Hydraulic systems are used to transmit force from one point to another via a fluid. This fluid is usually hydraulic oil, and the concept is based on Pascal’s law. Hydraulics are present in nearly all industries and play a critical role in enhancing operational efficiency. In this article, we will take a deep dive into hydraulic oils and explore them in more detail.
What is Hydraulic Oil?
One of the primary functions of hydraulic oil is to transmit power or energy. However, this is not its only function.
Some of its primary functions include:
- Transferring pressure and motion energy
- Transferring forces and moments when used as a lubricant
- Minimization of wear to sliding surfaces under boundary friction conditions
- Minimization of friction
- Protection of components against corrosion (ferrous and non-ferrous metals)
- Dissipation of heat
- Suitability for a wide range of temperatures, good viscosity-temperature behavior
- Prolonging the life of machinery
However, hydraulic oils also have secondary and tertiary functions.
Some of the secondary characteristics of hydraulic oils include high aging stability, good thermal stability, inertness to materials, compatibility with metals and elastomers, good air separation, low foaming, good filterability, good water release, good shear stability (in the case of non-Newtonian fluids), and more.
On the other hand, some of the tertiary characteristics include low evaporation due to low vapor pressure, toxicologically harmless, ecologically safe, and low flammability (fire resistance), all of which depend on how the fluid is formulated.
History of Hydraulic Oil
The principle of hydraulics has been around for a very long time. In fact, according to Hard Chrome Specialists, it may even date back to around 6000 BC, when ancient Mesopotamians and Egyptians used water for irrigation. Fast forward to the modern day, where hydraulics have been heavily influenced by Blaise Pascal, Joseph Bramah, Daniel Bernoulli, and William George Armstrong. A snapshot is shown in Figure 1 below.
Importance of Hydraulic Oil
Hydraulics forms part of the field of fluid technology, which can be further subdivided into hydrostatics and hydrodynamics.
For hydrostatic systems, the transfer of energy requires static pressure; hence, the pressure is high, but the flow rate is low. Fluids designed for these applications are known as hydraulic oils.
For hydrodynamic systems, the kinetic energy of the flowing fluid is utilized, resulting in low pressure but high flow rates. Fluids designed for these applications are known as power transmission oils.
As explained earlier, Pascal’s law forms the basis of hydraulics. Using the principle of the hydrostatic displacement machine, Pascal’s Law states that, “Pressure applied anywhere to a body of fluid causes a force to be transmitted equally in all directions. The force acts at right angles to any surface within or in contact with the fluid”.
Hydraulic systems utilize hydraulic oils to transmit power or energy to other applications, making them the second most crucial group of oils, after engine oils, due to their widespread use. As a result of their primary application, they can help save energy, reduce maintenance intervals and wear, increase machine life, and overall provide users with significant savings.
