Basic function
The pilot valve controls the stroke, direction and main control valve of the spool. The basic function of the pilot valve is supplied to the main control valve valve core to the main control valve valve core through the basic function of the primary valve, the base function of the primary valve, and supplies the output pressure (secondary pressure) of the pilot valve.
In order to make this function correctly, the pilot valve has the following functions.
1 The oil port (P) is supplied from the oil from the hydraulic pump.
2 The oil port is sent to the end of the oil port to the end of the control valve spool.
3 The fuel tank oil port (T) controls the above output pressure.
4 The spool is connected to the oil port to enter the oil port or the oil tank.
5 The pilot valve controls the output pressure, including a spring acting on the spool.
2. The function of the main components
The function of the spool is the hydraulic pressure supplied by the hydraulic pump in the oil port P, and the conversion oil path is converted to determine if the oil pressure of the oil port P reaches the output oil port, or whether the oil port pressure output reaches the tank oil port T.
A spring acting on the spool to determine the output pressure.
When the spring deviation changes, if the elastic force is inadequate, it can cause the push rod to be inserted and slide in the plug.
The displacement of the push rod is changed by the switch plate and the adjustment nut, and the displacement is controlled by the handle, and the handle can be tilted in any direction in the shaft of the universal joint.
The spring acts on the valve shell and the spring seat and try to return the push rod to the zero emission position to ensure that it is reset to the intermediate position.
Modern excavator operators feel the correct control through the reactions of the spring.
3. Operation
(1) Handle in the middle
The force of the spring determines that the output pressure of the pilot valve is not applied to the spool. Therefore, the spool is pushed up to the position of the oil port. Because the output oil port is only connected to the tank oil port T, the output oil port pressure is equal to the pressure of the fuel tank.
(2) The handle is tilted
When the push rod is pushed down, the spool moves down, then the oil port P is connected to the oil port, the oil flow supplied by the pump is fluent to produce oil pressure.
This pressure is equilibrated with the spring force when the pressure of the oil port is equivalent to the spring force of the handle tilting set. If the pressure of the oil port is increased above the set pressure, the oil port P is disconnected from the oil port, and the port T is connected to the oil port. If the port of the oil.
The pressure is reduced below the set pressure, the oil port P is connected to the oil port, while the port T will be disconnected from the oil port.
In this way, the secondary pressure always maintains a stable value. Moreover, when the handle is tilted over---angle, the upper end of the spool contacts the inner bottom portion of the push rod, and the output pressure is connected to the oil port P.
