Control Valves for Forklift
Forklift Control Valve - Automatic control systems were first developed over two thousand years ago. The ancient water clock of Ktesibios in Alexandria Egypt dating to the third century B.C. is believed to be the first feedback control device on record. This clock kept time by regulating the water level within a vessel and the water flow from the vessel. A popular style, this successful tool was being made in the same fashion in Baghdad when the Mongols captured the city in 1258 A.D.
Through history, a variety of automatic equipments have been used to simply entertain or to accomplish specific tasks. A common European design throughout the 17th and 18th centuries was the automata. This tool was an example of "open-loop" control, consisting dancing figures which would repeat the same task over and over.
Closed loop or also called feedback controlled machines comprise the temperature regulator common on furnaces. This was developed during the year 1620 and accredited to Drebbel. One more example is the centrifugal fly ball governor developed during 1788 by James Watt and used for regulating steam engine speed.
J.C. Maxwell, who discovered the Maxwell electromagnetic field equations, wrote a paper in the year 1868 "On Governors," which could clarify the instabilities exhibited by the fly ball governor. He utilized differential equations to describe the control system. This paper demonstrated the usefulness and importance of mathematical methods and models in relation to comprehending complicated phenomena. It also signaled the beginning of mathematical control and systems theory. Previous elements of control theory had appeared earlier by not as convincingly and as dramatically as in Maxwell's analysis.
New developments in mathematical techniques and new control theories made it possible to more accurately control more dynamic systems than the first model fly ball governor. These updated techniques comprise different developments in optimal control in the 1950s and 1960s, followed by advancement in stochastic, robust, adaptive and optimal control methods in the 1970s and the 1980s.
New applications and technology of control methodology have helped produce cleaner auto engines, more efficient and cleaner chemical processes and have helped make communication and space travel satellites possible.
At first, control engineering was carried out as a part of mechanical engineering. In addition, control theory was first studied as part of electrical engineering because electrical circuits could often be simply explained with control theory techniques. Nowadays, control engineering has emerged as a unique discipline.
The first control relationships had a current output which was represented with a voltage control input. In view of the fact that the proper technology in order to implement electrical control systems was unavailable at that time, designers left with the choice of slow responding mechanical systems and less efficient systems. The governor is a very efficient mechanical controller that is still usually used by several hydro plants. Ultimately, process control systems became accessible prior to modern power electronics. These process controls systems were usually used in industrial applications and were devised by mechanical engineers utilizing pneumatic and hydraulic control devices, lots of which are still being utilized nowadays.
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