About Hydraulic Systems
The Greek word ‘Hydra’ refers to water while ‘Aulos’ means pipes. The hydraulics word it comes from Greek by combining these words, which in simple English means, water in pipes. Man has been aware of the importance of hydraulics since ancient times. In fact even as early as the time period between 100 and 200 BC, man had realized the energy potential in the flowing water of a river.
The principles of hydraulics were been in use in early times, in converting the energy of flowing water into useful mechanical energy by means of a water wheel. The time passed and the science of hydraulics kept on developing. Were discovered more and more efficient ways of converting hydraulic energy into useful work.
The subject of hydraulics which dealt with the physical behavior of water at rest or in motion remained a part of civil engineering for a long time. After the invention of James Watt’s ‘steam engine’, arose the need for efficient transmission of power, from the point of generation to the point of use. Step by step many types of mechanical devices such as the line shaft, gearing systems, pulleys and chains were discovered.
Therefore it was thought the concept of transmitting power through fluids under pressure. This indeed was a new field of hydraulics embracing different subjects such as power transmission and control of mechanical motion, while also dealing with the characteristics of fluids under pressure.
Distinguish Hydraulics From Water Hydraulics
To distinguish this branch of hydraulics from water hydraulics, a new name called ‘Industrial hydraulics’. More commonly, ‘oil hydraulics’ was invented. The significance behind choosing this name lies in the fact that this field of hydraulics employs oil as a medium of power transmission. Water which is considered to be practically incompressible is still used in present-day hydro technology. The term water hydraulics has since been coined for this area of engineering. But by virtue of their superior qualities such as resistance to corrosion as well as their sliding and lubricating capacity, oils which are generally mineral-based are the preferred medium for transmission of hydraulic power.
The study of ‘Oil Hydraulics’ actually started in the late seventeenth century when Pascal discovered a law that formed the fundamental basis for the whole science of hydraulics. The concept of undiminished transmission of pressure in a confined body of fluid was made known through this principle. Later Joseph Bramah, developed an apparatus based on Pascal’s law, known as Bramah’spress, while Bernoulli developed his law of conservation of energy for a fluid flowing in a pipeline. This along with Pascal’s law operates all fluid power applications and is used for the analysis, although they could actually be applied to industry only after the industrial revolution of 1850 in Britain.
Later developments resulted in the use of a network of high-pressure water pipes, between generating stations having steam-driven pumps and mills requiring power. In doing this, some auxiliary devices such as control valves, accumulators and seals were also invented. However, this project had to be shelved because of primarily two reasons: the non-availability of different hydraulic parts and the rapid development of electricity, which was found to be more convenient and suitable for use.
Hydraulic Systems Replacing Electrical Systems
The early twentieth century witnessed the emergence of the modern era of fluid power with the hydraulic system replacing electrical systems.
This was a significant milestone in the rebirth of hydraulics system and hydraulic parts. After World War II, the field of hydraulic power development has witnessed enormous development. In modern times, a great majority of machines working on the principle of ‘oil hydraulics’ have been employed for power transmission.
These have successfully been able to replace mechanical and electrical drives. Hydraulics has thus come to mean, ‘the science of the physical behavior of fluids’.