The use of Parher hydraulic valve manifold and classification:

Press the control method of classification: manual, electric, hydraulic control
Classified by function: flow valve (throttle valve, control valve, flow diversion valve), pressure valves (pressure relief valve, pressure reducing valves, sequence valves, unloading valves), directional valve (solenoid valve, manual change to the valve, check valve, check valve)
By installation of: plate valves, valves,metric adapters modular valves, cartridge valves, valve cover [1]
Use is divided into one-way valve and valve. Parher hydraulic valve manifold A check valve: in turn allows only unidirectional fluid conduit, i.e., the reverse cut. Valve: change the pass, breaking the relationship between the different lines. According hose fittings to the spool valve in the number of job positions in the sub-two, three, etc.; according to the number of channels under the control of two-, three, four, five-way, etc.; points manually based on the spool drive, motor, electric , hydraulic, and so on. Figure 2 is a three way valve works. The supply port P, O is the return port,metric bolts  A, B is an output port leading to the actuator. When the spool is in the neutral position, all ports off, the actuator does not move; when the spool is moved to the right position, P, and A pass, B and O on; when the spool is moved to the left position, Parher hydraulic valve manifold, and B Tong, A and O on. Thus, the actuator can be positive and reverse movement.
The late 1960s, on the basis of the several hydraulic control valves on and developed the electro-hydraulic proportional control valve. Its output electrical signal (pressure, flow rate) changes continuously with the input energy. Electro-hydraulic proportional control valve according to the role of different, accordingly divided into electro-hydraulic proportional pressure control valves, electro-hydraulic proportional flow control valves and electro-hydraulic proportional directional control valve.