐scale components. The purpose of this paper is to present some preliminary representative results on dynamic responses of the two hydraulic circuits with and without a mass load.

The paper presents the newly developed dedicated test rig and its dynamic characteristics when used with water and oil as hydraulic fluid. Hydraulic pressures and motions of spool and piston in the two different fluids were of special interest.

The results clearly show their dependence on friction properties of selected materials in different hydraulic fluids. While the oil valve worked perfectly, water valve has some irregularity, linked with the small gap, the shape irregularity, the surface roughness and the poorer lubrication conditions in the water hydraulics compared to the oil system.

The observed irregularity of the movement of the spool in the water hydraulic valve has almost no influence on the movement of the piston rod of the water cylinder, which is a very promising result for future research on water hydraulics.

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.