Hydraulic Library User Manual - NUPET

Hydraulic Library 4.2User Manual4. Select the directional valve (Figure 1.27).You will not change any parameters but an understanding of the parameters ofSV00 will help you to set those of UD00. The spool has some state variableswhich are the first two items in the list. In Parameter mode, their values are theinitial values of these state variables. The spool position is a fraction and so isa dimensionless quantity in the range -1 to 1.Figure 1.29: Parameters of the servo valveThe next 12 items determine the hydraulic flow characteristics of the valvecovering the 4 possible flow paths. When the valve is in one extreme positionwith fractional spool position +1, P is connected to A and T to B. In the otherextreme position the spool position is -1 and the connections are A to T and Bto P.When the spool position is 0, there is no flow. To define the flow characteristicsof the valve in the extreme positions a flow rate pressure drop pair is used. Thedefault values of these are 1 L/min and 1 bar. These values can normally befound in a manufacturer's catalogue. The parameter critical flow number(laminar -> turbulent) is less important and can be left at its default value. Youcan find the details for any submodel if you click on the Help button. For SV00,this produces the dialog box shown in Figure 1.30.23