Parker-Hannifin Corporation
Open Center Control Valve

Abstract:

An example valve section includes: a housing having: (i) a longitudinal bore, (ii) a first and second workport passages configured to be fluidly coupled to an actuator, (iii) a first and second return passages, (iv) an open-center passage configured to be fluidly coupled to a source of fluid, and (v) a supply passage disposed between the first and second workport passages. The valve section also includes a spool movable in the longitudinal bore to shift between: (i) a neutral position that allows the open-center passage to permit fluid flow therethrough, and (ii) a shifted position that allows fluid to be diverted from the open-center passage to the supply passage, and connects the supply passage to either the first or second workport passage while connecting the other workport passage to a corresponding return passage of the first and second return passages.