ABSTRACT
This chapter discusses major types of directional control valves. Included are those operated manually and those with direct electrical operation, cam operation, and direct solenoid operated pilot valves, and the piloted directional valves that they control. Low flow capacity directional valves actuated by proportional direct current solenoids will be discussed as well as proportional and electrohydraulic servo pilot valves and the piloted directional valves that they control. Included in the materials will be the alternating current pulse-width modulated pilots used for positioning the directional valve spool by means of a piloting system and linear bidirectional electric motors used for positioning the flow directing element.
