TABLE OF CONTENTS After reading this chapter, the student will be able to:
Understand and explain the primary functions of a hydraulic fluid
Detail the various characteristics of hydraulics fluids
List the different types and categories of hydraulic fluids used
Understand the problems encountered with hydraulic fluids
Compare the common properties of the different hydraulic fluid types.
The working fluid is the single most important component of any hydraulic system. It serves as a lubricant, heat transfer medium, Sealant and most important of all, a means of energy transfer. These fluid functions can be clearly understood with the help of the diagrams illustrated below. Fluid characteristics play a critical part in determining the equipment performance and life. Hydraulic fluids are basically non-compressible in nature and can therefore take the shape of any container. This tendency of the fluid makes it exhibit a certain advantage in the transmission of force across a hydraulic system. Use of a clean, high-quality fluid, is an essential prerequisite for achieving efficient operation of the hydraulic system. Although early hydraulic systems employed the medium of water for transferring hydraulic energy, there are serious limitations attached to it such as:
Its relatively high freezing point (water freezes at 0 C or 32 F when the pressure is atmospheric)
Its tendency to expand when frozen
Its corrosive nature
Its poor lubrication properties
Its capacity to dissolve more oxygen leading to phenomena such as oxygen pitting.
This has necessitated the development of modern fluids designed specifically for application in hydraulic...
