Hydraulic Directional Valve Pdf

A directional valve is a valve that changes the direction of movement of the actuator by changing the direction of the oil flow. There are many types of directional valves, which can be generally divided into manual directional valves, motorized directional valves, electromagnetic directional valves, hydraulic directional valves, electro-hydraulic directional valves and other types according to different control methods. The principle of these types of directional valves will be briefly introduced below.

1. Manual directional valve

The operation mode of the manual directional valve is the handle, which uses the lever principle to push the spool to make movement in the valve body to achieve reversing. When the handle is pulled to the left, the pressure oil P communicates with the A port, the pressure oil enters the actuator, and the return oil of the actuator enters the B port, flowing back to the oil tank from the T port: pull the handle to the right, P passes B, A passes T, and the actuator will move in the opposite direction.

2. Motorized directional valve

The motorized directional valve, also known as the stroke directional valve, changes the internal oil circuit of the directional valve to achieve reversing when the stopper or cam movement on the actuator touches the spool of the travel directional valve.

3. Electromagnetic reversing valve

The operation mode of the electromagnetic directional valve is the attraction of the solenoid, which pushes the valve core to move in the valve body to achieve reversing by allowing the solenoid to be energized to attract the armature, and the valve core is reset by a spring after power failure. The picture shows the Rexroth 4WB electromagnetic directional valve, which is a three-position and four-way valve. When the left electromagnet is energized, push the spool to move to the right, P pass B, A pass T: the right electromagnet gets electricity, P passes AB passes T.

4. Hydraulic reversing valve

The hydraulic directional valve is to control the oil acting on the valve core, and when the control oil is under pressure, the directional valve is controlled. Hydraulic directional valves are often used in conjunction with other directional valves. The figure shows that when there is no pressure oil, the spring acts on the valve core on the far left, P through B, A through T: when there is pressure oil, the valve core is shifted to the right, so that P, T, A, B four ports are not through.

5. Electro-hydraulic directional valve

Electro-hydraulic directional valve is suitable for large flow occasions, because the solenoid can provide limited thrust, in the flow of large, the solenoid will not be able to push the core, and the electro-hydraulic directional valve is a solenoid directional valve as the pilot valve, hydraulic control directional valve as the main valve. The flow direction of the control oil is changed by the reversing of the electromagnetic reversing valve, so that the main valve is reversed under the action of the control oil.

The picture shows the Rexroth 4WEH electrohydraulic directional valve. The upper end is the electromagnetic directional valve as the pilot valve, the lower end is the hydraulic directional valve as the main valve, and the two oil outlets of the pilot valve act on both sides of the spool of the main valve. The figure shows the form of external control leakage, the control oil X of the pilot valve is introduced from the outside and does not communicate with the main oil circuit: the return oil Y of the pilot valve is returned to the oil tank separately. When the left solenoid is electrified, the pilot spool moves to the right, controls oil X into the right side of the main spool, and pushes the main spool to the left, so that the main oil circuit P passes A and B passes T; Conversely, when the right electromagnet is electrified, P passes B and A passes T.

Hydraulic conversion valves are widely used in life, and the requirements for the accuracy of production are relatively high. Elephant Fluid Power has been committed to producing high-quality products, adhering to the business philosophy of quality and customer first, so it has a very large number of repeat customers and has always had a good reputation in the industry. If you need a hydraulic changeover valve, choose Elephant Fluid Power, we will provide you with the best quality products and services.

Hydraulic directional valve diagram

Hydraulic directional valve troubleshooting

Hydraulic directional valve symbols

Hydraulic directional control valve types