الفهرس 
Chapter 1 : IntroductionOnly 14 pages are availabe for public view
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Abstract
Hydraulic systems are characterized by their ability to import large forces at high speeds and are used in many industrial motion systems, also, in applications where good dynamic performance is important. Hydraulic systems are also common in aircraft, where their high power-to-weight ratio and precise control makes them an ideal choice for actuation of flight surfaces.
Electro hydraulic flow control valves, either proportional or servo (EHSV), are used in industry in a wide number of applications like machine tools, testing equipment, mining machinery, fatigue testing, flight simulation, paper machines, ships and electromagnetic marine engineering, injection molding machines, robotics, steel and aluminum mill equipment and autonomous manufacturing systems. These systems have favorable size to power ratio, precise and accurate control, and ability to apply very large forces. Servo hydraulic systems offer several other benefits over their electrical counter parts. For example, hydraulic systems are mechanically “stiffer”, resulting in higher machine frame resonant frequencies for a given power level, higher loop gain and improved dynamic performance.
These investigations focus on the static and dynamic performance of a linear hydraulic system (displacement control system) under different operating conditions in case of connecting a proportional control valve. High technology is used for measuring and recording the experimental results, which achieves accurate evaluations. Experiments have been conducted under no-load. Then, system has been loaded by 5560 N and the experiments are repeated. Supply pressure has been changed from 10 up to 50 bar. Experiments have been conducted without connecting springs to the system, then repeated in case of connecting springs with stiffness 32 N/mm. for double rod cylinder and for single rod cylinder
It is concluded that Supply pressure decay in double rod cylinder was the same in forward and backward stroke. However, in the single cylinder the pressure decay in backward stroke was larger than in the forward one, and In the forward stroke, the supply pressure decay in the single rod cylinder was 7 % lower than in double rod cylinder. However, in the backward stroke the supply pressure decay in the single rod cylinder was 13% higher than in double rod cylinder
The dynamic performance of the system is affected by different operating conditions. Increasing of load the value of bandwidth frequency decreases. Also, the decrease percentage increases at high values of supply pressure. dynamic performance of double rod cylinder is better than the single rod one.