Question

write a brief history about development of hydraulic and pneumatic systems

Answer 1

Ans.1)History of Hydraulic Systems:-

Water has played a huge part in the advancement of mankind and has been a powerful source for us to harness for thousands of years, right up to present day. Harnessing the power of water has enabled us to carve out a living using water wheels: to produce our food, tools, wood, clothes, paper, iron, marble, cotton and wool. Today, “fluid power” or hydraulic power relies on pressurized fluid in order to produce power. It’s all around us, in everyday objects, but if we look back in time, it was a while before it was used the way it is today.

In Imperial Rome, water was used to power mills to produce flour, saw stone and timber. In Britain, water was used to extract lead from tin ore in a process known as “hushing”. Many years later this was developed into hydraulic mining which was used during the California Gold Rush.

In 1648, a young French mathematician and physicist, Blaise Pascal, made a discovery that was to become known as Pascal’s Law. Through his works he realised that “pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure variations (initial differences) remain the same”. This laid the groundwork for further insights into how fluids could be harnessed for energy and in 1738, Daniel Bernoulli first formulated what was to become known as Bernoulli’s Principle which describes the behaviour of a fluid under different conditions of flow and height. This was later used in the network of high pressured water pipes between various generating stations which used steam driven pumps and mills that required power, allowing power to be transmitted over larger distances. Unfortunately this particular project did not continue for long as the development of electricity was found to be a far more convenient and, at the time, a much more suitable way of powering devices.

It was towards the end of the eighteenth century (1795) when Joseph Bramah, patented the hydraulic press. It was based on Pascal’s Law which formed the groundwork for the science of hydraulics. Not long after, the Americans developed the technique of producing electricity using hydropower and hydraulic power plants began to be built. Once the industrial revolution had firmly established itself, engineers and industrialists across the world realised they could utilise Bernouilli’s principles but on a much bigger scale. In the late 19th century, the first hydropower scheme was pioneered by William George Armstrong whom many see as the grandfather of Hydraulic Power (along with Joseph Bramah). A keen fisherman, after spending the day fishing and looking at the watermill, Armstrong decided that it wasn’t the most efficient way of harnessing energy. Upon returning home, he set about designing a rotary engine that was to be powered by water. When nobody showed any interest in it, he set about a redesign, and ended up with a piston engine. This led to the development of hydraulic power-pipe networks (with hydraulic power pipes being used to carry pressurised liquid to transmit mechanical power from a main power source) which were used to power cranes throughout Britain’s cities and also in Geneva, Switzerland. As time has gone on we have seen the development of different hydraulic parts including seals, control values and accumulators, all of which have lead to further uses of hydraulic power.

Today there are many different forms of hydraulic power and water power that are currently being used or developed. The majority of them generate electricity but there are a few that are mechanical. We see examples of hydraulic power in use all around us today and probably the best place to see it at work would be on a building site: diggers, cranes, bulldozers and all kinds of heavy equipment vehicles rely on power from hydraulic drives to ensure they have the power to get the job done! A hydraulic drive is a device that uses pressurised fluid in order to drive the machinery and it is made up of many components, of which an important one is the hydraulic pump which can have a power density of up to 10 times that of an electric motor. It’s not surprising that we are still harnessing the power of these incredible pieces of engineering more than 200 years after they were first conceived.

Hydraulic power is currently being developed further year after year. It will be extremely interesting to see what the developments will be in the future.

2)History of Pneumatic Systems:-

Pneumatics have been used for thousands of years, ever since hunters used the blow-gun to take down their prey. Using their lungs, with a capacity around 6000 cubic inches per minute, they could produce a pressure of 1 to 3 psi. The first compressors were seen around 3000 B.C. to provide small puffs of air to aid in starting a fire. These simple devices evolved into larger, more sophisticated units used in metal smelting about 1500 B.C. Around the 18th century, mechanical compressors were capable of developing almost 15 psi. and were able to do more useful work.

It was not until the late 18th century that pneumatics began to take off as they were considered a serious industrial energy transfer medium. Many experiments were ran to test the power and expandability of pneumatic systems. A notable experiment, and unsuccessful one, was the attempt to power a mill with compressed air located at a waterfall 3,000 ft. from the plant site. It was here that the experiment began to fail. Clay pipe, useful for transporting water, was used to connect the compressor to the plant. To the dismay of workers, the pressure needed wasn’t enough because the clay pipe wasn’t air tight and thus a leakage occurred along the way.

Then came along the early 19th century. It was here that compressors were able to reach a higher capacity of 90 psi. and thus more work could be done. Pneumatics were used to power a tunneling project in Mt. Cenis, located in the Alps. If traditional drilling methods were used (manual) the project would have taken upwards of 30 years. Using pneumatic drills, operating on many miles of line, the tunnel was completed in just 14 years and it was open to traffic in 1871. This project caught the attention of many government agencies and they began to talk of compressor stations for city-wide power consumption.

Paris was actually the first city to try this in 1888 when a 65 horsepower (HP) rated compressor fed 4 miles of main wire with 30 miles of branch circuits delivering 90 psi. By 1891 the capacity of the motor was increased to 25,000 HP. Making this compressed air available everywhere was soon followed by pneumatic devices everywhere as well. During this time many engineers began to debate on whether compressed air or electricity would be the main source of power throughout a city and could be expanded into the future world. A technological evolution began where both electricity and pneumatics found their right homes. Electricity would become the most convenient on large-scale energy transmission while pneumatics were used in more industrial applications including power, process, and control services.