Abstract:Pressure flow properties of seven basicπbridge hydraulic resistance networks are studied and the pressure flow characteristic curves are obtained by simulation, while the pressure gain and flow gain ofπ bridge are deduced. Half bridge hydraulic resistance is only a special case ofπbridge network. The pressure control valve with theπbridge pilot control circuit has some pressure flow properties that the valve with half bridge pilot control circuit dosen’t have. For example, with the increasing of the overflow, the relief valve presents three kinds of performances, i.e. the control pressure increases, keeps constant and drops when the hydraulic resistance parameters inπbridge pilot circuit changes.

Key words: hydraulic resistance　network theory　application