The paper analyses and establishes the static property at zero position for underlap foursided spool control valve with radial clearance,and deduces the optimum seeking principle of presetting lap to ensure the makimum pressure gain at zero position.
分析、建立了具有径向间隙的转向液压伺服系统正开口四边控制阀零位静态特性，并在保证控制阀具有最大零位压力增益的前提下，提出正开口四边控制滑阀预开口量的优选原则。
