Patent attributes
A valve (1) comprises: a body (2); a bushing (3) slidably mounted on said body; a valve spool (4) slidably mounted on said bushing; said bushing and spool having respective control edges (5) that are adapted to cooperate with one another as a function of the relative position between said bushing and spool to vary the size of a control opening therebetween; a first drive (11) operatively arranged to controllably move one of said bushing and spool relative to said body; and a second drive (12) operatively arranged to controllably move the other of said bushing and spool relative to said body; whereby said first and second drives may be selectively operated to move said bushing and spool simultaneously in opposite directions to increase the dynamic response of said valve.
