Category Archives for Directional Control Valves
Directional Control Valves Classification by Operation Method and Spring Arrangement
These valves are classified according to the function, operation method, and spring arrangement. The operation method is classified into: manual, mechanical, hydraulic, solenoid-operated, electro-hydraulic, and pneumatic. The spring arrangement is classified into: spring offset for the two-position type, spring centered … Continue reading
Directional Control Valves Classification by Spool Types
The directional control valves in hydraulic systems must work such that when the spools are in a neutral position, the fluid flow patterns meet the purpose of the systems, in addition to causing reversible motion of the hydraulic cylinders and … Continue reading
Directional Control Valves Classification by Port/Position Count
The port count indicates the number of connectable lines, and the position count indicates the number of change- overs in the directional control valves. Table 4.1 lists the classifications. The valves with four ports and three positions are very popular. … Continue reading
Four-way Flapper-nozzle Control Valve
The four-way flapper-nozzle valve has two identical hydraulic circuits, one supplies flow and pressure to one side of an actuator, the other circuit supplies the hydraulic fluid to the other side of the actuator. In other words l the valve … Continue reading
Three-way Flapper-nozzle Control Valve
The flapper-nozzle valve has certain mechanical design advantages mainly the simpler construction and the feature of no close-clearance sliding parts as compared to the spool-type valves. However, flapper nozzle valves must be very .accurately designed to provide characteristics which exactly … Continue reading
Two-way Valve Constant-flow Source Characteristic
The two-way valve is merely a throttling valve having one variable-area orifice. When used in conjunction with a constant-flow source, the two-way valve can be used to position a piston actuator &s shown by Fig. 1.22. As indicated, a return … Continue reading
Three-way Valve Constant-pressure Source Characteristic
The three-way control valve uses only one control pressure line to the actuator with the normal pressure supply line and a drain or return line. This type of valve is illustrated by Fig. 1.20. As can be noticed, the valve … Continue reading
Four-way Open-center Hydraulic Valve
When a valve is designed to use a constant-flow source of fluid, the valve does not have its cont.rolling edges covering their corresponding port edges. Instead, each port edge is uncovered in the centered valve position. This type of valve … Continue reading
Hydraulic Sliding Spool Valve
The figure above shows a hydraulic sliding-spool valve. The piston inside the valve slides back and forth to block and release ports in the housing. This valve sometimes called as a piston type spool valve, the sliding-spool valve has a … Continue reading
Open Center Sliding Spool Directional Control Valve
In an open-center sliding spool directional control valve, the spool is designed to pass all flows on all its passages when the valve is centered. In some types, the fluid from hydraulic pump is passed to the reservoir through other … Continue reading