Pressure maintaining and speed stabilizing hydraulic system of hydraulic machine

The invention provides a pressure maintaining and speed stabilizing hydraulic system of a hydraulic machine. The pressure maintaining and speed stabilizing hydraulic system comprises an oil tank, a filter, a hydraulic pump, a motor, a one-way valve, a pilot operated compound relief valve, a two-position two-way electromagnetic directional valve, a three-position four-way electromagnetic directional valve, a double-hydraulic-control one-way valve and a one-way speed regulating valve. When the hydraulic machine works in the feeding working station, the left position of the three-position four-way electromagnetic directional valve is connected; oil liquid enters a first hydraulic cylinder rodless cavity through the one-way valve, the three-position four-way electromagnetic directional valve and the left one-way valve in the double-hydraulic-control one-way valve under the effect of the hydraulic pump; oil liquid in a rod cavity enters a second hydraulic cylinder rodless cavity through a pipe and returns to the oil tank through a speed regulating valve body in the one-way speed regulating valve, and a valve opening of the speed regulating valve body is set to be capable of achieving the stability of the motion speed of the hydraulic machine during feeding. The hydraulic system of the hydraulic machine has the advantages of being remarkable in pressure maintaining effect in the feeding working condition, stable in running speed, rapid in returning and high in efficiency.