When the spool valve of the main control valve is suddenly removed from the neutral position (to the working position), the reverse regulation pressure will drop (pressure drop is inversely proportional to the movement of the spool valve). As the reverse regulating pressure decreases, the flow rate of the hydraulic pump will increase sharply. Therefore, the speed of the hydraulic cylinder changes drastically, and the entire excavator vibrates strongly.
In order to prevent this kind of vibration, it is necessary to reduce the rate of change of the hydraulic pump flow rate.
When one of the actions of boom lifting, stick, swing and walking is performed, the pilot hydraulic control circuit is set
The contact of the pressure switch is closed (CLOSE). At this time, the EPOS-Gong controller will provide current (700mA, 3.2MPa) to the reverse control priority valve (electromagnetic proportional pressure reducing valve), and then gradually reduce its current value, reaching 150mA (OMPa) after about 1s.
Of the reverse pressure from the control valve (which drops sharply when the spool valve moves) and the pressure from the reverse control priority valve, the Shutle Valve selects the higher one and supplies it to the hydraulic pump regulator. This reduces the rate of change of the hydraulic pump flow.
