Excessive oil temperature in hydraulic system caused by valve core of the negative flow control valve on the operating valve group is not closed

If the valve core of the negative flow control valve on the operating valve group is not closed strictly, the hydraulic oil of the intermediate oil channel flows directly back to the tank, so that the negative flow control valve signal port does not produce negative flow control pressure. The main pump displacement is reduced. In this way, even if each reversing valve is in the neutral position or the cylinder moves slowly, the center rod of the main pump plunger rigid body will remain in the maximum displacement oil supply position relative to the drive shaft angle, so that the pressure loss is large and the oil temperature increases. At this point, the negative flow control valve should be removed for cleaning and repair.