In the hydraulic valve, the frequency of use of the directional valve is very high, the common types of directional valves are two-position two-way directional valve, two-position three-way directional valve, two-position four-way directional valve, three-way four-way directional valve, etc., let's understand it together.
1. Two-position two-way
The two-position 2-way directional valve has three oil ports, namely working port A, oil inlet P, and oil drain port L. When the two-position two-way directional valve is driven, the oil inlet P is connected to the working oil port A. The two-position two-way directional valve can also be normally open, that is, when in the stationary position, the oil inlet P is connected to the working port A. When the 2-position 2-way directional valve is in the stationary position, the piston rod of the hydraulic cylinder extends out. If the two-position two-way directional valve is driven, the working oil is directly returned to the oil tank, and the piston rod of the hydraulic cylinder retracts under the action of the external load. The 2/2-way directional valve acts as a selector switch to make the system have two different pressure settings, and if the 2-position 2-way reversing valve is actuated, the system working pressure depends on the set pressure of the second relief valve.
2. Two-digit tee
The two-position three-way directional valve has three oil ports, namely working oil port A, oil inlet P and oil return port T. The working oil can flow from the oil inlet P to the working oil port A, or from the working oil port A to the oil return port T, in both cases, the unconnected oil port is closed. When the two-position three-way directional valve is driven, the oil inlet P is connected to the working oil port, and the oil return port T is closed. The two-position three-way directional valve can also be normally open, that is, in the stationary position, the oil inlet P is connected to the working oil port A, and the oil return port T is closed.
3. Two-digit four-way
The two-position four-way directional valve has four oil ports, namely working ports A and B, oil inlet P and oil return port T. The oil inlet P is always connected to one working oil port, while the other working oil port is connected to the oil return port. When the two-position four-way directional valve is driven, the oil inlet P is connected to the working port A, and the working port B is connected to the oil return port T. The two-position four-way directional valve can also be normally open, that is, in the stationary position, the oil inlet P is connected to the working port A, and the working port B is connected to the oil return port T.
4. Three digits and four links
From a logical point of view, a 3-position 4-way directional valve consists of a two-position, 4-way directional valve and a stationary position. The three-position four-way directional valve has a variety of medium function forms, and the three-position four-way directional valve can be either a spool valve structure or an on-off valve structure. When the three-position four-way directional valve is stationary, the oil inlet P is connected to the return port T, while the working ports A and B are closed. Since the oil at the outlet of the hydraulic pump flows to the oil tank, this working position is called hydraulic pump unloading or hydraulic pump bypass. In the case of hydraulic pump unloading, its working pressure is only the resistance loss of a 3-position 4-way directional valve.
The above content is about the specifications of the directional valve, through the reading of the above content, have you learned more about the directional valve!
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