(1) The problem of two-position four-way reversing valve
In some designs, it is common to have a two-way four-way reversing valve instead of a two-position two-way reversing valve. The two-position four-way reversing valve can be changed into a normally closed or normally open two-position two-way reversing valve according to the need to block the A or B port [see Figure 3(a)]. In the application, the tubular connection can directly block the mouth to achieve the intended purpose, and the corresponding connection of the plate connection when processing the connecting plate can be processed. However, it should be noted that the four-way valve 0 can not be blocked, and the fuel tank must be connected to serve as a drain port. Because if the O port is blocked, when the hydraulic system starts working, the starting reversing valve can be reversed, and the hydraulic system can work normally. After a long time, the hydraulic oil leaking into the spring chamber has nowhere to leak, so that the reversing valve cannot be reversed. The hydraulic system will not work properly.
Dalan hydraulic reversing valve symbol
(2) Problems with electro-hydraulic reversing valves
The electro-hydraulic reversing valve is divided into four types according to the control method: the internal control internal leakage type, the internal control external leakage type, the external control internal leakage type, and the external control external leakage type. In the product samples and some manuals, it is not listed in four forms. Sometimes it is selected during the selection, but it is out of stock at the time of purchase. It also needs to be modified by yourself. Therefore, the structure of the electro-hydraulic directional control valve must be clearly understood. Get the form of the reversing valve you need. For the externally controlled directional control valve, since the control oil is separately introduced from the oil circuit other than the electro-hydraulic directional control valve, there is no problem in the use, whether internal leakage or leakage; The valve, because the liquid supply port of the pilot valve and the P port of the main valve are open, the structure is simple and convenient to use, but if the valve center function is M, H, K, X, etc. the main oil circuit in the middle position It is not possible to provide the control circuit with the necessary control pressure for the main spool reversal. Therefore, measures must be taken on the valve or hydraulic system (such as using a pre-pressure valve or increasing the back pressure and back pressure) to meet the electro-hydraulic directional control valve. Requirements for use.
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