Hydraulic fluids - Functions. Classification

Hydraulic fluids are force vectors.

They differ from lubricating oils only in detail, to such an extent that under normal conditions of use, for example, a mineral oil, provided it is not too viscous, can be both a lubricating oil and a hydraulic fluid. When investigating a synthetic composition, it's hard to say a priori "what we'll end up with"; it's only an inventory of properties that provides the final orientation.

Hydraulic fluid is often referred to as a functional fluid. By this we mean a fluid without which the machine cannot function.

The main function of the fluid in a hydraulic system is to transmit a force applied at one point to another. The force must be transmitted quickly and precisely. To perform this function satisfactorily, the fluid must be able to flow easily under a wide range of temperature conditions, and be as incompressible as possible.

In addition, service conditions must be optimal and operating costs reasonable.

To perform its essential functions, the fluid must combine a number of qualities, such as good lubricity, good heat transfer coefficient, good anti-wear properties and, as far as possible, good fire resistance.