In the master thesis discusses about the flow forces in hydraulic valves. Flow force is one of the force acting on the spool and has a significant influence on the operation of the valve. In the beginning of the thesis are presented forces operating in hydraulic valves with emphasis on flow forces. Also in the the beginning of the thesis are presented some studies about flow forces. For the purpose of experimental verification of flow forces two types of measuring system were developed. At the first measuring system, the flow force was measured with a force sensor, and the other with an electrodynamic actuator acting on the sound principle and which measures the flow force indirectly via the electric current. Flow forces were measured at various fluid flow conditions, different valve openings and different flow rates. After analyzing the measured values, the experimental results were compared with the results of a previously performed numerical simulation. It has been found that experimental results mostly match to numerical simulation with the exception of certain deviations, which are the result of the problems that we had during the measurements.
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